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kenuck Silver Member Nikonian since 03rd Nov 2008Sun 09-Sep-12 04:10 PM
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"Moon shots - Questar + V1"


Burnaby, CA
          

A first attempt with my old Questar and new Nikon V1. It's not as sharp as I'd like but a work in progress. Some issues -
- moon was fairly low on horizon after a warm day so atmospherics not great
- had difficulty with focus (on V1 only have EVF - no focus aids)
- David Busch's guide says electronic shutter may result in graininess (not sure why, but will try with mechanical shutter next time)
- will try with bean bag on scope to give it more mass to steady it while focusing

I welcome suggestions to improve...

Shot is full (no crop) 1/40sec ISO 200, EFL of 3.5in Questar with V1 is about 3200mm; Manfrotto tripod and 393 gimbal head, remote shutter release

Ken

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Attachment #1, (jpg file)

  

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DeanAZ Moderator
09th Sep 2012
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kenuck Silver Member
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DeanAZ Moderator Expert nature photographer Nikonian since 28th Apr 2007Sun 09-Sep-12 08:28 PM
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#1. "RE: Moon shots - Questar + V1"
In response to Reply # 0


Phoenix, US
          

Ken, I like less than full moon shots as it makes for more contrast in the shadow areas. I don't think focus is your problem but perhaps 1/40s is too slow and what you have is motion blur rather than an out of focus image. If you zoom into the image at 100% you may be able to diagnose the issue better than we can seeing the uncropped image here.

I'm sure there is some formula based on the focal length to account for the angular velocity of the moon (or stars and nebula) that will yield a sharp image. I know with my 70-300mm lens I shoot for an exposure of around 1/100 to 1/200s to get a sharp image.

Dean
Phoenix, Arizona USA
Nikonians Team Member
Website: The Splendid Silence of Light

Recent Trips: Grand Canyon 2012 Glen Canyon 2012 West Clear Creek

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kenuck Silver Member Nikonian since 03rd Nov 2008Sun 09-Sep-12 08:41 PM
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#2. "RE: Moon shots - Questar + V1"
In response to Reply # 1
Sun 09-Sep-12 09:13 PM by kenuck

Burnaby, CA
          

You could be right Dean. I did another shot at ISO 400 at 1/100 sec that seems slightly sharper but only on the left side (i.e. farther away) which made me wonder about focus.

I don't know how to do cross references on here but gvk had the following in topic #1119 (System 1 forum):
"The Earth's rotation contributes 360/24 = 15 degrees/hr of motion. The Moon's orbital motion reduces this a bit. This is also equivalent to 15 arcseconds per second (of time). So the Moon will shift in the frame about 1/2 degree, or its apparent width, in a bit over 2 minutes. For FOV 0.6 deg divided by 2592 pixels in the vertical frame of a V1 gives about 0.8 arcsecond/pixel on the sensor. So to keep blur from the Moon's motion under a pixel, you need to shoot faster than 1/15 shutter speed."

Assuming my combination had a vertical FOV of about 0.3 deg (maybe someone can check that) I came up with a minimum shutter speed of 1/30 sec. I'll definitely be trying higher shutter speeds to make sure, however. That low a shutter speed is dicey on any tripod - I'd have to bolt it to a rock to be sure its stable lol

Thanks for feedback

Ken

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kenuck Silver Member Nikonian since 03rd Nov 2008Sun 09-Sep-12 09:36 PM
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#3. "RE: Moon shots - Questar + V1"
In response to Reply # 1


Burnaby, CA
          

I did try zooming into 100% but could not see any evidence of lateral (velocity induced) motion blur, just a general fuzziness. Could be tripod induced. Next time I'm out I'll try a range of shutter speeds right up to ISO 3200 - see if I can see a difference.

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Mon 10-Sep-12 03:32 AM
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#4. "RE: Moon shots - Questar + V1"
In response to Reply # 0


US
          

Hi Ken,

Another Questar owner

I own a (original owner) '97 Questar 3.5" Duplex and a fork mounted mid '80s Queatar 7.

First, according to the Questar manuals the 3.5 has a minimum focal length of 1400mm when "close coupled" to a camera. That close coupling would include only the standard Questar swivel mount attached to the rear axial port, with a P mount attached to that, and then the camera.

Adding the standard 3 piece Questar extension tube set (all 3 pieces) would take you out to 1600mm. Using one or two of those tubes would take you to somewhere between 1400 and 1600.

The 1250 or 1300mm focal length is the "visual" focal length, based on the distance to the eyepiece, and it is not clear if that is an eyepiece in the control box port or the axial port . But the photographic focal length is somewhat greater than the commonly quoted "spec".

Using the formula that you are using, that would put you at a minimum 3750mm effective focal length (relative to FX), although I don't personally place a lot of value in that computation. I think it is misleading for various reasons, and this is a great example of why .

According to my calculations, the lunar rate of movement with the Nikon 1 should be about 2.106 pixels per second per 100mm focal length. The sidereal rate would be only very slightly higher at 2/15 pixels/second/100mm. That would be at zero degrees declination but even at the most extreme 25 degrees that the moon might hit, the rate would only decrease by about 12%.

That would put your rate of movement at 29.4 pixels per second at 1400mm, so about 1/30s for 1 pixel of blur. That is not your problem, although chasing the moon at that FOV from a fixed mount is not exactly easy and it likely adds to the general difficulties.

I've never gotten a better image from my Q 3.5 than I routinely get from the two 500/4's I've owned, working 700 - 1000mm. And even my 500/4 AFS and TC20E-II, which is not considered a very good TC, will give me better images than the Q.

My Q 3.5 has been star tested by very experienced Questar owners (once at Questar's 2000 "user day" event, which was followed by a Stella-Dela star party). I am very confident that my optics are fully up to the Questar standards and are essentially diffraction limited.

The visual views are outstanding and I cleanly split Gamma Virginis when it was separated by about 1.5", which is about the Rayleigh limit, given a few practical adjustments (technically that beats Rayleigh but it's a complex issue).

I've never understood exactly why my Q has not performed for me for lunar imaging (or terrestrial imaging).

The likely suspects:

I don't own a Nikon 1 or any modern mirror-less camera, and in particular nothing with an electronic shutter.

Mirror slap can be controlled with Mup, but shutter shudder cannot, without resorting to the hat trick, which is extremely difficult to do with the moon and can be counterproductive. So there your Nikon 1 might have an advantage.

And that makes me thing that the mechanical shutter might be counterproductive unless the electronic shutter is really bad.

Focusing through an optical viewfinder is extremely difficult because even close coupled the Q 3.5 is working f/16 and t/20. The t/20 accounts for the 30% central obstruction.

Liveview on my D300 did not solve my problem although it did make focusing a bit easier and more consistent.

The Nikon 1 is technically diffraction limited at f/5.9 or so, which is a long stretch from f/16. I think that puts a ceiling on the resolution you can expect (it's not really a 3200mm lens or whatever, taking diffraction into account).

This is all just to say that this is not easy to do, and I think you did a good job on your initial attempts.

I think shooting the moon low was a big part of your problem. The 3rd quarter moon is well placed this time of year but you need to get out around 3am or so to take advantage of it. And the air can be very still that time of the early morning.

It would also help to shoot on a motorized equatorial mount (like the Questar mount) but apparently you have a field model?

_________________________________
Neil


my Nikonians gallery.

  

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kenuck Silver Member Nikonian since 03rd Nov 2008Mon 10-Sep-12 04:14 AM
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#5. "RE: Moon shots - Questar + V1"
In response to Reply # 4
Mon 10-Sep-12 12:58 PM by kenuck

Burnaby, CA
          

Neil, I greatly appreciate your extensive analysis. I've used various Nikon cameras for about 45 years but I've never delved into the technicalities to the extent that you obviously have, so I have a few questions...
- why is the Nikon 1 diffraction limited at f/5.9? ...does this have to do with the small sensor (relative to DX or FX cameras?) UPDATE: spent some time on the Cambridgeincolour.com website so now understand this issue a bit better...so much to learn, so little time lol
- what is t/20?
- how can I tell if my Questar is up to standard optically (it's about 25 years old)

I know I had great difficulty focusing as everything was quivering so much - perhaps some added mass will help in that department.

And yes, I have a field model.

Again, I greatly appreciate your comments

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Mon 10-Sep-12 01:19 PM
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#6. "RE: Moon shots - Questar + V1"
In response to Reply # 5


US
          

Hi Ken,

>> - why is the Nikon 1 diffraction limited at f/5.9? ...does this have to do with the small sensor (relative to DX or FX cameras?)

The diffraction limits of the sensor are solely a function of pixel size, not sensor size, although the two obviously go hand in hand. For example, your sensor has exactly the same pixel dimensions as my D200 (10mpx) except the sensor is proportionately smaller, resulting in proportionately smaller pixels.

Diffraction is not a "solid wall" but more like an increasingly diminishing return on increased focal length for a given lens aperture (and here I mean true aperture, which is the diameter of the lens).

The effect of the math is that as focal ratio increases the size of the airy disk increases relative to the size of the pixel (sensor well).

Your D300 produces an airy disk the size of its sensor wells at f/8.2. Your Nikon 1 does the same at f/5.1, or about 1.5 stops wider.

Therefore, at f/16 your Nikon 1 should deliver approximately the same diffraction softness as the D300 at somewhere around f/25 or so.

Diffraction softness would not be obvious in any 800 pixel image such as your web posting here, but it would be very obvious if you tried to do deep crops.

>> - what is t/20?

Focal ratio is the focal length divided by the physical aperture (actually entrance pupil, which is the same with most or all telephoto lenses and astronomical lenses).

Focal ratio determines the maximum possible brightness (assuming 100% light transmission ratio or zero light loss). It also determines things such as the diffraction limits as a function of f/ratio.

Interestingly, resolution, as measured by the smallest *apparent* resolvable detail, is a function of lens aperture alone, not focal ratio or anything else.

And more interestingly, mirror lenses such as the Q have slightly better resolution in one way but less resolution than an equivalent diameter refractor lens in most other ways. Obstructed lenses produce smaller airy disks but divert that light into brighter diffraction rings. That benefits observations of double stars but slightly degrades images of extended objects, which are just about everything else, including the moon.

The transmission ratio (T-Ratio) is a number equal to the equivalent focal ratio of the lens required to achieve the same brightness, assuming 100% light transmission ratio, and is therefore the number you would use to compute exposure, for example.

As an example, the Questar 3.5 has an 89mm diameter lens, and lets say that the f/ratio is f/16 (per the Questar owners manual for photographic close coupled setups).

Lets say you have a standard "refractor" photo lens of identical diameter and focal length. All current Nikon lenses are "refractor lenses" because they have no obstruction (if you look through the lens you see no obstruction- you have a 100% circular aperture).

Ignoring the various light losses caused by light loss through the lenses (refractor) or the light transmission efficiency of your mirror and corrector (the lens on the front of the tube), your Questar would provide the same exposure as that hypothetical photo lens at f/20.

In practice, the light transmission of a typical photo lens is probably 95% or better so light losses can be approximated as negligible or nonexistent (that spec is never published but that is a guess based on opinions I've read over the years that have some credibility).

As a result, the t/ratio of a refractive photo lens is considered to be equal to the f/ratio.

Your Questar has a 30% central obstruction (measured as the diameter of the central obstruction divided by the aperture).

Questars were built with two different coatings- Magnesium Flouride (MgF) or "Broadband" (silvered?) coatings. If your serial# includes "BB" then you have Broadband coatings, otherwise you have MgF coatings

Questar Broadband coatings transmit about 10-15% more light, depending on who you ask. I've compared coatings and seen a difference, but that was when my coatings were only a few years old, and as I recall, the several scopes I tested it against were quite a bit older. This was at the circa-2000 "Q-Fest" and we had at least a dozen Q's all lined up in a row . I can't believe I've owned that thing for 15 years now .

If you do have BB coatings then your t/ratio may, at this point, be comparable to MgF coatings because they are not thought to hold up quite as well, and that depends on the climate it is stored in. In the Pacific NW you may not have the best of the climate part.

Minor coating degradation is not obvious when looking down the lens at the mirror. Your mirror could look perfect yet you might still lose 10-20% light transmission. If you see dark spots or areas around the rim of the mirror then you have a coating problem (regardless of coating formula). My understanding is that generally the coatings flake off from the outside in (the outer perimeter of the mirror).

The only way to test (without an optical bench) is to set your Q up side by side with a "new" Q and compare the views, taking into account the basic efficiency of the coatings involved so ideally you would want to compare with a sample using the same coatings.


>> - how can I tell if my Questar is up to standard optically (it's about 25 years old)

The basic test of any astro scope is the "star test", where you visually view a star of about 3rd magnitude or so at about 100X or so (for a Q3.5), observing the pattern as the star is taken inside and outside true focus.

You might be interested in Richard Suiter's Star Testing Astronomical Telescopes.... This is the standard bible for astro lens testing.

As an aside, this procedure could be used with any long photo lens *IF* a suitable eyepiece could be affixed to the lens, such that the required visual magnifications are attained. Years ago Nikon made such an adapter but I think it came with a fixed eyepiece of around 20mm focal length, which is not short enough to do the test. I would love to test my 500/4, or just be able to use it as a visual wide field refractor.

You would need about a 12mm eyepiece and ideally you do not want to use the built in Questar barlow to achieve it because then you are also testing the barlow, which is not in the photographic optical path (I assume you are shooting through the axial port).

I think it would be difficult to do a star test without a motor driven mount to stabilize the image. It's tough enough to do a star test without having to chase a star at 100x or more across the sky

Suiter uses computer generated patterns to simulate the out of focus airy disk patterns with various optical aberrations. In the real world those patterns are further disturbed (badly) by seeing. Suiter does simulate seeing effects but in practice it is almost a black art.

The best thing to do is to locate your closest astromonical club and enlist the aid of an experienced club observer. And a lot of amateurs would have the mechanical plumbing needed to mount your Q to their motor driven mounts (it's just a 1/4-20 or possibly a 3/8-UNC bolt- the Q provides both threads).

Another test you might be able to do is to try to split Epsilon Lyra (E Lyra), which is almost directly overhead now after the evening dusk. At around 10pm to midnight it will be a little lower, which might be easier with your gimbal.

E Lyra is the famous "double double", which is a pair of binaries, both visible in the same field, with each pair separated by about 2.2" (arc-seconds). And it is very easy to find as those things go.

Your Q should split a 1.5" pair so the E Lyra pairs should be very easily split in good seeing. You may need the standard 16mm eyepiece and the barlow to do it although in principle sharp eyes should split it without the barlow. It may be quite a challenge to do this with that gimbal and without a motor driven mount but it is worth a try.

You could also send your Q in for servicing but you would have to ship it and insure it to New Hope, Pa in the USA, which might be expensive, plus the cost of the service, which would be up to $500. That is the price for an astro model, which includes servicing the mount. The field model service should be a bit cheaper.

After 25 years, that is not a bad idea, especially if you have any issues with the control box mechanisms (focus or barlow). Questar will re-coat MgF optics (for a considerable extra fee) but not the BB optics (per anecdotal owner comments). Some owners have had Cumberland (the optics maker since forever) recoat BB mirrors but then you have to disassemble and reassemble the optical tube, which is not a "Harry Homeowner" job.

Mechanically your Q would come back to you in the same condition it left the factory 25 years ago, both mechanically and cosmetically. Questar takes a special pride in keeping the old scopes going- a rarity in today's disposable world. They strip the scope down to a bucket of parts, then clean and replace worn parts as necessary. I've seen the literal "bucket of parts" in the Questar shop during a factory tour.

If you have any questions about the condition of the scope, give Questar a call. You will most likely talk to Jim Reichert, who has run the operations "forever" and also handles most of the customer service calls. Before him I think his father ran the operations. It's a very unique company indeed . There is no first level support at Questar. It's all 4th level.

This was a long post. In another post I'm going to give you some thoughts on your Nikon 1 behind that scope because it is a subject of great interest to me.

_________________________________
Neil


my Nikonians gallery.

  

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Mon 10-Sep-12 03:04 PM
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#7. "RE: Moon shots - Questar + V1"
In response to Reply # 5


US
          

I took a second look at your image. My experience is that lunar images require a LOT of sharpening, more than normal images. And I think that is consistent with the experience of others here when shooting at very long focal lengths.

I downloaded your image and added a touch of sharpening- not much. I used about 19-5-0 in Capture NX2. I don't know what you did before posting it, or generally how the Nikon 1 reacts to sharpening but I thought that image improved greatly and it changed my thinking on the image. You may want to try that.

I have always believed that a P&S camera is inherently better suited for high res lunar imaging than a DSLR, for the same reason you mention, mainly related to the mirror and the mass of the rather large shutter.

Circa 2000-2004 I did a fair amount of lunar imaging with my Questar and my Coolpix 990 and a 995. What I wanted back then was a better sensor, which you have now in the Nikon 1.

In the modern age, historically most high resolution lunar and planetary imaging has been done with cheap consumer web cams or more expensive purpose built cameras using the identical sensor. I know that sounds strange but bear with me

I've used a Phillips To-U-Cam, which circa 2000 was about an $80 web cam, probably a bit better than some and maybe about as good as they got. It was, in its day, the "gold standard" of consumer web cams for astro purposes. Everyone owned one.

My To-U-Cam outputs a VGA size image and the sensor, although far smaller than my D300, has virtually the same pixel (well) size, so the sensor issues are not terribly dissimilar. It's just a smaller sensor chip with fewer pixels but spaced with a similar density.

Companies such as Imaging Source make purpose built astro cameras in the $600 range that, at the core, use the same basic sensor chips as cheap web cams. And if "price is no object' that is, historially, what you bought. Others got into the business, such as Celestron.

The differences were that the purpose built astro "webcams" had an option to eliminate the bayer filter, adding a stop of more of sensitivity (and resulting in monochrome images as the grand compromise). They also have more robust and faster USB/Firewire interfaces. Data throughput is or was actually a big issue in this pursuit, and in the day firewire was considered necessary, verses USB2. Now we have USB3 so that problem should go away.

The idea here is that you shoot a couple of thousand frames of your subject, creating an avi file. Then you split up the file into JPG stills. And then you use something like Registax (freeware) to stack the images and also to automatically cull out soft images shot during moments of poor seeing.

You've now effectively cut through the seeing, and it is more effective than anything you can do with a single still frame on any camera.

Those little webcam sensors are quite noisy and any single image didn't look too good in that regard, but noise is a statistical game. Stacking hundreds of images has the same effect as radically downsizing a standard DSLR image- the noise just disappears because the stacking averages out the noise, the same as sampling multiple pixels in a single still image downsize.

Diffraction is a very controversial subject where you see a lot of opinions. Some consider it a "pixel peeping" issue but in astrophotography, similar to wildlife photography, you never get as much focal length as you want and the end result is that you become a full time pixel peeper .

(High end high resolution lunar and planetary imaging is almost always reproduced at 100% pixels. Getting even 100 pixels across Jupiter or Saturn is quite a challenge!)

It is commonly discussed that you want a focal ratio such that the pixel size is larger than or at worst more or less similar to the size of the resulting airy disk. That's an oversimplification but I don't want to get into the minutia of that very complex subject right now.

Astrophotographers view this differently because it is standard practice to use heavy deconvolution routines when sharpening raw stacked high res astro photos.

And in fact, I think the conventional thinking now is that with pixel densities about the same as a D300 the optimum focal ratio is about f/32 or maybe even smaller depending on who you ask. That is at least two stops beyond what is generally discussed in the context of terrestrial imaging.

The idea here is that f/32 will deliver the highest magnification achievable before any further increases in magnification are simply "empty magnification" that does not yield additional true detail.

Personally I do not like heavy deconvolution in terms of "art". I think it always results in what I call a "jittery" look that I find difficult to look at. But it does bring out a lot of detail that can be retrieved from images that are, in priciple, shot well beyond the conventional diffraction limits.

And this is where I think there is a huge difference between how astronomical photography is pursued, verses terrestrial photography. I'm necessarily somewhat oversimplifying some very complex technology.

The point I'm making is that the small pixel sizes of the Nikon 1 are not necessarily bad for the purposes here. It does require a very different workflow. Registax provides some very comprehensive deconvolution adjustments, more than I've seen in traditional image editors such as PhotoShop.

If you think about the Nikon 1 in this context, you end up with a high class webcam imager that is capable of shooting at 30 or 60 fps without a moving mechanical shutter. And in this way that camera may actually be the ideal "astro webcam imager", at least relative to something like the Imaging Source cameras that do include RGB (Bayer) filters.

Imaging the moon at 30 or 60 fps, at f/20 or beyond, is not a trivial task. I don't know much about that camera. Can you slow down the frame rate? Something like 5-10fps might be better because of the shutter speeds that would be required. It's not the frame rate, per se, that is the problem, it is the need for shutter speeds along the lines of 1/10s or so. So you have to figure out what that camera does at those shutter speeds.

(and obviously we are running into the problems of doing this on a fixed mount, but it gets worse )

I have tried to stack lunar images shot on a fixed tripod with Registax but have never succeeded...

Registax has the ability to "shift" images because even the best astro mounts have a certain guiding error commonly called "periodic error" where the image wanders back and forth in right ascension (along the lines of identical declination). Basically the motor does not run at a precise constant speed but wanders on a cyclical basis due to slight tolerance issues in the worm gear drive.

And less than perfect polar alignments (and they are never perfect outside of a permanent observatory) result in a constant slight drift in declination, either northward or southward, depending on the misalignment.

Registax deals with all that, and supposedly quite well (I've had no problems with high res images shot from my Q7 fork mount at about 4500mm true focal length).

What Registax does NOT do well is deal with "rotation", where your series of images is not shot at a standard alignment relative to the lines of right ascension and declination. And I've found that it is impossible to maintain that constant orientation when chasing the moon from a fixed tripod mount.

(It might be possible to shoot with the tripod tilted to an extreme such that it points at the North Star, rather than the zenith but I've never tried that and I think the center of gravity issues would be quite problematic. Aside from that, such an alignment would turn a fixed mount tripod into a non-motorized equatorial mount, rotating along a fixed line of declination via the horizontal pan base, something we could talk further about).

What I'm trying to explain here, in a rather round-about way, is that in order to seriously image with the Questar, or any other lens working beyond 1000mm, you need to stack to cut through the seeing. And that almost certainly requires a motorized equatorial mount.

The Questar is a rather light and compact lens, as those things go. It doesn't require much of an equatorial mount and for lunar imaging you don't care a lot about things like periodic error because the exposures are short. If you were doing 30s or longer exposures then you do care because each exposure encompasses the typical cycle of periodic error, resulting in elongated star images. But your lunar exposures are more along the lines of some fraction of a second. Same is true for imaging Jupitor and Saturn, for example, which you can do with a 3.5 Questar.

If I were looking to get into this in a serious way, for reasonable money, I would be looking for something like a very basic smallish Vixen motorized mount that might have cost $500-$1000 new and probably trades on the used market for as little as $200-300 or a little more (all USD).

You don't need or really want the fancy things like computerized guidance. If you can't find the moon you need to pursue a different subject . And while computerized mounts can do very precise polar alignments (the alt-az versions), for lunar/planetary work you can do a fairly straightforward and quick alignment that is within a degree or so and that probably is close enough. Registax will take up the slack.

This gets into some complex issues but those are my general thoughts. Already having a Questar, for a couple of hundred bucks you could do some serious work. And again, I think your posted image might be better than it looks (as posted) but with a motorized mount you could do higher res eyepiece projection or use some barlows to accomplish the same.

P.S. regardless, I suspect you certainly could use a more robust tripod. Are you using a standard Manfrotto 055? A lot of Questar owners use a fairly inexpensive Manfrotto 3046 and seem to be happy with it. It's a very heavy tripod, relative to photo tripods, but is great for backyard astro work.

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kenuck Silver Member Nikonian since 03rd Nov 2008Mon 10-Sep-12 04:49 PM
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#8. "RE: Moon shots - Questar + V1"
In response to Reply # 7
Mon 10-Sep-12 09:27 PM by kenuck

Burnaby, CA
          

wow... I see why you're the moderator of this forum

Other than a bit of brightening of .jpg I did very little PP. I normally use Noisware for terrestrial but usually don't tweak any of the settings.

I'm using an older Manfrotto - not sure which model but based on specs looks like a 294, so moderately heavy but without the leg braces of the 3046

The V1 will shoot up to 60fps BUT need to use the shutter release on the camera which could be a problem...the remote requires one press per picture and there's a mandatory preview after each shot so about 1/second is the best I can do with the remote. I'll try locking it down and firing off a blast of ~10fps then stacking them.

When you talk about shoot many frames to create an .avi file - what sort of resolution are they? Another option for the V1 would be to simply shoot a HD movie to create the .avi file, but it's only 1080x1920 resolution.

Sorry I'm a little confused about your remark to shoot at about 1/10sec exposure - won't I get motion blur at that slow? - or are you assuming an equatorial tracking system?

I'll check out your suggestion for equatorial mounts...thanks

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Tue 11-Sep-12 08:58 PM
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#9. "RE: Moon shots - Questar + V1"
In response to Reply # 8


US
          

>> Sorry I'm a little confused about your remark to shoot at about 1/10sec exposure - won't I get motion blur at that slow? - or are you assuming an equatorial tracking system?

Yes, all roads lead to an equatorial mount . Tough to take it much further without one. And be aware that your stacking sequences will surely need to be done without interrupting things to realign a fixed mount.

>> When you talk about shoot many frames to create an .avi file - what sort of resolution are they?

The standard "webcam" ccd cameras that everyone uses for lunar and planetary images are anywhere from VGA size to about 1200x1600. The larger sensors come with some bandwidth compromises.

For planetary work you don't care about sensor size because your subject will be a couple hundred pixels wide, at best (and maybe in your dreams ). It is only lunar work where large sensors provide benefit.

The issue is not the HD resolution but downsizing the full image into HD, if that's what is done. It would be better to have an HD crop in the middle of the sensor, where pixels are mapped one-to-one. I think this was available on some DLSRs? Maybe not the Nikon 1.

For lunar work that downsizing to HD might not be so bad, but for planetary work you need the highest sensor density possible and that is what got me intrigued with the idea of the V1 here.

>> I'm using an older Manfrotto - not sure which model but based on specs looks like a 294, so moderately heavy but without the leg braces of the 3046

The 3046 is twice the weight or more than the 294. It is a very different tripod. Very different. More than the braces, the upper section dual-strut design adds tremendous value to that tripod and is why a lot of Questar owners use it.

The 294 is probably bested by the 055, just based on price point (never handled the 294).

If you are having vibration issues, that is the first thing to replace. If the 294 is not giving you problems then it's fine, but I would be surprised if it isn't, just knowing the Questar and the issues shooting at 1400mm and up. I don't think an 055 could do the job (am quite sure of it).

The 294 or an 055 is fine for visual work and the lighter weight is often a necessary compromise if the scope is used for birding, for example, walking the trails. But I think this (photography and especially astrophotography) is different.

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kenuck Silver Member Nikonian since 03rd Nov 2008Tue 11-Sep-12 11:05 PM
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#11. "RE: Moon shots - Questar + V1"
In response to Reply # 9
Tue 11-Sep-12 11:08 PM by kenuck

Burnaby, CA
          

Thanks Neil for your insights. Right now I think "seeing" is more of a problem than stability, but I'll keep it in mind.

I don't know how the pixels are mapped for video in the V1, however the chip is 3872 pixels wide - almost exactly twice HD resolution of 1920 pixels. HD is 16to9 so they use less than half of the vertical resolution. I did try a short (5sec) 1920x1080P 30fps video clip of the moon this morning but haven't had a chance to do anything with it.

Interestingly Venus was just coming up as I was shutting down this morning so I took a few shots with pretty much the same exposure as I was using for the moon...ISO 800 1/200 to 1/400s. They look a bit blown out - what exposure would you normally use?

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 11:46 AM
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#12. "RE: Moon shots - Questar + V1"
In response to Reply # 11


US
          

Last time I shot Venus was 1/5/2011, with Venus at mag -4.2 vs -4.5 now (about 0.3 magnitudes brighter or about a half a stop).

Exposure was ISO 400 f/8 1/250s. The planet was exposed about 230-235 on the 8 bit scale, which I thought was about right.

I would just chimp into an exposure, such that Venus is well exposed, into the 4th quadrant of the histogram, and not blown. I know that is not easy because it is so tiny, but that is the idea.

The only detail you might see on Venus's surface is the "Ashen Light" (google that), which is something that has been argued over for centuries.

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kenuck Silver Member Nikonian since 03rd Nov 2008Tue 11-Sep-12 10:10 PM
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#10. "RE: Moon shots - Questar + V1"
In response to Reply # 7


Burnaby, CA
          

I attempted to improve the "seeing" conditions - took about 50 shots between 3AM and 4:30AM this morning. Other differences are in ISO, shutter speed and PP. The shot below was about 24 degrees above the horizon on a cool (9C) night, however the magnified image in the LCD was still showing quite a bit of heat-related motion. I need to find a mountain I guess.

I also tried a couple "stacks" of pictures (7 and 28 images) using AutoPanoPro, however they don't appear to be significantly sharper. I also tried RegStax 6 but was unable to get it work with images taken without tracking

V1 + Questar ISO 800 1/100sec, uncropped, PP in Noiseware (auto) and sharpened in ACDSee (extreme setting) Gimbal locked, remote trigger


This is the setup. To increase stability I dropped the tripod down to 2 extensions, added a dolly (feet dropped to lift it off its wheels) and added a couple velcro ankle weights around the Questar

Ken

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Attachment #1, (jpg file)
Attachment #2, (jpg file)

  

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 12:12 PM
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#13. "RE: Moon shots - Questar + V1"
In response to Reply # 10


US
          

My rule of thumb is that I like to get the moon at least 45 degrees above the horizon, and that's for the 700-1000mm range, not 1400mm, where higher altitude may help a lot.

Your next good window is around Oct 4-8, at the next 3rd quarter. The First quarter will be very poor this time of year, with the moon never getting much above 30 degrees altitude. I would try to image it starting a few days after the full moon on Sept 29, and to the 3rd quarter on Oct 8.

The 3rd quarter moon always transits the meridian (due South and highest in the sky) at sunrise. You need to shoot sometime before... oh... 30 minutes or so from sunrise to get the contrast you need. So a couple of days before 3rd quarter (Oct 5-7 or so) is probably your optimal days, weather permitting, giving you high altitudes in darkness and a decent phase away from the full moon.

Have you tried flipping the gimbal bracket so the Q hangs under the bracket, which is on top of the center of gravity? I have been told that the 294 may balance well in that position if you adjust the bracket properly. I've never owned one so never tried it myself.

You may need to do that flip in order to image around 70 degrees altitude where the moon is highest in the sky. Or maybe not depending on things.

I'm curious about the plumbing between the Q and your camera. Is it Questar plumbing or something else? A close up image would be interesting.

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kenuck Silver Member Nikonian since 03rd Nov 2008Wed 12-Sep-12 04:52 PM
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#16. "RE: Moon shots - Questar + V1"
In response to Reply # 13


Burnaby, CA
          

Thanks, I'll keep those dates in mind.

I may have to flip the gimbal for high angle shots, however I think it's inherently unstable that way (think ball on top of hill vs ball in a valley) - at least it seemed like that when I tried it. The V1 is short enough that I may be able to get the high angles the way I've shown it.

I'm using the basic Q Nikkor F-mount adapter + FT1 to adapt to the smaller V1 mount. From back of the Q's control box to the sensor plane is about 82mm. I could use extension tubes and/or eyepiece projection but for now I'll keep it simple.

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 05:38 PM
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#18. "RE: Moon shots - Questar + V1"
In response to Reply # 16
Wed 12-Sep-12 05:39 PM by nrothschild

US
          

If that's just the FT-1 then I guess you are working the standard 1400mm close coupled setup. The FT-1 is bigger than I thought.

I would assume that the width of the FT-1 just sets up the standard distance from the lens mount to a DSLR sensor or film. So the 82mm distance is "somewhat misleading", if that makes sense, in terms of measuring extension tube length. I assume it "disappears" when using standard lenses and does not act like an extension tube.

Are there any optics in the FT-1 or is it just metal plumbing?

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kenuck Silver Member Nikonian since 03rd Nov 2008Wed 12-Sep-12 09:46 PM
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#21. "RE: Moon shots - Questar + V1"
In response to Reply # 18


Burnaby, CA
          

The FT-1 has no optics - it's just a mount adapter and electrical connector for the lens contacts for exposure, focus and VR (if any).

Interestingly it doesn't mind if the attached lens has no contacts, like the Q - focus is then manual, though it still provides center point exposure metering (A/M). This also applies to older Nikkor lenses, though it has a focusing aid for older AF lenses. With modern G lenses it provides center point exposure and autofocus as well as VR if the lens is so equipped. However, 3rd party lenses are hit and miss - with my Sigma 150-500 it said you need to have a lens to take a picture (someone at Nikon has a sense of humour)

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Thu 13-Sep-12 02:52 PM
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#22. "RE: Moon shots - Questar + V1"
In response to Reply # 21


US
          

You may want to give Sigma a call. My experience with one of their products (EM-140 ringflash), and something I've seen discussed from time to time regarding various lenses, is that they have trouble with firmware compatibility as Nikon issues new gear but in many or most or all cases they update their firmware and are very good at getting old gear updated, usually for free. This could be that situation.

That is interesting that the V1 meters non-CPU lenses. I hadn't even thought about that potential problem.

While I'm here I wanted to make a clarification on a previous comment about web cams. The Phillips To-U-Cam, and the successor SPC-900, were very popular, maybe not so much due to a great quality image, but due to mechanical issues.

The weak link in a cheap webcam is the $1.00 plastic lens. As I mentioned previously, the low end of some of the higher priced purpose built astro video-cams use the identical sensor chip.

Those Phillips webcams have lenses that are easily removed. Someone then machined an adapter that screws or inserts into the webcam body, with a 1.25" cylinder on the other end, allowing to fit into any 1.25" eyepiece adapter.

The result is a webcam that accommodates interchangeable lenses

You have to exercise care in storage since the sensor is then "permanently" open via that 1.25" eyepiece adapter. I keep mine in a clean zip-lock baggie and I have a plastic or rubber cap designed to seal 1.25" eyepieces against dust and humidity intrusion onto the lower field lens.

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kenuck Silver Member Nikonian since 03rd Nov 2008Thu 13-Sep-12 04:43 PM
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#23. "RE: Moon shots - Questar + V1"
In response to Reply # 22


Burnaby, CA
          

Regarding compatibility, I think it was Covey22 in the 1 System forum who said that any 3rd party lens with VR is not compatible. I know my Sigma 10-20 (no VR) works fine.

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Thu 13-Sep-12 05:35 PM
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#24. "RE: Moon shots - Questar + V1"
In response to Reply # 23


US
          

Interesting...

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 06:15 PM
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#20. "RE: Moon shots - Questar + V1"
In response to Reply # 16


US
          

>> ...however I think it's inherently unstable that way...

Your preaching to the choir . I've always thought it "strange" that the 234 was apparently designed to be used in that inherently unstable configuration, but I don't own one. I'm just passing that on. I would certainly use every caution, especially with that Q mounted on it

I've been told that there are several hole drilled into the bracket and you use the set of holes that best balances. Seems too "crude" (not enough granularity on the balance) but that's what they tell me .

Much of that goes back to a discussion we had about the 234 in the Tripod Forum a while back.

I agree - if you can swing the V1 through the "fork", or close enough, then you are set as is.

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kenuck Silver Member Nikonian since 03rd Nov 2008Thu 13-Sep-12 09:48 PM
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#25. "RE: Moon shots - Questar + V1"
In response to Reply # 20


Burnaby, CA
          

>I've been told that there are several hole drilled into the
>bracket and you use the set of holes that best balances.
>Seems too "crude" (not enough granularity on the
>balance) but that's what they tell me .
>
Actually, balance is achieved by sliding the camera plate back and forth in the 393's gimbal arm, so it's infinitely adjustable. I've never used the other holes - as far as I can see it just raises the gimbal arm to give it a shorter swing, allowing for a bit higher angles, but less stability with lenses with a high center of gravity like the Q. In its lowest (most stable) position the Q + short coupled V1 can swing right through 90 degrees (wouldn't be able to see anything in the viewfinder of course )

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Thu 13-Sep-12 11:15 PM
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#26. "RE: Moon shots - Questar + V1"
In response to Reply # 25


US
          

There are two balances. One the sliding plate for fore/aft balance.

The other balance is the vertical center of gravity. If the lens sits too low then it will never hold position- it always returns to level attitude even if the fore/aft balance is perfect.

If the lens sits too high then fore/aft balance cannot be achieved because it is comparable to balancing something on a free-rolling ball.

On a Wimberly gimbal that vertical center of gravity is critical and must be very fine set, which is why I questioned the granularity of 3 screw holes.

Some people prefer a low center of gravity because the gimbal does not respond quite as 'friction-less" and friction-less can be scary . I set mine to hold as large a range as possible.

All the above assumes the lens mounting bracket is flipped UP, so the lens hangs down under it, rather than the bracket resting in the lower position, with the lens on top. It sounds like you let it rest in the down position.

It may also be possible to achieve balance with the bracket up or down, depending on the height of the lens+foot and the holes used. In that case the bracket in the up position simply allows for a higher elevation before the camera runs into the gimbal or the mount. It is a supposed advantage over the Wimberly in terms of high altitude restrictions.

And again, this is just what experienced users tell me they do, to emulate the same functionality as a Wimberly.

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 12:30 PM
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#14. "RE: Moon shots - Questar + V1"
In response to Reply # 10


US
          

If you look at my recent post here about celestial movement, you will see that the field is moving about 29 pixels per second, assuming 1400mm. Looking at your plumbing in the above image, you are likely closer to 1500mm.

Looking at the image it appears that you have a couple inches of extension between your camera lens mount and the Questar swivel coupler. That is probably good for another 100mm or so.

If it were me I would try 1/50s ISO 400, if you are getting the noise I suspect you are at ISO 800. Otherwise I assume you are in a losing battle between the NR softening the image and trying to overcome that with extreme sharpening levels. The last image has a bit of the look I've seen trying to do what you did.

According to my numbers 1/30s will get you one pixel of blur, which is not terribly bad, and 1/50s gets you well under. But at those speeds your tripod and gimbal are getting a serious test, which is what lead me into that discussion.

And of course, this all leads back to the motorized mount discussion. Ideally you want to be shooting at base ISO, which I think is 100? That would put you at 1/12s or so. I'm not trying to hammer you over the EQ mount, just trying to explain why all the roads lead there so you can make a good cost/benefit decision.

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kenuck Silver Member Nikonian since 03rd Nov 2008Wed 12-Sep-12 05:04 PM
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#17. "RE: Moon shots - Questar + V1"
In response to Reply # 14


Burnaby, CA
          

Thanks Neil and you're right about the noise...ISO 200 to 400 was where I started with the first pictures then I got the wind up about possible motion blur so increased ISO and shutter speed. ISO 400 and 1/50 sec sounds like a reasonable compromise - noise on the V1 is fairly low at ISO 400.

I know, if I keep up with astrophotography that I'll have to get some kind of equatorial mount, however I'll have to wait a bit since the V1 and associated accessories set me back almost $2k (2 lenses, FT1, flash, GPS, extra battery, flash cards, etc) so I've already had this year's birthday and Xmas presents lol. Also, I know myself and when I get an equatorial I know I'd want the convenience of computer control...

Ken

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 05:43 PM
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#19. "RE: Moon shots - Questar + V1"
In response to Reply # 17


US
          

>> so I've already had this year's birthday and Xmas presents lol.

Welcome to the astronomically large money pit of astro-photography. I understand the feeling . You'll need a lot of time to research the right mount for you- there are so many options, especially when looking at older used mounts, which tend to be very cost effective.

I would start with something reasonably inexpensive, but good quality, and used. It is difficult to buy a German mount without having experience with one to understand the various nuances. Buying used will give you the chance to resell the first one without much if any loss after you figure out what you really want or need, should that happen.

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Vlad_IT Silver Member Nikonian since 21st Sep 2011Fri 13-Jun-14 02:43 AM
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#27. "RE: Moon shots - Questar + V1"
In response to Reply # 4


US
          

>Hi Ken,
>
>Another Questar owner >
>First, according to the Questar manuals the 3.5 has a minimum
>focal length of 1400mm when "close coupled" to a
>
>I own a (original owner) '97 Questar 3.5" Duplex and a
>fork mounted mid '80s Queatar 7.

>camera. That close coupling would include only the standard
>Questar swivel mount attached to the rear axial port, with a P
>mount attached to that, and then the camera.
>
>Adding the standard 3 piece Questar extension tube set (all 3
>pieces) would take you out to 1600mm. Using one or two of
>those tubes would take you to somewhere between 1400 and
>1600.
>
>The 1250 or 1300mm focal length is the "visual"
>focal length, based on the distance to the eyepiece, and it is
>not clear if that is an eyepiece in the control box port or
>the axial port . But the photographic focal length is
>somewhat greater than the commonly quoted "spec".
>
>Using the formula that you are using, that would put you at a
>minimum 3750mm effective focal length (relative to FX),
>although I don't personally place a lot of value in that
>computation. I think it is misleading for various reasons, and
>this is a great example of why .
>
>According to my calculations, the lunar rate of movement with
>the Nikon 1 should be about 2.106 pixels per second per 100mm
>focal length. The sidereal rate would be only very slightly
>higher at 2/15 pixels/second/100mm. That would be at zero
>degrees declination but even at the most extreme 25 degrees
>that the moon might hit, the rate would only decrease by about
>12%.
>
>That would put your rate of movement at 29.4 pixels per second
>at 1400mm, so about 1/30s for 1 pixel of blur. That is not
>your problem, although chasing the moon at that FOV from a
>fixed mount is not exactly easy and it likely adds to the
>general difficulties.
>
>I've never gotten a better image from my Q 3.5 than I
>routinely get from the two 500/4's I've owned, working 700 -
>1000mm. And even my 500/4 AFS and TC20E-II, which is not
>considered a very good TC, will give me better images than the
>Q.
>
>My Q 3.5 has been star tested by very experienced Questar
>owners (once at Questar's 2000 "user day" event,
>which was followed by a Stella-Dela star party). I am very
>confident that my optics are fully up to the Questar standards
>and are essentially diffraction limited.
>
>The visual views are outstanding and I cleanly split Gamma
>Virginis when it was separated by about 1.5", which is
>about the Rayleigh limit, given a few practical adjustments
>(technically that beats Rayleigh but it's a complex issue).
>
>I've never understood exactly why my Q has not performed for
>me for lunar imaging (or terrestrial imaging).
>
>The likely suspects:
>
>I don't own a Nikon 1 or any modern mirror-less camera, and in
>particular nothing with an electronic shutter.
>
>Mirror slap can be controlled with Mup, but shutter shudder
>cannot, without resorting to the hat trick, which is extremely
>difficult to do with the moon and can be counterproductive.
>So there your Nikon 1 might have an advantage.
>
>And that makes me thing that the mechanical shutter might be
>counterproductive unless the electronic shutter is really
>bad.
>
>Focusing through an optical viewfinder is extremely difficult
>because even close coupled the Q 3.5 is working f/16 and t/20.
> The t/20 accounts for the 30% central obstruction.
>
>Liveview on my D300 did not solve my problem although it did
>make focusing a bit easier and more consistent.
>
>The Nikon 1 is technically diffraction limited at f/5.9 or so,
>which is a long stretch from f/16. I think that puts a
>ceiling on the resolution you can expect (it's not really a
>3200mm lens or whatever, taking diffraction into account).
>
>This is all just to say that this is not easy to do, and I
>think you did a good job on your initial attempts.
>
>I think shooting the moon low was a big part of your problem.
>The 3rd quarter moon is well placed this time of year but you
>need to get out around 3am or so to take advantage of it. And
>the air can be very still that time of the early morning.
>
>It would also help to shoot on a motorized equatorial mount
>(like the Questar mount) but apparently you have a field
>model?

Neil,

you are killing me, man...

Best regards,
Vlad

  

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nrothschild Silver Member Neil is an expert in several areas, including camera support Nikonian since 25th Jul 2004Wed 12-Sep-12 12:48 PM
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#15. "RE: Moon shots - Questar + V1"
In response to Reply # 0
Wed 12-Sep-12 12:49 PM by nrothschild

US
          

I have some images I shot with the Q and my Coolpix 990 here. Some were probably shot with the CP990 close coupled to the swivel adapter, others were shot with eyepiece projection using some eyepieces I acquired that were machined with a thread that fit the CP990 filter threads (very handy feature!).

That was all done circa 2004 or so and I won't say I'm proud of all of them but it was the best I could do with the digital gear I had at the time. The CP990 is a P&S so it has an integrated lens that you can't work around, other than to do "afocal projection". The benefit of the V1 is that you get that cheap lens out of the optical path, and it vastly simplifies exposure calculations.

I'm also going to dredge up some images I shot with the Q and my DSLR's although those I definitely was not happy with, and why I used my 500/4 for ,y Lunar Phases project (plus the vastly simplified setup and take down time).

_________________________________
Neil


my Nikonians gallery.

  

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