Hi,
I understand most of the aspects of using a teleconverter to 'extend' reach. With a 2x converter, I double the focal length and loose 2 f stops.

Using an 85mm lens and 2x for example, the DOF for 40' and f16 will be ~33 to 50' or a spread of around 16'. Ok, what do I set the aperture at on the camera? I'm thinking f8 (down 2 stops at the lens) will give me f16 at the sensor? BTW the spread at f8 is only about 8'.

So what's the setting on the camera? f8 or f16??

Thanks,
Ray.

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Ray

A few things here.

First, Nikon TCs such as the TC 20EIII only work with a few lenses and the 85 is not one of them.

Second. the D700 will tell you what the F stop is, so you don't have to manually figure it out. In other words, if you put a TC20EIII on your 70-200VR f2.8 Nikkor lens, the widest opening that you would see is f5.6 (I might be off by 1/2 stop since I don't have a TC20).

Finally, you can do your calculations as if there was no TC. Whatever F8 at any given focal length and distance would yield will be what you get.

I'm not completely sure that that a was your question, so don't hesitate to clarify things if it wasn't.

jP

You can use a Kenko TC on the 85 MM. I use a 1.4 TC, and the D700 does not record the corrected data with the 85 mm and the 1.4 TC, so you do have to figure it out. I cannot use any of my Nikon TC's on this lens, as it is not an afs lens. Since my 85 mm is an f/1.4, by putting a 1.4 TC on it I get 119mm f/2 wide open. There are recent images in my gallery where I shot this combo with the lens stopped down to f/8 or corrected f/11. It worked well.

Bob Baldassano
My Nikonians Gallery

"Nikonians membership - My most important photographic investment, after the
camera"

Retirement is a gift of time - Don't waste it!

>First, Nikon TCs such as the TC 20EIII only work with a few
>lenses and the 85 is not one of them.
>

I don't have a Nikon TC - this is a Tamron-F 2x TC. Works fine with most, if not all, of the lenses I use with it. (< 50mm aren't supposed to work with a TC but I haven't tried my 24 or 28mm)

>Second. the D700 will tell you what the F stop is, so you
>don't have to manually figure it out. In other words, if you
>put a TC20EIII on your 70-200VR f2.8 Nikkor lens, the widest
>opening that you would see is f5.6 (I might be off by 1/2 stop
>since I don't have a TC20).

I have the TC and my Nikkor 85mm f1.8D on the 700 at the moment and the 700 will let me set the aperture all the way down to f1.8. I also took a picture and the data says the aperture was 1.8. Hmmm.


>I'm not completely sure that that a was your question, so
>don't hesitate to clarify things if it wasn't.
>
Thanks,

I really want the DOF of f16 and want to know what to set the camera at, ie f8 or f16?

Thanks,
Ray.

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Ray,

>I really want the DOF of f16 and want to know what to set the
>camera at, ie f8 or f16?

f/8.0

The TC doubles the fno. which you are set to. Set it to f/8.0 and it is f/16.0.

Scott Chapin
Powder Springs, GA, USA
Nikonians Team Member

Thanks for the answer, I appreciate it.

BTW, I just tried my 24mm (chipped)AIS f2.8 with the TC on my 700 and it works fine. I've 'chipped' all my AI, AIS and AI converted lenses so they work (meter and set aperture at the camera) the same on both the D700 and the D80. Now if I can just re-learn manual focusing...

I bought a Minolta x-370 new MANY years ago - still have it and use it once in a while.

Thanks again,
Ray.

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Hi Ray.

You said, "BTW, I just tried my 24mm (chipped)AIS f2.8 with the TC on my 700 and it works fine."

Okay, but I've got to ask, why? What's the point?

Even with the 85mm, I don't see what you're getting at.

Let's take the 85mm f/1.8 as an example. Multiple your 85mm by 2 and you get 170mm, and the lens essentially becomes an f/3.3. Plus you've lost some IQ getting there. You've got a 200mm f/4. Sure it's slightly longer and slightly slower (½ f/stop), but you've got its original image quality.

Now if you were going to take the 2XTC and put it on your 200mm f/4 or your 135mm f/2.8 from a focal length standpoint, I would understand that.

And if you're losing autofocus I'm really baffled about the choices you mentioned.

Ned
A Nikonians Team Member

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>Hi Ray.
>
>You said, "BTW, I just tried my 24mm (chipped)AIS f2.8
>with the TC on my 700 and it works fine."
>
>Okay, but I've got to ask, why? What's the point?

I wouldn't use a TC on a wide angle lens - I'm all set below 105mm. I tried it just to see if it would work - it did.

>Even with the 85mm, I don't see what you're getting at.
>
>Let's take the 85mm f/1.8 as an example. Multiple your 85mm by
>2 and you get 170mm, and the lens essentially becomes an
>f/3.3. Plus you've lost some IQ getting there. You've got a
>200mm f/4. Sure it's slightly longer and slightly slower (½
>f/stop), but you've got its original image quality.

The idea was/is to get longer reach with 'good glass.' I have an opportunity to shoot a symphonic band this season and it is 50+ members strong. I shot a rehearsal this week and thought I had focusing shortcomings with the 200/f4. Thinking about it more I now think it is camera shake - no tripod or monopod. Next time I'll have both.

I was hoping the 2xTC would give me auto focus at 170mm (it does) but focus and DOF may not be the problem. I just looked at the images again and I was mainly shooting at around f/8 and 1/60 ISO went to 8000. Between camera shake and the conductor & musicians moving the images weren't quite as sharp as I'd like. f/8 200mm yields about 2ft of range at a distance of 20 ft and about 3 ft at 30ft.
>
>Now if you were going to take the 2XTC and put it on your
>200mm f/4 or your 135mm f/2.8 from a focal length standpoint,
>I would understand that.

Boy, you did some homework on me!

I have at least 2 more rehearsals before the 1st concert so I have some opportunity to get it right. The 1st concert is probably the most important this season - it's their 50th season and they are bringing back the founder and original conductor for this 1st concert and want some good pictures - so do I!

I've done fairly well with the 70-300ED on my D80 at about 30-50 ft with good light (and a tripod) in the past so I might try that lens on the D700 next time, along with the 135 and 200 and at least a monopod. Hell, I'll probably bring everything and find what works best for me.


>And if you're losing autofocus I'm really baffled about the
>choices you mentioned.

I'm not losing autofocus, its that the older lenses are all manual focus and my eyes aren't as good anymore. Had cataract surgery this year... I also recently got split image focusing screens for both the D80 and D700 for manual focus - that works better me than the stock focusing screens on the camera.

Ned_L, thanks a bunch for making me think about this a lot more - I really appreciate it!

Ray.

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Ray, I am pleased to have helped.

The "Team" always likes it when members fill in their profile, as it really helps us help our members, by making our posts as relevant as possible. We in turn fill in our profiles so members can know a bit about us, and our photography.

I think you're on the right trail to get this done. If I were you, I would handle the next rehearsal like I would handle a wedding in a location new to me. For beach weddings, for example, I try to hit the beach at the same time of the day a day or two before the wedding so I know what light I'll have, and test how to use it. I come with a regimen that I've planned to test to decide what my settings will be.

I would go to the rehearsal with a plan of exactly what I would want to try in the way of lenses, ISO, aperture, shutter speed, and support. Set your plan up so you won't miss any viable combinations. Peak periodically via the monitor how you're doing as you go along so you could retune your testing as the rehearsal continues. Since sharpness was a problem, make sure you blow the photos up on the monitor to look at them. When you get home, of course, you can really see what you have. I think a plan like this will quickly zero you in to a solution.

Good luck. If you want to bounce any ideas with us here, don't hesitate. Let us know how you make out.

Ned
A Nikonians Team Member

-----------------------------
Visit my Travel Photography Blog and my Galleries.

Dof with converters is slightly complicated.
If you substitute a 200mm f2 for a 100mm f2, for the same focus distance you get twice the magnification, 4 stops loss dof because of the greater magnification, and the same shutter speed and aperture stay the same for exposure.
If you use a 2x instead of the 200 you get 2 shutter speeds slower for exposure, and loose only 2 stops dof.
However if you select 2 stops slower aperture on the 200 you get 2 stops more dof and 2 shutter speeds slower - the same as with the converter.
Summing up you get 2 stops more dof and 2 shutter speeds slower with a converter relative to unmodified settings with a lens of twice the focal length.

Photography is a bit like archery. A technically better camera, lens or arrow may not hit the target as often as it could if the photographer or archer does not practice enough.

Len Shepherd

I think what you say is correct, but it seems over-complicated to me. Another way of looking at it is that a 100mm f/2 lens with a 2x TC will offer the same focal length, maximum aperture (hence shutter speeds) and depth of field as a 200mm f/4 lens.

Brian
Welsh Nikonian
Check out the Nikonians Team pages

> Another way of looking at it is that a 100mm f/2 lens with a 2x TC will offer the same focal
>length, maximum aperture (hence shutter speeds) and depth of field as a 200mm f/4 lens.
That only applies using both lenses wide open

Photography is a bit like archery. A technically better camera, lens or arrow may not hit the target as often as it could if the photographer or archer does not practice enough.

Len Shepherd

>That only applies using both lenses wide open

No, it applies at all corresponding pairs of aperture settings.

A 100mm f/2 lens at f/2.8 fitted with a 2x TC will offer the same focal length, aperture (hence shutter speed) and depth of field as a 200mm f/4 lens at f/5.6. Similarly with the 100mm at f/4 plus TC and the 200mm at f/8. And so on...

Brian
Welsh Nikonian
Check out the Nikonians Team pages

Hi,

Ok, I got into this discussion late. I'm confused (not unusual). What you are saying is different than I've always thought. I'm definitely not saying you're wrong, just that I'm confused.

Can you tell me the reason behind your statement? I've always thought that putting a 2x teleconverter on a 200mm/2.8 lens should yield the same depth of field as a 400mm/2.8 lens, since the only thing that has changed that would influence depth of field is the focal length. I'm thinking that the diameter of the lens aperture hasn't changed, just the amount of light transmitted through the teleconverter.

Don't worry, I can take it if I've been wrong all these years.

Thanks,
Craig

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I'm sorry if Len's posts have confused you.

How you get to a given focal length and aperture is not relevant to DoF. A 200mm lens set to an aperture of f/2.8 and fitted with a 2x TC will give the same Dof (and focal length!) as a 400mm lens set to f/5.6. It's as simple as that

Brian
Welsh Nikonian
Check out the Nikonians Team pages

>Can you tell me the reason behind your statement? I've always thought that putting a 2x teleconverter on a 200mm/2.8 lens
>should yield the same depth of field as a 400mm/2.8 lens, since the only thing that has changed that would influence
>depth of field is the focal length.
Brian's answer is the "quick fix" - and all that is needed for those who do not want to know about "why".
The explanation you seem to want to know is something else has changed - the light transmission of the 200mm lens once the 2x converter is added.
One of the basics rules of physics is any change is offset by a compensating change.
The change in light transmission of the 200 with converter is offset by a compensating change in depth of field.
If a 200 f2.8 and 400 f2.8 are focused at 30 feet the 400mm lens magnifies the subject more.
The exposure times are the same - to make the maths easy assume a shutter speed of 1/1000.
Magnification has a greater effect on dof than aperture so the 400 records the equivalent of 4 stops less dof (not 2) than the 200.
When the 2x is added to the 200mm the magnification is the same as the 400mm, but the 200mm shutter time reduces by 2 speeds from 1/1000 to 1/250.
The change in shutter speed is offset by only 2 stops loss of dof, not 4.
If the 400mm aperture is changed from f2.8 to f5.6 both lenses now require 1/250 exposure, the 400 gains 2 stops dof at f5.6, and both combinations now have the same dof.

Photography is a bit like archery. A technically better camera, lens or arrow may not hit the target as often as it could if the photographer or archer does not practice enough.

Len Shepherd

>thought that putting a 2x teleconverter on a 200mm/2.8 lens
>should yield the same depth of field as a 400mm/2.8 lens,
>since the only thing that has changed that would influence
>depth of field is the focal length. I'm thinking that the
>diameter of the lens aperture hasn't changed, just the amount
>of light transmitted through the teleconverter.
>

I thought I would chime in to provide information that may be helpful and to further my own knowledge in this area.

I think where you are going awry and getting confused is using the f-number as the aperture, it is not.

A 400mm lens at f/2.8 provides 4 times the aperture area than a 200mm lens does at f/2.8.

By placing a 2x teleconverter on the 200mm lens you effectively provide a focal length of 400mm. But the aperture remains the same size. A 200mm lens at f/2.8 has an aperture diameter of 71.43mm. With the 2x teleconverter and effective focal of 400mm the f-number now becomes f/5.6 (400/71.43=5.5998).

Pete

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Aah...the light bulb comes on. I am one of those guys that wants to know the why of things. I hate it when I'm slow about these things. . This is such a great place to find these discussions.

Thanks guys,
Craig

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