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Subject: "Nikon D40X, a Telescope & the Moon - Help!!!" Previous topic | Next topic
RobRen Registered since 20th Nov 2007Tue 20-Nov-07 05:41 AM
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"Nikon D40X, a Telescope & the Moon - Help!!!"



          

I’m really hoping that someone here can help me.

I have a Nikon D40X and a Celestron NexStar 114 Telescope.

What I want to do is use my Nikon to take a picture of the moon. My teenage son is taking a digital photography class in high school and has decided that one of his projects will be the moon.

To attach my camera to the telescope, I purchased a Lumicon 1.25” camera adapter and a T-ring adapter that fits the opening to my camera (once my regular lens is taken off).

When looking at the moon through my telescope, the moon is sharp and bright. The craters are very visible.

I took my eyepiece from the telescope and fit it inside the Lumicon 1.25” adapter. I then attached the T-ring. Just to see how it looked, I attached this new combination to my telescope without the camera and checked to see if the moon still looked sharp and bright. I adjusted the focus and the moon looked great!

I then took off my Nikon lens and attached the camera to the adapter set-up. When I looked through my camera’s viewfinder, the moon was still there but no longer looked sharp and bright. I adjusted the focus on the telescope but it still didn't look good or clear. I don’t know why, so that is my first question.

Second question is what f-stop and shutter speed I should use to use to take the picture.

Third question. When I turn the camera on, I get a message telling me that the lens is not attached. The camera will only work in Manual mode. I can change the shutter speed but the camera won’t let me input in an f-stop. How come I can’t input an f-stop?

I’m at my wits end. This once fun project has turned into a nightmare.

  

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fidget Registered since 23rd Dec 2003Tue 20-Nov-07 09:23 AM
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#1. "RE: Nikon D40X, a Telescope & the Moon - Help!!!"
In response to Reply # 0


GB
          

Hi,
Answer to your second question. As there will be no electical contacts on your telescope adaptors there will be no aperture communication to camera. Camera must be set on manual and shutter speed set. Aperture will be determined by what ever the telescope gives and you wont be able to change this. You will have to sort out the correct shutter speed by trial and error.
Good luck, Brian

  

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dwig Registered since 30th May 2004Tue 20-Nov-07 11:56 AM
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#2. "RE: Nikon D40X, a Telescope & the Moon - Help!!!"
In response to Reply # 0


Key West, US
          

The Celestron Nexstar 114 SLT has a 1000mm focal length and a 114mm aperture, which yields a focal ratio, f/stop in camera speak, of 1:8.77 or f/8.77. This aperture applies to setups where you are mounting the camera at prime focus. When you do eyepiece projection the focal length is effectively increased and the f/stop is reduced.

I would recommend mounting the camera at prime focus if thats possible with this scope. That is, using the T-adapter without adding the eyepiece. This will make the scope a 1000mm f/8.8 lens. The scope has no iris for adjusting the aperture so no camera could set an f/stop. If you must add the eyepiece, you will find that you have to refocus through the camera.

The moon, is the same distance from its light source, the sun, as the earth. The bright face of the moon is fully lit by the sun just as the earth is during the day, hence the exposure is very similar. Proper exposure follows reasonably closely to the "Sunny-16 Rule". Exposure for a full moon is generally around f/11-f/16 with the shutter speed set to a numeric value the same as the ISO. f/16 & 1/200th using ISO 200. With your scope fixed at f/8.8, your only exposure controls are ISO and shutter speed. You'll find 1/500 @ ISO 200 a good starting point. If you find you have vibration problems, you could use a higher shutter speed and a correspondingly higher ISO.

I would recommend that you check out the astrophotography how-to sections at both:

www.astonomy.com
http://www.astronomy.com/asy/default.aspx?c=ss&id=12

www.skyandtelescope.com
http://www.skyandtelescope.com/howto/astrophotography

-----
dwig
nikonian in paradise
-----
use: cp8400, cp990, cp950
retired: F,ELW, 21mm, 45 f/2.8 GN
used to own: S2, SP, F2, F3, 20mm f/3.5, 35mm f/1.4, 35mm f/2.8, 43-86 f/3.5, 50mm f/2, 50 f/1.4 (for S2/SP), 55mm f/3.5 Micro, 105mm f/2.5, 105mm f/4 Micro, 300mm f/4.5, 180mm f/4.5 (for 4x5)

  

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quick5pnt0 Registered since 12th Nov 2007Fri 23-Nov-07 01:42 AM
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#3. "RE: Nikon D40X, a Telescope & the Moon - Help!!!"
In response to Reply # 0


Dingmans Ferry, US
          

I can change the shutter speed but
>the camera won’t let me input in an f-stop. How come I can’t
>input an f-stop?
>

The reason you cannot change the f-stop on the camera is because there is no lens. The lens is what has the aperture which is what you're adjusting when you change the f-stop. No lens, no aperture, no f-stop....other than that of the telescope of course.

Mike
Mustangs | R/C Truck

  

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