Astro: Camera Telescope adapter question


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Jul 10, 2014
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I was attempting to attach my camera to a celestron scope I have the adapter but I encountered a problem.

When I attached the adapter and the lens, telescope lens, the camera was saying that there was no lens attached and would not take an image. I dint expect this and was caught short in terms of solotutions plus it was 4 am. What did I miss?, first time I tried this.

Camera Nikon d5100
Scope Celestron Newtonian design maybe 5 inch diameter, not mine.
Adapter Celstron Nikon

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I don't know the 5100
but there are no electrical contacts with the telescope adapter to the camera. So the camera thinks nothing is there. There should be a setting in your menu somewhere to turn off something.

You'll have to change the "release" mode - ie, the camera will take a picture any time the shutter button is pressed (irregardless of AF is achieved as it won't be, you'll focus the telescope independently), whether the image is in focus or not. And maybe also the Focus Mode.

It would be the same as putting on a totally manual lens.
It's better to test all this stuff during the day so you can clearly see things.
Take photos of far away buildings, people, etc.
The camera doesn't recognize the T mount adapter as a lens, and that is expected and okay. Was the camera in Manual mode? If not then try that. Some cameras will also allow Aperture Priority with "no lens", but others may not. P, S, and other auto modes will not work on any camera.
I use the same adapter with my D50 and D300s on my Newton type telescope.

The camera will show the error F-- (no lens mounted) in the viewfinder, which you can ignore.
If you didn't set the camera to Manual AF the AF indicator in the viewfinder will constantly blink because the AF system does not have a lens CPU to communicate with. but that should not matter. It doesn't with my 2 Nikon's.
Be sure you press the shutter button fully.

You will not have any metering and the only exposure settings you can control at the camera are the ISO and the shutter speed. You can stop down the telescope aperture, but you can't make the telescope aperture larger.

You will need to set the shutter release timer (2 seconds to 5 seconds delay before the shutter opens) and put the camera into timer mode so the camera/telescope can stop shaking from you pressing the shutter release.
From what I can tell... your model requires you to be in MANUAL mode if you want to shoot without a lens attached.

This makes sense because when the camera is attached to the telescope it cannot control aperture or focus. The only thing the camera can control is ISO and shutter speed -- but it would never be able to meter accurately when shooting the night sky and you would really want to manually control all settings anyway.

One other thing... it's possible that the newtonian telescope will not be able to provide a focused image when the camera is attached unless you use a 2x barlow. Not _all_ newtonian scopes have this problem, but it is extremely common. From the point where the camera's nose-piece (the adapter that allows it to fit onto the telescope) mounts, there's approximately an extra 2" back to reach the camera's imaging sensor -- but the mirror on the telescope was designed to bring an image to focus at a closer distance. The focuser on the telescope needs to be able to rack the focus tube inward and many newtonian scopes don't have enough focus travel.

This isn't an issue on refractors or SCTs because the telescope is designed to be used with a 90º diagonal adapter -- and that adapter adds about 2" to the focal length of the scope. So refractor and SCT owners simply remove the 90º diagonal (which subtracts 2" from the focus path) and then attach the camera (which adds about 2" right back into the focus path) and the telescope is focusing the image right where it was designed to focus.

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