DSLR Connection to Fast Refractor?

[galaxy-gazer]

Hello everyone!

I have a Celestron Omni f/6.5, 660 FL refractor, and I am trying to connect and take picture of Saturn (specially) through my Nikon DSLR, but I simply cannot see the target on my camera’s display, I have tried it in 2 ways - connected the camera through a T-ring (over the focuser directly), and in 2nd method I “sandwiched” an eyepiece inside the adapter and connected to my camera, what am I doing wrong?

thanks

sam

[powerlord]

t-riing method is best. The other way is called projection imaging.

You probably do not have enough length for the DSLR to focus (55mm is the usual). With maks/SCTs they sometimes have enough focus to make it, but with a refractor, you probably need an extension tube between the t-ring and the scope.

how exactly is the t-ring attached to the scope just now ?

[Clarkey]

As powerlord has said you probably need an extension to compensate for the lack of a diagonal. The other think to do is to try focusing in the day on a distant object, you will then know roughly the right position to focus.

[jacko61]

As you say you can't 'see' the target in the display, I wonder if you have a long enough exposure setting?  Using my canon, I find I sometimes need to set the highest ISO and longest exposure to get the target visible enough to focus. Then I'm usually able to take the ISO back down to 600 or 800 in APT for the imaging session.

Graeme

[galaxy-gazer]

3 hours ago, jacko61 said:

As you say you can't 'see' the target in the display, I wonder if you have a long enough exposure setting?  Using my canon, I find I sometimes need to set the highest ISO and longest exposure to get the target visible enough to focus. Then I'm usually able to take the ISO back down to 600 or 800 in APT for the imaging session.

Graeme

Can’t even See through the viewfinder / display screen - daytime it’s okay, too bright anyways

[galaxy-gazer]

6 hours ago, powerlord said:

t-riing method is best. The other way is called projection imaging.

You probably do not have enough length for the DSLR to focus (55mm is the usual). With maks/SCTs they sometimes have enough focus to make it, but with a refractor, you probably need an extension tube between the t-ring and the scope.

how exactly is the t-ring attached to the scope just now ?

T-ring attached directly to the camera body (no lens on the camera) and then it’s connected via a tube to the telescope 

[michael8554]

The Focal length is 660mm.

Measure 660mm from the front element, that's roughly where the DSLR sensor needs to be.

Measure back from that point to the focuser, in the middle of its travel.

Subtract 55mm for the DSLR + T-Ring, that's the length of extension tube you need.

Get the closest available and fine-tune with the focuser.

Michael