Focal Reducer: Help!

[Rihard]

Hi all,

I recently bought a 2" Antares 0.5x focal reducer (filter thread) and a 2" prime focus T-adapter (threated for filters).

Today I tried it for the first time with both my Celestron 80ED and my Skywatcher 200P and 2 different dSLR cameras (Canon 1100D and Nikon D7000), but I couldn't see absolutely anything

I also tried to add an extension: a 2" eyepiece holder that I normally use to reach focus with the 80ED and my Nikon,  but in this case it didn't help at all.

I have been trying every possible combination, but it behaves as if the reducer is too far from the camera sensor:  I tried to manually hold the reducer between my dSLR and the scope's focusser, without using any adapter other then my hands, and I could see a clear image in this case.

What should I do? Do I need a different adapter?

I just can't figure out which sort of adapter would keep the reducer so close to the camera to allow focus and support the whole thing hanging from the focusser

So I'm totally lost with this - any advise will be greatly appreciated !

Thanks all !

[Davey-T]

I'd email them to see if they know how far the imaging chip should be from the F/R , if you set up a light bulb a few feet away and hold up the F/R  and a sheet of white card you can project an image and measure the distance from F/R to image to get an idea of the focal length of the reducer.

Dave

May not work at all with 200p

[Davey-T]

Bear in mind that a focal reducer does just that, moves the ccd chip forward by 100-200mm compared to where it is normally.

Dave

[Rihard]

Hi Dave,

thank you for your reply. I will try to send an email to the reseller to see if they have any tip on this.

I have google'd for some infos and on this website they state that the Antares FR has a focal lenght of 158mm, thus the working distance should be 79mm.

I measured my Nikon D7000 and the sensor is at least 5cm down the body, and the 2" T-Adapter adds another 5cm, so if I am not wrong, this means that with my current setup the FR is about 100mm away from the sensor rather then 79mm, could that be the issue? In that case I think it might be just a matter of getting a shorter adapter or something like that?

I wouldn't mind if it won't work with the 200P (it's ok for me at F/5), but it would be great if it would work at least with my slow F/7.5 Celestron 80ED.

Cheers

[Davey-T]

May still focus alright but will end up with different reduction . I think  I've got a book with the maths in somewhere, will try to find it.

Dave

[Davey-T]

Don't know if you've seen this thread, may be relevant 

Dave 

http://stargazerslounge.com/topic/200925-focal-reducer-for-an-equinox-80/