Atic 0.5 focal reducer

Hi

I got this focal reducer at a good price. I was trying it out the other night with the atic16ic and the image seems to have a lot of nasty vinieting mess towards the corners. Then again maybe it was just not seated correctly :roll:

I wonder has anyone else used this reducer and come accross this result? (Aparently it is a clone of the similar antaris reducer.)

Where should one place the reducer in the optical train to get the best results.

Thanks

DB

The FR should be right in front of the camera. There should nothing between the camera and reducer.

David --

The closer to the CCD you have it, the less vignetting you'll get.

(You'll also get less focal reduction, and whatever vignetting does occur will have a sharper light fall-off. But you still probably want it as close as you can get it.)

-- Jeff.

Hi

This is the shot that I got.

farm2.static.flickr.com/1048/953777391_6124824205_o.jpg

Any ideas on what is caused the stuff in the corners?

Thanks

DB

DeeBee,

It does look like everything is misaligned. The vignetting you see at the bottom should be at the top too. It looks like the misalignment is in the vertical. Check three things.

Check the CCD hasn;t become unseated in its socket.
Check the focal reducer is tight in its frame.
Check everything is screwed nice and tight (camera, reducer)
DO not use a star diagnol. Put as little between the optics and CCD as possible.

Hi David,
In order to test if its the CCD chip or not then take one image and rotate the camera 180 degrees, if the abberation does not move in the image then its the CCd position, if the aberration moves then the optical path is out, I've seen mis-collimation cause this effect.

Vignetting is often caused by having too much of a gap between the CCD and focal reducer.