Flare from Compressor/Field Flattener

Am I the only one in the world who has trouble with field flatteners/fpocal reducers on an SCT?

After having a few otherwise great shots ruined by lens flare while using a standard 6.3 compressor/field flattener on my C9.25, I decided to run a test. I borrowed three field such things from my friends (three Celestron, one Meade). I stuck them in the tube, pointed at the Pleiades, and got the following, from all four of them. And I often get this kind of thing when using a flattener. It appears to come from stars just outside the FOV, although I don't know if that is true. I have done all the obvious (looking down the barrel for anything shiny, etc.)

Oh, I should add that I do not notice it when using the scope at F10 (without flattener/reducer).

What is your experience? Is this a common problem. Is there a trick to using the field flattener/Corrector/Focal reducer that overcomes this?

Alex

Attached Image:

I see this all the time on the Meade, but I never thought about it having to do with the reducer. (I don't recall if there is currently a Meade or Celestron 6.3 reducer installed.) I just assumed it had something to do with something shiny "upstream". Just within the last couple of weeks I had considered trying to install a knife-edge on the front end of the JMI focuser - that would make it before the flattener. I do have a standard "worst case" ready for testing - the horsehead:

http://www.fortlewis.edu/observatory/image_detail.asp?ID=150

This was 4 ten minute images. Each one was "dithered" by >~10% of the frame. That makes the ring move around. You can still see the reflection "ghosts" in the dark area. That has been my solution, but it would be good to know if it is really in the flattener.

By the way - my biggest concern using the reducer has been the stars turning into little comets around the edge. Especially if the spacing or alignment isn't perfect.

I would really hate to lose the extra field of view.

Charlie

Alex,
I have a C8 and I use a Celestron 0.63X reducer/corrector. I have not experienced these flares. As Charlie says, I find the distance to image surface critical for star shapes, but that's about it.