Lens (?) Flare

I'm getting strange lens flares or something using my 20D. I do not get in all photos. However, If I have a long exposure or high ISO on a bright object (so far only M 42) I get arcs or someting on other parts of the frame. I have done what I consider the obvious (looking up the tube, etc. for uncoated or bright spots). It does not happen with my Canon lenses or apparently with my TV 85. It has happened only on Orion nebula so far. I have tried to get it to happen with Sirius (another bright object). It happens with both my Celestron 6.3 reducer and Lumicon Easy guider.

The "flare" is not always there, even with the same object.

Here it is on an M42, notice just up near the top in center of frame.

Any ideas?

Alex

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Hi Alex, I might have the same problem except mine is with the horse head. I have a few curved sleeks and some light/cloudy spots toward the top. I am going to have the lab rewash my slides and see if that fixes things. If not I'll have to reshoot.

regards

Joe

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That is definitely flare caused by a bright star just out of the FOV. It happens when your adapters or reducers aren't properly set up to reduce internal reflections. I had it with some custom adapters and my STL-11000XM. The insides were anodized black, but it didn't matter--the bright star plus the long exposure picked up the arcs.

You won't see it with the star *in* the FOV-it has to be just out of the FOV.

If you have an adapter in there, try painting the interior with the flattest flat-black paint you can find. That fixed it for me. Ideally, the insides of adapters should be grooved and painted flat black, or flocked. That will eliminate this problem.

Jeff