Could This Be The Problem

[leon]

Hi Guys, a few days ago I posted a question, hopeful for suggestions for a problem that I was having with my images, of late.

The problem, as some of you may be aware was that I was always left with a very bright central circle in all my images, forcing me to darken all my images so that they were reasonably acceptable for posting.

I may have found the problem, however I would like to ask, could this be it.

I Image with the 5D, and the Canon angle finder, which I use for focusing, this works fine, and all is good.

However when the camera is exposing, the camera displays a continuious red glow from the rear or the camera, this is actually pretty bright on any dark night, as are the other red lights of the from the guide camera, G11 hand controller, etc.

While I image I always turn my Canon Angle Finder downwards to prevent dew, but by doing this it is very close to the red light on the back of the camera.

I have now changed this habit and use a proper cover for it in the upright position.

I feel the central brightness in my images has been the light leaking through the uncovered angle finder, while the camera is exposing frames up to 6 minutes each.

What do other people think of this theory, could this be the problem.

Leon

[h0ughy (David)]

that does sound plausible?

[skwinty (Steve)]

Hi Leon
Quite possibly as the Canon 40D comes with a specific patch to cover the viewfinder and the manual says to cover the eyepiece when not covered by the eye.
I tested my 40D and during the day and sunlight definately gets through and spoils the image (especially if you are taking a dark, then the whole image is white)

[leon]

Yea Guys I think this may be my problem, only time will tell when I can get out there again, weather permitting.

Thanks for your response.

Leon

[Zuts]

Originally Posted by leon

Yea Guys I think this may be my problem, only time will tell when I can get out there again, weather permitting.

Thanks for your response.

Leon

Hi Leon,

I dont think this is the problem. Vignetting is caused by a light droppoff towards the edge of the image from the focussed light cone. Your images have vignetting but your flats dont seem to remove them or to remove the dust bunnies. As Fred pointed out your flats are too bright and wont help to remove dust bunnies and vignetting.

I might be wrong but if you had light leakage from the back of the camera then you would expect it to be across the whole image and not look like vignetting.

I would try and take some more flats and keep on going until when you look at them you can see the dust bunnies clearly and a well defined light dropoff towards the edges. Then apply these flats and see if they solve the problem.

Paul

[leon]

Thanks Paul, yes mate I will do that as well, but the other issue of light leakage is probably something I should resolve as well.

Might as well get it right, and eliminate all the possibilities

Thank You.

Leon

[acropolite (Phil)]

Leon, I seem to remember a thread not long ago where someone else had this problem.

[leon]

Well there you go Phil, although I will redo the flats properly I do believe this is my problem.

Thanks for the Thread.

leon

[OneOfOne (Trevor)]

I think you have experienced a "duh" moment!

[leon]

Yep that sounds about right, a bit of a senior moment.

Leon

[RB (Andrew)]

Always cover the viewfinder/anglefinder when exposing.
It's good practice and it's a shame to ruin a nights run because of an oversight like that.

Whether it's causing your problem, time will tell but start to cover it anyway.