M51-Bad Vignetting(need help)

Started by RazorsEdge, 06/12/2005 03:15AM
Posted 06/12/2005 03:15AM Opening Post
I am not sure where to post this since it is not a CCD or film image.
While imaging with a Meade LX200 and the Canon 10D I experience REALLY bad vignetting. In this example of M51, without dark-frame subtraction, only 8 (of 45) - 1 minute frames have been stacked. I have already subtracted a radial gradient in PhotoShop and am left with what I call the "doughnut nebula" smile. The images where taken at 800iso. The effect shows up almost immediately once one- or two frames are stacked.

If anyone has experience imaging with the LX200 and 10D and has any suggestions as how to reduce/eliminate this effect within the setup; it would be appreciated. I am supposing I would either need to move the camera closer or futher.

Thanks in advance.
Brian Edgerly



Attached Image:

RazorsEdge's attachment for post 24884
Posted 06/12/2005 03:35AM #1
Hi Brian...

Looks like something that a "Bias" or "Flat Field" image should correct... I am sure the experts will chime in here soon...
Posted 06/12/2005 03:20PM #2
I would like to see the image before you did anything to it. The image you posted dosen't look like vignetting. That would be were the light falls off at the corners and would be bright in the middle. Looks like some dust somewere on the optical path. A good flat would correct that but a cleaning would work better.
Posted 06/12/2005 11:52PM #3
I agree Tyler. Seeing the untuched image is definetly vignetting. The donut in the first image looked like dust.
Brian are you using a reducer?