M45 - The Pleiades

Very nice image Dave! Fabulous detail there!

Another great image Lads.
I just love that blue nebulosity!!!

I dont understand why the vignetting is assymetric or why its red??. I've captured vignetting and it didnt look like what you've captured there.
here is an example of daytime vignetting, scroll down to the bottom of the below page..
www.ugcs.caltech.edu/~pinkston/astronomy/canon-g2/

If that was happening on my setup, I'd suspect light was entering through a gap in the offaxis guider port, near the prism and reflecting of a filter and getting into the camera.

To me it that looks like some sort of internal reflection is going on ?!?!?
Was any filter used?

Dave.

The assymetry is just because the histogram is teetering on the line between the red becoming very very apparant and the detail of the shot itself being lost. The reason its red is because during the exposure there isnt so much light falling on that part of the chip allowing much more dark current to build up.

Just need to get my 2" setup organised and that will be a thing of the past!!

Super image Dave & Jed!

Dave.

The assymetry is just because the histogram is teetering on the line between the red becoming very very apparant and the detail of the shot itself being lost. The reason its red is because during the exposure there isnt so much light falling on that part of the chip allowing much more dark current to build up.

Just need to get my 2" setup organised and that will be a thing of the past!!

ahh, so you're really pushing the levels here to get the horsehead, thus increasing the noise in the image.
But, are you saying that less light = more dark current on the chip, I cant see how this can be or how this explains this shape as the intrinsic 300D red noise pattern is very different to whats in the image, but, I'll take your word on the 1.25 inch setup is somehow causing this artifact.

I really didnt mean to be labouring the point, its just that I find this kind of stuff very interesting.

Dave Lillis wrote:

ahh, so you're really pushing the levels here to get the horsehead, thus increasing the noise in the image.

Actually Dave the histogram is balanced just about as far as the vignetting will allow it but in fact its not pushed very far at all. The horsehead is clearly visible on the raws for example. We just pushed it as far as the noise/vignetting would allow it. If the vignetting were not there we could push it a bit further still. Because there is a good few images in the stack the histogram is quite tolerant of a bit of pushing.