Internal reflection (I Think) !

[The Viper]

Here is a heavily stretched image of M51 from a few nights ago. The setup   ED80-lp filter- 0.85 reducer/flattener- spacer- atik460ex. The camera is OSC. Can anyone confirm what this is, and how to remedy it. BTW the distance between reducer and camera chip is 0.5mm out, measured with calipers. Any info would be most welcome.

[lensman57]

Hi,

I don't know what has caused the curved line at the bottom right but I have posted a couple of images in the camera discussion section taken with my 428EXC with not so dissimilar border artefacts such as yours but mine are much more pronounced. I don't think 0.5mm of error in FF/FR spacing will cause much heartache with a F7.5 scope.

Regards,

A.G

[andrewluck]

Try removing the LP filter and reshoot the picture.

Cheers

Andrew

[Hugechris]

I have a similar issue with my set up I manage to image the out if focus internal reflection of the shadow of my secondary. It's very annoying. No obvious way to get rid of this. I have also seen this issue from some of the observatory class scopes on long exposure too. So we are in good company

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[ollypenrice]

Photoshop!   *

I get this kind of thing from time to time as well. Do you get it on all images?

Olly

* Copy layer underneath. In Curves pin the background sky where it is (which in my case is around 23 per channel) and then drag the curve above that down to horizontal right across to the other side. This white clips out all the stars and gives a uniform background sky. Then just erase over the artefact in the top layer.

[Hugechris]

Thanks for the tips. Will try that out on my abysmal m31.

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[tekkydave]

Was there anything bright out of the field of view in that direction e.g. street light, the moon etc?