A quick snap of the Iris

[JamesF]

Whilst the 80ED was working ok M27 last night, I had a bit of a play with the Photoline 72 and ASI174MM.  This is 75 minutes of 300 second subs.  No filters as I only have one set, but I did take darks for this one.  What's intriguing me is the apparent diffraction spike on a single star to the bottom left.  I haven't worked that one out at all yet.

I have the TSRED 279(?) reducer/flattener for this OTA, and I think ideally it needs it.  The frame is slightly cropped to remove the edge artefacts from stacking, but the stars close to the edge definitely look a little stretched to me.

Now I think of it, I think I might actually have a spare luminance filter.  I wonder if it's worth using that in preference to no filter at all.

James

[john2y]

It looks like something in the imaging train isn't parallel, otherwise the stars would look the same in all corners. Check the tightness of everything. Definitely use the L filter as it cuts UV/IR. 

[JamesF]

I don't think there's much that can't be parallel, to be honest, but without checking I can't recall exactly how I put it all together so I'll do that.

James

[Stub Mandrel]

Nice blend of dark and light, FOV very close to what the 130P-DS would give.