M3 LRGB TeleVue NP127is + 0.8x reducer

[ChrisLX200]

Another glob, this time M3 - and also an LRGB. 7 x 300sec per channel. You may wonder why a refractor should produce a diffraction spike, and I wondered that myself! Upon stripping the optical train down I discovered a sliver of dry paint maybe 2-3x thickness of a human hair and maybe 20mm long had come off and attached itself to the field lens of the reducer. That was the cause of the spike    This image was taken without my LPAS filter and the light pollution was obvious in the form of gradients and red colour cast, neither have been completely processed out.

ChrisH

[PaulB]

That's a very tight ball, that has been very well exposed.

Did you use shorter sub frames for the core. I notice it isn't blown out.

[ChrisLX200]

I think the core is not as compact as M92 so I got lucky, I would normally go for 10min subs but that would certainly have blown it. These were all 5min subs. The 490EX doesn't have a big well depth (about 18K IIRC) so at f/4.16 using the reducer it is all too easy to quickly saturate the stars.

ChrisH