Dolphin Nebula shot on the 140 APO

January 1, 2025

Ryan William sent this great image

SH2-308

Airy Disk 140APO w/ 0.92x reducer

900" x 45 HOO each

Dolphin Nebula

837mm f5.9

I did a test:

Do an electronic Autofocus in GREEN
Filter Offsets turned OFF
Put on Batinov mask
Take 12 second exposure
Check result (batinov mask centered)
Switch to Red (offsets are off!)
12 second Exposure
Switch to green
12 second exposure

Then I cycled through the 3 subs to see if the angle of the batinov mask line changes between Red, Green, or Blue - thus indicating if any channel is out of focus compared to the other.

But I've done a lot more testing since then too (this was an old draft email I meant to send weeks ago)

Now I've had lots of time with the scope.

Thought you should know optically it's basically perfect. My blue channel is sharp as a freaking tack now.  1.6-1.7 HFR in good seeing.

The telescope is so good I'm selling my ESPRIT150 that I just bought. I was gonna sell the 140 and keep that but I can't sell it.  I cant get rid of it, I love it too much.  It's objectively nicer than the ESPRIT.