Focus - What's that ??

A clear night again. Yippee and it's a friday, no work tomorrow. I got out to try an early flare, but the sky was just too bright at 1900. A little later was the ISS pass. I decided to try a little experiment, and shot a single 66 second frame at 18mm with the kit lens. This is the result.



A little later, and I went back out, this time with the scope to try my hand at a third set of Prime Focus images. Anyway, I went through the normal setup routing. Levelled the scope, powered up, dropped the 5mm Ortho in the diagonal, and set about using the Celestion SkyAlign. I ran through the normal sort of stars, three as wide apart as possible. After a moment, alignment failed. Ok, this has happened before. Hit undo and tried again. Another 3 stars, another failure. This is silly. Bear in mind, that with the slewing and jiggering to align this can take a good 5 minutes. Ok, I power down the mount, leave it for a moment, power back up and try again. Another set of stars, another failure. Hmm, thinks I scratching my head, what on earth is going on here. I powered down again, pulled the power from the mount completely. Left it for a couple of minutes, powered up and tried yet again, for a fourth go. Another failure. At this point, I'm ready to kick the alignment into the middle of next week, but not being quite that fed up, decided to try a one star align. Picked Mirfak, it's bright and I know exactly where it is, which is always good. Used my normal alignment process, and this time it works like a charm.

Next, I swapped the diagonal for the camera, and set about getting focus. I checked Mirfak through the viewfinder, being nice and bright I can see it through the camera. Fired a couple of test shots, looking good. Ok, first target, M33. I used the goto to point the scope in the right place, fired a couple of quick test shots to check positioning, looking good. Set the timer and set it going. In the meantime I used the 10x50 bins to have a look around Cassie and Andromeda. The usual suspects. M31, the Perseus Double, the Owl cluster, Kembles Cascade amongst others and meandering around Cassie generally.

Once I'd finished grabbing the data, some 30 frames, I thought I'd try M27. Used the goto to slew, a little out of central, but an easy shift to bring it back. Set the timer and away that went. I had another wander around with the bins, there's just so many stars in and around Cygnus. I found the coathanger, probably a few clusters, but I can't be sure, and I definitely found M39.

A little later and the capturing done, I shot some darks and bought everything in. I started then to process the data. I stacked both sets of images in DSS, then went onto to process them further in PS. It was only at this point I noticed that something really didn't look quite right. I couldn't get the M33 stack to do a thing. The M27 stack was a bit better but still wasn't right. I looked and looked. It's only a small thing, but the image isn't quite in focus. Damn it...

Here's the rather poor M27 result. The nebula is clearly there, but it's just not sharp and clearly defined as it should be.



It's supposed to be clear again on Saturday night (in fact it is and I'm capturing data as I type this, look for another post soon) and I intend to try both of these targets again.