oag woes

The new helical focuser arrived from AliExpress. All €23 of it. It's supposed to save time but in this case, exactly the opposite. Unlike the nice fat €45 helical focusers, the cheepo version has a ledge part way down which prevents being able to push the camera any further into the focuser.

Easy fix: Fortunately for the 6" f8, we don't need a coma corrector so we can have as much back-focus as we like. Enter the EOS to t2 adaptor. Great. Except now we don't have enough inward focus, or rather we do, but it's dangerously close to not being able to focus at infinity and remember, we only have non-distant objects upon which to obtain par-focal imaging to guide camera.

To err on the side of caution, several hours later, and with perfectly sized m5 bolts to the rescue, the primary mirror is now around 10mm further up the tube. Prism to sensor distance is now 65mm and there's a few spare mm free for the helical guide focus.

Did it work? Well, despite the atmospheric conditions and 100% humidity, of course I had to try it anyway and yes, the helical mechanism is a godsend for getting both cameras in focus. It only took me 16 hours to work it all out, do the engineering and perform the tests it but hey, c'mon. I saved €22. Next time, I get the one which just works. Probably.

Here we are through the post Borrasca Gloria haze:

open cluster m36 in auriga
450d on nt150l    43x3min @ ISO400

Reprocessed. Not much difference. Blue a bit better?



And the saga continues. They made me do it proper. Siril's photometric colour calibration to the rescue...



Now in StarTools: