Knowing I was heading to a fairly dark sky (much darker than suburban Brisbane, Australia), I checked photopills for conditions when I would be there, and was very pleased to have an early-setting crescent moon and a long period of galactic centre visibility. Following the photopills mantra of “plan and pray” (the prayer being for good weather), I packed my tripod, star-tracker and Samyang lens.
Alignment to celestial South seemed to work ok, but I still didn’t get point stars for my longer exposures, so maybe my tracker wasn’t quite right, or I have somehow damaged it. (A barn-door device).
This, however, is my favourite capture, the best compromise between high ISO noise and long exposure-time star movement. I haven’t managed to get any joy out of the astrophoto denoise module in darktable. However, fiddling with the various tone curve options - base curve, filmic, and sigmoid, I found the most pleasing signal/noise and aesthetic result by cranking up the contrast on sigmoid way high. The black/white/black frame is needed, I believe, to prevent the eye from wandering to the edges where the star-field ceases, but instead to linger in the colour and light of the core.
Well, I know nothing really about astro processing but… Everything I read a couple of years ago (and subsequently forgot, before I received my as-yet-unused camera tracking platform) was geared around GIMP / PS / AP and not raw editors. It assumed the raw / FITS subs would be initially processed in DeepSkyStacker, Siril or the like.
So here goes nothing, in ART 1.20.1 and nothing else.
Hey Len, thanks … I, too, have previously thought “all or nothing” - that only traditional astro-photography comprising tens if not hundreds of images (lights, darks, biases, whatever) - was going to give reasonable results. But in preparing for this trip, and reading up photopills guides, I was determined to have a go with single exposure, particularly because I had a tracker that I’ve only used a couple of times.
As lamented, it seems that my tracker wasn’t any help, and so my shorter exposures are better for two reasons:
shorter star-trails
less heat-related sensor noise.
The snag is that the boosted ISO value gives amplification of noise.
Yeah, I need to try mine camera tracker. It’s a Sky-Watcher Star Adventurer 2i Pro Pak, plus other little tidbits I added. Actually I did “use” it once in my back yard just to verify it tracked, but the conditions there are totally useless for any astrophotography (trees, light pollution, buildings, etc.).
I fixed up a tripod from some legs I hand on hand and even bought a hard case so I could carry everything in one place:
Problem is I have a non-weather-sealed consumer DSLR plus non-sealed lenses. It’s too warm here during the summer in typical summertime conditions (never mind haze, humidity and mosquitoes) and now is crazy warm at night. It never drops below 80F / 26C at all. That’s about 20 degrees F too warm at best, so thermal noise would kill me. During the winter, the dew is horrendous.
That was two years ago and it sits in a closet. It’s likely I’ll never use it so I shouldn’t have bought it at all. And of course now Sky-Watcher has released the Star Adventurer GTI with goto, so the resale value of this one has tanked.
Mine is a relatively-inexpensive nyx tracker (from https://nyxtech.us/)
Barn-door style, but with the curved thread, should be fairly accurate; I’ve never had the trigonometry and calculus fluency to get my head around the math, so I trust those who do.
My camera is weather-sealed, but like you, I don’t have usually have easy access to a good astro-photography location.
PS - that’s just a screengrab from nyxtech website
This is actually (for me at least) more of a factor in terms of learning rather than imaging (once theoretically competent). If I was competent, I could just set up the shots, kick it off, then process the images - I.e., a single sequence.
But learning is iterative and the “shoot, stack, view, wretch, identify / fix error” cycle would go a lot faster if one could simply step outside and repeat. However the no-sky-at-home situation means for each iteration having to drive 30, 60, 90 minutes or more to a dark site, sit around in the mosquitoes while awaiting hundreds (?) of subs (for a single iteration), then driving home again to examine them.
