TiffsAndAstro

So I don't need exact back focus as long as I can focus the stars? Ie moving the focus tube will compensate for incorrect back focus? Or is perfect back for required to get stars In Focus and not egg shaped? Apologies if this is a particularly dumb question

Ty for this. I've watched a few videos and my t ring should give exactly 55mm. But what if it doesn't? Not sure how I'd order a possible fraction of a millimeter spacer. I think for now, I'll try and improve the tilt and then ask if anyone can see a back focus issue, but I'm open to suggestions:) Ok then, after looking at your link they go down to 0.4mm. is it just a case of trial and error, slowly building up the spacers and looking at the results?

So...about back focus.... I assumed sort of, that as long as i can move the focus tube via the focus knobs in and out past focus and back, then if its in focus, its in focus. But now im wondering if i have to get the exact back focus right before i then move the focus knobs? i can't see what difference it would make, but then there's lots of things i can't imagine that do actually happen I mean, if the back focus is spot on, there's no need for focus knobs, surely? and yet they exist any chance you know of a good video or link which would explain this? especially with a dslr if its much different from a osc.

All I meant was the zwo camera leaves the option of it working with the asi air in future. I'm a massive Nina fan, but the asi air is still very appealing

Would in be possible to buy the Flo zwo guide scope bundle, plug it into Nina on a laptop to slew and plate solve and leave the main scope free to look through? It's £200 seems to work very well for ap, but why not visual, too? Can try it out before getting an asi air, plus you have a zwo guide cam that will work with aso air if you go for it

i did some test subs 60, 120, 180 and 300 seconds with guiding going. I think my stars are a little oval shaped, but they seem exactly same oval shape in all those test subs. so i suspect the alignment of my camera/reducer/focus tube is a tiny bit out. next clear skies i have a plan to fix or reduce this shape. also i reduced the wait to settle time from 10sec to 6sec to improve speed but will change that back, as i had a yellow nina warning about camera not being ready. Also any good suggestions for a 'final' test run. Ideally something high up and not a boring cluster I'm thinking m101 as it's about the biggest spiral visible all night? Also other people will be a decent judge of what's possible with my gear and so any remaining major issues?

Hmm that's not what i worked out by the online tool, but its very likely i did it wrong. https://www.astrohowto.com/interactive-dithering-calculator/ i have a sw 72ed 420mm f5.9 and the zwo miniguide scope f4 120mm with the zwo120mm min guidescope bundle. All on a sw gti with a proper tripod now. using nina.

yeah watched a decent video on hfr. not entirely sure how to use the graph display of it in nina yet, im assuming higher plots show more stars and tighter stars? which is good ? I also need that bahtinov grabber. not sure if it an addon or built into nina now, but it looks very very useful

I'm reading through it as I get a chance but will take a while. My pc is ok but getting old

Er, why would my pc performance make a difference on reading a guide? Also what is jtol ?

Jtol? You're totally correct about I should learn to use siril rather than just how to click a few buttons to get a result. That will take me some time and more useful when I have decent data to plug onto it. I'm hoping the "dialing it in" stage will end at some point.

it can't be as easy as just setting it to flip. which i didn't obviously will try that next. also i have some sort of mental block about meridian flips. i sort of see when they're happening but i can't picture in my head why it can't just carry on tracking. i think its related to the 'block' so scope can't rotate past + - 90 degress? i guess having a counter weight above camera might be bad its hard to mentally picture. its possible im over thinking it as for HFR, i have no idea how it works and have struggled to google a video. i assumed it was for autofocus but clearly not. if you have a link or anything like that it would be much appreciated. i will trawl Cuiv's back collection and be very disapointed if its not covered. yeah multi star auto guiding sounds cooler than not, so ill give that a go to. got a bahtinov mask on the way for my guidescope but not really sure its nessecery. Watching a good video on hfr by chrizzleys observable universe. I need hfr

bit late to the party, sorry. also new to siril and basically use the pre provided scripts. how would i try this out via the scripts? copy an existing one, rename it and replace the bit of the script that shows my master bias location as =2048 rather than an actual location?

ty for your kind words. i have plenty downtime to watch youtube videos and ask dumb questions on here i was pretty much doing what you suggest with flats before i used nina. and the previous (and only) time i used nina flat wizzard it seemed great. i need to pay more attention to the images from my camera whether its taking flats lights or whatever. also before processing. i think i have autoguiding going well enough. and my focus have improved lots, though maybe still room for improvement. im actually still very happy about not even using my polar scope no more emission nebulas before i get a osc though. besides, its galaxy season and pinwheel looks to frame reasonably big in stellarium. meridian flip management is my next problem i think. my mount flipped out last night on markarian's chain when (i think) it got to the meridian. also maybe a new user profile (or whatever the correct term) in phd2 see if it will then show the x/y thing mentioned above. without that im dubious if my guiding is as good as stated.

ty so much will have a read now. while i intend to get a proper osc camera, i still like the idea of having a dslr i can use in a very portable battery powered setup so anything that would improve my 600d is welcome

I have no idea how or what I'd even subtract 2048 from. Any idea what terms I can Google for info?

ty for this. i changed the value in nina to 7 pixels as this is the value i got from the online tool. this then effects how much guidescope dithers. i just wanted to get the correct value, didn't really study the reasoning using just my very overexposed flats seems to have removed the walking noise. I've post a quick post process of rosette nebula and for about 46minutes, i think its ok. it at least shows my guiding/dithering seems ok. rosette is not a great target to remove background/gradients i think. espectially with so little integration time.

also trying some variants on stacking, i noticed half my flats look black, half white and one grey one. i did them via nina's flat wizard and it worked really well one other time i used the wizard. could this be caused by crap flats? im running a few more test stacks with/without flats etc ***** its crap flats. no idea how crap flats could introduce what looks like walking noise. will post a quick stack stretch for second opinion. i can see hints of rosette nebula, if i squint. but it could just be noise and/or because just 45mins total integration on a stock dslr.

I recalibrated ag between those two targets but the (looks like) walking noise looks very similar in both after drizzle stack in siril. This makes me think it could be either the amount of dither (I calculated it twice online to make sure) or how often, which seems to be based on guessing. Next clear skies my plan is one hour no dither, one hour 12 pixels see how the turn out. M106 because it's up and relatively big? Unless anyone can suggest another test? Or target.

I put a quick stack above. Stars shapes look ok and are least of my issues we Apologies if I sound snarky it's not intentional. I'm on mobile phone right now and old I'm genuinely grateful for all the help and suggestions from everyone. Even 900sl

Also, while my numbers seem to be good, and polar alignment was just a couple of seconds in both axis, my gear is cheap, so it's more than possible my gears overall error/accuracy is larger than these reported numbers. Not sure where that leaves me, but next clear skies I'll test guided but not dithered. Maybe the inaccuracy of my gear will provide enough 'natural' (lol) dithering by default.

I used the online tool and it said 7 pixel dither would be correct for Nina. I've not changed the multiplier in phd2 Rather than minimise walking noise I now seem to have it if you look at my second pic above, I took it after I changed scale to arc seconds in Nina. Correct cam and scope etc are listed if I look in phd2 Also dithered every three frames because I could only find examples of other people guessing. 'more' for shorter subs. I guess it's my baseline

7 pixels in nina i checked (i think) astro tools to calculate it. or some online calculator ill try 12 next clear skies, ty.

Cuiv the Lazy Geek, sorry. he does a lot of videos on nina. i guess this pattern i'm seeing after background extraction, is walking noise? i was dithering every 3 frames (by 7 pixels) so bit disapointed my 2 hours on markarian's chain also has similar noise. ill try not using drizzle on both later, but its a bit disapointing

I changed it from showing pixels in Nina rather than phd2 that should be ok. Apologies for the photos but I wanted a quick way to get an image on here. Doing a screen shot on that laptop then saving then transfering to my desktop is a pain. I think my image scale is 2 arc seconds per pixel. Stars didn't look tight in test shots, but I was possibly really zooming in. Stacking stuff now. If I did learn anything last night it's 1 resetting up guiding etc when changing target loses me imaging time. 2 image targets after meridian flip or Google auto meridian flip and implement. I skipped a cuiv the lg on meridian flip, guess I'll go watch it now Ty for looking and helping. Seems I have auto guiding at least working ok in theory.