The Admiral

You most certainly can and welcome. Indeed, nice small and round stars, and an excellent 1st DSO. What camera are you currently using, how many subs and what sort of exposure? Certainly processing can't be undervalued, and although Photoshop can and is used for astro work, you might wish to look at other more specialised applications. I'm sure you already appreciate that there are essentially 2 types of trailing with Alt-Az imaging, field rotation which depends on the direction you are pointing the scope, and the degree of tracking. The former you can't do anything about, apart from limiting exposure duration, and the latter seems to involve black magic and in what mood the mount is in! Levelling and aligning are both critical though, but even after taking all the care you can, sometimes things just don't work out. I think if it was me I'd hone your skills with your existing camera. Don't foget that the larger the sensor the more obvious the field rotation will be at the frame edges, so you will end up cropping. Keep posting your images! Ian

I think he uses Regim, Neil. To be honest, I 've not got my head around how these values affect the final outcome, and I certainly haven't done any tests. By the sound of it, you have. Ian

My DSS is set to a Kappa of 2, no of iterations=5; I don't recall ever changing them. Is there not a reset to defaults option somewhere? Cheers, Ian

To be honest I just leave it at default, and that applied to DSS and now to AstroArt. I think the problem of not using darks is when there is a need to correct for amp glow. I found an interesting thread on CN: https://www.cloudynights.com/topic/487977-can-we-talk-seriously-about-flatdarkbias-frames/ Ian

Or just don't use darks . Replace them with a good quality master bias. I think DSS has a bit of a fit (or should that be FITS? No? Too early in the morning.) if you have file names replicated in several places, so make sure that the true master bias, and the master bias used as a dark, are named differently. It's a while since I used DSS now. Also use Kappa-Sigma clipping. Seems to work for me, but don't ask me why. Ian

I like that Nige, it's starting to take on a 3-D appearance. One question though, do you ever sleep? . You must have some confidence in the weather forecasts to be up at that time. Ian

That's nice, and revealing. Ian

My first thought is just use more subs. But, if you are limited for time, then I'm not sure it would work like that. Straight off the top of my head, I would have thought that the noise levels would have risen in proportion to gain, i.e. ISO, but the noise would only have reduced as the root of the number of subs. I've come to the view, rightly or wrongly, that provided your 'sky' exposure is getting a way up the histogram, then ISO won't make any difference, for the same exposure. (I've never been clear on whether read noise increases with gain or not!). Except, and as Steve points out, you do gain from the improved dynamic range at lower ISOs. The base ISO that Uranium235 refers to is essentially the ISO at which the sensor output is not amplified before the ADC, and so offers the maximum dynamic range. When I've more time I'll take a look at that link. Ian

Gosh! Well done that man Ian

Yes, the Moon isn't helping and it's a fight to get anything! I'm not sure that you would achieve much by increasing the ISO would you? The image would require less stretching but you will be starting with a noisier image. At the end of the day, it's photons, photons, and yet more photons . Ian

Nice wide-field shot Fabien, with lots of 'spinners' visible; it's a rich area of sky. And that's with only 7 minutes of exposure, with a lot more frames you might even get some colour into the galaxies. It would be interesting to plate-solve and get idents for them all! Ian

Boom-.... Ian

Sadly, in the wrong part of the sky for me, and in any event, I'm afraid you won't catch me out of bed at that sort of time Ken! A half-hearted astronomer

Don't get too paranoid Neil . But it strikes me that it is a tall order anyway, given the lousy weather and shortening nights, irespective of the equipment used. Not to mention the Moon Ian

I got my StarSense 3rd week in March and used it (grappled with it!) for the first time on 25th. Since then I've had no opportunity to use it again, mainly because it has been cloudy or the forecasts were predicting poor conditions and I didn't feel like hauling everything from upstairs into the garden. And now the nights are getting rather short (and I'm not by nature a night-owl ). I suddenly got interested in the latest challenge, until I realised that it was time limited and there would likely be no chance of imaging this side of summer. Pity, it's made for us Alt-Az imagers! Ian

Welcome! You'll find that experimentation forms a large component of this thread, so I'd recommend that you do try galaxies and nebulae. Ian

You've done well with that DorsetBlue, but as is so often the case more can be found in images by being more assertive in the processing . It does no harm to push things hard just to see what is there, and with StarTools I find that the initial images often don't look so good but are reined back as processing proceeds (some may argue they don't look so good when I've finished, either ). Probably above 65° going by Stellarium, but not only that, field rotation demands a much shorter exposure the higher the altitude and the closer to North/South. Ian

Strange isn't it? As you know I've moved from DSS to AstroArt in order to stack my Fuji RAFs directly without having to convert to DNG, so I haven't tried any of this bias for darks malarkey in DSS, but it does seem to work fine in AA, and saves me a lot of time. I can't see any difference between your three outputs, what do you think? Aah, I see you've taken the plunge with PI! Now you really have moved over to the very, very dark side . Then again, if you're using PI, why are you stacking in DSS? Ian

What was the outcome Nige? Ian

Nige, look at the Alternate Calibration Process II. Unfortunately, it is a bit convoluted to find. Use the link, go to 'Users Manual', go to 'lights, flats,......how to make them', then click on the first 'here' link. Sensible approach, do it the simple way first . Interesting to hear what you get. Ian

Now I'm confused. You shouldn't need the bias as well, surely? I think I would have just used the separately stacked bias instead of the flats dark, and a copy, re-named, as the dark. In AstroArt, I only have catrgories for flat dark and dark, both of which I replace by the master bias. Ian Edit. Can you mix raws and tif files in DSS? Try using DSS to stack the bias frames (raws?) and save as a fits. Dunno, might help!

Failed indeed! What file did you put where? Bias frames taken at same ISO? Was it totally blank? Ian

Good point, and if you go for a spotting scope check that they can accept standard eyepices. My Opticron has a proprietary fitting, and doesn't. Ian

That's my understanding Nige, but if you use DSS I think you might have to re-name one of the bias files 'cos it doesn't like duplicate files. I guess whether it's a dark flat, or just the bias, doesn't really matter. You might find something in this recent thread: https://stargazerslounge.com/topic/289900-does-it-work-out-with-bias-and-flat-frames-only/ Ian

Oh, and buy from an established astro dealer, such as the owner of this site, rather than a department store or the pile 'em high and sell 'em quick emporia. You'll get a 'proper' astro tool rather than something that just 'looks good'. Ian