BrendanC

Hey Vlaiv! Yes, I can, and here's the link: https://1drv.ms/u/s!AqovBuVZMwj3k5Jx0oOVsBtGCbWzsA?e=QSp0Tx Would be great to get your take on these too, cos you're fab.

Great, thank you. I'm now going to compare the light leak darks with the library darks in the way @vlaivsuggested, to get some of idea of what's going on with the focuser, but it's good to know my comparison will be a fair one now. Thanks again all.

Thanks for responding. :) Right - so the only reason I wiped was to get some insight into what StarTools reckoned to the 'flatness' or otherwise of the files. I'm totally prepared to accept that this isn't a valid test, and it would be a great relief if not! Here are the frames just stretched in StarTools, no wipe, but this time a bit bigger to give more detail. For the light leak test... ... and for the library darks... I could see even when stretching them first time around that they looked a lot healthier. It was when I did a wipe that I freaked. For the darks, the amp glow to the right is what I would expect to see and is a known pattern for the ASI1600. So, if just a stretch is a more indicative test, would you say that these don't look too bad? That is, I may not have a light leak, and my darks might be OK? Thanks, Brendan

Hi all, TL:DR - I might have a light leak and/or I might have crap dark calibration. If you know of such things, your help would be very much appreciated. Recently I had cause to worry about my calibration files. I've moved to mono - an ASI600-Cool, with a 130PDS - and the results are OK, but it's a fight. My flats have turned out to be part of the problem at least, so I've got a Lacerta box on order, to replace my cheapo LED panel. Hopefully that will sort that. HOWEVER...! I also recently wondered whether I was getting light leakage through the focuser tube. Tonight on advice from @vlaiv, I covered the front of the OTA with the dust cap, two hats and a towel, and the other end with a hat (which is always on it to try and stop leakage anywaye), and another towel. I took four 10-second subs with the Luminance filter, gain 139, offset 50, while pointing my head torch at four different sides of the tube. Then, I did a stretch and wipe on the four images in StarTools, and got this. Fairly conclusive, you'd think. THEN, out of interest, I decided to put my actual darks, from my darks library, through the StarTools test. Here are the results - from a 60s dark, then a 180s dark, then a 1140s which I'd use for narrowband, all at -15C: The first and last are slightly smaller because I cropped them, to make sure StarTools wasn't doing it's 'thing' of creating weird artefacts around images if the edges aren't clean. SO... what can this all mean? QUESTION 1: Are my darks crap? These were taken with the lens cover on, two snoods wrapped around that, then tin foil wrapped around that, secured with elastic bands, leaving space for the inlet and outlet grills and fan, and put in the fridge simply because it's the easiest place to achieve darkness (or so I thought). It's my third attempt to get them right and honestly, I don't know what to do next. More tin foil? Secured with tape? Or, is this just the sensor response, amplified by StarTools? I can see that the 1140s dark has the typical amp glow to the right, but it's the other stuff that bothers me. A lot. QUESTION 2: Can the ASI1600 leak from anywhere else? As in, from behind, through the fan mechanism? QUESTION 3: Finally, if I do have a light leak in the focuser tube, what's the best fix for a 130PDS (Newt) with an autofocuser? Any/all advice very welcome. This is becoming quite a long, hard slog. Thanks, Brendan

@Clarkey I'm in a Bortle 4 zone which isn't bad. I'm still trying to decide what the best exposure times are. Thanks for the link, I've seen the video before and it's excellent. I also have Sharpcap Pro which I intend to use for its Smart Histogram feature some day soon. @ollypenrice Yes, that would be a good idea I guess, but then it would also come down to their respective quality scores I suppose.

I ask because with my trusty old DSLR, I knew exactly how the camera behaved in different parts of the sky, so to the (hang about, has a think, sticks tongue out) East for example I know I get more light pollution from the local village, and as I go towards the zenith, this reduces very quickly. So, I could take, say, 120s exposures when shooting East, and on the same night do 180s facing West where there's less light pollution, but as I went up, I could increase from 120s to 180s and even 240s. Provided I calibrated like with like, using the correct darks, everything was fine. HOWEVER, I'm still wrestling with getting my ASI1600 to behave with LRGB, and I'm wondering whether mixing durations like this just doesn't work with a more sensitive camera. So, to mix (with correct calibrations, to get the most exposure), or not to mix (to keep everything consistent)? Your thoughts?

Thanks everyone. Given that the NEQ6 is rated for 25KG, and my kit probably comes in at less than 6KG, I think I'm tending towards the cone error suggestions rather than OTA or saddle sag. Right, I'm going to stop typing now before that animated GIF causes me to have a fit...

That's what I've been doing for the past 2 years too! It's just that while going through my subs I spotted this and thought it was an ideal example to show what's going on. If this is cone error then I might give Cone Sharp a go - or, I might just continue to live with it. https://www.sharpcap.co.uk/conesharp

Hmmm, interesting. I just have the standard Sky-Watcher mounting, nothing fancy, but it seems to grip the OTA fine. Definitely one to think about though, thanks. I can totally see how even a slight twist pre- and post-flip could cause this. I still don't really actually know what cone error is though, and whether this is it.

Hi all, Continuing to familiarise myself with my ASI1600MM-Cool. I think I'm starting to understand that I have light pollution that my trusty old EOS1000D didn't pick up as readily, which I can see when I compare before/after flip images because the sky gradient shifts around too. HOWEVER, on going through this, I've noticed something I knew was happening, and decided to take the opportunity to get some insight into it here. Watch this: (Ignore the very faint sat trail in the after shot, that's not the issue). See how there's a field rotation before and after? This is a 130PDS on an NEQ6 mount, so the mount shouldn't have a problem with field rotation. Is this cone error? I've never seen an example of it before so this is the closest guess I can make. It's not a serious problem in that I can still get images out of this, but it does mean I have to crop more than I'd like to, for example with nebulae. Any takers? Thanks, Brendan

Hi Ivo, Tested it just now. v3.90 connects to my camera fine with the drivers from the ZWO page (https://astronomy-imaging-camera.com/software-drivers) and from your downloads page (https://www.astrophotography.app/downloads.php). v3.99 and v3.99.1 don't connect, although ASCOM connection still works. I have sent the log file to your support email address. Hope this helps. Regards, Brendan

Absolutely, no problem. I'll try it asap over the weekend, making sure I know exactly what state the machine is at each point.

Hi Ivo, I was holding back on giving specifics because I don't know them yet! All I know is that after updating to 3.91, I couldn't connect. I then got a bit mixed up as to whether I had installed the latest drivers as per the downloads page, so after a bit of fiddling, I decided to go back to 3.90, with the old drivers, and it was fine. So I'm back to where I started, but I'd like to methodically go through this some time and ascertain whether there's a problem, or this is user error. It could be that I was actually trying to use 3.91 with the old drivers. The ASCOM drivers still worked fine throughout. I'll let you know when I know - unless you'd like me to share the log with you?

I quite like using the beta releases because it's nice to help test them, but I'm afraid I also had a connection issue last night with v3.91, despite using the new ZWO drivers. Went back to v3.90 with the old drivers and it was fine so yes, I agree, for now I'm sticking with stable releases.

It hasn't recurred. I think sometimes it's possible to have a completely unique set of circumstances that cause a problem once, and once only. The unfortunate thing from my end is that it was one of my first ever shoots with my new camera so obviously I spent ages going through everything until I zeroed in on it being plans with starts after midnight. If it happens again I'll let you know.

No problem Ivo. I'm not actually human, I'm a small rodent with pointy teeth.

@Spaced Out Hey, I think I just realised, you're the first person I found when I Googled for 130PDS and ASI1600! https://twitter.com/northumb_astro/status/1348964180146212870 I know this is a big ask, but given that you know what to expect from this kit, would you mind taking a very quick look at four of my individual flats and letting me know whether they look about right to you? They're here: https://1drv.ms/u/s!AqovBuVZMwj3kvU5Oenqb053RaZT2Q?e=PweYkj I also included the four calibrated master flats in a subfolder if that's relevant. No problem if not, you've already been very helpful.

Quick question: what was your opinion of the TS GPU corrector? I keep hearing good things about it and am tempted.

Thanks @Bibabutzemann and @Spaced Out

Hi all, I'm trying to get to grips with why I'm getting vignetting with my ASI1600 and 130PDS. I'm using the 8 position EFW with 1.25 inch mounted ZWO filters, and the Sky-Watcher 0.9x coma corrector. I'm looking into various fixes, including the TS Optics non-reducing coma corrector, but if anyone has a similar (ideally identical!) optical train, and they're NOT getting vignetting, it would be good to know. It's definitely all set up correctly. Thanks, Brendan

I like kittens.

Thanks, and that's a good call too. I've flocked opposite the secondary, painted the vanes and internal screws black, but not flocked or painted the entire inner OTA. I might just do that. Thing is, throughout the past two years of DSLR photography, I never had these issues. So, given that it seems my capture technique isn't too bad, and I'm getting the hang of processing LRGB and narrowband, I'm now wondering whether it's a simple case of the ASI1600 being so much more sensitive and picking up light pollution where the DSLR didn't, both in the taking of subs and lights from the flat panel. I had a similar experience when I moved from an AZ to an equatorial mount: suddenly the step up in equipment reveals inadequacies in other areas, techniques, knowledge etc.

In a word, yes! It makes no sense whatsoever. Mind you, the message that APP showed was also factually incorrect and very misleading, and caused me no end of grief going through everything several times before posting. On top of that I also found a mysterious bug in APT while shooting. It's been a nightmare getting all this to work.

'Interesting' is one word for it! The full story (so far) is here: https://www.astropixelprocessor.com/community/main-forum/critical-warning-flat-field-calibration-2/

Wow. This is brilliant advice, and makes it even more urgent that I do the vlaiv test. I can totally see now how the LED light could leak into the focuser tube and cause all sorts of havoc with the flats. And you're right about how a few minutes' exposure could really show up any local light pollution. Thanks!