BrendanC

Have done all those things! Not flocked the entire scope, just behind the secondary. Have recently chopped the tube and installed a baffle a while ago. So, I need to figure out a way of enabling >1 sec flats with a lightbox that I purchased specifically to help with flats, which at the dimmest setting produces flats of considerably less than a second. No idea how I'm going to do this. I could put bits of paper or a t-shirt or something between them but the whole reason I got the box was to get as pure light as possible, because I suspected using paper etc was giving me bad flats. I'm still very interested in what @vlaiv has to say about flats taken with this camera. Yes. I've tried putting the ASI1600 below the OTA but it doesn't work with the rings and auto focuser. Everything balances fine, and as far as I can tell I'm not getting any focuser slop. Why?

Nice spot, thank you. That's probably something to do with me running the same plan to produce flats as for dark flats. When I import them into APP I apportion them manually so it's not an issue.

Good point, thanks for this. I'm working on removing the bad subs. I still have no idea why I get gradients on everything else though. Btw I started at 11pm, not 10pm.

Thanks again Vlaiv. I'm completely stumped. I have absolutely no idea what could be causing this. I'll see if I can do a longer animation maybe using PIPP and try to understand this, but I'm afraid I'm back to square one. It's good to know the calibration's fine though.

Thank you @tomato. Maybe there was fogging too? I really don't know. One thing I'm consistently seeing is that people are genuinely getting better results with PI than with StarTools. I simply cannot get the stars right in StarTools, and it's creating havoc with the gradients too. I'm currently trialing PI so perhaps I'll just spend more time on seeing how I get along with that. I understand that this is a faint target, and it's not so much what's going on with the DSO as what's been happening around it that's been bothering me.

Thank you again @vlaiv That would be par for the course given my luck so far! I've had a weird bug in APT in which a plan would crash if it ended after midnight, and then another where the camera wouldn't connect. Both took several hours to isolate, and were among the very first sessions I had with the camera. Neither of them were to do with anything I was doing wrong (I actually helped Ivo fix the second one, which was until then a showstopper for the v4 release). I'm right now stacking the top 80% to see if that makes a difference (I wish APP were a bit faster). I'm also going to experiment with neutralising the background, which strictly speaking I shouldn't do when using StarTools but if it works, it works.

OK, so I'm back. Here's some food for thought... Here's NGC 4236 using all my data, which is about 7 hours' worth. Slightly better maybe but still bad stars. Here are some examples of what I've been up against - these are just taken into the StarTools Compose module, binned, wiped, and then given an AutoDev stretch to show what's going on in the data. Gradients a-plenty. They were all taken in quite radically different sky conditions, different place in the garden, different methods of capturing flats and darks, different offsets and gains - but still, mad gradients and stars. I've been able to make something of them, but this is after judicious cropping and fighting the gradients, which I just feel I shouldn't be having to do with this camera. Regardless of how faint NGC 4236 is, one day I really will want to do a full star field, for example an open cluster, and I just won't be able to that at this rate. So, state of play is: Bad stars - is this microlensing? Too much exposure? Too little? (btw I know the 'bitemarks' are the result of the focus tube impinging on the FOV which I'm also going to fix soon) Gradients - is this a light leak? Bad filters? Bad flats? Too little data? I don't quite see how more data will fix these gradients. @vlaiv Here are the averaged masters (plus stacks) that you asked for, all done at 32-bit in APP, 901MB in total, which hopefully you can download now (and anyone else who fancies a go): https://drive.google.com/drive/folders/1wt0HEs7_vwI--TeWzWcmMQO7MIKoXgQh?usp=sharing You've already helped me establish that my library darks are ok, but that I might have a leak in my focuser tube. So, I've got the focuser tube wrapped in a snood, which also has tin foil lining it. However, I must admit I haven't since tested this using ImageJ as you recommended, which I probably should. I am sorely tempted to try, one night, actually wrapping the whole scope in foil, just to try and block out any extraneous light whatsoever, and see what difference it makes. I'm still very puzzled as to why this should be happening though, given that I was achieving 300s exposures with my DSLR, with perfectly flat wipes in StarTools. I should also mention that Ivo, the creator of StarTools, is very much of the opinion that my problem is with my flats, which is why I got the Lacerta box. However, given that you have short flats exposures then what do you make of this: @inFINNity Deck - how do I determine whether I have one of the older models that has this problem? Is it possible that Vlaiv's model doesn't have this issue? Other points: Which one? And, out of interest, why did you go back to a DSLR after the 1600? And then back to mono? Really don't want to change the scope too. I've invested 2+ years getting to know it, and it's a fab little performer. As I said above, I was achieving 300s exposures with the DSLR with none of these problems. The light box, when taking flats, is absolutely butted up against the OTA, with a retaining mask around it, there is no light leaking out from that at all. Yes, and I do use one. At the end of the day, my real worry is that, after all this, if I did then decide to go back to an OSC - not least because I also find the 4x time/storage/processing etc very fiddlesome with mono - and I continue to have these problems, I'll be totally at a loss. I find this all constantly gnawing at the back of my mind, like tooth ache, and it's not a good way to live currently. It's like those threads you read in the forums, and think 'Thank God that's not me' except, this time, it's me. The other big problem is that I'm doing this totally on my own, with nothing to compare anything with. I'm toying with the idea of contacting a local astro club to see if they could help. So, if anyone's reading this who lives in Oxfordshire or Bucks, and would like to help (and I'd be prepared to pay), then please feel free to message me.

Thanks all. I guess what's really bothering me is the weird gradients I'm getting with everything I shoot, plus bloated stars, not just this instance. Integration time doesn't seem to make much difference. I really appreciate @david_taurus83 taking the time to do this, but still I can see mottling in the background and artefacts in the stars. On this basis I would still want to sell the camera. As I said, I'm away today and tomorrow but will give serious thought and feedback to all of your helpful suggestions, plus provide @vlaiv with what he needs. I'm still minded to move back to an OCR but let's see how things go here first. Thanks all again.

@vlaivI'm afraid I'm away from home this weekend and there's only so much I can do with my mobile phone. I'll see what I can do when I'm back. @inFINNity Deck I've heard of the micro lensing effect but these are not especially bright stars. If this camera can't handle them then it's not a viable camera.

Thank you. I'm working on the theory that my flats aren't working - I've heard tell that the ASI1600MM-Cool doesn't like flats of a short duration. Mine are taken with the light box at the dimmest setting, so without adding paper/t-shirts etc that's as long as they get. But I would very, very much appreciate your input.

Thanks, but I just cannot face another round of 'what if'. I need someone who has an ASI1600MM-Cool, preferably with something like a 130PDS, who knows what might be going on here. @vlaiv, I understand you have this camera? If you have some spare bandwidth and time, would you be able to look at my data please?

I am discouraged though! Very! Thanks for responding though. Looking through my data again there seems to be the mother of all dust motes on the red filter, which I've noticed once before, but I don't understand why it hasn't been fixed by the flats. Regarding alignment, when you say you find it difficult to align LRGB, surely you use stacking software? Anyway, I'm just going to leave this now and see what the consensus is. I'm still very tempted to leave this all behind because it's a money pit, and I'm very uncomfortable shelling out hundreds of pounds on fixes.

Hi all, So about two years ago I got more serious about my astrophotography and invested in an NEQ6 mount to go with my 130PDS and astro-modded EOS1000D. I had a hoot - really enjoyed it, got my workflow down with APT and StarTools, produced some images I was really proud of, all good. However, I'm probably moving (back) to London in the next few months, and figured I should make the jump to mono, as that's probably the best way to make this work there. So, I got an ASI1600MM-Cool - and I just cannot get the results I should be getting, specifically with LRGB. Narrowband is OK, but I want to shoot broadband too. There are two major problems: * Weird, wacky gradients in my stacked/calibrated files which I have to fight in StarTools to overcome * Bloated stars, on all channels See NGC 4236 below. It's just not what I would expect, and it's as good as I can get it. I'm fairly confident I could have done better with the DSLR: Details are: 3:35 hours (L 114x50s, R 16x150s, G 16x150s, B 16x150s) Gain 75, offset 15, cooled to -20°C Bortle 4, No Moon during shoot 25 flats and dark flats per channel, 50 darks per sub length 130PDS, NEQ6, ASI1600MM-Cool, ZWO EFW with 1.25" mounted ZWO LRGB & Baader HSO filters, Sky-Watcher auto focuser with HitecAstro DC Focus controller APT, PHD2, APP, StarTools, Photoshop, NoiseXTerminator Getting consistent answers on this when I consult the forums is like asking ten experts on anything what the problem is: you get ten different answers. They've encompassed: * My flats are wrong - so I got a Lacerta light box and dimmer. Still there. * My bias/offset is too high - so I just did an evening reduced from 50 to 15. Still there. * I have a light leak in the focus tube - so I've got a snood with silver foil wrapped around the focus tube. Still there. * My darks have light leaks - so I've redone them with said snood and foil in the fridge. Still there. * There's an ambient light source somewhere - there's a faint, distant street lamp that never caused a problem before, moved the scope away from it behind a wall anyway. Still there. * My focus is out - but I've checked APT's autofocus routine with a Bahtinov mask and it's spot on. * I've got pixel leak - I mean, really, what can I do about this or test it? * The filters are the wrong way around - nope * My filters aren't any good - but they're the ZWO filters that should work with the camera * StarTools isn't up to the job - don't know, tried the PixInsight trial, meh, still think there's something wrong somewhere that processing just won't fix ... among others. To date, nothing I've really produced is as good as I was getting with the DSLR. And the last shoot, last night, even my stars were all wrong which I think is probably collimation, which I think I might have fixed today, but I'm not sure I care any more. So, right now, I really am, at last, on the verge of giving up. Four months down the road, I've reached a dead end. I cannot figure out what I'm doing wrong, and I just can't face another round of research, advice, trying to address X, Y and Z, build more libraries, spend a night or two gathering data, processing, waiting with baited breath and pounding heart, hoping against hope... and seeing the same crap come out. It's actually starting to get me down, and this should be an enjoyable hobby. I simply cannot afford to throw more money at this, for example with new filters or software eg PixInsight. So, my options are: * Sell everything and end this madness * Get my kit to work * Sell just the camera and invest in an OCR, which is kind of what I wanted to do at first anyway but I'm not sure an OCR will hack it in London (although I could consider a dualband filter) So, what would you do? If you have a VERY GOOD IDEA what could be going wrong, please feel free to offer advice, but PLEASE don't speculate because I've had enough of going through everything every time. If you'd like to take a look at my latest data - my fourth abortive attempt at NGC 4236 - then it's here, flats, darks, dark flats and subs, the whole thing (14GB): https://1drv.ms/u/s!AqovBuVZMwj3k7IhjlZENYMs2gXAvQ?e=0A26GS (the stars aren't right in these subs, but that's only as of last night, after messing around with collimation, which as I say I think I've fixed since) At the end of the day, this really is just a hobby, and I have to keep this in perspective. I could even go back to a DSLR, but as I say, I'm tempted to go just one step back to a cooled colour astro cam and get, say, an ASI1533MC, which would match the scope and guiding system. Ideally I'd get my current kit to work, but it really, really is not having it. And if this continues to get me down, I'm prepared to jettison the whole thing and move on. Cheers, Brendan

Ah, right, just re-read my original post and I can see that, when I say 'shooting East' or 'shooting West' it could mean east/west of the pier, as in, pre/post flip. Soz. I'm using my loose, decidedly amateurish terminology here to mean 'shooting over the local village where they've build a load of matchbox houses for the plebs' and 'shooting over the once-bucolic countryside which was all fields before the plebs came'.

All I know is that, from experience with shooting to one side of my garden, where there is a buildup of local housing and streetlights, I could never expose as long with my DSLR as I could when shooting to the other side which is more fields. Same as when shooting close to the horizon as nearer the zenith, but I understand that's also about air mass. I'm not talking 60cm here! There's obviously a continuum from one extreme to the other, it doesn't suddenly step up or down every 60cm, right? Now that I'm using a much more sensitive camera, it would appear to have exposed a light leak in my focuser which I think I've fixed. But that still leaves open the question regarding differences in sky conditions. One way to test this, I've been thinking, is Sharpcap's Smart Histogram feature. I have in mind a plan to create a grid of coordinates, have the scope slew to them, and measure the sky brightness and calculate an optimum exposure time. I might even do that tonight, and I'll share my results here.

I'm sorry Vlaiv, but when I read your posts, they're dazzlingly brilliant and all I can think to say is 'wow'. My small contribution is that I used the Entropy Weighted Average algo in DSS with mixed results. Sometimes it was OK, but for complex images such as the Rosette Nebula, with lots of stars against a rich nebula background, it created very noticeable halos around the stars. Pity because as you say, it seems ideal for this situation (which is also why I used it). Also, DSS doesn't seem to be very actively developed any more. I'll hand this thread over to folk who want to go into this deep dive, but before I do, have you ever worked with the developers of stacking and/or processing software? If not, you should, it seems you have a lot to offer especially in relation to your algorithms and insights. I've been experimenting with Siril recently and am finding it measures up very nicely alongside the pay-for APP, and to get your ideas into an open-source solution such as Siril would be wonderful. Same with processing: I'm a big fan of StarTools, because it's so elegant and algo-driven as well as affordable, and I wonder what you could do to improve that too. Just an idea!

Yes, this is about amp glow, but my other trials and tribulations have been about light leaks, flats, bugs in software, exposure times, gain, offset, ADUs, and a bazillion other things with this mono setup. It's very like when I moved from an AZ mount to EQ, the increased sensitivity and different workflow have both been quite tough to surmount. Aaaaanyway, to cut a long story short I lost my mind I think that, as of last night, the way ahead is clear. The new flats from my light box seem to have made a big difference, as does going down to -20C, and wrapping the snood around the focus tube, well, I'm not sure what positive difference it made, but it didn't cause a problem so it's staying. Very first cut of the Sunflower Galaxy, still to add luminance and a touch of Ha: I possibly could have done this with the previous calibration files and at -15C, but this was a dream to process. I almost didn't have to denoise at all. I have tried without darks, but I didn't like the result. I may try it again sometime, but at least I've overcome some more hurdles with a lot of help from the good folk here.

Interesting feedback, thanks. I must admit I hadn't really considered not using half the sky! But doing two objects in the 'good' half makes sense. Having said which, you could class the lower half as 'bad' too, which leaves me with just a quarter of sky.

I'm getting close to that actually, and then throwing it in the docks.

@Padraic M The only difference is the 4GB onboard RAM that the Pro has, to help with shifting data quickly. I've opted to wrap a snood around the focuser, inlaid with tin foil, which I tried last night and it seemed to work, as in the focuser could still move in and out, and the images didn't seem adversely affected. As for taking darks, I always go totally neurotic about light leaks, so the last time around I had the camera in the fridge (because it's the easiest place to assure dark without it getting too warm), with two snoods on the lens cover, tin foil around that, elastic bands holding it all together tightly with just the fan grilles left for cooling. With my new light box, unfortunately I couldn't get one small enough for the 130PDS so mine's for the 150, and I'm going to improvise with an inlay around the circle on the box so that extra light isn't cast onto the focuser tube when taking flats. Perhaps I should just go back to observing? It was so much easier...!

Wow, my first ever mention! I must be becoming popular. Here's the link and yes, you're right - Vlaiv is the man with all the answers, and gives a very interesting analysis of my darks:

Unfortunately, it does incur amp glow. I know what you mean though. With my DSLR I eventually stopped using darks because I got exactly the same result with just bias - and the difference in time and effort in just taking a few quick bias snaps, versus building an entire darks library, was huge. So perhaps I can consider taking shorter exposures without darks, but I'm afraid longer subs really do show the thermal signature of the ASI1600's sensor. Bit of a bummer really, and to be honest I'm starting to regret my move to mono.

Wow. This is incredible analysis. So, the upshot is: if there is a slight leak in my darks, it's not significant, so they're still viable; but I do have a leak in my focuser tube. Meanwhile I'm going to think about getting down to -20C for my subs. I have read that there is a difference between -15C and -20C but having seen your 60s I can see that it could have a real impact. Right, well, this means things aren't great in that I have a light leak, but not as bad as I thought in that the darks I'm using are still OK. Hopefully now I've taken delivery of my light box, my new flats will also help with calibration (bearing in mind I'll have to retake all the dark flats too...) Again, thank you Vlaiv. I know I keep saying it, but I mean it! Thanks, Brendan

Thank you again. This is all really useful input. When you say 'we need numbers for that', do you mean to compare your masters with mine, or to compare my garden darks with my master darks? The full details for both are that the 60s and 180s are taken at gain 75, and the 1140s at gain 200. The masters are a stack of 50 each. They're all at offset 50, at -15C. I chose this temperature because the camera wouldn't go to -20C in the house, which was at 22C, so that told me I might have difficulty getting to that temperature in summer, so figured this could be a good approach for consistency and ease of calibration. However, I can see that yours is smoother, so that could be why. I might reconsider this decision. It's certainly extremely useful to see yours. I'm pretty much 'flying blind' here - I have no idea whatsoever of what I should be seeing, nothing to compare anything against. If you'd like to look at the individual subs, I just put five of each into that shared library darks folder. No problem if you have other stuff to do! However, I'm going to download that software and take a look myself, to see what I can figure out. Thank you once more Vlaiv, you're a great contributor to this forum and I really appreciate it. Cheers, Brendan

Thank you Vlaiv. So, looks like I do have a light leak. The 10s shots are the ones I took in the garden last night with the scope covered. The others in that folder are masters from my darks library, and are 60s, 180s and 1140s in length. I still don't know whether they're viable or not as per your darks library, so I need to find out. So, questions now are (to help me replicate your tests and be able to do them for myself in future, for example to analyse those masters in the darks library): 1. What software are you using to get those ADU values? 2. How do you 'subtract' one sub from another? I know this is the essence of stacking but what package would I use to do this? Thanks, Brendan