Seanelly

A big welcome from your Ottawa neighbor. Your enthusiasm shines through your introduction. I've had a Dob scope for many years but only started into imaging recently, and so share some of that fresh excitement you exhibit. I've received an embarrassing amount of help from this group and can tell you that if you have a question that can be answered you'll find the answer here. Enjoy!

Friggin' awesome.

A beautiful image.

Thanks for the lead on the free app Fitswork4. If I can correct my problem and minimize my costs with PS at the same time I'm all over the suggestion!

Thank you for the response and suggestions. I didn't think that flat/dark/bias frames were much of a mystery until now, as from what I read here in the past they sounded simple enough, though flats seemed such an arbitrary thing from the various info I gathered, but then I figured it was an indication that flats' gathering had wide parameters. Another example of corner-cutting on my part to try and get images as quickly as possible.

Here it is, Carol. About 11 hours of 5m raw exposures at 1600i unprocessed from DSS with 40d, 48f, and 75bias frames (all in master frame format), taken with a modded Canon T6i. I'm looking forward to seeing what you can do with it. I have a question about the two calibration frames, darks and flats, that I'm hoping you can enlighten me on. I've read that they should be taken at the same iso and temp as the light frames, and I took care of that in the first session (there were a total of three sessions (actually four, but last night I could only get eight frames before clouds gathered) in the image provided), but what about added data in later sessions when the temperature is different? The first session, when the cali frames were produced, was in -15C, the next two sessions were in -10C, and last night's meager eight images were at -5C. Are these temperatures close enough to use the same darks and flats masters for all the data? If not, how do you get around adding more data to an image when they are taken at different temperatures? Autosave004.tif

On a whim I de-selected the 'CANON EOS REBEL XTi' (seemed closest to my REBEL T6i) in DSS and selected instead the 'CANON REBEL' and my problem is now manageable. It takes a couple of strong curve changes with the usual levels adj to start noticing the bands, and I can work around this. I do so love SGL and all the great members willing to spend time on others' problems. Thanks, and the way things are going, you'll probably read me soon enough on another technicality!

My banding problem is now reduced to a workable state. It takes two good curve stretches to start hinting at them. In DSS I de-selected the 'EOS REBEL XTi' (the closest the list comes to my camera) and selected instead the 'EOS REBEL' (there is also an EOS REBEL XT, but I did not try it). If you are using DSS do you know what camera is selected? I'd like to think I helped someone for a change.

By the way, do you know what the difference is between the 750D and 760D? I can't find any variation in the specs.

Definitely the symptoms I'm seeing if I really stretch out the image. Perhaps someone with a good grasp of PS will chime in, but in the meantime I'll start asking questions on their forum and reading up on the options. Thanks for the help.

Hi again, Carol. Well, a restacking with a Rebel DSLR selection in DSS has improved the image, but not completely eliminated the banding, as even with a mild curve stretch they start making their ominous appearance, and now that I know they are there, it's all I can see. I'm reminded of the time my father took me with him to get new tires for the family car (this was 50 years ago when just about every car had whitewall tires) and all the way home I could look at nothing but the whitewall tires on every other car around us! Seriously, Anthonyexmouth above has delivered an unsettling bit of proof that it could be the AF pixels on the DSLR sensor, which if true leaves me wondering why anyone would use a DSLR for astroimaging. But the fact that they do and do it well makes me wonder even more what the heck I've done wrong here. Maybe when I add more data, and understand Adobe PS better, I can hide these artifacts. I've never been 100% sure of my flats, as it seems such an arbitrary process, with many stated ways of achieving results, but then this may just be an indication that the parameters are wide, and so I will restack without them and see what gives, also the darks and biases if the bands persist. Also I will try another Canon selection in DSS, as there are three for the Rebel. Thanks for hanging in there with me.

Hi, thanks for the input. The latter half of what you've stated is bang on, as I'm counting 7 bands of 5 or 6 tightly grouped lines in each, but I'm baffled by the stretching you mention as a possibility, as the bands are evident even without a curves stretch, as shown in the first image I posted, which only has a level adjustment, while the second image does have a slight stretch, but very slight, and could not be defined as 'really stretching' in any way. I thought Carol's reply might be the ticket (I did not select my DSLR camera in DSS), but as it turns out, while the right DSLR selection has seen the bands faded to a degree after restacking, it is still evident with a slight curve adjustment. I'm going to try several restackings again if necessary while leaving out of each either the darks, flats, or biases, as Rush has suggested, to see what effect that has, as I'm not 100% confident in my flats being bright enough, at least, but your pinning the tail right on the donkeys ass with that info about the sensor has me wondering if I made the wrong choice in going with a modded DSLR over a CCD camera. The Canon T6i (750D) has the upgraded DIGIC 6 processor, one of the reasons I was convinced to go with it, but if this is the best it can do, I'm surprised that anyone is using it for astroimaging. There surely must be a way around it in Adobe, but I've only had the program for a week and don't know it very well. I'm a rookie with pretty much everything I touch in this pastime!

Thanks for responding. I will try as you suggest if Carol's discovery doesn't pan out (the DSLR box was not checked in DSS). I'll restack with that done and see what I get. (Man, every time I think I've got everything under control, something else pops up!)

Thanks for responding, Carol. You're on to something here, as I'm checking the settings now and the box was not checked for a DSLR (just before you answered I edited my post to add the modded Canon T6i 750D I'm using). There's no hiding my ignorance in all this! But while there are three selections for the Digital Rebel, I don't see a selection that exactly matches my DSLR, a Canon EOS REBEL T6i (750D). Is close enough okay, or do you know which of the three I should choose? (I'm thinking you have access to DSS).

How frustrating! 3 sessions and 11 hours total of data on M81 and M82 and I can't get rid of these horizontal lines that litter the full image. I've cropped M82 to give you a better look. Both examples shown here are 11hours of 5m exposures at 1600i with modded Canon T6i and went untouched from DSS with 50 each of dark, flat, and bias to Adobe PS. The d,f, and bias frames all came from the first 3.5 hour imaging session, at about -15C, and the other two imaging only sessions were around -10C. The first (1) image shown has a careful levels adjustment only in AdobePS, and the second (2) image has an additional very light curves adjustment. After the first 3.5h imaging session was processed I thought the lines would go away as additional data was added, but that is not the case. Something tells me the problem is from the dark, flat or bias frames, but I was very careful in collecting them and I've looked at each one individually along with every light frame and all data looks good. The only thing that I can think of is that perhaps the flat frames were not bright enough? I've left both images as tif files to download so that you can see them exactly as they are. Further info, if possible, available upon request. Ideas, suggestions, or a solution would be greatly appreciated, as I have no idea what in Heaven's name (or Earth's) is happening here. (1) DSS 11h 2m 5ex 1600i level adj only.tif (2) DSS 11h 2m 5ex 1600i level adj and slight curve.tif

You can't and I can't. But cannabis is legal now in Canada, so I'll let you know what shapes I see.

Thanks, I'll check out the link. (What a great image, here!)

I have Affinity on my list of potential software. Now that I have a 64-bit operating system I will look into it. What I like about it thus far is that you can buy it, rather than continuous monthly subscription, and it has good reviews as an alternative.

Hi, thanks for responding. I'm beginning to realize that processing the data is pretty much everything when it comes to Orion, and that surely must be the case with all other data as well, which makes sense. I just got a dedicated laptop for the scope and data processing, as my old one was running 32-bit Windows and Gimp imaging led to crashes, so I should be good to go with Gimp, but AdobeCC ($!) will have to wait a while, yet. So much to learn, and such weather to learn in. I got 40 minutes of Orion data last night (8x5m between two trees!) but set-up was in -18C and tear-down was -20C (Ottawa, Ontario), and my limited experience and the continuous crappy weather not giving me a chance to practice, set-up was long and brutal even with hand and toe warmers! Tear-down was as fast as humanly possible, all the stiff cables and ice-cold paraphernalia quickly placed in the covered plastic container I use to keep the laptop and camera remote warm (I have a lightbulb on inside), and the whole mess then laid out in the den to warm up and dry off before repacking. My wife is beyond thinking I've lost my mind, given the fact that I've been out with the Dob so often in cold weather that she's given up trying to analyze what makes a man do such a thing voluntarily time after time. And now this. We have an unspoken agreement, I think: I don't question the strange stuff she does and vice-versa!

Hello, again, thanks for the link. I checked out the video, but he does not explain how he manages to achieve the spectacular final image with such core detail shown at the end, other than a couple of hints, being 'hundreds' of ten-second images combined with many three-minute images for a total of several hours of data. He does not mention any special changes to the camera settings during imaging, which leads me to believe that he is somehow using the ten-second images for the core and the long-exposure images for the outer structure, though in what way is not mentioned. P.S. I just found his U-tube video on processing all (3h, 8m) of the Orion data in AdobeCC, and he mentions using just the default parameters in DSS and removing the final stacked image straight to Adobe without any alterations, so that tells me that his final image is achieved stricly through Adobe processing. I willl now watch that video in it's entirety, but I will not be able to use the help for a while, because I do not yet have Adobe Photoshop. I just shelled out for a dedicated laptop for running the scope and processing the data and have used up my financial 'allowance' for a while. All this info is great to have, however, as at some point this year I will have the software and hopefully the data and more experience to achieve better results.