Did a total of 87 minutes of integration on M101 and 66 minutes of integration on M81 & 82. I am not too good at processing the final image, so here's 2 of each pic. Which do you like best? Equipment used was Pentax K1, Pentax DA1.4 teleconverter, Pentax DFA 150-450, iOptron zeq25, and cheap Neweer intervalometer. All subs were 180 seconds, ISO 1600.

You show big improvements from day to day! Do you sleep in betweeen ?

I like the second version of M81/82 better. The crop does not deliver more information and the smaller version has better stars and detail and the better overall look in my eyes. The second version of M101 is perhaps a bit less stretched(?) which I like better in this case.

If you allow some manoevre critique......

The stars are a bit undefined. This may be a result of guiding issues (perhaps periodic error of the mount - you do not autoguide, do you?) and perhaps in this context a question of sorting out enough bad subs. Also the lights are generally too bright/burnt out. So perhaps you can optimize your setup and/or the pp-workflow. With the K1 you have enough reserves in the darks and a low noise sensor. Perhaps you can be more critical and reject more bad subs. And it may be better to shoot at ISO 400 or 800 to gain dynamic range. With the darker subs it is then perhaps necessary to improve processing skills on the dark side but you could preserve details on the bright side.

But maybe the burnt lights come from the processing (did you use DSS or Sequator for the stacking?). If so I would suggest to preserve the right part of the histogram by using star masks and/or apply stretching techniques that have less effect on the lights (i. e. proper anchor points in the PS curves tool).

The background brightness in your images is way lower than RGB 10,10,10 which is very dark. Though the empty space is 0,0,0 in real life it is common to have to have it brighter in the images to get a less harsh impression on the contrasts and a more "natural" look. I would advise to set the standard black level of the black eyedropper in the PS levels tool to 25,25,25 (by double right mouse click) and apply this value repeatedly on the background during the processing to hold the background level up and prevent yourself from clipping data accidentally.


If you like you can provide the stacked file and I would see what I can get out of it.

Yeah, I like the second version of M81/82 too. It seems clearer and having a little space around the galaxies gives you that sense of space! :-P

Dropbox - M101.tif

Dropbox - M8182.tif

I used Sequator due to DSS crashing even with 3.3.6 and using that file you sent. It simply doesn't like the file sizes. This evening I can post the files I used to stack.

We'll see if my DSS eats them - I will try in the evening after you did the upload. As you have my mails adress you can also sent me a zip-file via WeTransfer.

If you use Sequator you should produce a linear unstretched file if nothing els helps concerning the overexposed stars. Try this:

- check "unify exposure" when you set the "star ímages" when you have subs with different exposures or sky conditions
- uncheck "auto brightness"
- look if "high dynamic range" alone helps against overexposed stars, else uncheck it
- as a final option set the "color space" to linear. The image will appear darker and DSOs less prominent but the data are in and you can dig them out in pp like you have to do with the DSS results.

Just loading down the tiffs. Is it ok for you if I to post the results here or would you prefer a PM/mail?

Sure, feel free to post them here!

Ok, tomorrow.......

Had to send you a Google Drive link because the zipped set was so big.

Hello Scotty, the data are processed by DSS.


First I did a short try on the Sequator files you shared here. I could get a quite good result with the galaxies but could not get back the overexposed stars and galaxy cores. I have the original sub now. I will try an own Sequator stack later perhaps.

DSS managed the original subs without bigger problems. The only thing is that I must as always follow the workflow I described in the other thread: load files: save file list, close DSS, open again, load list, register, close DSS, load list, stack files. If I do not close in between DSS crashes in the final step of stacking. Perhaps consider to take your DSS problem into a CN discussion if others have the same problems as you have.

After the registration I saw that the quality of the subs of both images varies linear in a wide range (M81/82 from 876.48 points down to 3.46, M101 from 475.42 down to 8.58) . So I choosed for M101 all better 200 (21 lights, 62 minutes) and for M81/82 all better 300 points (17 lights, 53 minutes of light). I discarded the rest.

The result is quite good in my opinion. If it were 3 times more subs it would be great (for the galaxies, perhaps not for the stars). The oval stars do not result from tracking issues but from astigmatism/coma as I think. The stars are no pinpoints but feather at one side. I have the same issue with my Sigma 70-200 2.8 OS.HSM EX....if wide open. It is great for daylight use but not for stars if wide open.

If you allow some recommendations: I would try to get DSS running. It really delivers. Sequator may also deliver good results, but not with your actual settings. With the actual technical setup you must throw away half of the subs not to ruin the stack. Therefore I would shoot more hours or in several night on the same object. You will be astonished about the difference between one and three or more hours of integration time. And I have to say that your data are really good enough to motivate you to bring your processing skills up to let you get the best out of them. Hope you do not mind my criticism !

So here is my approach to your data of M101 and M81/82. The images here suffer a bit from beeing scaled down but I hope you like them and that seeing the quality of your catch pushes you foreward . I sent you the processed files via dropbox links later.

M101



The image of M101 shows 8 galaxies in total!




M81/82 with NGC 3077 in the upper left:

Awesome! I will do it like you say with DSS. I forgot the shut it down between steps portion. I do have a 65mm quad coming and an 8 inch RC on the way too. I also have a Williams .8 field flattener too. The 65mm quad will likely be here Monday so may see first light Monday night. The RC Wednesday. I have enough invested now that there's now way I am going to back out! I may try running one target Monday night until bed, and since I am so far up here that all I have to worry about is wildlife I may run the mount for the rest of the night on another target. Supposed to be clear and dry.

Wow! Thats a tech-battle! You make me jealous . The weather here is poor and stays quite poor. Much work and absence fro my scope for me the next time. Waiting to hear and see from you here in this place after first light of your new equipment. Good luck and clear skies!!!

One more thing: I tried on Scottys originals with Sequator but the stars kept being saturated whatever I tried. The I loaded them into lightroom and saw that they were saturated already in the original subs. So no wonder that Sequator delivers burnt saturated bright stars.


A strange thing is that Lightroom (CC2015.8) crops all the K-1 DNG images into a 1x1 format with 4912 x 4912 pixels when importing! Has anybody an idea why?????

I took the shifted the lights ruler to zero and lowered the brightest stars to 60% brightness with that and exported them as DNGs. But again Sequator delivered saturated/burnt stars. So I will stay with good old DSS and its 32 bit files that are more forgiving when handling bright stars.

That's because I actually took them in 1x1 crop mode originally, so it likely read that the exif data said to do ti that way and did it that way.

Isn't the point of an equatorial mount the ability to track? I'm not being critical. It's a serious question - wouldn't the idea of spending $1000 on a rig like this be the ability to find and track targets?