M3 questions

Hi Frank,

Possibly, Photoshop has a problem with handling 32bits TIFFs that APP creates from your stack. I have it on the RFC list to give you the possibility to save it as 16bits TIFFs and possibly this will help you in the export to Photoshop. Sara has requested this. The 32bits FLOAT data from APP is normalised in the range of 0 to 1 and maybe this gives a problem for PS in correctly interpreting the data.

Another question, do you need to open the tiff with Camera Raw? Can't you just load it as TIFF into PS? Is the results different then or the same?

Cheers,

Mabula

Thanks a lot! This helped. Somehow the "open automatic with camera raw" was turned on and somehow this messed up the image mode. 

Now it opens in 32 bit and after converting to 16 bit all looks great. 

Here is the result. Just some mild 2px Unsharp Mask, levels slightly darker, and the Astronomy Tools Color blotch removal and space noise removal.

Actually the least post processing I have done and the best result so far (still way to go though 😉 )

Mhhh... looking back at the original from APP and this one I am still not happy... the convert to 16bit is somehow very lossy or I am doing something completely wrong. With which software are you guys doing the post processing?

Posted by: Frank

Mhhh... looking back at the original from APP and this one I am still not happy... the convert to 16bit is somehow very lossy or I am doing something completely wrong. With which software are you guys doing the post processing?

Hi Frank, 

I agree, the first APP version is better. More signal to be seen in the background and less saturated stars. In your latest version it seems you have thrown away information by being too aggressive on the black point in levels and possibly being too aggressive on the sharpening possibly?

Regarding post processing in photoshop or other applications, I personally do everything in APP nowadays but used to use Photoshop a lot.

Maybe have a look at this video on post processing in APP using RGB data if you haven't done so already?

https://www.astropixelprocessor.com/post-processing-background-and-star-color-correction/

Let me know if that helps 😉

Mabula

Thanks Mabula, will look at it tomorrow!

Actually I watched your "Light Pollution CBG, CSC" video. This helped a lot. Also I exported the result into Photoshop as Jpeg which also made things a lot easier.

That is the latest version. Lets see if I can get more out tomorrow after watching your post processing video.

Ok, super. I went through your post processing video again and did most of it in APP, I think this is now the most I can get out of these subs. The noise generated by a DSLR at 25-30degrees is just not funny...

Any suggestions for improvement are always welcome 🙂 Thanks for your help again!

Best F-

Hi Frank,

Yes these 2 are certainly better 😉

In your latest version, I think the colors are very good! Bluesish stars (in the previous version those stars were more cyan) in the globular cluster and some yelow/red stars as well. Really looks good to me. (similar to the colors in Sara's M13 😉 )

There is some reddish noise in the background, maybe you injected some saturation into the background? Otherwise, the stretch is maybe a bit too strong... for the data.

Regarding suggestions for improvement:

How much integration time (how many light frames and their exposures) and what kind of optics and camera did you use?

What Iso did you use if it's a DSLR?

Could it be that focus was not yet perfect?

Kind regards,

Mabula

Thanks for your reply and your suggestions.

Yes the red is somehow strange. I tried to fiddle with the saturation threshold but even after light pollution removal etc I could not completely get rid of it. It can well be that it really is some light pollution residue, I am quite close to Cologne and M3 moved straight over the city this night. 

I tried several exposures as I am not quite sure still how long to expose globular clusters. I mixed around 20 * 60s, 20 * 180 and 20 * 300 all ISO 400 to see what the result was. I had to ditch a lot of subs as my mount (Bresser Exos-2) is actually not as good as I hoped, I am currently trying to send it back to the dealer and get a HEQ5. As for the OTA it is a GSO 6'' Imaging Newton with 600mm focal length. The cam is an EOS 1000Da with Baader MPCC and an IDAS LPS D1 filter. 

I am still struggling with the collimation. It looks fine to me through the cheshire but maybe I need to seek someone in the area with more experience to help me set up the secondary... So yes focus might not have been perfect even though I used a Bahtinov mask

Best F-

How lovely it is to have a day off and fiddle around with stars  😉 

Here is the latest version. As suggested a little less stretching / curves to 65/60 and 185/190, just very mild level adjustment in the blacks around 2-4 per color, very mild unsharp mask (50%, 2pixels) and high pass filter overlay 2px radius. 

I think this is the most natural looking of all.

File over 15MB so here is a dropbox link:

www.dropbox.com/s/z8fg3tf9djt6jie/M3-St-5.png?dl=0

Edit by Mabula:

converted the PNG in dropbox to a JPG at 80% quality:

Very nice Frank, I think this is probably as good as you can get from the data. The colors are good and we can  see some faint signals in the background 😉

Further improvements should probably come from having the newton a bit better collimated I think. This should help in better and sharper details 😉

And... for your EOS1000Da it's probably good to use a bit higher iso to reduce read noise somewhat? Do you know how the read noise changes per iso for your camera?

Check this link:

http://www.sensorgen.info/CanonEOS-1000D.html

By increasing the iso to 800 or even 1600, you might get less noise in your background 😉 The read noise gets quite a bit lower if you increase the ISO for your camera, so I would definitely try this.

Cheers,

Mabula