Do Your Best Please! M57

[aGreyarea]

Hi All,

I rarely get out anymore but I recently managed to get a couple of subs before the batteries went.

However its been more than 2 years since I tried to process an image and I dont have the fabled PS to do it with so have been trying to use GIMP. This time I cannot even stretch the histogram properly and just want to see if its me or something Ive done wrong. The image is a stack of 6x 3min subs of M57 no flats or darks and I know they will help but Ive achieved better results than this before with fewer, shorter subs.

Please have a go at it and post what you get. Its over 100mb so please get it from here:

https://www.dropbox....70ymq0/m572.TIF

Many thanks

Liam

[billhinge]

Here is my effort, not sure what your issue was ? I'm sure others can do better

[aGreyarea]

Hi Bill,

Thanks very much. I'm definately going wrong somewhere, this is what ive got.

I tried clipping the right end of the histogram, not clipping the right end, lots of gentle curves, really steep curves, cropping/not cropping the edge off before getting started on the levels and all the combination of these. All the time, it just seems to sort of 'puddle' into blobs of colour on top of each other with no detail in between. I'm missing something simple i'm sure but I cant see what. I thought it should be:

Levels if required

Curves

Levels

Curves

(and repeat until you can see the nebula) Ive done this until its quite bright and also til I can just see it

Set final black and white points

improve local contrast between levels

sharpen/ blur

thats as far as ive been previously and been happy (for me!) with the results. But no matter what else happens, when I apply curves, the light/colour/whatever just starts 'pooling'.

What am I not doing?

Many thanks!

m272.TIF

[long_arms]

Hello,

Here's my attempt. I first opened the tiff in gimp and ps and got nothing but a faint outline of the nebula.

First of all (I'm assuming you stacked with dss).

Open deep sky stacker...on the processing menu, open picture file and select that tiff.

Now on the luminance tab at the bottom adjust the midtone. Then boost the saturation and balance the RGB and press apply and you should see a beautiful nebula . This is what I did anyway (I am pretty inexperienced tbh)

Then I did generic noise reduction, levels,curves etc in cs2 all of which I'm sure you can do in gimp. Oh and cropped it.

Dan

[billhinge]

Hi

I didn't do anything special other than used pixinsight.

I had another go from scratch to see how reproducible it was - no problem

This time I settled on a slightly different colour balance

This was just a histogram stretch

Use of the masked stretch script

DBE background extraction to get rid of vignetting and colour tint (there was a lot)

curves for contrast and saturation inc use of the star mask

followed by the Repaired HSV separation script and background enhance script

took about 10 mins so not claiming it is wonderful processing

You can just about see the central star in M57 but I notice your focus is slightly out - see crop

[Daniel-K]

you need more darks but its not bad

[andrewluck]

The image is very noisy and needs more light frames stacked to reduce this. Either the focus was off or the telescope was dewed as the stars are miniature doughnuts,

That said, the data looks quite nice and with a lot of noise reduction loos like this:

Processing here is done in Pixinsight.

Andrew

[NickK]

Um.. can I be pedantic .. it's not M57 but M27 Dumbell Nebula

[aGreyarea]

Hi guys

Thanks all for your comments. Thanks also for noticing it's M27 and not M57. I did realise just after posting but couldn't see how to edit the post.

Anyhoo, thanks everyone for your your feedback and comment. As I thought, the image is as it should be. Either I'm just doing it wrong (not the first time I've been accused of that...) or there is a problem with how gimp reads my image. How do you save an image as a thumbnail on this. I attached image m272 above, the colours or light just pools into big blobs when I try to use curves. Any ideas what's wrong or what I'm doing wrong?

[long_arms]

Anyhoo, thanks everyone for your your feedback and comment. As I thought, the image is as it should be. Either I'm just doing it wrong (not the first time I've been accused of that...) or there is a problem with how gimp reads my image. How do you save an image as a thumbnail on this. I attached image m272 above, the colours or light just pools into big blobs when I try to use curves. Any ideas what's wrong or what I'm doing wrong?

When I opened the tiff file with gimp and photoshop it was as you attached. Pools of big blobs.

When I opened it in deep sky stacker thats when I was able to see the proper data, save the image after a few adjustments and then edit with gimp or photoshop.

Dan

Edit: To attach a picture so its a thumbnail save it as a png and attach that :-)

[Jannis]

I'm not very good as processing yet, but as i haven't done any for a while, i wanted to give it a try anyway.

I was struggeling a bit with the stars within M27, as well as the stars in general as it's a bit out of focus.

Well, anyway, this is how it looks after a short while in photoshop.

Edit: i may have oversaturated the stars a bit though, but the whole thing looks completly different on my laptop and my calibrated display. >_<

[russellhq]

More data and better focus definitely is the order of the day.

[Jannis]

I have to say it's a bit interesting to see all these different results from the same raw data.

Different star shapes and size, different details within M27, different M27 colors, different background noise, different framing and so on.

[aGreyarea]

AndrewLuck, DanielK, Billhinge, Longarms et al,

Thanks all very much for your efforts and tips, while following your advice earlier today, I reopened the tif in DSS and rebalanced the RGB and played with the Luminance etc, it made a huge differance to the final image! Only when I opened it in GIMP, the opened image still did not even resemble the image I had just saved in DSS. When I clicked 'Revert' to reopen it from the disc it came up with a message saying the file is 16bit and GIMP will only manage 8bit! No wonder I was only getting the attached.

Does anyone know, is there a way to convert the saved DSS TIF into an 8bit image without losing any quality, or can I only process a 16bit image with suitable software?

Completely aside, with regard to the focus, I used the live view and zoomed in to 10x and after 3-4 minutes of playing could not get the focus any closer than it was. I used to use APTs FWHM to achieve best focus but have noticed halos on almost all the bright stars in all my images ever. I wondered if this might be a feature of the F4 system, a collimation error, a reflection from the UHCS filter and/or the corrector possibly, some sort of pixel overflow or if it the result of a combination of all the above? Its just difficult to believe I never once got the focus right!

[Jannis]

A bit confused to hear GIMP only support 8 bit? Your original TIF was so dark, that almost all the data would go lots when converted to 8 bit without stretching ity first. So indeed no wonder you couldn't get any data out of it.

But, hmm, alternatively PS CS2 is available for free from Adobe.

If not to be used for processing, it will be good for stretching the image roughly, then convert to a format GIMP will handle. But i'm still very confused about the whole thing, as so many here use ony DSS and GIMP, and get stunning results. I kind of find it hard to belive it only supports 8 bit...

Edit: regarding focus, have you tried a simple focus mask? Easily made in 30 min, and absolutely free. I had my batinov mask cut out of a 1.5 or 2mm stainless steel plate after i first had given a homemade one a try. Homemade got me right on focus, but the maching made one was even easier to use. Though a bit heavy, lol.

[lensman57]

Hi All,

I rarely get out anymore but I recently managed to get a couple of subs before the batteries went.

However its been more than 2 years since I tried to process an image and I dont have the fabled PS to do it with so have been trying to use GIMP. This time I cannot even stretch the histogram properly and just want to see if its me or something Ive done wrong. The image is a stack of 6x 3min subs of M57 no flats or darks and I know they will help but Ive achieved better results than this before with fewer, shorter subs.

Please have a go at it and post what you get. Its over 100mb so please get it from here:

https://www.dropbox....70ymq0/m572.TIF

Many thanks

Liam

Hi Liam,

Just read your post, a bit late I guess but I did a quick process of your data in StarTools and a conversion to Jpeg in CS2, the data is not bad, a few darks, and flats to remove the the hot spots and vignetting and yes perhaps a few more subs would help as the image is noisy but as a whole is on a par with the stuff that I get. Hope that you approve. It took longer to download the file than to process the data BTW.

Regards,

A.G