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Hi guys, Ive been working on this one for quite a while and I don't know what to think of it. Is it good, is it bad, please give me the harshest critics, don't just say it's  good for the sake of it. What would you do to make it better. It's 7 hours worth of exposures from 60sec to 600sec taken with a qhy10 cooled at -15°C stacked in dss and processed in photoshop and lightroom.
Thanks.LRM_EXPORT_20180816_072511.thumb.jpg.856ea665d86d8ca7d4259ab23086c0bb.jpg

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6 minutes ago, carastro said:

Looks pretty good to me, the only thing I would do is brighten is up a bit in Curves, maybe duplicating the layer so you can rub out the core each time as you stretch it.

Carole

Thanks Carole. I will try to brighten it up. To be honest this is the first time I use layers to protect the brighter areas.

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24 minutes ago, carastro said:

 maybe duplicating the layer so you can rub out the core each time as you stretch it.

Carole

Doing that will just add processing power and if you want to adjust stuff later when you have more layers, would make it difficult. The better option is to use a blank curves layer set to act on all layers below it. Same effect but with almost no increase in data size.

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4 hours ago, emyliano2000 said:

Hi guys, Ive been working on this one for quite a while and I don't know what to think of it. Is it good, is it bad, please give me the harshest critics, don't just say it's  good for the sake of it. What would you do to make it better. It's 7 hours worth of exposures from 60sec to 600sec taken with a qhy10 cooled at -15°C stacked in dss and processed in photoshop and lightroom.

Hi

Well, I would say that this very good. 

What is good is that you have a balanced background that looks good in terms of brightness, the aspect ratio of your stars is good and the central core is well processed and is not "blown out".  You also have good star colours and you also have some colour in the main body of the galaxy.  Personally, I'd have expected to see this in the Deep Sky section, rather than a beginners forum.

You have a slight green cast which can best be seen on the companion galaxy M101.  Within PS the best way to fix this is to run the plug-in HLVG which you can download for free http://www.deepskycolors.com/archivo/2010/04/26/hasta-La-Vista-Green.html  The galaxy is too dim with respect to the background.  Whilst you can correct this this with some additionally stretching,  you may obtain a better result result by adopting an LRGB processing approach where you process the Lum and RGB data separately. Here, if you only have RGB data, then you can create a synthetic L within PS. To get the brightness correct, stretch the Lum component via a non linear process (I use DDP) such that the interesting parts of the galaxy (not the core) of the galaxy have a PS information reading of 170 to 190 counts. You'll probably also need to perform a separate stretch for the core and/or to perform dynamic range compression and then blend the results together.  Note that if you go above 200 on the L brightness you will find it difficult to generate colour when you perform the subsequent LRGB recombination. I'd also suggest you increase the colour saturation of the main galaxy using the Lab colour mode of PS as this should help to reveal the Ha regions and minimize chromatic noise.

On the acquisition front, I don't see why you are using a range of sub exposures from 60s to 600s -  I'd suggest you experiment by attempting to take the longest exposure that is practical for the object, your site and your equipment. This approach will maximize your capture of faint details. For example on this particular object at my site and with my equipment, I'd just use 600s subs.   Your 7 hour integration time is a good target.  

Hope this helps.

Alan    

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Thank you very much Alan. I'm not that experienced for the deep sky section just yet ?

53 minutes ago, alan4908 said:

You have a slight green cast which can best be seen on the companion galaxy M101.  Within PS the best way to fix this is to run the plug-in HLVG

I did use it but going strong with it was changing the overall colour too much.

On all the luminance things that you said, it's a lot to take in, I'm still leaning ?. I only extracted the luminance once on a different target and I only copied it on top of the rgb, nothing else.

51 minutes ago, alan4908 said:

On the acquisition front, I don't see why you are using a range of sub exposures from 60s to 600s

This is the first time I'm using anything else than a dslr so I have a lot of practising to do.

 

55 minutes ago, alan4908 said:

use DDP

What is DDP?

 

56 minutes ago, alan4908 said:

I'd also suggest you increase the colour saturation of the main galaxy using the Lab colour mode of PS as this should help to reveal the Ha regions and minimize chromatic noise.

I need to find out how to do that. I've been using Match colour so far.

I could add some Ha data to it, I have an astronomik 6nm that I could use.

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13 hours ago, emyliano2000 said:

I did use it but going strong with it was changing the overall colour too much.

On all the luminance things that you said, it's a lot to take in, I'm still leaning ?. I only extracted the luminescence once on a different target and I only copied it on top of the rgb, nothing else.

I normally use HLVG on the medium setting and sometimes apply it only selectively via masks.

A good quality free video tutorial on how to perform LRGB processing is here: http://www.astronomersdoitinthedark.com/dslr_llrgb_tutorial.php  If you want world class astrophotography PS tuition then I'd highly recommend Adam Block's video https://adamblockstudios.com/categories/DimensionsOfPhotoshop

13 hours ago, emyliano2000 said:

What is DDP?

DDP = Digital Development Processing = a non-linear way of stretching objects to reveal faint details. I use a program called CCDstack to perform the initial DDP stretch on the Lum layer.  You can download a free trial of CCDstack here http://www.ccdware.com/products/

Personally, I wouldn't be concerned about the amount of your total experience before posting on the Deep Sky forum - some people have years of experience but produce inferior images to the above.  Don't forget that it is the result that counts....

Alan

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22 hours ago, alan4908 said:

Hi

Well, I would say that this very good. 

What is good is that you have a balanced background that looks good in terms of brightness, the aspect ratio of your stars is good and the central core is well processed and is not "blown out".  You also have good star colours and you also have some colour in the main body of the galaxy.  Personally, I'd have expected to see this in the Deep Sky section, rather than a beginners forum.

You have a slight green cast which can best be seen on the companion galaxy M101.  Within PS the best way to fix this is to run the plug-in HLVG which you can download for free http://www.deepskycolors.com/archivo/2010/04/26/hasta-La-Vista-Green.html  The galaxy is too dim with respect to the background.  Whilst you can correct this this with some additionally stretching,  you may obtain a better result result by adopting an LRGB processing approach where you process the Lum and RGB data separately. Here, if you only have RGB data, then you can create a synthetic L within PS. To get the brightness correct, stretch the Lum component via a non linear process (I use DDP) such that the interesting parts of the galaxy (not the core) of the galaxy have a PS information reading of 170 to 190 counts. You'll probably also need to perform a separate stretch for the core and/or to perform dynamic range compression and then blend the results together.  Note that if you go above 200 on the L brightness you will find it difficult to generate colour when you perform the subsequent LRGB recombination. I'd also suggest you increase the colour saturation of the main galaxy using the Lab colour mode of PS as this should help to reveal the Ha regions and minimize chromatic noise.

On the acquisition front, I don't see why you are using a range of sub exposures from 60s to 600s -  I'd suggest you experiment by attempting to take the longest exposure that is practical for the object, your site and your equipment. This approach will maximize your capture of faint details. For example on this particular object at my site and with my equipment, I'd just use 600s subs.   Your 7 hour integration time is a good target.   

Hope this helps.

Alan    

I am sure you are correct in suggesting "only use the longest exposure", but I am coming at this from an amateur photographers standpoint. If I did that in conventional photography much of the image would be grossly overexposed. Why is astrophotography different?

 

Thanks

 

Jack

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16 hours ago, jACK101 said:

I am sure you are correct in suggesting "only use the longest exposure", but I am coming at this from an amateur photographers standpoint. If I did that in conventional photography much of the image would be grossly overexposed. Why is astrophotography different?

Taking the longest exposure that is practical for the object, your site and your mount helps achieves a key objective for deep sky images, which is to maximize the signal to noise ratio (SNR). Since SNR = signal divided by noise, you are attempting to maximize the signal (via the longest practical exposure) and minimize the noise (eg by going to a dark site, cooling the camera or stacking subframes).  For faint objects, the wanted signal is sometimes only just above the noise floor. In conventional day time photography the signal levels are generally very high compared to the noise level so you can obtain a good SNR ratio with a relatively low exposure time. From a practical perspective, your longest exposure will be determined by the object (the brighter parts may become overexposed), your site (light pollution) or your equipment (your mounts tracking accuracy).

Alan

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I had another go at it and I think I like this one much more. The core is not blown out, you can see the structure of the galaxy, and you can just make out the Ha regions and some star clusters.

I think I will add one more session of 600sec exposures and one more session of Ha to make the Ha regions really stand out.

Happy days ?

Tell me what you think.

Emil

LRM_EXPORT_20180819_130348.thumb.jpg.0a8456175fe1c0e3103ced7ec5206bdc.jpg

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On 16/08/2018 at 07:55, carastro said:

Looks pretty good to me, the only thing I would do is brighten is up a bit in Curves, maybe duplicating the layer so you can rub out the core each time as you stretch it.

Carole

Ditto Carole ...... great picture!

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