Pleiades

[Daf1983]

Another clear night! Captured about 3 hours of data just before Xmas, using my Canon 600d and evostar 80ed. For some reason, dithering didn't work during the session, so it's a bit noisy. 

Still not happy with my processing skills, although I feel I'm getting there slowly. I've had 2 attempts at processing this.

Any CC with regards to processing would be welcome, also let me know which you prefer .

Dafydd

[happy-kat]

hard to decide which is an overall preference, I like the colour of the nebulosity of the second, both I would be very happy with

[Ags]

The second looks a bit cleaner to me too. Both very good, better than I have ever done.

[Mr Spock]

2nd looks better to me. Processing is an art form of its own - a complete mystery to me I'm afraid 

[ollypenrice]

What software do you use for post processing? We need to know that before we can offer too much advice.

My own feeling is that, if I can see noise reduction in the image, there is too much of it - and I feel I can see it in the second.

The most important thing in post processing is being able to process some parts of the image differently from other parts, so sharpen some areas and noise reduce others. Boost colour in some areas and reduce it in others Any program with layers makes this easy when used with selection tools like Colour Select.

Olly

[Daf1983]

Hi, thanks everyone for their comments.

@ollypenrice I use photoshop for my processing, for which I also have the astronomy set plug ins and astro flat pro. I agree with you with regards to the noise reduction in the 2nd photo.

 

[Xgaze]

Hi Dafydd,

Both are beautiful images, well done.

I know nothing of AP as yet but, in my opinion, the top one has more detail surrounding Pleiades. I feel the extra stars give the image more depth.

Thanks for sharing.

Tony

[ollypenrice]

1 hour ago, Daf1983 said:

Hi, thanks everyone for their comments.

@ollypenrice I use photoshop for my processing, for which I also have the astronomy set plug ins and astro flat pro. I agree with you with regards to the noise reduction in the 2nd photo.

 

A man after my own heart. You could experiment with layer masking for the bright stellar cores.

- Make a new and much milder stretch, stopping once the cores look about right. Don't worry about the nebulosity.

- Paste this 'cores stretch' as a top layer over the full stretch.

- Create a layer mask for the top layer and paste a copy of the cores stretch onto it. It will be greyscale.

- Put a very big blur into the greyscale layer mask. (Try a Gaussian blur between 3 and 6.)

- Use Curves to manipulate the Layer Mask. You want to increase its contrasts massively, so pull down the bottom of the curve and push up the top. The dark parts will get darker (more opaque) and the bright parts will get lighter (more transparent.)

 

What will happen is that the layer mask will only be transparent where the bright signal lies - that is around the cores - so only the softer stellar cores will be applied to the lower image. Some jiggling with the mask and the top layer should let you get a seamless blend of the two different stretches. This technique is often used to blend different sub exposure lengths (eg for M42) but often all you need to do is blend two stretches, a hard and a mild.

Olly

[Daf1983]

1 hour ago, ollypenrice said:

A man after my own heart. You could experiment with layer masking for the bright stellar cores.

- Make a new and much milder stretch, stopping once the cores look about right. Don't worry about the nebulosity.

- Paste this 'cores stretch' as a top layer over the full stretch.

- Create a layer mask for the top layer and paste a copy of the cores stretch onto it. It will be greyscale.

- Put a very big blur into the greyscale layer mask. (Try a Gaussian blur between 3 and 6.)

- Use Curves to manipulate the Layer Mask. You want to increase its contrasts massively, so pull down the bottom of the curve and push up the top. The dark parts will get darker (more opaque) and the bright parts will get lighter (more transparent.)

 

What will happen is that the layer mask will only be transparent where the bright signal lies - that is around the cores - so only the softer stellar cores will be applied to the lower image. Some jiggling with the mask and the top layer should let you get a seamless blend of the two different stretches. This technique is often used to blend different sub exposure lengths (eg for M42) but often all you need to do is blend two stretches, a hard and a mild.

Olly

Thanks for taking the time to explain this, very much appreciated! I have experimented a little with a masks, but with limited success to be honest. This gives me a much better idea of what to do👍 I will definitely give this a go when I have the time. 

[ONIKKINEN]

Looks like the background is gone after your noise reduction, which could be wanted or could not be, depends on what you want. Olly already tipped you on the layer masks and their power in processing, but ill give you one method of easily removing colournoise from the background. Try this method before going for noise reduction tools, it could lead to a more natural look.

Easy to do in photoshop: Select -> Color range and then from the dropdown select "Shadows". Adjust the Range and Fuzziness to values that have all of the background selected (white) but none of the signal you want to preserve. Depending on your image and type of background this can be difficult, so just choose what fits your data best. Then click OK and you have a selection across the screen. Then go Select -> Select and mask and finalize the parameters of the new layer mask. You could put a small Feather effect on this so that the transition between values is more subtle. Could be important for some images. When happy select the Output To mode to be new layer with layer mask.

Then on that new adjustment layer just drop saturation by as much as you want. -100 will make the background monochrome and looks out of place in my opinion, but experiment on the exact value in your image. Since you selected only the background, only the background loses saturation and the interesting bits should remain whatever colour they were. Sometimes all it takes is desaturating the colournoise instead of trying to fight it away, but often it takes a bit of both.

[Daf1983]

1 hour ago, ONIKKINEN said:

Looks like the background is gone after your noise reduction, which could be wanted or could not be, depends on what you want. Olly already tipped you on the layer masks and their power in processing, but ill give you one method of easily removing colournoise from the background. Try this method before going for noise reduction tools, it could lead to a more natural look.

Easy to do in photoshop: Select -> Color range and then from the dropdown select "Shadows". Adjust the Range and Fuzziness to values that have all of the background selected (white) but none of the signal you want to preserve. Depending on your image and type of background this can be difficult, so just choose what fits your data best. Then click OK and you have a selection across the screen. Then go Select -> Select and mask and finalize the parameters of the new layer mask. You could put a small Feather effect on this so that the transition between values is more subtle. Could be important for some images. When happy select the Output To mode to be new layer with layer mask.

Then on that new adjustment layer just drop saturation by as much as you want. -100 will make the background monochrome and looks out of place in my opinion, but experiment on the exact value in your image. Since you selected only the background, only the background loses saturation and the interesting bits should remain whatever colour they were. Sometimes all it takes is desaturating the colournoise instead of trying to fight it away, but often it takes a bit of both.

Noise reduction is definitely something I need to work on, so thank you for the tips. I'll give this method a try when I get the chance

[ollypenrice]

3 hours ago, ONIKKINEN said:

Looks like the background is gone after your noise reduction, which could be wanted or could not be, depends on what you want. Olly already tipped you on the layer masks and their power in processing, but ill give you one method of easily removing colournoise from the background. Try this method before going for noise reduction tools, it could lead to a more natural look.

Easy to do in photoshop: Select -> Color range and then from the dropdown select "Shadows". Adjust the Range and Fuzziness to values that have all of the background selected (white) but none of the signal you want to preserve. Depending on your image and type of background this can be difficult, so just choose what fits your data best. Then click OK and you have a selection across the screen. Then go Select -> Select and mask and finalize the parameters of the new layer mask. You could put a small Feather effect on this so that the transition between values is more subtle. Could be important for some images. When happy select the Output To mode to be new layer with layer mask.

Then on that new adjustment layer just drop saturation by as much as you want. -100 will make the background monochrome and looks out of place in my opinion, but experiment on the exact value in your image. Since you selected only the background, only the background loses saturation and the interesting bits should remain whatever colour they were. Sometimes all it takes is desaturating the colournoise instead of trying to fight it away, but often it takes a bit of both.

I do this as well but by a different means: I don't use a mask, I just select the background I want to de-colour-noise by using the colour select tool to find it. I'll expand the selection by one and feather by one and just reduce saturation on the selection.  I think the result will be the same as yours. Which is easier? Neither is difficult.

Olly

[dannybgoode]

12 hours ago, ollypenrice said:

if I can see noise reduction in the image, there is too much of it

Couldn't agree more.  In both AP and terrestrial photography people obsess about noise way to much.  Sure, sometimes it can detract from a picture but so often people kill detail for a 'perfect' noise free image which is anything but perfect because of it!

[alacant]

On 28/12/2021 at 15:38, Daf1983 said:

which you prefer

My preference, first. It has more stars.

[Daf1983]

Had another go at processing this data from scratch following the advice from @ollypenrice and @ONIKKINEN. Not sure if I prefer the overall image to the first attempt, but I definitely prefer the more natural looking background (even if it is noisier). Thanks again for the advice, as I've learned a lot about how to use layer masks in photoshop after doing this. Might have another go at processing my M42 data to see if I can preserve the core using the technique Olly outlined above

[ollypenrice]

I think your latest one is black clipped, ie jet black sky with nebulosity jumping out because the faintest stuff has also been discarded. I very much liked your original and fairly light background sky.

Olly

[Daf1983]

20 minutes ago, ollypenrice said:

I think your latest one is black clipped, ie jet black sky with nebulosity jumping out because the faintest stuff has also been discarded. I very much liked your original and fairly light background sky.

Olly

I agree! The original does seem to have more detail, I'll have another go🙃