What makes a good image of a cluster?

[Filroden]

With the Moon almost full and not wanting to be up at 3am to catch the Milky Way, I've taken a look at some of the clusters that are visible at the moment. As a novice photographer, I sort of know what I'm aiming for with images of nebula and galaxies, but photos of clusters leave me cold. What do you think makes an interesting image of a cluster?

By way of example, here's a single 30 second exposure I captured a couple of nights ago which I processed to remove all background gradient and noise - so simple when you don't have to worry about feint detail in nebula or galaxies. I could just stretch the image, isolate the stars and then remove all background. But it leaves me with (in my opinion) a cold image. Is it just I need more exposures to go deeper into the star field, shorter exposures to get more colour in the stars or is it composition? Would welcome your thoughts (knowing it's quite subjective!).

[estwing]

mods would this be better in deep sky imaging?

[Filroden]

4 hours ago, estwing said:

mods would this be better in deep sky imaging?

Oh, you're right. I'd intended to post this in imaging, not observing. Sorry.

[ollypenrice]

I'm sure they'll move it. It's a very worthwhile thread.

My answers as to what to go for in a cluster would be...

- Deep background, the opposite of your black clipping suggestion. It's often there:

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-nmcNvss/A

Or highly unexpected backgrounds, a Fabian Neyer speciality: http://www.starpointing.com/ccd/ngc869_ngc884.html

- Good strong star colour. Try to get the colour right into the cores.

- Differential processing of star size and colour intensity in order to emphasize asterisms. Personally I declare this when I do it, as with Kemble's Cascade.

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-SgKgDDN/A

Olly

[Stu]

20 hours ago, estwing said:

mods would this be better in deep sky imaging?

Sorted ?

[Filroden]

2 hours ago, ollypenrice said:

I'm sure they'll move it. It's a very worthwhile thread.

My answers as to what to go for in a cluster would be...

- Deep background, the opposite of your black clipping suggestion. It's often there:

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-nmcNvss/A

Or highly unexpected backgrounds, a Fabian Neyer speciality: http://www.starpointing.com/ccd/ngc869_ngc884.html

- Good strong star colour. Try to get the colour right into the cores.

- Differential processing of star size and colour intensity in order to emphasize asterisms. Personally I declare this when I do it, as with Kemble's Cascade.

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-SgKgDDN/A

Olly

Those give me some good ideas to aim for though I need to be realistic in terms of my current set up. However, if i take a lot of subs at various exposures I can probably layer the stars based on magnitude to better control colour and give that range of size/intensity. I doubt I can ever get to detect the feint Ha emission from my location and with AltAz, but there is definitely more I can do with the processing.

I also realise that I actually like to see diffraction spikes in star fields which I can add in processing but I'm not sure how much of this then becomes art!

1 hour ago, Stu said:

Sorted ?

Thanks Stu

[ollypenrice]

11 minutes ago, Filroden said:

Those give me some good ideas to aim for though I need to be realistic in terms of my current set up. However, if i take a lot of subs at various exposures I can probably layer the stars based on magnitude to better control colour and give that range of size/intensity. I doubt I can ever get to detect the feint Ha emission from my location and with AltAz, but there is definitely more I can do with the processing.

I also realise that I actually like to see diffraction spikes in star fields which I can add in processing but I'm not sure how much of this then becomes art!

Thanks Stu

Personally I think multiple sub lengths are usually a waste of time and just add noise, workload and confusion. There are exceptions, most obviously M42, which can only be done this way. And I use cameras with big pixels and deep wells, so my need for short subs is diminished. Even so, do you really need short subs? It is dead easy to find out. You simply look at the linear (pre-stretched) stack. If nothing is over exposed (saturated/burned out) in the linear image then nothing needs to be burned out in the final stretch. What you may need are multiple stretches, not multiple sub lengths. Mutiple stretches and photoshop layers are wonderful things...

Olly

 

[ollypenrice]

PS Phoney diff spikes? Please don't!!!

Olly

[Filroden]

5 minutes ago, ollypenrice said:

PS Phoney diff spikes? Please don't!!!

Olly

I know. I did see what they could look like but a natural image feels right. I did check my single sub and other than two or three stars I hadn't overexposed any others and had colour data throughout, so I'll work more on the double cluster and maybe some globs too.

[symesie04]

Yes tough one as it is a individual feel. But agree with much of the above. I think tight stars are a must as after all thats the subject of the image. And colour has to be vibrant, those giants blues need that crisp blue and those oranges need to be warm. Not easy i wouldnt of thought. Most of the time when i see cluster images im left a bit underwhelmed but just now and then i think wow that looks beautiful. It needs to look like the proverbial jewel box.

[Filroden]

1 hour ago, symesie04 said:

Yes tough one as it is a individual feel. But agree with much of the above. I think tight stars are a must as after all thats the subject of the image. And colour has to be vibrant, those giants blues need that crisp blue and those oranges need to be warm. Not easy i wouldnt of thought. Most of the time when i see cluster images im left a bit underwhelmed but just now and then i think wow that looks beautiful. It needs to look like the proverbial jewel box.

For me, I want my image to give me that same sense of "wow" that looking at the cluster visually gives. When I look through the eyepiece the field gives me a real sense of depth whereas my images feel flat. I think you're right about the colour - I almost want to feel the contrast between fire and ice, and I like the jewel box analogy.

When we finally get another clear night, I'm going to spend a little more time on the double cluster and really experiment with different processes. I played around with my single image again last night and even cropping in closer to the cluster helped.