M51 - A learning experience

[OzDave]

This is the third serious outing for my QSI 683 and trying to learn how to use the LRGB filters.

I planned the whole imaging session and had my gear setup well in advance so that I'd be able to start acquiring images as soon as the sky went "Astronomically Dark". I managed to image all night and stopped just shy of 5am.

I managed to capture the following:

L: 18x10mins unbinned

R: 7x10mins unbinned

G: 7x10mins unbinned

B: 7x10mins unbinned

I meant to bin the RGB filters, but discovered I'd forgotten to do that when it came time for meridian flip and so I figured I'd just continue unbinned.

I calibrated with 15 darks and 20 flats per filter. Pulse guided with PHD and EQMac.

This is the first time I've tried subs longer than about 3 minutes and I've discovered what a difference that makes in terms of noise and the ability to stretch the resulting stacked images.

After much playing about in Photoshop, I'm still not really happen with things but I decided to post a crop of the galaxy to see what people think.

I'm not sure if I've done well with colour balance, and I definitely don't like the stars much. After balancing and saturating the RGB layer (and maybe other things), the stars all grew a blue halo which I'm not really sure what to with. Anyway, it's probably one of my better images to date, but still plenty of room to improve.

I'd be interested to hear what people think. I know it doesn't really compare to some of the M51s I've seen here, but it's better than what I was managing to achieve say a year ago...so I must be learning something.

David

[SteveA]

Hi Dave,

I think that looking pretty good...

From the quick look I've had I would say its a tad on the blue side.....but its so subjective really....

I'm not sure what happened with your stars!....and as a PI user I can't really advise.

Having just spent a bunch of time on M51 I have to say I like your image....Its a good target to learn the ropes on, detail and lots of different colours..it has the lot.

Steve

[Black Knight]

I'm viewing the image on my phone, but it looks fine to me!

Sent from my mobile using Tapatalk, so please excuse the speeling and granma!

[Gina]

Great image

[OzDave]

Hi Dave,

I think that looking pretty good...

From the quick look I've had I would say its a tad on the blue side.....but its so subjective really....

I'm not sure what happened with your stars!....and as a PI user I can't really advise.

Having just spent a bunch of time on M51 I have to say I like your image....Its a good target to learn the ropes on, detail and lots of different colours..it has the lot.

Steve

Thanks Steve, it could be a bit blue. I've not properly calibrated the colour balance on my filters so I had to guesstimate the colour balance based on what I'd seen before and what appealed to me.

With the stars, I got a blue halo around them from some of stretching. I think maybe when I stretched the blue curve to achieve a better colour balance. I might try a reprocess of the data, but this image is already the 3rd time round the loop...

I think if I try this again, I'd go for binned colours and also more of them. The colour layer is quite noisy compared to the luminance, so the extra images definitely help.

David

[ollypenrice]

You can probably get more out of your present colour data. Some Ps tricks:

- Convert your RGB to Lab colour mode.

- Split channels. In channels a and b go to Image, Adjustments, Brightness and Contrast and lift both a and b to 30. Recombine channels.

-Apply your L to this in blend mode luminosity at 30 percent. Increase saturation, reduce noise (eg Reduce Noise or Gaussian Blur or both.) Save.

Re apply Lum to this at 60 percent and increase saturation, reduce noise and save. Now it may take a full application of L.

Olly

[Quatermass]

Using the High pass filter in PS would help sharpen up the dust lanes for you but it looks great lots of lovely detail and the colours are lovely.

[Steve 1962]

Very nice image - maybe a little soft on the focus?....or is that my eyes??

[Chris]

very nice, lots of detail:)

[Russe]

You can probably get more out of your present colour data. Some Ps tricks:

- Convert your RGB to Lab colour mode.

- Split channels. In channels a and b go to Image, Adjustments, Brightness and Contrast and lift both a and b to 30. Recombine channels.

-Apply your L to this in blend mode luminosity at 30 percent. Increase saturation, reduce noise (eg Reduce Noise or Gaussian Blur or both.) Save.

Re apply Lum to this at 60 percent and increase saturation, reduce noise and save. Now it may take a full application of L.

Olly

I need to try that too!!