How's my processing?

[Star Gazer]

After my previous attempts at M31 I thought I'd have another bash, but this time with a few darks as well as lights.

5x240 at iso 800 lights.

I had to abandon Astroart just could't understand how it makes everything so orange. Also abandoned Maxim DL due to the numerous 'out of memory' errors and subsequent crashing. How people part with good money for Maxim is beyond me. Obviously the don't use it for image processing.

So it's back to DSS and a bit of Photoshop. Here's my result:

This is my first decent image, which I'm quite pleased with.

However I'm interested in any advice or criticism, especially why the image is in black and white when processed in DSS. In my previous thread:

="http://stargazerslounge.com/imaging-image-processing-help-techniques/163286-what-am-i-doing-wrong.html"

I did get some advice, but no mater what I try I only get B&W.

I have some, but not too much LP where I live; do you think a light pollution filter would help preserve the colour in my images?

Lastly what do you think about the noise in the image? Is this to be expected with a Canon 7D? I used 8 dark frames to help with noise? Here's a 100% crop to show this in more detail:

Thanks for looking

[RobH]

That's a very nicely captured and processed M31....perfect round stars and a tightly controlled core.

No idea why DSS is doing what it's doing as I don't use it. I use Maxim for capture and calibration, plus producing a TIFF when using a colour camera, and then Photoshop does the rest.

I've had no issues with Maxim except when trying to stack too many large files. When I need to do this I stack them in batches of about 10, and then stack those batches.

You also need to use the 'FILE/COMBINE FILES' command, which will only have one two images open in the memory at once.

Cheers

Rob

[Jannis]

Great image with tons of details!

When it comes to image noise; concidering the 7d have roughly same high-ISO noise as the 550/600D, i'd say it's probably around where it shuold be. I guess the only way to reduse it is to stack many many more frames together. 5 frames isn't really many if the goal is to have lowest possible noise.

[Star Gazer]

Hi Jannis,

I agree I wanted about 10 frames but even that might be too few. If I wanted minimal noise how many lights and how many darks would you shoot?

[Star Gazer]

No idea why DSS is doing what it's doing as I don't use it. I use Maxim for capture and calibration, plus producing a TIFF when using a colour camera, and then Photoshop does the rest.

I've had no issues with Maxim except when trying to stack too many large files. When I need to do this I stack them in batches of about 10, and then stack those batches.

You also need to use the 'FILE/COMBINE FILES' command, which will only have one two images open in the memory at once.

Hi RobH,

Thanks for your help

I really want to get going with MaxIm if I can especially as I want to avoid the B&W I get with DSS.

I know ths is a bit cheeky of me but would you mind briefly documenting the steps in MaxIm that you take to get a reasonable image I can play with in Photoshop.

I did try the file/combine option but I still had memory issues even though task manager said only 65% of my machines memory was used. I am using a Mac running a virtual machine running Win 7. I give the virtual machine 4 GB but I dont think that's an issue.

Once again thanks for your help.

[Jannis]

Hi Jannis,

I agree I wanted about 10 frames but even that might be too few. If I wanted minimal noise how many lights and how many darks would you shoot?

If i remember good, doubling the number of frames in will lower the ISO noise 1 step.

Meaning, for example, if your current 5 frames gave a result similar to ISO 800, then 10 frames would look similar to ISO 400. then 20 frames would be like ISO 200, and 40 frames would be like ISO 100.

In your case, the 5 frames you took at ISO 800 is equal to 1 at frame at around ISO 250-280. So with another 5 frames the result would have dragged it down to around ISO 125-140 (correct me if i'm wrong, i'm half asleep and my head doesn't calculate very well atm, lol) wich in theory Should give a bit less noise and give you the ability to drag out a bit more details.

...in theory, that is...

[Jessun]

Star Gazer, I think that is a fabulous image! i never came anywhere near it.

I use a 600D and found that DSS didn't recognize the CR2 files properly, so I used Canon's own software to convert each image to 16 bit TIFF and you can do this in a batch so it's really quite simple. After that DSS was happy and all colour!

I had also similar noise pattern as you - to the point that I concider the images useless for further processing, so a lot worse than yours. I since found and turned off the camera noise reduction setting, and I now give it a rest 30 seconds between each exposure to let it cool down and 'settle' in the chip. (Don't know for certain what goes on in that chip but it sure does benefit from a bit of rest... stay away from live view btw)

After these simple steps I have not seen this noise pattern again. Don't know how similar the chips are in these cameras but try the above.

I haven't yet come across any software function that can cure it so best do it at imaging!

Once you get colour in that image it will be stunning - and I'll be envious...

/Jessun

[RobH]

Hi RobH,

I know ths is a bit cheeky of me but would you mind briefly documenting the steps in MaxIm that you take to get a reasonable image I can play with in Photoshop.

/QUOTE]

I'll try to post something tomorrow re. this....it's late now and I expect to be up all night as it's clear (miracles do happen!)

Re. noise. Your noise levels are fine....you only have 20 minutes total exposure, which is nothing TBH....to stretch the faint regions of M31 without noise issues you need hours of exposure.

The advice re. letting the camera cool sounds good.

Darks....they don't remove noise in general, they remove only the noise that builds up over your given exposure length. Like lights, the more you have the better. If you use too few, you will end up adding noise to the final image. Go for at least 20 darks, no matter how many lights you have.

Cheers

Rob

[Castor and Pollux]

Hi Star Gazer,

I know that you posted this a liitle while ago but I've only just joined the Forum. I had a similar problem with DSS at first in that it turned all my lovely colour photos into B&W! I found a simple fix though.

Once DSS is finished stacking if you go to the third tab (called Saturation) you'll find this is set to 0. If you increase this to 18 then, hey presto, the colour comes back into your image. You'll need to play around with the number for each image but a value somewhere in the range 15-21 is usually about right. Apart from this quirk, I'm beginning to really appreciate the value of DSS. Hope this helps. Cheers.

[Anweniel]

Also find the stacked images in DSS come out naturally in B&W, as Castor and Pollux says, adjust saturation level after stacking and before saving. Personally I adjust to about 20% but not always (go for what looks about right)

[Star Gazer]

Castor and Pollux, Anweniel,

Thanks for the tips. I have only been using DSS occasionally since my earlier post. Strangely when I used it the images maintained their colour. Don't know what I did differently, certainly didn't play with the saturation tab

In the mean time I have been using PixInsight and get great results except the noise seems even worse. Check out my thread from yesterday (no replies yet)

[sloz1664]

Have a look on Astronomyshed forum. There is an in-depth DSS processing feature using the M42 as an example. Should help..

cheers

Steve

[dph1nm]

Lastly what do you think about the noise in the image? Is this to be expected with a Canon 7D?

Remember that much of the noise seen in astro images is inherent in the objects themselves and in the sky background, due to the physics behind the emission of photons. i.e. nothing to do with the camera. This can only be improved by accumulating more exposure time (well, OK, you could buy a camera with a higher QE, but I don't think this varies very much between DSLRs).

NigelM