My stacking woes

[Jeff]

Ok, I gave this stacking thing another try.

I took 40 - 30sec images of M65 & M66 in Leo. (part of the triplets) I also took 8 dark frames. All in sRAW1 on a 50D. First problem was that DSS wouldn't recognize the raw files even though I had the latest version 3.2.2 and it said it would. Could it recognize the full raw maybe & not the sRaw?

Second, I batched them all out to jpeg and stacked them that way (it used 29 frames). Below is what I got:

So my question(s): What do I do next? Do I still need to adjust the settings? Is this a normal looking output for this step? Do I not have enough data at 30sec subs to get anything worthwhile?

I read Baz's article on stacking and it seemed to make sense. It's just not working out the way I thought it should I guess.

Any suggestions on what to do next?

[cruiser]

Hi Jeff,

I have a 40D and DSS has no problems stacking the raw's from it although I use full raw. Not sure if there is any difference in the files from a 50D.

When I finish stacking the shot can looked very washed out as in your shot as DSS is applying certain settings. You would be best saving the file using the save option that says 'embed adjustments in the saved image but do not apply them'.
The image should then be a lot darker and you need to open it up in something like photoshop and adjust the curves and levels to bring the detail out.

I am no expert in using levels and curves myself but I hope this helps and I am sure others will have help in regard to loading the raw files.

Brett

[chris.bailey]

I dont think DSS recognises sRAW files. I would not stack jpgs, TIFFS are much better.

Dont be surprised if the output from DSS is odd (though if anything it usually looks very dark) but do save out as a TIFF without applying any DSS corrections. Open that TIFF in Photoshop, convert down to 8 or 16 bit (DSS natively saves as 32 bit) and open levels. You are aiming to get the black point carat just to the left of the start of the histogram but without clipping (use ALT when adjusting to show clipping) leave the white point alone and then move the midpoint to the left to get a dark but not black background. I had a play with the very small part of your image and it looks to be a little red, indeed your DSS histogram shows it to be so. You may therefore need to also adjust the colour balance in photoshop.

By all means post up a larger unadjusted image and I'll have a play (I reckon the data looks pretty good and worth processing)

[Adrena1in]

Dont be surprised if the output from DSS is odd (though if anything it usually looks very dark)
That's the opposite for me...my stacks ALWAYS look really bright and rubbish, but when I save the TIFF and open it up into a Paint package it *then* looks ncredbly dark, until I adjust the levels and what not. To that end I never pay attention to the final screen in DSS.

[chris.bailey]

That's the opposite for me...my stacks ALWAYS look really bright and rubbish

Only the case if you have adjusted the screen stretch function (slider in top RH corner)

[chris.bailey]

Output Tiff from DSS is likely to be a little this...

http://www.pbase.com/chris_bailey/image/108873090.jpg

but with some careful levels adjustment (and inversion and a few other bits) becomes this..

http://www.pbase.com/chris_bailey/image/108902656.jpg

You do have to learn to trust the data you collect and to treat it as a starting point. Processing that data is the key to getting great images from good data. I also prefer to use PixInsightCore instead of Photoshop as it is far more geared to processing the kind of data found in astro pictures i.e. pictures that start life with most of the data squeexed into a very narrow part of the overall range.

[Jeff]

Wow Chris, talk about a diamond in the rough!

Thanks for the tips everyone. I'm going to have another try at this will all the recommendations.

Will post the results.

Edit: OK, one problem solved. DSS will not use sRaw files but I loaded up a couple of full 50D RAW files and it did recognize them. So it looks like I'll be astro-shooting Raw from now on.

[Adrena1in]

So it looks like I'll be astro-shooting Raw from now on.

Be interested to know how you get on, because I've never managed to get a stack of RAWs which looks better than a stack of JPGs, (though my post-processing skills are seriously lacking, so I'm sure it's always something I'm doing wrong.)

[chris.bailey]

i think a lot depends on how much pulling and stretching you need to do. A RAW holds a lot more data than a jpg in my experience, mind, I normally image with a CCD so have fits files to contend with.

[Karl Johnston]

Output Tiff from DSS is likely to be a little this...

http://www.pbase.com/chris_bailey/image/108873090.jpg

but with some careful levels adjustment (and inversion and a few other bits) becomes this..

http://www.pbase.com/chris_bailey/image/108902656.jpg

You do have to learn to trust the data you collect and to treat it as a starting point. Processing that data is the key to getting great images from good data. I also prefer to use PixInsightCore instead of Photoshop as it is far more geared to processing the kind of data found in astro pictures i.e. pictures that start life with most of the data squeexed into a very narrow part of the overall range.
WOW!!!!!!!!!! You got all that information back from that little black glob ?

[A.S.I.G.N. Observatory]

Ok, I gave this stacking thing another try.

I took 40 - 30sec images of M65 & M66 in Leo. (part of the triplets) I also took 8 dark frames. All in sRAW1 on a 50D. First problem was that DSS wouldn't recognize the raw files even though I had the latest version 3.2.2 and it said it would. Could it recognize the full raw maybe & not the sRaw?

Second, I batched them all out to jpeg and stacked them that way (it used 29 frames). Below is what I got:

So my question(s): What do I do next? Do I still need to adjust the settings? Is this a normal looking output for this step? Do I not have enough data at 30sec subs to get anything worthwhile?

I read Baz's article on stacking and it seemed to make sense. It's just not working out the way I thought it should I guess.

Any suggestions on what to do next?

Hi Jeff,

Don't despair mate. Look at the tabs on the bottom.

1. Play lots with the Luminance tab, especially midtone sliders.

2. As for your red green and blue channels, use the sliders to make all three coloured towers in the histogram lay on top of each other, so they occupy the same space. I usually bring the red and the blue to the green.

3. With the Saturation, I usually turn mine up between 12 to 21%.

You will never get it perfect in DSS. But you will get it close and see the hidden data at the very least. Once you are reasonably happy, save it as a TIFF and go play with it in photoshop.

Most of all, HAVE FUN!

Baz.

[troypiggo]

Try some of the other RAW formats. It works with my 30D's RAW files in sRGB colourspace. I don't use the Adobe colourspace.

I also wouldn't convert them to JPGs to work with. Better to use TIFF as it's lossless, JPG you'll lose some quality in compression.

As Baz suggested, once the stack is complete I play with the Luminance a little. I was getting the really dark outputs like Chris showed, but found that if I went into the Lum tab after the stack and changed all 3 angle sliders (Darkness, Midtone, and Highlight) from their defaults (0, 10, 0 resp) to 45 degrees, and the values from their defaults (80, 33, 50 resp) to 0, I got the nicest looking output from DSS without too much mucking around. Everything else is done in post-processing (Gimp or Photoshop). You can save the above luminance changes and load it as required.

[chris.bailey]

I personally would not play around too much within DSS, as Luc himself admits, it is a bit of a blunt stick

[Jeff]

Urg.....praying for good weather still.....and for the pesky moon to go away. :)