Problem With Colors on most DSOs - Specially M51

[aacc66]

Hello,

I had been trying on my weekends to do some DSO imaging with my Sony a7s (un-mod) and F/10 Edge Celestron 9.25. Unfortunately, my DSOs are coming out with no color. Specially with M51. This is my basic process:

-12 exposures of 500 sec - ISO 3200 - Sony a7s (I had another set of 10 with ISO6400 and the same 500 sec)
-4 Darks 500 sec - ISO3200
-20 Flats
-DSS for the staking
-Startools for the processing
-I am in a red zone - Using Astronomik CLS Filter

I was not doing dithering last time, but I plan to do it next time...but I doubt that is the problem.

These is my Startools process:

-Straight from the Autosave file from DSS to Starttools after renaming the file
-Open with: "Linear, was bayered, is not white balanced"
-Crop the file due to artifacts and Vignetting ( I may use the AutoDev to figure out my Vignetting)
-Do default wipe
-Develop with the "Home In" Button until it settles
-Contrast - Default settings
-HDR (with Reveal DSO algorithm and Noise Suppression at 100%) - the rest default
-Create Star Mask
-Sharpening with middle or large features at 200%
-Deconvolution with defaults
-Flux for details
-Life for "more=less"
-Color cap green-to-brown and play with saturation
-Stop tracking and follow de-noise rules
-Sometimes a I go back to colors and re-saturate

Still, I don't seem to get more than one color, unless it is in the background.

I cannot upload the fit file generated by DSS. I am not sure if you need that file as it is 140MB, but if you do need it, is there a way to get it to your side?

Thanks.

Alvaro



-

[Amaranthus]

Did you get the debayering correct in DSS? My Sony NEX uses a RGGB pattern. You could also try applying dcraw directly - it should allocate the correct debayering.

If you're happy that you've done this, and you can see the colour in DSS, then your image is probably desaturated, and the colours can be drawn out in the Color module (crank up the saturation).

You could also try loading the files in a different way. Load using LRGB, and allocate the same image to each of the R, G and B channels.

If you zip the FITS file, it should compress and then be uploadable to a site like DropBox.

[aacc66]

Amaranthus,

Quick question (I will try to provide more information later). Do you apply dcraw to the raw files before registering and stacking them with DSS? is that correct?

Thanks

Alvaro

[Amaranthus]

I've done both (applied dcraw manually to the RAW files and then used the TIFFs in DSS, or let DSS do the debayering). I get more consistent and controlled results with the former. Search around on this forum for dcraw and you'll find recommendations from Ivo on what settings to use to get the 'cleanest' data for Startools.

[midwayexpress]

A couple of notes.

First, I had an awful time getting color with the CLS filter in any program. The problem is that the CLS filter just separates the histogram too much. My colors got much better when I switched to the IDAS filter.

Second, make sure that you have turned off the color calibration in DSS. DSS doesn't like this but the images come out much better if you do this in StarTools and PixInsight.

Third, to get the colors right in StarTools I create a fat star mask, hit the sample button, and then go back to mask clear and invert and then let the color tool apply the previous sample to the entire image. Also for galaxies you need to increase your dark saturation.

Finally, how long are your exposures? We are having a bit of a debate about how long OSC exposures should be on Cloudynights but one thing you need to make sure of is that your red histogram is at the very least clearing the left wall.