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Old 17-03-2013, 04:10 PM
LewisM
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Colour conversion issues

Recently bought an SXVR-M25C OSC CCD. Really nice camera, but I have some issues.

The B&W FITS images are nice, but when I run the colour conversion, in either the SX software or Maxim DL, I either get NOT MUCH colour, or ODD colours - for instance, last night's M83 was almost entirely purple, other stars and all!

Running m42 thorough it reveals basically nothing - no red, little blue, and importing a converted TIFF into PS leaves me with obvious stretch artifacts etc, as well as usually some remnant of the FITS matrix!

What the heck is going wrong here!?

I did NGC 3324, and it shows some red in SOME of the photos, yet others later will be predominately purple again.

Does this sound like a hardware/software issue, or am I just not doing things right?

And it's being a NIGHTMARE to stack anything after colour conversion too (which MUST be done prior to stacking of course) - all subframes are wrong size/channel etc, (unless I bin the lights 2x2), and even then, I end up with a pixelated mess of a result. I am more or less limited to single images (crap detail / colour) because of this stacking weirdness. And if I use the continuous image function, it adds the new data on top of old... great in theory, but usually get field rotation after 4 x 5min subs, meaning throwing out EVERYTHING! (learnt that the HARD way!)

Starting to pull my hair out here! Some shots look FINE prior to conversion, then after, there will be pixels everywhere and no detail etc. Was getting better results with a DSLR!

Any tips / ideas?

Does any available software auto-colour convert without having to do all the 100000 dance steps of Maxm and SX software? CCDautopilot??? I am now using Maxim, but figuring out flat/bias subtraction is a nightmare.

Attached are some samples - the BETTER ones!

Lastly, if I set the temp to -40 on a 27 night, it will get to about 0.9, then start increasing again to about 3.8 = this does not seem right.
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  #2  
Old 17-03-2013, 05:50 PM
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gregbradley
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MX25 used to use the same CCD sensor as the Nikon D70. I used this as a modded camera for some time when I first started in astrophotography.

I used to use Images Plus as it has superior handling of colour images.
Not sure about Maxim etc but I used to find not many programs handle colour images that well.

Greg.
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Old 17-03-2013, 06:41 PM
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Shiraz (Ray)
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Hi Lewis. your camera will not do 40 below ambient. the spec is approximately 30, which is about what you got (actual value depends on airflow around the camera). In any event, if the temp is creeping up, you may be pushing it too hard - try at 5C or even 10C in warm conditions - even at 10C, the CCD produces only .02 e/s/pix thermal noise. According to the manual, do not try to operate at extreme cooling when the air temperature is high.

re colour, try it one step at a time - maybe the first step is to do as the manual says and try it out with a pinhole during daylight to make sure you can get some reasonable colour. next step is astro without darks, biases, flats etc (make quite sure none of these is switched on) and just try to deBayer some lights with all calibration turned off. Colour conversion doesn't look hard - the SX manual suggests switch on the Colour smoothing filter and the Anti-alias filter – you can experiment with the other options as you gain more experience. Now click on ‘Create image’ and you should see that the grid pattern disappears and is replaced by colour image data. edit: if this does not work, see Bretts post following.

"all subframes are wrong size/channel etc" - ?? sorry Lewis, don't understand this - are you getting an error report?

you mention binning - that messes up the Bayer encoding and the manual warns against using it with a colour cam

Last edited by Shiraz; 18-03-2013 at 09:59 AM.
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Old 17-03-2013, 08:34 PM
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bert (Brett)
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I'm not sure what program you using for debayering. But likely no colour or screwed up colours most likely will be your bayer matrix offsets. Essentially you have to tell your program which pixels are red, green etc.

-30 delta is all you get with the sx cameras. They are only single stack peltier cooling. That said they are still very clean at around 0 degrees.
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Old 17-03-2013, 10:45 PM
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Quote:
Originally Posted by bert View Post
I'm not sure what program you using for debayering. But likely no colour or screwed up colours most likely will be your bayer matrix offsets.
Lewis, the manual tells you where to find these and how to re-set them if they have been scrambled (for the SX software). also might read http://www.iceinspace.com.au/forum/a...p/t-81432.html

Last edited by Shiraz; 17-03-2013 at 11:14 PM.
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Old 18-03-2013, 10:16 AM
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Hey Lewis,

I use DSS 3.3 beta for debayering (it reads them in the lights list) so when I click on them they convert to colour and I can see the details when I adjust the sliders.

It means they dont need to be debayered before stacking as DSS takes care of it all.

If it looks wrong, I simply adjust the FITS settings for debayering until its correct, I use generic GRBG for my Sony sensored Atik.

DSS beta 3.3.3 rocks and gives me an output that requires very little post processing.

Give it a go.

Cheers

Chris
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Old 18-03-2013, 10:56 AM
LewisM
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Well, I FINALLY go it to work, and the images are, as I expected, JAW DROPPING!!!

I checked a check in DSS (yes Chris, I use 3.33) that I did not MEAN to (forcing interpolation) MEA CULPA, MEA MAXIMA CULPA!!! (******** me)

OK, ignore original thread, moving right along

Interesting that DSS does not list SX cameras in the list - I had to trial several generic bayer matrices to get it perfect.
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Old 18-03-2013, 11:05 AM
LewisM
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Bit of an improvement

This is only 1hr 50min of lights, with a 5" refractor at f/9.2 (will use FR next, at f/6.2). NO darks, flats, or bias - the SXVR-M25c does not usually require darks, as is fairly evident, but now that I have this sorted, will use the flats and bias I took the other night and do it that way. Image is totally unprocessed apart from what DSS does. Processing will be fun

Looking forward to adding more data, but as is typical in QLD we got 2.5 great nights, now grey and wet again. This was always just a familiarisation run anyway - bugs sorted, carry on
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Old 18-03-2013, 11:12 AM
LewisM
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BTW, it's a GREAT camera. I cannot praise it enough. Only my initial ineptitude caused the issues
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Old 19-03-2013, 10:54 PM
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That's looking REAL nice Lewis,

A bit of crud from skyglow, but that's expected. The colours look nice and the details are great.

I think this is the same chip as the QHY8 and the Orion SS Pro II if its the 6MP Sony.

Well done

Cheers

Chris
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Old 20-03-2013, 01:02 PM
LewisM
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Same sensor as the QHY8PRO.
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