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Canon 6D Hutech mod first light

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#1 jimegger

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Posted 22 April 2014 - 03:20 PM

The night sky is rapidly deteriorating with the suns rays now coming over the northern horizon all night. As a consequence , the atmosphere is glowing with atoms being illuminated by the radiation above. I spent a lot of time fiddling with the color balance and found a close "sweet" spot toward the end of imaging just before dawn started to shut it all down. The 16 inch f 4.5 reflector was used which shows vignetting in the full frame. The 2 inch nose piece on the camera is the cause of that and no getting around it now. I had the camera temp set at 3200 K at the end which seems to even in daylight give the best color balance. NGC 5985 was shot at several different color balances at ISO 800 for all of them for 11 subs total. The wind was playing havoc with the scope with gusts moving it around but things turned out well in spite of it all. I'll try again tonight if it is clear.

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#2 mmalik

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Posted 22 April 2014 - 03:32 PM

Congrats on your 6D; good first light, bit purple shifted. Regards

#3 jimegger

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Posted 22 April 2014 - 04:39 PM

I just did a color test with the camera in the daylight. The camera was set to compensate for the red sky conditions lending a bit of blue to these pics set at 3200 K. Now outside in daylight testing the camera shows colors more accurately at 4400 K. It is so sensitive to red that the sky getting the rays of the sun high up shows up readily on the cameras sensor. It will obviously be picking up the Ha very well indeed when shooting such objects.

#4 Samir Kharusi

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Posted 22 April 2014 - 09:38 PM

I am not clear as to why you are bothering with color balancing. Presumably you shoot Raws. Consequently you are free to change the color balance at any time. What is done normally: Set up a Custom White Balance during mid afternoon sunlight (not in the shade) using a white card or sheet of paper or T-shirt (or a photographic grey card if you have one handy) and use that Custom White Balance for practically all your photos (daytime or astro). The daytime jpegs will come out great, and for astro all you will require is minor tweaking using an eyedropper on a star halo or similar, something that you want to end up white. I am also not clear as to whether your mod is with an astro UV/IR cut or clear glass (or none). You always need a UV/IR cut filter somewhere in your optical train if you are actually chasing a reasonable white balance (e.g. for daytime photos). No UV/IR cut and it's impossible to white balance a daytime photo. As for the color of the night sky, it is toffee colored even at the darkest sites on Earth. The grey sky you usually see in processed astro photos is a totally artificial concoction that is set in post-processing. It's not a "perfection" that depends on how accurately your camera is behaving. It is simply, deliberately, set, artificially. I set mine to a dark greenish blue but even if you set your background sky to red, it'll still be closer to the "real" toffee color than the usual grey. I hope the above can help make you totally relaxed about color balancing astro photos :tonofbricks:

PS using the color temperature selection tool is not the best way to fix white balance in a modded camera. Custom White Balance is much more reliable and once set it should work any time that a daytime Kodachrome film works. Well worth reading the instruction book ;)

#5 jimegger

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Posted 22 April 2014 - 09:58 PM

You are absolutely correct Samir about how to set up the camera. Here in the arctic the skies are MUCH redder this time of year as the suns rays hit the upper atmosphere , the same rays that make a blood moon during a lunar eclipse.
For the shots you have seen posted here I did not use raw but went with the jpegs to keep processing simpler. My 6D does have the UV/ IR cutoff filter in it so it is capable of good daylight as well as astro shooting. This camera will have me on a learning curve for a while which is something I look forward to - keeping things interesting ! By the way , nice and very interesting website you have Samir !

#6 calypsob

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Posted 24 April 2014 - 08:57 PM

If you always shoot raw you can white balance perfectly in post processing with ease. Jpegs are no good for astrophotography. Does the 6D vignette on a 2" focuser?

#7 coinboy1

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Posted 24 April 2014 - 09:53 PM

A full frame camera should not vignette with a 2" focuser. You need to get the Ultra-wide 2" adapter and not a 2" T-adapter. The difference between the two is great when it comes to vignetting. I have very little vignetting with my Canon 5D full frame + SharpStar 65EDQ.

#8 jimegger

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Posted 25 April 2014 - 02:27 AM

The vignetting depends on the f value of your scope as well as the size of the focuser and how the bottom tube of the focuser intercepts the scopes light cone. The ultra wide adapter would get rid of any vignetting if the light cone is not cutoff by the focuser tube at the bottom ala low profile focuser for example. On my 12.5 inch it just barely vignetts at the extreme corners of the frame. I have an ordinary 2 inch T ring and that is the reason for it on my scope. It even does it in the 9.25 inch f/12 refractor due to the T ring.

#9 SunBlack

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Posted 28 April 2014 - 03:56 PM

a bit purple yes....






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