Jump to content


Photo

Confused again!!

  • Please log in to reply
10 replies to this topic

#1 WhitenerJ

WhitenerJ

    Viking 1

  • -----
  • Posts: 569
  • Joined: 06 Feb 2012
  • Loc: Waxahachie, Texas

Posted 07 December 2012 - 06:05 PM

Ok just when I think I got the white balance, IDAS filter, and my modded T2i figured out, I get confused again. I'm trying to figure out when imaging using BackyardEOS how to use the histogram when different white balance settings affect the hisogram. Some setting shift the colors all over so. Before I modded my T2i I was able to get a fairly stable histogram in BYEOS to guide me on exposing. I would always aim for 1/3 to 1/2 of my histogram for the correct exposure. So now how do I know where to aim and which white balance setting to use. Should I use Auto or do a custom white balance or what? Help me out guys!!

Thanks, Jason

#2 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 5407
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 07 December 2012 - 08:02 PM

Here is what I use (leave custom default); complete settings at the end of this... doc.

Attached Files



#3 WhitenerJ

WhitenerJ

    Viking 1

  • -----
  • Posts: 569
  • Joined: 06 Feb 2012
  • Loc: Waxahachie, Texas

Posted 07 December 2012 - 08:18 PM

So daylight, right? Do you have a sub I could look at to see your histogram?


Jason

#4 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 5407
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 07 December 2012 - 08:26 PM

Yes, daylight; one sub here... (10min, ISO1600)

#5 fco_star

fco_star

    Surveyor 1

  • *****
  • Posts: 1774
  • Joined: 13 Dec 2010
  • Loc: Texas, Midland

Posted 07 December 2012 - 11:34 PM

mmalik.... if the camera is modded + CLS-CCD filter don't you have to use custom balance to fight the (green/bluish) color?

#6 mmalik

mmalik

    DSLR camera modifications

  • *****
  • Vendors
  • Posts: 5407
  • Joined: 13 Jan 2012
  • Loc: USA

Posted 07 December 2012 - 11:41 PM

mmalik.... if the camera is modded + CLS-CCD filter don't you have to use custom balance to fight the (green/bluish) color?


Yes, that's what I meant; may be didn't say it right. Thx

#7 pfile

pfile

    Gemini

  • -----
  • Posts: 3168
  • Joined: 14 Jun 2009

Posted 08 December 2012 - 03:25 PM

you don't *have* to use a custom white balance. all the white balance data is is 2 multipliers stored in the EXIF header of the CR2 file. some programs read the white balance data and automatically scale the channels. some don't. some can be configured to ignore or pay attention to the white balance data.

if you are serious about it you need to do color calibration on your images anyway, either G2V or something like PixInsight's ColorCalibration. assuming your stars or galaxy core are not blown out, color calibration can fix your color casts.

having said that, usually simply balancing the histogram channels in PI or PS gets you most of the way to proper color balance. of course if the DSO is Ha-rich or something then this won't yield good results.

#8 nofxrx

nofxrx

    Vendor (HyperCams & Mods)

  • *****
  • Vendors
  • Posts: 5241
  • Joined: 12 Jul 2005
  • Loc: Palm Bay,Florida

Posted 09 December 2012 - 05:49 PM

It doesnt matter what WB setting you use for capture.
But I prefer to use the same CWB setting I use for daytime...it just seems to make post processing/color balance later easier..

However, for using the BOC histo to judge what exposure settings you should be shooting for..
If your channels are separated, like you showed me before, Jason, just shoot so that however far apart your channels are try and find the center of the channels(combined channels, not each separate channel's center, know what I mean?) and use that as your "line" for determining 1/3-1/2 on BOC Histo..

Atleast, that is what I do..

Maybe someone with a bit more experience will chime in..

EDIT, pfile has beaten me to it lol

#9 WhitenerJ

WhitenerJ

    Viking 1

  • -----
  • Posts: 569
  • Joined: 06 Feb 2012
  • Loc: Waxahachie, Texas

Posted 09 December 2012 - 06:24 PM

So in this sample image I would aim for the blue peak as my guide for the 1/3 histogram exposure?

Posted Image

Jason

#10 nofxrx

nofxrx

    Vendor (HyperCams & Mods)

  • *****
  • Vendors
  • Posts: 5241
  • Joined: 12 Jul 2005
  • Loc: Palm Bay,Florida

Posted 09 December 2012 - 07:26 PM

Yep.
Since you are looking at the individual channels Histo, this is pretty normal AFAIK...I think if you switched to a Luminance view, it MIGHT show you one single peak/curve...IDK..
But, that looks perfect to me as is. The R channel being the most dominant, obviously being modified..and B being more dominant than G due to the LP in your area, and the 'color' of the sky itself..

This is from my UNmodified D800..not much, but you can clearly see that the channels do not line up perfectly..and is more of a result of the WB used(AWB in this case)..
Once modified the result will be VERY similar to yours.

I would like to see if others chime in and show a histo of a single exp.. :)

Attached Files



#11 nofxrx

nofxrx

    Vendor (HyperCams & Mods)

  • *****
  • Vendors
  • Posts: 5241
  • Joined: 12 Jul 2005
  • Loc: Palm Bay,Florida

Posted 09 December 2012 - 07:29 PM

Oh, that was not an actual AP attempt..it was a stationary tripod. I was catching some lightening storms out east HERE on the coast, and above the clouds was a perfect sky, so I just pointed up and snapped a pic...so this is NOT what I would consider a "set up/planned" exp..just F/4 ISO 400 and 20sec..I would probably double that exp length, or double the ISO for a "proper" image..






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics