Custom White Balance, what do you do when it won't take ?

[colinbm]

Custom White Balance,

CWB, what do you do when the camera won't take it & says Failed ! ?

[dabateman]

Try again or increase the exposure to +1 or +2 . That usually helps. If its way off I might also try -1 to see if that works.

Sometimes I am blowing out the white card and not knowing it.

You can also take a white card image and WB later off it in photo ninja. Just save and apply to next shots.

[colinbm]

Ok, I think I get it now....With Automatic lenses they get the correct exposure for you, but with the Manual lenses you need the exposure set correctly first...!

[nfoto]

Not every camera system will alllow custom W/B in camera. This really is not that important as you ought to set the w/b later, for example, off a slab of PTFE in Photo Ninja or equivalent.

 

You could argue that a good w/b in camera will prevent you from getting say the red channel blown out, which may be relevant. However, set the camera to b/w mode and you get the largely same result without the associated hassles of a w/b. Then, later during post processing, set the appropriate w/b. All of this presumes you have been shooting in RAW format.

 

The real case for having a proper "UV white" balance in camera is strong, however, if you do UV video. In fact, this is the main reason I kept my Panasonic cameras running all these years as they can obtain UV w/b without any hiccups directly in camera.

[colinbm]

Thanks Birna

[ulf]

I keep my WB in the camera constantly at a normal VIS setting.

The reason is that then I can roughly identify the filter type used from the colour of the tiny jpeg preview images, attached to the Raw file, even if I just shoot RAW.

This argument is just valid if switching between many filters, as I do.

[colinbm]

Thanks Ulf

When switching filters & before setting a new CWB some of the images on the screen are very artistic, by themselves, even if they are not the ones we typically see for accuracy in presentation for biological studies.

[Andrea B.]

Yes, as you have noted the proper manual exposure must first be set when measuring WB in-camera. And, of course, the more light the better, so use a wide aperture setting.

 

However, remember two things:

• In-camera WB doesn't always work under every UV or IR filter even when proper exposure is set.
  

• If a WB is measured in-camera, it is not always "accurate".
  (Assuming there is such a thing as an accurate white balance.)
  This means that if you set an in-camera WB against a UV-stable white target, that WB can change if you re-balance against the white target in a converter.
  Most likely this has something to do with "temperature" range in the camera and in the converter.
  (Always look for the converter which supports a very wide temperature range in its white balance tool. As an example, Photo Ninja supports 2000 - 15000. There are converters which can go a bit lower than 2000. The names escape me at the mo.)
  

And then there's Andrea's Lazy-girl UV WB Method. Just click around on the raw pinks/reds and/or raw magentas/violets, until all traces of pink, magenta and violet are gone. You should be left with only blues, yellows, gray/black/white if a broad band UV-pass filter was used. Sometimes blue or yellow or both can be missing. Also dark yellows can look olive-greenish and pale blues can look almost like pale purples. But a color sampler will tell you what you have.

 

I added the mention of this Lazy WB thing even tho it might not work on Foveon cameras. Somebody let me know, OK??

[eye4invisible]

Problems setting a CWB in IR and UV was one of a few reasons why I switched from a Nikon D3200 to a Sony A7.