Convert Custom WB to Degrees K

Forgive me if I missed this in the manual. Is there a way to take a Custom WB, and then have the camera tell you what the numeric Degrees K is? The reason I'd like to do this is that it is kind of a problem to change memory cards in the middle of a shoot and have to retake a custom WB. If I could know what the number is after taking a custom WB, then I could just dial it in with the number and be done with it.

nope, cant do it bro..

You didn't say what camera you wanted to accomplish this with. I am not familiar with the Canon 1DMk2N or 1DMK2, but in the case of the Canon 20D you would press INFO to see your current camera settings before you remove the memory card. It tells you the white balance temperature there (page 62 of your user's manual).

Once you've set a custom WB, you don't need the white/grey image used to create it anymore. The custom WB will remain until you set another. You can delete that image or change cards to your hearts content.

steve

FYI, the color temp you see in Info is the setting that you have set via the menu. It has nothing to do with the color temp of the custom WB.

This is the real answer to your question. CWB isn't dependent on the picture being available once you've set it.

Besides this not being necessary (see my earlier post), in most cases it's not possible. The K measurement is simply a shift along one axis of the color spectrum, generally from Amber to Blue as those are natural light source variances. A custom white balance may also contain a Magenta/Green shift to remove a color cast possibly caused by brightly colored walls or green a skin tone casts due to foliage. Because a CWB can also contain these non Amber/Blue corrections, it sometimes cannot be represented as a color "temperature".

I apologise if this is clear as mud

Best thing is to shoot in RAW. I just take a shot of a reference gray card and copy the AWB setting to any frames taken in the same light in my RAW convertor to get the same effect as a CWB. A lot less fiddiling about in the field.

Thanks for all the info. I wasn't aware that you could remove the card and the Custom WB would still work. I guess that's what I get for "assuming" that it would be a problem. So, I don't need to worry about it. As for the Custom WB not being equating to a temperature, that seems odd... but I'll take your word for it. From working with WB, it seems that its always a temperature. If you shoot in RAW, when you look at the image while it still has it's RAW capabilities, it seems that the Custom WB is represented as a temperature, and in fact you can also tweak it up or down. I still would like to be able to equate the Custom WB to a number, though... because when I have multiple bodies that I'm shooting with in one venue, and I want to have the WB match, it would be much easier using a number.

As for shooting RAW being a solution, its not for me. I do not want to have MORE processing to do when I get back to the office... I want less. I want to get the WB correct at image capture time and not have to fiddle with it in capture RAW. My workflow is JPEG for most shoots, and I only use RAW when I'm shooting a small number of images and need the maximum amount of editability. It may just be my lack of skills, but I'm a JPEG shooter 97% of the time.

The color temperature as specified in degrees Kelvin generally works well for heat induced lighting, such as that from an incandescent light or the sun. It corresponds to the radiated light from a "Black Body" material as it's heated to different temperatures.

A custom white balance, OTOH, will attempt to remove any color cast, even those falling outsode the Planckian Locus. There's a nice chart showing where Temperature based color casts fall in an XY color space on the following wiki page. It also explains why Florescent lighting is sometime "teh suck" (I learned that technical term from Lord_Malone )

http://en.wikipedia.or​g …related_color_t​emperature

I fondly remember how simple and enjoyable life used to be with my T50. I pressed the shutter and liked it! No concerns about WB, focus, DOF, exposure metering and shutter speed and whether they were all going to come together at the same time If things didn't work out, I blamed it on the film lab .

s