understanding the EX1r custom white balance
 

I am noticing something strange

I am shooting interiors, and the correct white balance is very close to the 3500K preset

actually if I put the EX1r in full auto it will go to 3400K.....fair enough

now...if I instead try to do the custom preset (A or B), it goes to 2500K, which is way too cold and definitely wrong

how can this be? can anyone explain?

Describe your procedure for this step.

Exactly how are you doing it? What is the room/lighting setup? Where are you holding the card? What is the card made of? How are you setting the exposure before white balancing? How much of the frame are you filling with the card? Is the camera's white balance offset feature turned on?, etc.

How do you know the custom white balance is wrong? Are you checking the color with scopes or a properly calibrated professional HD monitor? Your perception of what looks right, or best, may be influenced by an incorrectly setup monitor or the ambient lighting where you're viewing the picture. I am reminded of pilots who don't believe their instruments and fly into the ground. :-) In my experience, it is more likely that it's the auto-white balance value that is wrong, unless you have not followed the proper techniques for setting a custom white balance.

Just to add to Doug's post. Custom Preset simply stores a value in the camera. There is a procedure in the manual (albeit poorly written) on page 48 entitled "Executing Auto White Balance". To set a value, you have to put a white card or piece of paper in the lighting, aim the camera at it with the switch in the preset you want to set and then you press the Wht Bal button. The camera then calculates a new value to store in that preset. If you use auto white balance on the same white card, I would expect it to read the same as when it calculates the preset.

I am actually not using any card, I am very casually pointing at a white wall, or even pointing at the light (not close-up)

my point is precisely that: regardless of the method I use (card or not card), I would expect the the custom white balance I put in A or B to give the same reading as in full auto mode, all conditions being equal, and it's not

it's just a judgment based on the playback.
it seems like the custom value is way off, whereas the auto balance looks more correct to my eyes, and anyway shouldn't the EX1r use the exact same mechanism to determine the white balance in both cases? the difference being that with full auto it can shift if the light changes obviously

I just came across this thread in the recent posts feed, I don't know if I can help, but I have a suggestion.

The reason you use a card is to match the light where the subject will be. If you point at the light, you will likely get a very blue-hued WB.

Try the process again using a card or even just a piece of printer paper. Make sure you fill the whole frame with the card/paper, and that the card/paper is under the same light as the subject. I'm probably going to miss your response, since I don't frequent the EX3 forum, but I think this should remove some of the variables from the issue here.

Excuse me, but it seems like your wasting our time by not disclosing this in your first post. If I had known that, I never would have posted. I don't really have the time to help someone who is "casually pointing at a white wall" and then wondering why he doesn't get good results. Please try to conduct some serious white balancing, then ask other people for help if you still have trouble.

And BTW, with auto-white balance, the camera is just making a guess as to what the color should be. Obviously it's going to be wrong more often that it is right. The camera can't tell whether your wall is pure white, bone white, teal, sky blue, parchment, or ivory. That's just one reason why auto-white balance should never be used under any circumstances.

Absolutely not.

It should be used if you want people to randomly change colors in the middle of your scene!

Sorry I couldn't resist.

-Garrett

I just had a good play around with the EX1's ATW.. That's a strange beast indeed.
White card lit with warm white fluro has ATW and manual agreeing at 3600K.
Change to very blue LED and manual WB gives 7000K and ATW will not budget from 3600K...at first.
If I go from my preset of 7000K ATW will hold that 7000K. If I came from the camera's preset of 3200K ATW still holds that 3200K. Changing ATW speed seemed to make no difference. Switching Off Shockless White finally got ATW to budge CT from whatever preset it started at but only if the seriously blue lit card didn't fill the frame, even when it decided to budge it never got anywhwere near 7000K.

I wish I could make some sense of the EX1's ATW, I've had a shoot where it might have been useful. The same shoot had a much lesser camera in ATW giving a better result. I had several goes at doing a manual WB of the EX1 off a white card and within a couple of feet the reading went from 2800K to 6500K and a few minutes later when the cloud cover outside the building changed it all changed. For the sake of an easier experience in post I gave up and left the EX1 in its 3200K preset.

I find your reply quite snappy Doug. I humbly want to point out I just used the procedure as suggested at page 48 of the manual, albeit it may no be the way pros do. I still do not understand why with all things being equal the White balance algorithm of the ex1r doesn't give the same reading whether taken automatically or "upon request" done pressing the WHT BAL button. That's the only thing I wonder.

That's interesting Bob. You seem to confirm some of my doubts although what I experience is different: my manual WB results seem to be constantly "colder" than the ATW. in your case it seems like ATW doesn't work properly whereas in my case it seems like the manual WB doesn't, or at least works in a way I don't understand

can someone just do this test, and point the camera to one specific area in a room, do a custom white balance, then switch to auto white balance (not using full auto mode, or else other parameters would be changed by the camera), and see if the values are close or the same?

Federico,
at the same time can I suggest you try repeating you test with the camera stable e.g. tripod or on a table, and point it a an evenly illuminated white card. A piece of A4 / foolscap paper would be good enough for this test. Light the card with a daylight source and then repeat your experiment.

I agree with you 2500K does seem very low, the only source I've had that low is candlelight. I'm just very suspicious based on my own tests that something else is going on here.

Good. I meant it to be snappy. :-)

I was being diplomatic... take it easy : ) especially you should treat better one of your customers he he
my question is still on BTW : )