Let's get anal about white balance with flash

DocFrankenstein wrote in post #4820554
Very good.

And pressing the button on the top right side of the camera makes the shutter go "snap"

"Doc", you may be very knowledgeable in this area, but the only thing you have provided is a bit of casually thrown out info and curves that my 3 yr old granddaughter could have drawn....and probably as accurate (flat, uniform spectrum of sunlight?)

How about some documentation, detailed examples....preferably recent and in raw.

Plus....a little respect for your fellow posters.

mbellot,

You'll probably want to click on each image at least 4 times and average the results. The amount of consistency between clicks should give you some clue on the reliability of your measurements.

What's the numeric tint scale in Bibble? What are the numerical values at each end of the tint scale? Can I assume that a positive tint number indicates adjustment toward magenta, indicating that the light source was on the green side?

jrsforums wrote in post #4820761
How about some documentation, detailed examples....preferably recent and in raw.

I'll do that right after every advisor of the bees publishes a scientifically accurate report as to why they are "good lights" in a peer approved journal.

Until then, I have better things to do.

DocFrankenstein wrote in post #4814887
Some people don't care. Some people don't seem to notice. Some people equate baul buff to Jesus or Muhammad ibn ‘Abd Allāh and are ready to defend it to death.

Most repeat what they hear from others. "get the bees, get the bees" having never tried anything else.

I think I've learned my lesson....If a discussion board on lighting is filled with posts about alien bees and speedlites then stay away.

DocFrankenstein wrote in post #4820836
I'll do that right after every advisor of the bees publishes a scientifically accurate report as to why they are "good lights" in a peer approved journal.

Until then, I have better things to do.

OH...I forgot....you are superior and can pontificate about Jesus and Allah...

Anyway....what we were just discussing was the sensor's reaction to different lighting and it's correctability....or did you forget....not alien bees ability to produce light properly.

DocFrankenstein wrote in post #4820836
I'll do that right after every advisor of the bees publishes a scientifically accurate report as to why they are "good lights" in a peer approved journal.

Until then, I have better things to do.

Doc, I think John has a good point. How about showing us some examples or references to support what you've been talking about. If you can't come up with any after you've been called on it, then what's the point of discussing this further and sending the whole thread off on a tangent or worse, taking the thread downhill with your smart-ass retorts.

For what it's worth, I do agree with some of your points. But you still need to provide references or convincing examples when challenged to do so. You know what they say, "Either put up or shut up".

Curtis N wrote in post #4820764
mbellot,

You'll probably want to click on each image at least 4 times and average the results. The amount of consistency between clicks should give you some clue on the reliability of your measurements.

What's the numeric tint scale in Bibble? What are the numerical values at each end of the tint scale? Can I assume that a positive tint number indicates adjustment toward magenta, indicating that the light source was on the green side?

Curtis,

The tint scale runs from -100 to +100. -100 results in a greenish cast and +100 results in a pinkish (magenta?) cast.

Attached is a table of five samples per image with average and standard deviation calculated. It still seems awfully consistent...

Any more thoughts, or should I just consider myself lucky?

mbellot,

Based on your data, the light seems to have a significant shift from full to half power, and is reasonably stable from that point down.

The tint readings seem to indicate that the light has a strong greenish tint. You may want to consider if the surroundings played a role in this. For example if the GM card was propped up on a table with a green tablecloth. Eliminating the effect of bounced light is the hardest part of getting accurate results using this method.

Curtis N wrote in post #4822433
mbellot,

Based on your data, the light seems to have a significant shift from full to half power, and is reasonably stable from that point down.

The tint readings seem to indicate that the light has a strong greenish tint. You may want to consider if the surroundings played a role in this. For example if the GM card was propped up on a table with a green tablecloth. Eliminating the effect of bounced light is the hardest part of getting accurate results using this method.

Hmmm. The table is a dark gray laminate so I doubt that affected it.

I did have an overhead (4') fluorescent light on behind me, but two 40W CW tubes shouldn't put out enough light to have an affect, should they? The FL light was easily 3x the distance of the strobe from the GM, maybe more.

Other than that, there was a white freezer to GM left and the basement is covered in light brown wood paneling and the GM was propped up between two (black) legs of a light stand.

I can try to drape some dark blankets around the area tonight if you think it will make a difference.

EDIT: Curtis, as I said in my first post, the calibration markings are lousy on this strobe. If you look at the apertures the first step is actually from full to ~1/4 power (f/18 to f/10). I'm going to try to recalibrate the markings using my Sekonic this evening and reshoot at actual (approximate) power stops.

mbellot - I looked but could not find if you had indicated which lights you have...

Titus213 wrote in post #4822605
mbellot - I looked but could not find if you had indicated which lights you have...

I didn't. Quite intentionally.

However, I will say they are not Brons or Bees.

I want to get an "unbiased" evaluation. So far it seems they are a bit "green" in output color (or my reflections are), but otherwise not bad.

mbellot,

It's hard to know if the table below your GM card, or the fluorescent lights, may have affected the data.

But it's far enough off-neutral that you might try another method. Maybe clamp the GM card on top of a light stand or something, to minimize any surface reflections in front of it, use X-sync shutter speed and turn off the fluorescent for at least one shot, and see if it changes the data.

Curtis, thanks for the ideas. I'll give them a shot this evening.

Curtis N wrote in post #4823039
...turn off the fluorescent for at least one shot, and see if it changes the data.

Save yourself the test shot...Just meter the scene for ambient light, and if the f/stop and shutter speed used for the flash exposure differs from the ambient light reading by more than 2.5EV, the fluorescents are making NO difference in the world as it registers as BLACK!

When you measurebate God kills a kitten