Just when I thought I had it...

Sorry to re-submit this but my previous post wouldn't edit.

I have been reading these threads in the White Balance forum with much interest then found this while Googling: http://www.bythom.com/graycards.htm

Would somebody in the know kindly explain please... what are we to believe? For exposure setting purposes which is the best grey card manufacturer for digital and is it 12 or 18%??? Confused!

Another question I have is are there different white balance kelvin settings for the northern and southern hemispheres? Where would I find the most reliable white balance setting chart on the net because they all seem to differ slightly from what I have found?

Many thanks for the help

My response would be: Interesting, but it doesn't matter. Use whatever you have, and learn how to translate it to how your particular camera(s) meters. They're all a little bit different anyway.

WB is a different matter. Typical 18% gray cards are not really color neutral. Better choices there include the WhiBal and the GretagMcBeth ColorChecker.

Different WB north and south? That sounds goofy to me. Neutral is neutral. Remember that outdoor color temp changes constantly depending on time of day and any number of other factors. That's not the same as "neutral." A true neutral setting — "correct" in the technical sense — will remove all the wonderful color from a sunset, to take the most obvious and frequently cited example.

So, could color temp (not "neutral" WB) be different in the northern and southern hemispheres? I suppose so, just as it can be different at different latitudes in the northern hemisphere. I vividly recall getting up one morning in a hotel just off Lake Geneva on the French side, looking out the window and thinking, "So that's why the Impressionists painted it that way — That's really what it looks like!" ;-)

But still, neutral is neutral, wherever you find yourself. But neutral might not necessarily be what you really want.

(The critical thing, of course, is to remember when in the southern hemisphere to hold your gray card upside-down.)

[/ramble]

Nill
~~
www.toulme.net

Thanks for the reply. I'll remember to hold my grey card upside down when south of the equator ) What do I do when ON the equator?

Only joking...

Place it on edge, of course

On the side edge of the grey card or the edge of the equator ;o)

Incidentally I emailed tamrac as one of my day packs is the tamrac adventure 9, I haven't had a response from them but I was curious as to whether anybody who has the bag has tried using the grey foam dividers inside the bag as a "grey card"? I used to have a Lowepro bag and the foam dividers in it were also grey. Is this coincidence or deliberately done do you think?

Hi Theo,
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[FONT=Verdana, Arial, Helvetica, sans-serif](and make sure that the card is angled about 30 degrees between the lens axis and the light source so that you're really seeing the reflected light[/FONT]

Click to expand...

Maybe its me, but I just can't work out what that means.

Many folk use the whibal and I think they go to great lengths to get the right sort of material, one that is consistently neutral. They may have an explanation. I think your dividers are grey 'cos they have to be some colour, I do not think it would be any specific grey shade, or a material that is specifically selected for grey card duties. But it may be good enough in some situations. I think it may be easy to test, if you have different coloured light sources.

Best wishes,

Ray

Quote:
(and make sure that the card is angled about 30 degrees between the lens axis and the light source so that you're really seeing the reflected light)

Were does it say this?

I was thinking about it - if the grey foam dividers were suitable it wouldn't make much sense really because if they were it would put other companies that sell grey card out of business.

Hi Theo,

The link you gave, re the wrong gray values, there was some text down the right hand side. It gave a pseudo technical explanation of how to use grey cards, iirc.

The whibal site, if you've not found it, probably tells you all you need to know.

Best wishes,

Ray

It is a very interesting article.
I learnt more than b4.