Do optical WB filters improve RAW color latititude?

Started Aug 26, 2012 | Discussions thread
Barrie Davis
Barrie Davis Forum Pro • Posts: 21,460
Re: Do optical WB filters improve raw color latititude?

Mako2011 wrote:

Olaf Ulrich wrote:

Vitruvius wrote:

I am wondering if an optical color correction filter can enhance a digital raw file.

Yes, they can.

Enhance compared to what? The same "enhancement" is now better done in PP. May note have been the case 4 years ago, but is now.



Vitruvius wrote:

I am thinking that digital raw files would have more color latitude if they were pre-white-balanced during exposure by a color correction filter. Not sure though.

Yes, that's correct. Using colour-correction filters to pre-balance the light colour in ligthing situations that are far off from daylight does increase dynamic range indeed. In typical tungsten light you will gain approx. one f-stop worth of dynamic range, or even more depending on the light, the filter, and the camera. Of course, this will come at the expense of a considerable loss of light, as these blue colour-correction filters are pretty dense. You'll lose about two or three stops of light. When shooting hand-held, this usually will force you to crank up the ISO setting in order to avoid camera shake. And the higher ISO setting then will offset the gain in dynamic range from the pre-balancing.

So using these 80A or KB12 or KB15 filters in dim tungsten light is useful only when you can shoot from a tripod at a low ISO setting and use slow shutter speeds without problems ... i. e. no hand-held shooting and no fast-moving subjects. When you need faster shutter speeds (and hence, higher ISO settings) then using those colour-correction filters will do more harm than good.

Well said

It would seem, therefore, that for any one ISO it is a matter of either concentrating the noise in ONE channel (blue) when using no 80B in tungsten conditions...

... or spreading the noise more equally across all THREE channels by using an 80B to pre-balance the light to an assumed daylight sensitivity...[???]

Well, I did some tests a few years back (using Konica Minolta A2 camera, also Canon D20 dSLR) and found there was precious little difference, either way. I also tried it with the Panny LX3 rather more recently, and found it was even more of a waste of time... and light strength.

So that's all good then. Carry on.

"Ahh... But the thing is, these guys were no ORDINARY time travellers!"

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