White Balance under Sodium gym lights?

[ampguy]

Hi Brian

Hi Brian

I'm a bit confused:

> As to the advantage over shooting a white piece of paper, it has several.

> First, you only have to take one photo - not one photo with and one without the paper.

With all my WB customizable digicams I just take one photo.

> Second, if you shoot JPG, then you do not have to WB in post-processing. Shooting a piece of paper, you do.

?? I shoot JPGs only.

> Third, I'm color-blind. I can't properly set WB from a white piece of paper, I end up with color casts that I can't see, but you normals can.

OK, so here we are getting to something I have a question about, does the expo disc set your WB differently than if shooting a piec of white paper or grey card?

> Fourth, it is a set-and-forget kind of thing. The cap is in my bag. ...

Got it, I like the idea of convenience of the expo-disc, great idea.

Thanks, but not sure where you're going with the double exposures and all in your first parts of explaining the expo-disc. My main question is if the expo-disc works differently than just shooting white or grey paper when doing the WB preset thing (one click, not two).

You can use the expo disc or its clones with either RAW or JPG shooting.

If you shoot RAW, when you convert in post-processing, you choose 'Camera WB' as your starting point (I use UFRaw, not sure what the choice would be for other programs). If you use JPG, you should be good to go.

I do not know if there is any appreciable difference between shooting through a "white lens cap" and the expo disc - I have not tried shooting through a white lens cap, and indeed, have never seen such a thing. Someone here mentioned that they used a white coffee-can lid or something like that - hey whatever works, I guess. I know the expo disc is purpose made and works very well for me.

As to the advantage over shooting a white piece of paper, it has several.

First, you only have to take one photo - not one photo with and one without the paper.

Second, if you shoot JPG, then you do not have to WB in post-processing. Shooting a piece of paper, you do.

Third, I'm color-blind. I can't properly set WB from a white piece of paper, I end up with color casts that I can't see, but you normals can.

Fourth, it is a set-and-forget kind of thing. The cap is in my bag. I get into a situation with wonky lighting, like a school gym, and I do the 'set custom WB' thing on my camera, hold the expo disc over the lens, hit the shutter, and if it says 'OK' then I'm done. Unless the light changes (like from ambient light coming in windows as well as gym lighting), I'm good to go for the entire event. I might reset WB if I change lenses.

I mean, to me it is dead easy and works great. I've posted about it many times, and many are the people who have gone out of their way to comment on what a fraud it must be, how they can set WB brilliantly by performing fifteen steps instead of the expo disc, how WB is a crock anyway, and all manner of sour grapes thereunto pertaining. I have not met one person who has used an expo disc (or one of its clones) who doesn't like it and add it to their bag of tricks permanently. But hey, whatever floats your boat. I got mine, I love it, and if no one else likes it - groovy.

 

[bmattock]

I'm a bit confused:

> As to the advantage over shooting a white piece of paper, it has several.

> First, you only have to take one photo - not one photo with and one without the paper.

With all my WB customizable digicams I just take one photo.

OK, so you're saying you set WB by shooting at a piece of white paper with 'set WB' function in your camera. Gotcha. I misunderstood - thought you were taking a photo of the scene with the paper in it (and presumably one without the paper) so you could use the eyedropper in post-processing to set your white point. My bad.

> Second, if you shoot JPG, then you do not have to WB in post-processing. Shooting a piece of paper, you do.

?? I shoot JPGs only.

See above - I misunderstood you. Sorry!

> Third, I'm color-blind. I can't properly set WB from a white piece of paper, I end up with color casts that I can't see, but you normals can.

OK, so here we are getting to something I have a question about, does the expo disc set your WB differently than if shooting a piec of white paper or grey card?

I do not know. I have tried setting WB by putting my camera on 'set custom WB' and pointing it at something I believe is white (like a t-shirt or something along those lines) and it often works. Sometimes it doesn't. So far, my expo disc hasn't been wrong. Occasionally it is too dark to use properly - it will give me a 'NG' on my Pentax *ist DS when I try to set the custom WB using the expo disc with a slow lens in dark quarters.

When I've used something 'white' in the photo and the eye-dropper trick in post-processing to set a white point, my color vision causes problems - I end up with color casts and don't know it.

> Fourth, it is a set-and-forget kind of thing. The cap is in my bag. ...

Got it, I like the idea of convenience of the expo-disc, great idea.

Thanks, but not sure where you're going with the double exposures and all in your first parts of explaining the expo-disc. My main question is if the expo-disc works differently than just shooting white or grey paper when doing the WB preset thing (one click, not two).

No, now that I understand you properly, it's the same. Just works better for me, is all.

 

[ampguy]

Thanks Brian

Thanks Brian

The expo-disc is definitely a great idea, but a little pricey for me. From the exterior looks of it, it does look like there might me something useful, it's that pyramid cat tongue texture, like old Tiffen fliter holders, that might be useful in some way for gathering more light than just a flat surface.

OK, so you're saying you set WB by shooting at a piece of white paper with 'set WB' function in your camera. Gotcha. I misunderstood - thought you were taking a photo of the scene with the paper in it (and presumably one without the paper) so you could use the eyedropper in post-processing to set your white point. My bad.



See above - I misunderstood you. Sorry!



I do not know. I have tried setting WB by putting my camera on 'set custom WB' and pointing it at something I believe is white (like a t-shirt or something along those lines) and it often works. Sometimes it doesn't. So far, my expo disc hasn't been wrong. Occasionally it is too dark to use properly - it will give me a 'NG' on my Pentax *ist DS when I try to set the custom WB using the expo disc with a slow lens in dark quarters.

When I've used something 'white' in the photo and the eye-dropper trick in post-processing to set a white point, my color vision causes problems - I end up with color casts and don't know it.



No, now that I understand you properly, it's the same. Just works better for me, is all.

 

[bmattock]

The expo-disc is definitely a great idea, but a little pricey for me. From the exterior looks of it, it does look like there might me something useful, it's that pyramid cat tongue texture, like old Tiffen fliter holders, that might be useful in some way for gathering more light than just a flat surface.

I hear you. I got lucky, they were getting rid of their old stock of plastic-rimmed ones, so I got one cheap. Also, there are alternatives:

http://www.flickr.com/groups/diyphotographynet/discuss/72157603931692288/

http://www.tapstream.com/sections/gear/diy/cheapodisc.html

http://www.camerahobby.com/Digital_WhiteBalance.htm

If I had to buy one at full retail, I'd be looking at alternatives too. I just got lucky with the price a couple years ago.

 

[ampguy]

Thanks Brian

Thanks Brian

Will try the coffee filters and see how they work.

I hear you. I got lucky, they were getting rid of their old stock of plastic-rimmed ones, so I got one cheap. Also, there are alternatives:

http://www.flickr.com/groups/diyphotographynet/discuss/72157603931692288/

http://www.tapstream.com/sections/gear/diy/cheapodisc.html

http://www.camerahobby.com/Digital_WhiteBalance.htm

If I had to buy one at full retail, I'd be looking at alternatives too. I just got lucky with the price a couple years ago.