Has Anyone in this forum Used ExpoDisc for white balance?

[Denniscasey]

I have read about a product called ExpoDisc from ExpoImaging (link http://www.expoimaging.com ). The "theory" appeals to me because company says QUOTE "By setting white balance as an incident filter rather than as a reflective target, the ExpoDisc avoids the common problems and inconveniences associated with using gray cards, white cards and calibration targets" When I shoot race car events or general scenery the "subject" is often far away and in light that is different from where I am standing--difficult to white balance using same light subject is in.

It would seem this ExpoDisc would be ideal for these types of conditions, but has anyone actually used the ExpoDisc (or a similar device) with HMC40?

I just wonder if the white balance "mechanism" or the 3 MOS sensors of HMC40 would cause problems with this or similar devices--most examples seem to involve DSLR cameras.

 

[Denniscasey]

Also, does the theory behind ExpoDisc make sense or is it another version of something that has been tried in the past but did not work?

 

[BobDiaz]

The device appears to blur all the image information into one group. In theory it should give a reasonable approximation of what the color balance should be, BUT if there's a strong dominant color in the shot, it could fool the system.

The other possibility is that you move the camera to where the subject is and point at the light source(s) through this filter. That would give a much more accurate reading, because you're looking at the light coming onto the shot and not the colors of the shot. This reminds me of the light meters that read the light falling onto the subject. IF you are measuring the light falling onto the subject, the color reading should be accurate.

I can't see why this would be any better than a white card, but to me it looks like if it's the second approach, it should work OK.


Bob Diaz

 

[Denniscasey]

The device appears to blur all the image information into one group. In theory it should give a reasonable approximation of what the color balance should be, BUT if there's a strong dominant color in the shot, it could fool the system.

The other possibility is that you move the camera to where the subject is and point at the light source(s) through this filter. That would give a much more accurate reading, because you're looking at the light coming onto the shot and not the colors of the shot. This reminds me of the light meters that read the light falling onto the subject. IF you are measuring the light falling onto the subject, the color reading should be accurate.

I can't see why this would be any better than a white card, but to me it looks like if it's the second approach, it should work OK.


Bob Diaz

Thank you Bob. In many cases I can't move the camera to where the subject is (i.e. a distant bit of scenery is in different light from where I am situated with camera). Even if I had more experience to set white balance by using manual settings in camera it seems the HMC40 does not have any means to "dial in" a color temperature (two choices: 3.2K or 5.6K) anyhow (from conversations on this forum) like many DSLR's have so the only option is to use a manual white balance to try to get accurate rendition of color. I have had several bad experiences with ATW so don't rely only on that.

The only way I had hoped this device would be better than white card balancing was in those cases where camera (and white card) could not be in same light as subject. I wondered if this device's use of "incident" light vs "reflected" light (off white card) could white balance on light subject was in that camera was aimed at.

I really like the HMC40 and it gives amazing results so this is in no way a criticism of camera (other than perhaps it would be nice to have a wider range of color temperatures available to dial in).