White balance lens cap?

[airfang]

http://photojojo.com/store/awesomeness/white-balance-lens-cap


Has anyone actually used one of these? Looks convenient... wondering its actual performance.





Also, if I am using a gray card for custom WB. If I am shooting portrait I simply place the gray card at the subject's face. But say if I am shooting a wide landscape, where should I place the gray card in the scene?

[Steve Eisenberg]

Regarding the white balance lens cap, you would need a separate grey card for exposure setting help (if the need arose). With a grey card, you can take care of WB and/or exposure setting. The lens cap would be handy for use with Custom White Balance, as you need the entire frame filled. Not so for post-processing, where you use the eye dropper.


For Post-Processing, The grey card (for WB)just needs to be exposed to the same light source. In a landscape scene (with no flash), just hold the card in front of the camera and shoot. I've placed it in the scene, and held it in front of the lens, both ways work fine. With flash, placement is more critical. It needs to be the same distance away from the flash as the subject. So if your subject holds it in front of their face, or in their lap, it is fine. It just can't be in front or behind. The same rules apply if you are using fill-flash in the landscape/outdoors.


You can see how with the flash, you couldn't use this method for Custom WB unless you had a huge grey card to fill the frame...