# iphone app grey card!



## Reyna (Apr 26, 2011)

i was looking into buying a grey card and saw they have an iphone app grey card! what do you think about this? think it would actually work?! lol


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## Stradawhovious (Apr 26, 2011)

I would say no.

Its my understanding that a grey card serves two purposes and the iphone would fulfill neither.

First, the gray card is used as a tool to obtain an exposure reading by _reflecting_ available light off of a card that is a constant 18% shade of gray. The iPhone will not supply reflected light. It is back light by LEDs or some such light source, and as such will be worthless for this purpose.

Next, a gray card can be used for a custom white balance. The iPhone's display will vary based on the available light so it will be visible in bright light as well as low light. I would think that the ever changing brightness of the display will wreak havoc on your ability to get a proper and constant reading, and make your white balance all kitty wompus.

I could be wrong though, I frequently am.


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## KmH (Apr 26, 2011)

I concur.

Holly, since you shoot people the X-Rite ColorChecker Passport is a great tool to have.


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## MissCream (Apr 26, 2011)

I did a search for it on my iPhone and read the reviews because I didn't think it would work. All the reviews said that it doesn't because of the reasons posted above.


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## Reyna (Apr 26, 2011)

thank you all. i just thought i'd check!

keith, idk if you remember telling me about fp high speed sync, but i appreciate your help with that! the nikon d7000 with my flash does the job!


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## KmH (Apr 26, 2011)

Yes. I pointed out that your D60 could not do FP sync. I critiqued some of the first photos you posted here at TPF.

I highly recommend you start using the shift key. Your posts don't look very professional with out the appropriate capital letters. I sure hope you don't communicate with clients using all lower-case.

I don't think you're devoting enough effort at learning the technical side of doing photography.


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