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dichro1 · Nov 21, 2006, 9:07 PM

I am not clear on the difference between TTL auto operation and P-TTL auto flash operation on the new digital cameras.

What is the difference, and what are the limitations?

amazingthailand · Nov 22, 2006, 7:05 AM

On film cameras TTL (Through The Lens) metering was a way for the camera/flash to measure the actual exposure and respond accordingly.

With digital there have been variants of that (D-TTL, I-TTL - both Nikon) that have refined the basic TTL idea and do essentially the same thing, but in a more refined way. Canon, I believe, also have a TTL variant.

I have not heard of P-TTL specifically, but I suspect it is a manufacturer's specific implementation of TTL for use with their cameras.

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Nov 21, 2006, 9:07 PM	#1
dichro1 Junior Member Join Date: Feb 2006 Posts: 18	I am not clear on the difference between TTL auto operation and P-TTL auto flash operation on the new digital cameras. What is the difference, and what are the limitations?

Nov 22, 2006, 7:05 AM	#2
amazingthailand Senior Member Join Date: Aug 2002 Posts: 851	On film cameras TTL (Through The Lens) metering was a way for the camera/flash to measure the actual exposure and respond accordingly. With digital there have been variants of that (D-TTL, I-TTL - both Nikon) that have refined the basic TTL idea and do essentially the same thing, but in a more refined way. Canon, I believe, also have a TTL variant. I have not heard of P-TTL specifically, but I suspect it is a manufacturer's specific implementation of TTL for use with their cameras.