Comments on: Photocast Network Roundtable Discussion #2

By: RaymonWazerri

RaymonWazerri — Fri, 20 Apr 2007 23:20:33 +0000

Hey,
I love what you’e doing!
Don’t ever change and best of luck.

Raymon W.

By: Jeff Curto

Jeff Curto — Tue, 06 Feb 2007 12:10:08 +0000

Thanks for the feedback, Adam… I’ll send that on to the group. I agree that it feels more like a “roundtable” when we are able to interject, etc.

-Jeff

By: Adam

Adam — Tue, 06 Feb 2007 11:47:57 +0000

The parts that I think are great are when everyone has something to say on a topic and you have a dialog. The parts where someone just gives a monolog seem out of place in this format.
To this end talking more on non-technical subjects would be great in future, as these are the ones where everyone has something to say.

By: Gerry Allen

Gerry Allen — Fri, 02 Feb 2007 14:07:28 +0000

Jeff,
I have not yet listened to the 2nd roundtable yet, ( my suggestion for a name would be something todo with knights - the photoknights podcat or something like that) I listened to the first episode which I thoroughly enjoyed. I liked the mixture of the creative and technical. So I look forward to many more roundtables.

By: Jeff Curto

Jeff Curto — Fri, 02 Feb 2007 05:40:51 +0000

Actually, it’s not quite that. I couldn’t come up with it off the top of my head while we were chatting during the recording session. I’ll be clear up front that I’m not a “math guy” (that’s why I’m a photographer!) but here’s the skinny:

Photographic exposure is a logarithmic situation. This is another way of saying that exposure functions in an exponential fashion, not a linear one. So, when we move from one aperture to the next larger one, we double the amount of light. Moving one more aperture larger doesn’t make 4 times the amount of exposure than the first situation; rather it makes 8 times the amount of exposure. This ratio continues on up (or down) the scale.

So, since light is being handled in an exponential way, we end up with a reflectance value of 18% being in the middle. Another way of saying it is that half of all the reflected light in the world is darker than 18% reflectance and the other half of all the reflected light in the world is lighter than 18% reflectance.

Kind of a neat story about Kodak, though… might help explain how they got into their current-day situation!

By: James Kellar

James Kellar — Thu, 01 Feb 2007 15:45:50 +0000

I was listening to the second roundtable and the question came up about how 18% gray was chosen as a standard. I heard many years that some folks at Kodak took over a thousand photographic prints cut them into small squares and then measured each of the squares and then averaged all the readings, and the average was 18%. Now I’m not sure if this is true, but knowing a bit about the history of Kodak it makes sense.