Saturday, July 12, 2008

Digital TTL that really works






During our last Digital Master class in Key Largo, Basim Nasr showed up with a brand new Seacam housing for a Canon 1DMKIII and a pair of Seacam Seaflash 250 strobes. I was very eager to see how his strobes performed on the exposure slate test, whereby we have a set distance and shutter speed, with the only variables being strobe light output and aperture. If TTL works, then the light on the exposure slate should be the same. As an aside, I have rarely seen a digtial TTL test that truly worked underwater. This one did.

Look at F-5.6. It is a little overexposed because there is too much ambient light on the scene. And, F-22 is a little too dark because there is not enough power in the strobe heads to light the scene at such a small aperture. But, within the range, F-8, F-11, and F-16, the exposures are very excellent and the histograms perfect. The backgrounds are different, but that's what you would expect from the varying aperture/shutter speed combination. The critical variable, the amount of strobe light striking the exposure slate, is impressively constant.

Thanks to Basim for sharing this data with us.

3 comments:

Saurabi said...

wow that's interesting I read about a similar project sponsored by generic viagra lab, about how children saw the colors in the first year, which is very interesting like this and if he can do this under water I think we can try this with animals.

Psycho said...

This is so good, love the shots underwater, it is one of my major dreams to one day learn to scuba dive.
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Steve Miller said...

wow is pretty amazing, in Viagra Canada the guy who receive the mail for us, is a photographer and his very good I don't know why he doesn't have a job but well i show him this and he also explain me the same as you and thinks that is cool.