Macro the 1/f rule and flash duration

Started Sep 8, 2008 | Discussions thread
JimH Forum Pro • Posts: 12,911
I want to try your diffusers :)

I like your idea of using a very low-loss material for diffuser manufacture.

Most of what we use probably absorbs a lot of light (or reflects it back towards the flash tube). And that does make our flash pulses longer - which is bad

I may try to shoot some shots of a gray card, using the manual power settings on the MT-24 EX, with both heads firing at 1:1. I'll adjust the flash power to center the spike in the histogram.

And that will then give us an idea of the flash power levels required at different magnifications using the MP-E65, with the MT-24, with no diffusion, both heads firing, at some arbitrary f/stop setting.

I could then try the sto-fens to see how much higher power is required. I don't have any puffers, but I'd like to try them too.


You know what would be neat? I'd like the flash to report the power level used for each head after each shot in ETTL mode. Wouldn't that be nice?

You could use ETTL, even with some FEC, to get the exposure right. Then you could look at the flash and know what to dial into the settings if you wanted to "lock that in" for manual shooting. In fact, it should have a button that does just that: It should let you "lock in" the most recently used flash power, and then shoot in manual, at those power settings, until you "unlocked" it with another button press.

Now THAT would be a handy flash for me! I want that on the MT-24 and on the 580. For doing series of portraits and multiple macros, I often prefer manual flash because it eliminates variability due to different clothing people have on or movement and changes in the background. (Or spasmodic behavior of the 40D with the MT-24).

But having an easy way to immediately transfer a "successful" flash setting from the ETTL mode into the Manual mode would be a really powerful tool.

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Jim H.

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