What's a good Flash for NEX-5R?

Started Jan 17, 2013 | Questions thread
Bart Hickman
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DSLR's do not meter flash this way...
In reply to otoklikBG, Jan 18, 2013

otoklikBG wrote:

I'm sorry that my lack of terminology caused confusion.

By TTL I wanted to say that camera controls power and focus of flash unit to comply with what cameras light metering deduces that it needs. Camera takes light metering of ambient light, adjust parameters for itself and for flash unit and then takes photo firing flash only once.

No modern DSLR's do TTL this way AFAIK (unless Sony is special--I know Pentax, Nikon, and Canon do not work this way.)  And I believe none of the main brands has any flash mode that works this way.  I don't see how this could ever work without knowledge of the subject distance and reflectivity.

All DSLR's use pre-flash TTL firing a small metering flash followed by the main flash.  NEX is the same way.  You can test this by cranking ISO to 100 and aperture to something small (so the flash will go for full strength) and you'll only hear a single "pop" from the main flash.  If there were two equal strength flashes, you'd hear two pops.

In the "old" days, TTL was implemented using a meter inside the camera body that detected light bouncing off the film.  The camera would fire the flash and the light power would be monitored in real time and the flash would shut off once the correct amount of light was seen.  This obviously requires no pre-flash

Modern sensors are so efficient they don't reflect any light, so this method of TTL has disappeared.

The closest thing to this is auto flash which uses a thyristor mounted on the flash unit that measures scene lighting in real time, much the same way as TTL did (except it's not through the lens, so it's not called TTL).

AFAIK, no DSLR has auto-flash in the built-in flash.  Only pre-flash TTL and maybe manual mode.

It so happens that Sony hot-shoe flashes don't have the auto-flash capability (which is a damn shame IMO).  But this doesn't have anything to do with NEX vs DSLR.

Bart

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