Dependable (cheap) Radio Slave

Started Apr 17, 2013 | Discussions thread
Sailor Blue
Sailor Blue Forum Pro • Posts: 12,575
Re: Dependable (cheap) Radio Slave

mbloof wrote:

Since when is off camera ETTL not a good idea?

I'd recommend getting two YN568EX's, a light stand and a hotshoe mount/lightbox and have some fun!

TTL basically assumes the subject and background add up to 18% gray.  E-TTL and i-TTL add in a small correction for measured subject distance as reported by some, but not all, lenses.  If the subject plus background are brighter or darker than 18% gray then the TTL exposure will be off.

A good example would be taking a photo of a bride in a white dress with a white wall for a background.  Alternatively think about a groom in a black suit against some dark green shrubbery.  The TTL exposures would result in gray and depressing images is both cases.

If your background or subject brightness changes, even if the subject to flash distance is fixed, then the TTL exposure changes.  Just zooming in or out, which change the subject to background ratio in the image, is frequently enough to change the exposure.

You can pretty much expect to have to individually correct the exposure of each and every image taken with any form of TTL.

If the subject to flash distance is constantly changing, then TTL is a good idea since it will get you close to the right exposure, especially if you are good at applying Flash Exposure Compensation.

If the subject to flash distance is fixed, which is usually the case with off-camera flash, manual flash power control will give you identical exposures every time.  Changing clothing, backgrounds, or zooming would have no effect.  Even if the exposure is off a bit it is only necessary to correct it on one image then apply the same exposure adjustment globally to all the other images.

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Living and loving it in Bangkok, Thailand. Canon 7D - See the gear list for the rest.

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