Explain on-camera TTL flash please

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Archive 2009 · Explain on-camera TTL flash please

cwebster
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p.1 #1 · Explain on-camera TTL flash please

Can someone please explain, or point me to a clear explanation of how the pop-up flash TTL works on a Canon 50D.

I assumed that in Manual exposure mode, the pop-up flash would put out maximum power, controlled by FEC. That doesn't seem to be the case.

I shot 4 pictures of my cats, with 1 f/ stop increments of smaller aperture, expecting so see some difference in the photo/histogram. None.

Can I operate the on-camera (pop up) flash in manual mode somehow?

I am used to working with a manual flash where I have to calculate aperture values from distance and guide number, and would like to have a similar degree of (non)control from the pop-up flash.

Thanks,

<Chas>

May 08, 2009 at 05:52 AM

trumpet_guy
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p.1 #2 · Explain on-camera TTL flash please

The pop-up flash uses only Canon's E-TTL algorithms, not manual mode.
If you want manual mode you will need to use an external flash.

To read up on the auto flash system in significant detail, check out the
very informative explanation here:

http://photonotes.org/articles/eos-flash/

May 08, 2009 at 06:37 AM

snurresprett
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p.1 #3 · Explain on-camera TTL flash please

Like he said, the popup is full-auto, always. Manual popup is a Nikonism, unfortunately.

May 08, 2009 at 10:38 AM

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