E-TTL vs TTL

Curtis Cunningham · #1 11-05-2007, 08:17 AM

I have a 420 EX, and in the course of different threads it's been suggested I shoot TTL for certain scenes. What's the difference between TTL and E-TTL, and how do I choose which I want to shoot with? (I'm using a Canon Digital Rebel XT).

ChrisPerry · #2 11-05-2007, 09:23 AM

the only opiton you have is eTTL.
Back in the beginning of flash there was no metering - you figured it out yourself.
then there was 'auto' - a cds cell in the flash unit and a chart on the back of the flash for setting aperture and distance to subject.
the TTL (thru the lens) metering came along- the metering was done in the camera not theflash.
eTTL is electronic TTL and the way all cameras do it now.

Jerry Skrocki · #3 11-05-2007, 12:07 PM

E-TTL is short for evaluative through the lens flash. An ETTL capable flash can fire a pre-flash that is evaluated by the camera's metering system prior to the shutter opening. The camera's meter then utilizes this information when it makes the balanced exposure.

DougAxford · #4 11-05-2007, 01:26 PM

The problem with any of these is that the flash or camera has to assume through it's intelligence what your scene looks like and how much light it needs to fire. As a pro, we encounter many scenes that don't fit the program correctly and the resulting shot is junk. That's why someone said to shoot, check LCD, adjust and re-shoot. Problem is, it may be too late to re-shoot in many cases.

I've also got a 420, cheap from another forum. I bought it without realizing it was auto only. Piece of junk IMHO. That's why it was sold by the other photog. You're better off saving up for a decent flash, just my opinion. Want to buy a second one?? BTW, we tried using it wireless as a slave unit and it's OK but not great. I'd still rather be on manual settings.

Doug

Walter_Kimmel · #5 11-05-2007, 02:01 PM

Basically, the E-TTL gives you 2 separate exposures: one for the flash, which you can lock in with FEL Lock, and the other for the background. You can fire a preflash aimed at your subject, lock the flash exposure in, recompose and shoot. The background will (hopefully) be properly exposed by the camera, and the subject by the flash.

On my 1DII I have the option of using this E-TTL or setting the system to "average" the exposure. I have found E-TTL to unpredictable.

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