Flash Question
k2butter
Registered Users Posts: 259 Major grins
What is the difference between TTL and E-TTL... I was thinking of getting a TTL since they are less expensive.
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If not, I will try to outline my understanding of the differences then.
Ziggy may be better at answering this than me, since he uses Sigma flashes almost exclusively.
Moderator of the Technique Forum and Finishing School on Dgrin
Im going out on a limb here and Pathfinder is "the guy" to ask but as far as i know the digital rebel XT ( I think thats your camera ) does not support TTL flash.
Cameras which support TTL flash:
The T90 and virtually all EOS film cameras except the EF-M and the Rebel T2/EOS 300X/EOS Kiss 7. The digital cameras - all cameras with a D in the name (including the D30, D60, 1D, 1Ds, 10D, 300D/Digital Rebel/Kiss Digital, 1D mark II, 1Ds mark II, 1D mark II, 1D mark IIN, 1D mark III, 20D, 20Da, 350D/Digital Rebel X/Kiss Digital N, EOS 400D/Rebel XTi Digital/Kiss X Digital) do not support TTL.
IMHO, this is one of those situations where it pays to get the latest technology - E-TTL II. I know its more expensive ( Canon 580EX II ) but from my experience ( very limited ) its "way" of doing things seems to yield more consistent results. I say that from the point of view from people "not expert" with flash photogrpahy. Of course if flash is your thing then you will manage with whatever you get. I dont know your level of experience with flash photography but it seems to me from what i read that people with the 580EX II have an easier go with flash photography than those who choose another. Im currently taking a flash photography course with Charlie Borland and the people with the 580 EX II dont seem to question or get confused as much as the people with other type flashes.
But hear what pathfinder / Ziggy and others have to say as my thinking might not suit your needs .......
troy
While there are serveral flash technologies which claim TTL (at least), since we appear to be talkng about Canon cameras, I'll stick with that discussion.
Canon developed a TTL technology for film cameras which used the film plane itself to determine exposure (bevieve it or not).
Since digital SLRs don't have film, a different technology had to be developed. Canon, and most other digital SLR cameras, use the same exposure module for both ambient (available) light and the flash exposure. Since digital SLR cameras don't measure the exposure when the mirror is up, a different method is used. Canon E-TTL technology uses a "pre-flash" to gather most of the flash exposure information before the mirror moves out of the way.
E-TTL II is the latest flash technology and uses distance information based on feedback from the lens and autofocus. The distance information "quenches" the flash to the amount required by the distance information, avoiding the miss-information that can be relayed using E-TTL alone. (An extremely light or dark subject as well as no background or a reflection can throw off E-TTL calculations.)
For best results use an E-TTL II flash like any of the Canon "EX" series flashes or the Sigma 500 Super DG series flashes.
Moderator of the Cameras and Accessories forums
The older method in film cameras worked, because some of the light that came through the lens while the shutter was open, was not absorbed into the film, but reflected off the surface of the film directly, and then measured. This does not work with silicon sensors because they are do not tolerate this kind of extra light and get all hazy. Manufacturers go to extreme lengths now to prevent light from bouncing off the front of a sensor inside a camera. Hence, no TTL as used in film cameras.
That is why Canon uses a pre-flash, before the shutter opens, to measure the exposure. After the measurement, the flash fires again while the shutter is open.
The full discussion of TTL versus ETTL is long, quite detailed and can be tedious unless you are seriously interested in the specific details.
The best discussion I am aware of on the web is here
I have posted this link many times, because it is the most clear, detailed, and helpful discussion of the EOS flash system on the planet, covering TTL, ETTL, and ETTL-II including camera bodies, flashes, lenses, and the underlying philosophy/plan in each of the modes of use of the EOS flashes. This link is vastly better than the manuals that come with the EOS flashes, trust me it is true!!
I think Ziggy will agree that your choice really comes down to a Manual flash like the Sunpak 383 that Shay uses, or a Canon ETTL or ETTL-II flash like the 430ex or the 580ex or the newer 580ex II, or one of Sigma 500 flashes that used ETTL in the Canon system. Most users will definitely want a flash with ETTL or ETTL-II unless they are very familiar with flash and know exactly what they plan to do with it.
If you really want to learn flash for professional use, the Strobist - http://strobist.blogspot.com/2006/02/welcome-to-strobist.html - is a great place to hang around, but they use manual flash only - you must know how to set aperture, shutter speed, flash intensity by your own self, and not depend on the camera and flash to make settings for you. This seems complex if you have never tried it, but gets easier with experience, and gives more control of the results than automatic cameras and flashes.
Whew, I've kind of run on here.
If you still have more questions about flash, shoot away, and we'll all jump in and try to make our answer clearer for you.
Moderator of the Technique Forum and Finishing School on Dgrin
Anyhow, I am really trying to "Get" the tech side of photography now that I have this camera... maybe one day I will upgrade again, but for now, I am enjoying my hobby as a nice way to relax....