E-TTL, active focus point, and compensation

SDK^ wrote:
Just going back to Custom Function 14 – Auto Reduction of Fill Flash
Can someone please explain the difference this makes and the possible situations you might use either option

Thanks

As is explained in the 10D maual on page 150, when auto reduction of fill flash is enabled, the flash output is reduced so that it does not light up the subject that you are flash filling as brightly as the nature light source does of the background. This usually results in a more natural look, especially if the subject is in the shade.

If you need to light the subject with full flash power, say when you don't really care about the background but you do want the subject to be properly exposed, then you would disable the auto reduction.

I just did an experiment on this and came up with the following conclusions:

Case 1: When shooting in Autofocus mode with CF4=0, Evaluative metering seems to be used for metering the flash.

Case 2: When shooting in Autofocus mode with CF4=1 ("*" button sets focus), Center-weighted average metering seems to be used.

Case 3: When shotting in Manual focus mode (doesn't matter if CF4=0 or CF4=1), Center-weighted average meterng seems to be used.

This is very interesting because, for the subject I used--a very dark brown stuffed bear filling the entire center circle that makes up partial metering area against a white wall filling the rest of the viewfinder, the flash using center-weighted average metering underexposed by about one stop.

Both EC and FEC were set to 0 in all cases.

Great post Tom.

ETTL is a mystery to many of us. The manual for the 550EX is very confusing.

My congratulations to the happy couple!

Tapeman wrote:
ETTL is a mystery to many of us. The manual for the 550EX is very confusing.

As a frustrated 550EX user, I heartily agree with this sentiment. And yet these and other forums are filled with their share of true believers---those who swear by their 550s, those who go on to blame its failures upon well-intentioned camera users and manual readers. "Get to know your equipment," they say, "and all will be well." In other words, do a lot of trial and error, and then you'll understand which settings you'll need to make in any given conditions.

However, as we all know, no two exposures are made with exactly identical conditions, and so the trial and error just seems to go on and on. I feel that I should be wearing a T-shirt with a message that reads: "I'll need to take at least 3 flash shots, so stay right there after the first one."

It amuses the bejeebies out of me to conclude that all this talk about plus or minus 1/3 and other methods of compensation reveals how truly non-automated the 550EX is. There's a heckuva lot more tweaking that needs to be applied by intuition and hunch on Canon's flash than any of us needed to use with our old Vivitars on rangefinder cameras.

OK, 550EX defenders, have at me now!

Floyd Lawrence

And it amuses me when I read people ranting and raving about a piece of equipment that's gotten the best of them. As far as I'm concerned the 550EX is a flash just like any other flash I've used with any of my cameras, digital or otherwise. And I've used a heck of a lot of them, manuals and auto, Vivitars, Sunpaks, etc. They all serve one purpose and that's to provide light for the camera. And the same laws of physics apply to all of them, whether there's "intelligence" built into them or not. I'm surprised you're not complaining about the Evaluative metering used by the camera when shooting pictures without the flash. Or are you?

And for the record, I'm not a defender of the 550ex or even ETTL for that matter. I'd be just as happy using my old non-dedicated Sunpak flash if it worked with my 10D.

u02bnpx wrote:

Tapeman wrote:
ETTL is a mystery to many of us. The manual for the 550EX is very confusing.

As a frustrated 550EX user, I heartily agree with this sentiment. And yet these and other forums are filled with their share of true believers---those who swear by their 550s, those who go on to blame its failures upon well-intentioned camera users and manual readers. "Get to know your equipment," they say, "and all will be well." In other words, do a lot of trial and error, and then you'll understand which settings you'll need to make in any given conditions.

I really don't share your frustation. I've encountered but a few rare instances where the E-TTL is apparently confounded and I've tried to illustrate at least some of them here for the benefit of others.

I haven't encountered that much trouble with the system, even as a relative novice.

Well, what on earth is exposure compensation for but to compensate for unusual conditions. If a flash exposure is off by 1/3 or even 2/3 stop, it is easily corrected in EVU before it is even converted to JPEG and without any significant loss of fidelity.

Yes, the system requires some input from the user on occasion, but it is a heck of a lot more useful than than having to change the aperture for every shot based on distance to the subject (which is often unpredictable). E-TTL is not without its faults, but it is quite spontaneous, or at least it has been in my use. I can basically pick up the camera, compose, and stand a very good chance of getting a good exposure almost every time.

If you want something that requires no thought at all, then you probably need a point-and-shoot camera.

Floyd, you are absolutely right. That 550EX must be a piece of design junk.

You better pack it up and send it off to me right now. I'll take it off your hands, purely as a friend would do.

(By the way, I have one already, and also one 420EX.)

---Bob Gross---

[/QUOTE]And it amuses me when I read people ranting and raving about a piece of equipment that's gotten the best of them. [/QUOTE]

Err, cat got your tongue?

the much-discussed 550EX

The response to my deliberately grouchy post was predictable. First, I'm probably some anti-technology Luddite who dislikes getting stumped by a piece of equipment.

Of course I do. And so do all of us. Or am I the only one whose Windows XP has crashed for no apparent reason? The only one who has grumbled about the lack of compatibility between my cable company and the TV and other equipment that I own? (This has stumped three of the cable company's technicians.) The only one who has ever noticed a discrepancy between a statement in a user's manual and a real-life experience with a piece of equipment?

Another post suggests that my wish to enjoy brainless photography (an unwarranted conclusion) indicates that I'd be happier with a point and shoot. It might be more accurate to say that at times (e.g., when antsy grandkids won't sit around waiting for me to make multiple histogram checks and compensation adjustments) I'd like to put my 10D shooting mode on "P" and shoot flash with at least point and shoot results. The manual for both the camera and the flash implies that I should be able to do that. But on these occasions, I usually reach for my S400.

Third, someone has suggested that they would take my 550EX off my hands. Thanks for the offer. I'll consider giving it to you if you'd be willing to pay me $350 for shipping and handling. But enough of the cynical and sardonic.

On a more serious note: I've read enough posts in this and three other forums to be assured that I'm not alone in my 550EX frustrations. And goodness knows, I've tried every conceivable combination of custom functions, metering patterns and exposure modes, diffusers, and compensations that have been suggested. I've read the links to Canon and others.

Through it all, I've learned one thing for sure. The "fix-it" solutions for proper use of the 550EX run a very broad spectrum indeed. For this reason, I can't conclude that all who complain should either use a point and shoot or give away our 550s. Too many of us are willing to take the time to master an instrument that, for all of its fine points, has not met with the acceptance one might have reasonably expected. Else why would we be reading and writing to forums such as these? I could ebay the darn 550 in a flash, but I'm determined to improve my results with it.

Trust me, my reasons for writing here have nothing to do with vanity. I appreciated Tom's "experiment," which made more sense than much in the 550 manual. But, in the long run, it's of minimal help when I have one chance to take a shot and little time to input more than the most basic adjustments for existing conditions. On this score, I'd love to hear from photojournalists who have had experience with the 550.

As for the speculation that I'm probably dissatisfied with the 10D's evaluative metering, let's save that for another thread. Let's do the same for the focus point discussion that always seeems to come down to "use the center point only with custom function 4.1." My oh my, the fun we could all have kicking those cans around again.

Floyd Lawrence

And that is why we do this - to improve our use of the tool. I don't believe that I need to tell you that you should read http://photonotes.org/​articles/eos-flash/ a couple of times, as I believe that you've already done so. But I think that sometimes, in doing so, one gets too many ideas as to how to take the perfect picture. This is a very flexible flash system, and a very intelligent one, but it is also complex.

And I'm glad that you appreciate it - Its simply a matter of me familiarizing myself with the E-TTL and sharing my experiences. My experiment here simply deals with shooting extreme dark and light subjects. Get your center focus point over the face and this won't be an issue most of the time.

I believe that a couple of photojournalists loiter around here - I'd like to hear from them as well.

Well, I haven't touched CF 4 - and I don't particularly like using FEL as I don't want to flash people twice - that kind-of destroys the sponteneity of the situation. But I do use the center focus point most of the time and I will dial in a little compensation on occasion if my subject is exceptionally dark or light. The results of this experiment are representative of how effective that trick is.

Hopefully, we can keep this thread on the learning side of things. While I understand the dissatisfaction of some with the reduced predictability of this system, I also think that it isn't nearly as bad as people make it out to be.

Focus point above the straw hat

Is there a way to meter prior to focusing?

What does FEC and EV stand for?

I too shoot 10D, 550EX for about a year now.

Thanks for your pictoral explanation for flash adjustment.

You forgot...

You left off the most important feature when shooting with flash;
FEL !!!!!!!!!!!!!!

Much less work and much more ballanced results.

Rod

FEL - flash exposure lock allows metering before focusing. It also produces a flash when you meter along with the actual "real" flash that you get when you take the picture. I haven't messed with it yet, since it takes a bit away from those "spur of the moment" shots. That'll be next month's experiment.

FEC is "flash exposure compensation". Its similar to exposure compensation except that instead of varying the aperture and/or shutter speed, it varies the flash light output.

EV stands for "Exposure Value". Its just a measure of "brightness" of images, based on f-stops and shutter speed. Here's a link that gives a brief explanation:

http://www.chem.helsin​ki.fi/~toomas/photo/ev​.html

Hope this helps a bit.

Tom, great post.

ETTL is not a good system. It is even "worst" in a D60 (similarly a D30). I've got terrible exposure by using flash for the first few months. After studying and doing trial and errors, even my wife can do a consistent exposure for using it. (My wife usually does not care about any technical issues of cameras -- though she knows something.)

However, I have to repeat -- ETTL is not good. But we can overcome it:
- by reading Tom's post; and
- by practice.