Canon 20D with 550EX probs

I have a 20D, & normally use a Metz 54-3 flash but have some lack of

user knowledge with it, giving me inconsistant results. Today I

borrowed a friends 550Ex to shoot a function job tomorrow night.

Using the settings of evaluative metering, centre spot focusing on

camera & ETTL on flash, my test shots of indoor portraits in the

evening are all coming out underexposed. I can rectify this by

adjusting FEC, but with the 20D & the ETTL, shouldn't it produce

acurate exposures without having to adjust FEC? Am looking to upgrade

to the 580 in future but need help with the 550 for this gig

tomorrow. Any suggestions appreciated. Chris

to add further...from other posts & forums I have read up on about this issue - its seems it is fairly common to add up to a stop FEC on flash to solve this problem. Would this be the only and best solution? Forgot to mention I am shooting in P for this exercise.

<i>I can rectify this by adjusting FEC, but with the 20D & the ETTL, shouldn't it produce acurate exposures without having to adjust FEC?</i>

<p>

In a word, "Yes". In practice, "No".<p>I find that flash exposure is very, very subjective. Apparently, Canon and "the general public"

have different views proper exposure.

<p>

BTW: The 580EX will offer no improvement in exposure.

Same experience here with the 580EX and 20D. I regularly dial in up to +2/3 FEC to get the exposure I like for indoor portraits. When I forget I make the correction later in PS. The difference is hardly noticeable if there is any.

 

Although not a big deal, it is annoying. Maybe the idea behind this behavior was to protect the highlights by deliberately underexposing a bit. Or maybe I do not fully understand how this thing works.

Have you tried using camera in manual mode. Set shutter speed to 1/30 to 1/60 and set f-stop to 4 (or something that you'll need for depth of field). This usually works well when the strobe is your dominant source of light. I don't have experience with Canon flashes but I am curious if M mode would make a difference.

Pawel's suggestion works well for me (20D/550EX). I put the camera in manual mode, center focus point, and set shutter & aperture to appropriate settings. I then use FEL (flash exposure lock) on a mid-tone part of the scene (this uses the center focus point), autofocus on an appropriate point (usually the subject's eyes), focus lock, recompose and shoot. It sounds complicated, but once you do it a while, it becomes second nature.

<i>Although not a big deal, it is annoying. Maybe the idea behind this behavior was to protect the highlights by deliberately underexposing a bit. Or maybe I do not fully understand how this thing works.</i><p>I think that's exactly it. Too many people fill half a scene with a white tablecloth. . .or take a portrait in front of a mirror.

Shooting with manual mode on the camera won't change the way the flash responds if you leave the flash in E-TTL. Using FEL works but is not practical when shooting events during which there are shots needing to be taken where you can't stop to do FEL before shooting. Using +2/3 or +1 compensation and using your head to evaluate the scene brightness and tweak flash exposure is the best way to deal with the situation.

 

As for the flash always underexposing, I would remind photographers who shot during "film days", that you probably tested your flashes and found the manufacturer's guide number to be optimistic, usually by about 1 stop. Manufacturers test their flashes in optimum situations, probably in light/white medium sized rooms, and assign the optimum guide number they can possibly get away with to the flash, for marketing purposes. I don't see much difference here. I meter tested my 20D/580EX combo with the flash on manual--same story, the guide number is optimistic by about 1 stop, so it makes sense that you have to do plus compensation when using E-TTL.

 

Curiously, I used an old 380EX on my 20D before I bought the 580EX, and found that it didn't need as much + compensation (none to +1/3). So if you want to shoot on Program with a minimum of compensation and save some money to boot, pick up a used 380EX. The only disadvantages are the lower power and the head doesn't swivel. You can still control FEC from the camera body.

<i>I can rectify this by adjusting FEC, but with the 20D & the ETTL, shouldn't it produce acurate exposures without having to adjust FEC?</i>

<p>

The flash system is typically designed to produce a flash exposure that averages the scene out to be 18% mid-tone grey (if you were to see the image only as grey tones). But that may be darker than what you may prefer, or darker than what the scene should be. Of course, the camera has no way of knowing your preferences, or that the scene should be brighter than what it is exposing for. For example, average Caucasian skin tone is +1 to +1.5 stops brighter than 18% mid-tone grey. Left it its own devices, the camera system will probably render a typical portrait darker than what you would prefer, especially if it's metering off of lighter skin tones. That's where you (the photographer) come in. You need to TELL it what changes or adjustments you want-- in this case, by dialing in the appropriate FEC value. In the case of dedicated studio portrait photographers, they typically don't use any automated TTL flash at all. Instead, they use manual flash so they can tell the equipment EXACTLY how much flash to use. But whether using TTL flash or manual flash, let's not forget that you are the photographer and you will need to give your equipment the necessary human input to get the results that YOU want.

For my taste, I find that EOS DSLRs tend to overexpose about 2/3 stops. Hence I usually

dial in -2/3. Obviously, very light (none required) or dark subjects (-1.5) need appropriate

adjustments. However, I prefer a natural balance of ambient and fill. In dimmer light I have

to use + EC (brighten ambient) and - FEC (darken flash) to get a natural balance.

 

Juding from the diverse tastes for flash expose on this forum, everything from deer-in-

headlights-look to balanced fill to slight catchlights, it's impossible for Canon to calibrate

flash exposure and make everyone happy. Hence, all the exposure options and overrides.

Thanks to everyone for their information & very helpful suggestions. I did follow Pawel & Rob's suggestions of putting camera to M, & using FEL. I also tried the FEL in P mode as well. There was a slight improvement when using FEL, and M was quite good too - although I noticed P was chosing the same aperture & shutter as I had selected in M anyway on this occasion, so results were very similar. For the function tonight I with adjust FEC about + 2/3 stop to be on the safe side. I will try to use the FEL as well - its not that tricky! Thanks a million folks.

Chris

This may be a liitle late, but you can use for future event. set the flash metering from evaluative to average via the Custom Function menu. I got more consistent result with this mode.

 

Regards,

Alan