20D and 580EX - underexposures are the rule

I just got my 20d last week and there's no question that all flash pictures are way under exposed and have to be edited. But has anyone tried the old fashion way of using the GUIDE NUMBER that alway works on film cameras. But you need a flash that can go to full manual and put out maximum for that. I think only the most expensive canon speedlites do that, mine dont. I'm still trying Av settings, and I'll try overexposing the flash next. I also think the default white balance is set wrong for flash, but that's another story. If we all keep trying, maybe we'll figure it out.

Most of these issues come down to inexperience with ETTL flashes. Have a read around and see if you can learn something, and pay special attention to using FEC for light colored scenes. Film has a lot more exposure tolerance than digital, so I guess that unless you're good and fast at your sums, ETTL will do better, so long as you understand it. I can get reasonably consistent exposures with ETTL now, after some practice.

Agrrh ! I think my 20D is going back to Canon. I bought the Canon SD500 Elph for my daughter and I took the same shot with each camera on full auto. The dark one if with the 20D [$ 2,500] the better shot is with the SD500 [$ 490]. This can't be right.

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The printer on the left is in the foreground, do it again without that. Remember how we said the flash exposes for the foreground? That's the key here. Also, ETTL exposure isn't linked to the active focus point. The reflection off the fireplace might also be making a difference, but the print is a more likely solution.

Again, i'm going to suggest you re-read this thread, because you don't seem to have taken in the information so far. I'm not having a go at you, just making a suggestion to help you learn

I have read that calibration (or replacement) helps in some cases, but I still think the problem here is more likely to be technique than the equipment. I'd like to see the photo from the 20D taken again and posted, with the suggestion I made above - ie make sure the printer isn't in the frame.

Tim, I think your not getting the point. You shouldn't have to worry about what's in the foreground before you take a picture. The ETTL system isn't worth losing the spontaniety of the shot. But I wouldn't send the camera back for that since I can correct the under exposure quickly by adjusting the level control in my editing program. I would try increasing the exposure control or even putting the flash on manual and using the guide number method. Pictures taken out door seem to be OK.

I understand that some people want to treat a DSLR with external flash as a point and shoot, but that's not what they're for. They're tools that assume a reasonable amount of knowledge and experience from the user. If you don't want to bother with that use a point and shoot. I think I have the point just fine.

All I'm saying Tim is that some people want to use a DSLR for the many advantages it has over point and shoot cameras. This under exposure problem can be managed easily without having to become an expert on the ETTL system. Which may not be the best thing Canon ever invented.

I agree that some people might want a "dummy mode" on a DSLR, but I (politely) disagree that's what should be provided. DSLRs are about giving power and control to the user, but that comes with a burden of knowledge. I don't want my camera making all the decisions for me, I want to have control. For example, maybe I want to expose the foreground and leave the background dark - that's my decision. If not I use Av mode with the flash as a fill.

Every problem on this thread so far can be worked around if the user knows that ETTL exposes the foreground with the flash. If you want the background exposed as well the solutions are:
- Shoot in Av mode, the longer shutter speed will exposure the background, but will be harder to hand hold.
- Bounce the flash (might work, might not).
- Use directed light or a 2nd flash.

If people don't want to understand and explore the options, then a high end point and shoot is probably a better, cheaper choice.

I agree with you in principle. The problem is that I want to have the control of exposing the background with my flash without having the camera force me to expose only the foreground. I might want to crop out the foreground and just use the background. I think Canon should have given us the option of firing the speedlite at maximum force and pemit us the option of choosing the proper f stop to expose the part of the scene we think is important. I think some of the speedlite models can do that, unfortunately my 220ex cant. I don't like automatic exposure, Tim. I prefer a spot meter for outdoors and a manual flash for indoors, but I still like the other aspects of using an SLR.

My 550EX and the 580EX can be used in manual mode, that might suit you better.

Thanks for the info Tim.

I had a S30 and G3, and I can say that there was a definate improvement in flash performance going to the 300D.
Now, with the 20D, the flash improvement with ETTL-II is even BETTER.
Sure the pictures were brighter with the S30 and G3, which seems to look more pleasing to some, but at the same time they would blow the highlights, much like Confalone's second picture above.
This is technically incorrect, as you can not recover lost highlights, but you can recover detail in the shadows (although at the expense of some noise).

And Tim is correct, the 20D uses ETTL-II which is evaluative, and does not rely on the autofocus points. This is a TREMENDOUS improvement (for me atleast) over ETTL which the older cameras like the 300D use.

Before you send the camera back, you might want to check your C.Fn-14 setting and make sure it's not on 1 (Average).

From the EOS Bible.

Sounds like averaging would be better for people who want a point-and-shoot style flash to me, but i've not played with it at all.