Another flash question - Is this right?

[mlfrancis]

I've had my Digital Rebel since November and have read everything there is to know about it. Pretty much driven off all my friends and some relatives because that's all I talk about. :lol:

http://www.pbase.com/image/26150453/medium.jpg

Camera Model: Canon EOS DIGITAL REBEL
Firmware: Firmware Version 1.1.1
Shutter speed: 1/60 sec
Aperture: 4.0
Exposure mode: Program
Flash: External E-TTL - 420EX, but can duplicate with internal as well
Metering mode: Evaluative
Drive mode: Single frame shooting
ISO: 400
Lens: 50.0 mm
Focal length: 50.0mm
AF mode: AI Focus AF
Image size: 3072 x 2048
Image quality: Fine
White balance: Auto
Color space: sRGB
Saturation: Normal
Sharpness: Normal
Contrast: Normal

Here is a sample. I had about convinced myself that it had to do with the tonality of Caucasian skin being (from my readings) about 36% reflective. Thus, the camera tried to get it to 18% and thus underexposed. Now I am back to thinking, "this just can't be right." So, here is this post.

I can reproduce these shots day in and day out in Auto, P, and every other mode using the internal and external 420EX flash using both the kit lens as well as the 50mm f1.8II. Non-Flash shots look fine. Oh, I can do the software hack to boost the FEC to +2/3 and it helps, but is still aweful. This was set back to FEC 0 for the sample shot.

Should I return my camera for Service, or should I learn to shoot? (and get a 550EX where I can FEC)

Any help would be much appreciated.

Thanks in advance,
Michael

[dtrayers]

You didn't say if you were using a single focus point or if you tried Flash Exposure Lock.

E-TTL flash will bias the exposure for the focus point. It figures anything in focus is the subject and the camera should expose that properly. It's hard to tell from your picture where the focus point was.

At any rate, if you haven't discovered this site grab your favorite beverage and have a read.

http://photonotes.org/articles/eos-flash/

Understanding how E-TTL works goes a long way to proper flash exposure. Just getting the 550EX for FEC won't help if you don't have a good grasp of E-TTL.

[ilya]

Pls post EXIF info

[mlfrancis]

Oh yeah, I've read almost everything I can lay my hands on on E-TTL and been to that site many many times. Great info there for sure.

That particular shot I had set to P mode but auto selection of the AF point. It had the center one selected and it just between my son's ear and eye.

I've read about the tonality of different skin types and reflective meters used in these cameras, and it does seem to have something to do with it. I take the exact same shot of an African American friend of mine and it comes out GREAT! She has a coccoa toned skin. I do the exact same shot of my kids and I get underexposure.

Almost all my flash shots are interiors portrait style of my kids and they almost always have skin as the selected AF point.

If I do a FEL on something darker, then of course the shot comes out much better, but still seems a little on the dark side. Not to mention it just doesn't seem like it should be that hard to take a portrait shot. If I can't get a portrait style shot out of it without doing a FEC +1 when only caucaision skin is selected and the camera won't let me do a FEC without buying another flash... I think we're getting ripped. ;-)

I know they are different animals and aimed at a different target, but my G2, even using the 420EX would never give me a shot so dark.

I'm going to be down at another Wolf Camera this weekend. If they have another in stock I might play around with it to see how badly I can hose it's shots.

[mlfrancis]

Oops, I thought clicking the picture would take you to the Pbase site, but it doesn't do what I thought. Here is the EXIF for the shot. I will also add it to the first post.

Camera Model: Canon EOS DIGITAL REBEL
Firmware: Firmware Version 1.1.1
Shutter speed: 1/60 sec
Aperture: 4.0
Exposure mode: Program
Flash: External E-TTL - 420EX, but can duplicate with internal as well
Metering mode: Evaluative
Drive mode: Single frame shooting
ISO: 400
Lens: 50.0 mm
Focal length: 50.0mm
AF mode: AI Focus AF
Image size: 3072 x 2048
Image quality: Fine
White balance: Auto
Color space: sRGB
Saturation: Normal
Sharpness: Normal
Contrast: Normal

[Tom W]

Probably a silly question, but do you have any exposure compensation on that picture?

I made a basic levels adjustment in Photoshop Elements and came up with this:

http://home.comcast.net/~trwilk3/Images/test1.jpg

It appears that the whole picture was underexposed. How are the non-flash pictures?

[mlfrancis]

No exposure compensation nor flash comensation was applied. That shot is as plain as you can get without going to green box auto, and it will do the exact same thing in auto. Granted, auto will revert back to parameter 1 and I am shooting in parameter 2. I think auto will switch back to 100ISO as well when using the external flash, but stay at 400ISO for the internal. Doesn't matter, all flash shots with my kids as the subject come out underexposed.

The shots look pretty darned good if I use the 420 and bounce it off the ceiling. It is just those straight on shots. No matter if it is Auto, P, Av, one of those canned modes or whatever.

Non-Flash shots come out great.

I know you can edit it out. In fact I've started shooting RAW for everything and most assuridly when doing anything flash related so I can apply the exposure comensation during the RAW conversion to boost it. But the fact is you shouldn't have to shoot in RAW to get a simidecent shot particularly in Auto. I can't had this camera to my wife even set to auto and get anything worth a darned if the flash is used.

[Tom W]

maybe you answered this already, but is the result the same with the built in flash, or just the 420EX? If its just the 420, then I'd borrow another EX flash and take a few shots. You want to use the process of elimination to isolate the probable cause of your problem.

[mlfrancis]

All modes and all flashes.

[ilya]

Seems like a problem, unless other Reb owners can say they're getting the same results, which I doubt. See if you can "hose" another cam!!

Ilya

[clos]

Try this...

-Keep the exposure compensation to +2/3 or +1 if you can. I need to do the same thing with my 420EX as well...I've learned to live with it.
-Continue to bounce off the ceiling it looks better anyway. Hey if your in a tiny room or have a wall immediately behind you point it backwards a bit.
-Get out of Auto mode and go to Manual mode set the shutter speed to 100 (with your 50mm lens) and set your aperature under 5.6 as desired.
-Change ISO to 200 or even 100 if you can get away with it.

Good luck!

-Clos

[kufel]

Remember, that in P EOS flash system will do everything to match the foreground to the background. Especially if you say that bounced off shots come up OK, I think this is the case. Try manual... I always shoot manual, unless I do fill in flash. Set your aperture to 4 or 5.6, time to 1/125 and try it. I know that the owner's manual is crappy, but the site that is mentioned at the beginning of this thread will explain everything to you. Of course - your background will be dark if you do that. Do that as an experiment, bounce the flash for your regular shots, it's the best technique anyways.

[mlfrancis]

I took about 20 shots and almost all stink. My post the other night was with the 50mm f1.8, but all these were with the kit 18-55 lens; I wanted to be able to get wider than the 50 would allow. Doesn't matter much, I get the same effect with each lens.

http://www.mindspring.com/~mlfrancis

You can hover your mouse over the thumbnails and it will give a comment in a popup. Click on the shot to get a 1024x768 version of the shot and full EXIF. (BreezeBrowser is great!)

I put comments under each image to specify which AF points were selected at the time the shot was taken. I also put all EXIF data for each shot. I took them in JPG mode and shrank to post, but that was all I did. I just wish I could post the histograms. Almost all are 2 solid stops from the right.

I took some with the internal flash, some with the external 420EX, some at 400ISO and some at 800ISO. Even a couple with EXP Comp +2. I waited to get the flash ready light and waited for the whine from the external to stop. Fresh batteries all the way around.

There are a few there that can be explained away, if the theory is right and it produces such bad shots, by the center AF point being selected over my daughter's face. However, there are just as many other shots that have more AF points selected over shirt, something in the back, and they are just as bad.

I didn't post it, but I did a FEL on my son's black shirt, then recomposed on him and the shot came out looking fairly well, a little over exposed, but not too bad at all. Trouble is it shouldn't have looked anywhere near alright! I FELed it on a dark black color and he was standing 4ft from me zoomed in for a headshot.

If you really want to see two that confuse me, the bottom row third from the last looks pretty good... the very next one has same settings and looks like crap. Granted there was only 14sec between the shots and even I would assume the flash wasn't charged, but the whine stopped and I had the ready light illuminated on the flash and in the viewfinder so it had to be ready, right?

I know it is a lot to ask, but can someone try something similar and let me see how different it looks? It would be much appreciated.

If you have made it this far into my rambling... Thank you very much.

Happy clicking,
Lynn

[ilya]

Although I don't have a rebel, I just can't believe its normal to take an underexposed picture with a 420EX, at 800 ISO with EC +2, at 1/60 F5.6. With my 10D and my 420EX at those setting, this image would be blown out to heck. Take it into a store where you can replicate the exact same shot with a new Rebel side by side.

[mlfrancis]

I'm really hoping to this Saturday. Going to take a free Flash class at one of the local photo shops. Don't plan on getting much out of the class, but I hope they have a DR that I can compare with. Mine is going with me.

Thanks for the reply, now I am feeling a little better, or a little less crazy anyhow. ;-)

[nosquare2003]

Seems strange. Are you sure there's nothing harmful for the software hack?

For your information, my D60 tends to underexpose 1 stop consistently using external flash and I can live with that.

[dtrayers]

Michael,

Your model is quite the ham! :D

Consider for a moment what the exposure would be if you didn't use flash. It looks like there's just some normal room lighting, so I would expect something like 1/4sec at f/4 and ISO 100. Maybe slower. Since the room may be pretty evenly lit (though dimly), the exposure would be fairly even. Of course, 1/4 sec is too slow with such an active model, so you use the flash.

Now, in P mode, the camera will set a minimum shutter speed of 1/60 to prevent blur due to shake. It won't go over 1/200, the sync speed. It will try to adjust the aperture to expose the entire scene without the flash, which will be wide open. But that isn't enough, so the parts of the scene not illuminated by the flash will be dark. The camera will control the flash output so the subject is correctly exposed, and it assumes anything in focus is the subject.

So, for example, if the camera has picked 1/60 at f/4 (slowest shutter without shake, wide open, which we know will underexpose without the flash), it will control the flash output (based on the E-TTL prefire) such that the subject gets enough light. The rest of the frame is on its own.

Many of your pics have a properly exposed subject. Nothing is blown out, and nothing is really dark. It's the background that's dark. Just what I would expect at 1/60 and f/4. Notice that the pictures with bounce have a better exposed background. That's from the excess light from the flash. Since it's bounced, the camera had to turn up the output to properly expose the subject. A lot of that extra light illuminated the background.

I think most of those shots look just as I would expect. A properly exposed subject and a dark background.

I don't know what photo editor you use beyond BB, but if you have Photoshop you can select the subject and look at the histogram for just the subject. You'll see that it's pretty well exposed.

I downloaded one pic and did a couple of screen shots of Photoshop CS:

Total Histogram
http://home.comcast.net/~dtrayers/photos/image-histogram.jpg

Subject Histogram
http://home.comcast.net/~dtrayers/photos/subject-histogram.jpg

[mlfrancis]

Thanks for all the work and pointers. I agree those shots, the wide angle ones the subject seems well exposed, but what happend to the 50mm closeup shots? The subject in those turned out very dark. I've read that caucasian skin is about -1 stop off 18% gray and if the camera usually underexposes by 1 stop as nosquare2003 says his D60 does, that would give me the 2 stops I am missing, right?

How about this for a test. I will do it later tonight, but what if I do a FEL while pointing at an 18% gray card, and then do a 50mm close up shot. Shouldn't that come out tack on, or maybe 1 stop under if it is like nosquare2003 is saying. Thoughts?

Thanks again,

[rodbunn]

I have done a ton of tests myself for the same reasons above. The best result is like you are going to test; a gray card at the same distance of the subject, FEL, then move the card and shoot. This will get the subject right. The background @ 1/60 could be dark, so I put the camera in Manual, and slow the shutter to lighten the background. In Manual, the F-stop will determine the "subject's" exposure, and the Shutter speed determines the background light. This is all great IF you have a subject that will STAY STILL :lol:

Good luck,
Rod

[neil_r]

Seems strange. Are you sure there's nothing harmful for the software hack?

For your information, my D60 tends to underexpose 1 stop consistently using external flash and I can live with that.

True,

My D60 underexposes 1.5 stops (2 stops with Stofen & bounce) with a 550 EX . It is so consistant I dial it in and forget about it.

Neil

[dpanicc1]

Didn't read all the posts so this may be a repeat.

Keep in mind the flash illuminates the subject and aperature/shutter sets the camera to properly expose ambient room light; they're independent. Two exposure measurements are taken when the shutter is pressed half way: one for the shutter/aperature (ambient room light) and a pre-flash that determines flash duration (subject). Therefore, flash compensation will lighten or darken the subject while shutter/aperature adjustments will set exposure for ambient room light.

Having said all that, I agree with others here: take the camera out of auto mode and use TV, AV or full manual. If you use Av, set the shutter speed to the DRebel's x-sync in the configuration menu otherwise your subject will probably be blurred if ambient room light is dark.

I only use the center focus point because has someone mentioned exposure is biased by the active focus point. In auto, you have no clue and you're at the camera's mercy for focus point hence exposure.

Hope that helps.