Question on 550EX Exposure

Hi.
I have been using my 300D and 550ex flash for taking pictures of my nephews and nieces on Christmas Day and I have set the camera to Manual mode at 1/60 Sec and F8.0 (using bounce flash off of the ceiling with a stofen omnibounce attached) following helpful advice from another post.
I am pretty pleased with the results but I noticed that the camera exposes at -2 stops (?) I have worked around this by increasing the FEC on the flash to get the histogram across to the right more and also by shooting in RAW to allow me to set the exposure aftwerwards.
I was just wondering if it is possible to stop the camera underexposing in the first place?

Could you also tell me how the sample pictures here look to a more trained eye as I am not sure whether I could get them better or not by changing any settings (Do I need to increase/decrease exposures etc when importing the RAW data) Images have been cropped and reduced considerably in size.

Many Thanks

Skids

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I'm not sure how far or close your subject was from the camera but let's go through the math and see what we get. The 550EX has a guide number of 42 meters or 138 feet at ISO 100 (50mm). At f/8, the flash will cover a subject within 17 feet from the camera (assuming a hotshoe mounted flash).

The Stofen further decreases the distance covered by the flash by a factor of 2.5. Hence, the distance covered by the flash with the Stofen attached is now down to 6.8 ft, at ISO 100. If you shot at ISO 200, the distance will increase to 9.6 ft. At ISO 400, 13.6 ft. and at ISO 800, 19 ft.

If you were shooting at ISO 100 or ISO 200, and the subject was farther than 7 or 10 feet from you, that may explain why you were getting underexposed pictures. If that's the case, you can increase the ISO to get a farther reach from the flash. Or increase the aperture. Or do both. You can also remove the Stofen at the risk of getting harsher lighting.

I think that this is just another example of how bad the E-TTL is. With a Stofen in a normal room (so you get bounce off of the walls and ceiling) you should easily have enough juice to get a correct exposure.

As for a solution, I play the +/- on my 10D/550 like a piano. Don't be afraid to make a test shot and if you need to go to 2 & 1/2 + then just do so. And trust your histogram not the review screen. Fly by instruments and you won't crash.

Yep, increase distance, increase the ISO. Just get fimilar with how to change the ISO quickly. That's what I do anyway, the ISO 400 looks great, it's more important to get that exposre right.

With the 300d I found it will underexpose by default by around 1 stop. That added to a bounced flash and white (ish) frame, (that is most of the shot includes white or near white fore and background) will result in the flash trying to make all matter an average 18% grey. In the examples you have there is a great deal of bland color and therefore I suspect it is using the average grey to calibrate flash output.

You should tell the flash (in that scenario) to expose @ +1.5 stops and that should give you a .5 stop under.... perfect? well no but close without blowing your highlights.

Another thing is to use 800 iso to get less flash and more ambient. F8 is also a little less than ideal too (IMO), I would select f 5.6 or less and isolate the subject from the background a little.

Regards.

This is not true unless you are in a small room, or unless you crank up the ISO a lot. Go through Leo's math.

---Bob Gross---

Thanks for the information guys.

Could you tell me how the attached pictures look after I have imported them from RAW and increased the exposure.

I still do not have an 'eye' for this and don't really know if they look OK or not. I do think the colour seems a bit muted though.

Please be as critical as you wish as I need to learn.

ETTL/II works very well if you pay attention to the idiosyncracies of EOS Flash and the new algorithyms of ETTLII that separate flash metering form the active AF points.

1. When using flash in ETTL(300D)/II(20D, 1DMarkII, 1DS MarkII), always put the camera in Manual Mode and the Flash in ETTL/II. That is the only way to avoid the Auto Reduction of Fill Flash. This is one of the major causes of underexposed shots.

2. Flash metering is subject to the same kinds of influences that fool ambient metering. Bright white subjects tend to fool the flash system into underexposing and black subjects tend to overexpose. ETTLII has made this a little better by separating the AF points from the flash metering and by ignoring the very brights and darks in evaluative mode.

3. In ETTLII, you can get more consistent exposures sometimes by using CFn. 14-1(averageing) for interior shots.

4. Use your flashes Guide Number as a general guide to whether you need to increase your ISO or move closer.
The relationship between the distance your flash can cover and the Guide Number is:
Distance(meters/feet) = Guide Number(meters/feet) / f stop at ISO 100
At ISO 200 multiply by 1.4
At ISO 400 multiply by 2

5. When you use a diffuser like the Omnibounce, be sure to add the stops you lose to the equation.

6. If you are using bounce flash, be sure to include the distance to the ceiling and from the ceiling to the subject. Also, watch your flash angle and distance from the subject or you could be bouncing behind the subject.

I have found ETTL and ETTLII even more so, to be very reliable flash systems.

Here are some flash pictures I did last weekend with a 1D Mark II and a 550EX tilted to bounce off the ceiling:
http://www.pbase.com …ergerphoto/chri​stmas_2004
Happy Holidays,
Scott

skids, I think those two photos are just a little under exposed but not by much, nothing that you couldn't compensate for in EVU or DPP (or ACR, whatever you use). The advice here is right on the money about the bounce/diffuser screwing up your ETTL-II. It's normal. BTW, even if you up the ISO, you'll still have to do the FEC because ETTL takes the ISO into account.

Practice makes perfect. You're doing pretty good right now.

Happy shooting

My definition of a normal room IS a small room. Eight foot white ceilings and pastel coloured walls. More to the point I've lots of images at EXACTLY that setup where the histogram is right in the middle.

snibbetsj wrote:
...... even if you up the ISO, you'll still have to do the FEC because ETTL takes the ISO into account.

What does that mean?
Increasing the ISO, increases the distance the flash can travel and provide accurate exposure by way of it increasing the sensitivity of the camera sensor to light. It does not in any way change anything in the ETTL system. If the reason the image is underexposed is because the subject is highly refective, then FEC may still be needed in addition to raising the ISO.
Perplexedly yours,
Scott

scottbergerphoto wrote:
ETTL/II works very well if you pay attention to the idiosyncracies of EOS Flash and the new algorithyms of ETTLII that separate flash metering form the active AF points.

1. When using flash in ETTL(300D)/II(20D, 1DMarkII, 1DS MarkII), always put the camera in Manual Mode and the Flash in ETTL/II. That is the only way to avoid the Auto Reduction of Fill Flash. This is one of the major causes of underexposed shots.

2. Flash metering is subject to the same kinds of influences that fool ambient metering. Bright white subjects tend to fool the flash system into underexposing and black subjects tend to overexpose. ETTLII has made this a little better by separating the AF points from the flash metering and by ignoring the very brights and darks in evaluative mode.

3. In ETTLII, you can get more consistent exposures sometimes by using CFn. 14-1(averageing) for interior shots.

4. Use your flashes Guide Number as a general guide to whether you need to increase your ISO or move closer.
The relationship between the distance your flash can cover and the Guide Number is:
Distance(meters/feet) = Guide Number(meters/feet) / f stop at ISO 100
At ISO 200 multiply by 1.4
At ISO 400 multiply by 2

5. When you use a diffuser like the Omnibounce, be sure to add the stops you lose to the equation.

6. If you are using bounce flash, be sure to include the distance to the ceiling and from the ceiling to the subject. Also, watch your flash angle and distance from the subject or you could be bouncing behind the subject.

I have found ETTL and ETTLII even more so, to be very reliable flash systems.

Here are some flash pictures I did last weekend with a 1D Mark II and a 550EX tilted to bounce off the ceiling:
http://www.pbase.com …ergerphoto/chri​stmas_2004
Happy Holidays,
Scott

You must be the only person in the world that found E-TTL to be reliable.

If you must know Dave, the fact that Canon thought of me when designing ETTL/II makes me feel very special .

All I can tell you is what I experience. The pictures I linked to in my post below, were shot with a 550EX in ETTL II, and a 1D Mark II in Manual mode with Cfn. 14-1.

With regards to ETTL, here is a set of shots using (2) 550EX's and (1) 420EX in wireless ETTL, ratios on, using a 10D in Manual Mode :
http://www.pbase.com/s​cottbergerphoto/ayana_​bailey

If I had problems with it, I would be the first to ****. **** is one of my hobbies.
Regards,
Scott

I was looking at the pics.
I am new to flash and please indulge a basic question..
1) I was looking at Scotts bounce pics, I have been trying verticle bounce and a notch clicked fwd and like the backlite and "softness" on the faces, ( i have a 420ex,drebel) and would like to know how to fill a little in the front, does this Lumiquest 80-20 Pocket Bouncer work for this?
thanks

scottbergerphoto wrote:
If you must know Dave, the fact that Canon thought of me when designing ETTL/II makes me feel very special .

All I can tell you is what I experience. The pictures I linked to in my post below, were shot with a 550EX in ETTL II, and a 1D Mark II in Manual mode with Cfn. 14-1.

With regards to ETTL, here is a set of shots using (2) 550EX's and (1) 420EX in wireless ETTL, ratios on, using a 10D in Manual Mode :
http://www.pbase.com/s​cottbergerphoto/ayana_​bailey

If I had problems with it, I would be the first to ****. **** is one of my hobbies.
Regards,
Scott

E-TTL in wireless seems to work very well. In fact wireless TTL is the only reason that I didn't switch back to Vivitar 283's.

But I've got HUNDREDS of shots where E-TTL failed. And these were just were things like mundane corporate cocktail party shots. I'd shoot and it'd be a stop hot. I'd turn around and it would be two stops under! Of course I would get great exposures too, but it was like the flash was just guessing and guessing badly.

E-TTL II seems to be working better. It still requires some care but at least the exposures seem to be within 2/3 of a stop (over or under) now. In any case I thought that Canon invented E-TTL II for ME!