Friday, January 18, 2008

G9: Flash with Gadgets

The G9 accepts external flash and that means: Gadgets! Photographers seem to love flash gadgets. I have several and want more because they promise to solve my flash problems. But which gadget to get next? Which of the gadgets that I already have is actually the best?

Time for a little testing: G9, Canon 580EX, various attachments, a simple scene in a small bedroom. For consistency, do as many do and set the camera on Program Mode, low ISO (100), auto white balance, flash set at ETTL, use the in-camera jpg without any additional processing.

Rounding up the usual suspects, I arranged them so that some shadows would be cast on the walls. Here’s the first shot. The flash was provided from the built-in flash on the G9. Not too bad – better than I expected! Shadows are hard but almost hidden because the subjects are at approximately the same height as the flash. Exposure seems OK but the histogram indicates (to me) about one stop underexposed. The wall on the right is a little bit bright. No red eye! Let’s try the big flash.

With the Canon 580EX mounted on the G9 and pointed directly at the subject, the result is about the same as using the built-in flash. The 580EX sits high on top of the G9 so the shadows have dropped a little and are more visible. The wall on the right is still a bit bright. The histogram still indicates underexposure – a little less than one stop. Time for a bounce.

This picture was taken with the 580EX pointed straight up at the ceiling. Lots of differences here. The color is a bit off; oh yeah, the ceiling really isn’t white. It’s a kind of creamy color; like the walls but lighter. Shadows are almost gone. I like this but would have to change the color balance (good thing I shot in raw + jpg). The histogram still indicates underexposure. There’s a little white card on the 580EX for directing some of the bounce flash forward, time to pull it out.

The little white card on the 580EX is intriguing. At first glance, there’s no difference between this picture, made with the white card extended, and the previous one. Take a closer look. There’s a little more shadow just behind Elmo. How about that -- that little card really does work!

With the background work done, it’s time for a gadget! Many people swear by the simple Sto-Fen attachment. I’ve had one for years but use it infrequently because it really seems to eat light. The Sto-Fen must be ordered specifically for a particular flash but once you get the right one (and heat it with a hair dryer to expand it the first time) it slides easily onto the 580EX thereafter. For this shot , the 580EX, with the Sto-Fen, was pointed straight up. Well, look at this! The Sto-Fen creates harsher shadows than the simple bounce flash! Or did it? The shadow behind Elmo is more visible but the shadow from the headboard at the extreme right has almost disappeared. Some describe the Sto-Fen as producing a “bare bulb” effect by casting light all over the room. The colors are perhaps a little better. The histogram still indicates about the same underexposure – perhaps a little better.

Some photographers use the Sto-Fen at a 45 degree angle instead of pointed straight up. Here's that variation. With the Sto-Fen (really the flash head) at a 45 degree angle, the shadows look a little more harsh to me. Still underexposed according to the histogram. I don’t see a benefit here (mental note: point the Sto-Fen up).

The Lumiquest Pocket Bouncer reminds me of a big white card attached to the flash head. In fact, many photographers make their own. With the flash head pointed straight up, the main panel of the Pocket Bouncer is at roughly a 45 degree angle. Well, this is interesting. Using the Pocket Bouncer, the shadow is still behind Elmo and the histogram still indicates underexposure. The color balance has shifted and is a little better – probably because less light is being bounced around off those cream colored walls and ceiling. Not exactly what I was hoping for. In the future, I won’t be embarrassed by using the big Pocket Bouncer on top of the huge 580EX on top of the little G9.

The underexposure, apparent with every gadget and even with direct flash, did not surprise me. For all shots, the little white bunny was the focus point and therefore the ETTL information was taken there. But it seems to me that the Canon ETTL system almost always underexposes. This feeling goes back to the 380EX, 420EX, a Canon film SLR and my Canon G3. Many others seem to feel the same way (although some disagree). Therefore, except for this demonstration, I almost always increase the flash exposure compensation when using a Canon flash in ETTL mode. Up to this point, I’ve liked the simple bounce flash with white card extended, so here’s another one with that setup but with +1 flash exposure compensation. (Uhh, this one is actually a little overexposed but I’ll leave it in the posting to show humility and, besides, I’d already taken down the scene. )

Although all the above pictures are directly from the in-camera jpg, the G9 was actually set for raw + jpg. Next, I examined every raw file to see what else could be learned.

First of all, using Adobe Camera Raw (ACR) to process the raw files, I changed the white balance to “flash” instead of “auto”. For all the pictures, this essentially corrected the colors. Of course, the G9 could have been set for “flash” white balance (instead of auto) in the first place and the in-camera jpgs would have turned out OK.

What about the exposure? Based on the ACR automatic exposure adjustment, the built-in G9 flash underexposed this particular scene by about ¾ stop. The Lumiquest underexposed it by about ½ stop. All other configurations were underexposed by about ¼ stop. So my interpretation of the histogram and resulting flash exposure compensation was indeed off. A better adjustment would have been be to add about ½ stop of flash exposure instead of the one full stop that I added in the final picture. Even so, my +1 stop adjustment was OK according to ACR! In addition to the automatic exposure adjustment, ACR attempts to recover “overexposed” highlights. For that last shot, ACR did not adjust the “exposure” but did change the “recovery” and “brightness” settings.

So I like this one the best; it’s the raw conversion of the previous shot (bounce, card extended, +1 flash exposure, auto process in ACR from raw).

Lessons learned: Most of the time the basic bounce flash, perhaps with the white card extended, produces the most pleasing results for my tastes. Add about ½ stop of flash exposure compensation when using the Canon flash in ETTL mode. Conduct some additional testing out-of-doors; perhaps the Pocket Bouncer might prove more beneficial out-of-doors or in a large room. Continue to shoot in raw mode.

Note: Your own interpretation, tastes, preferences and mileage may vary considerably. These are easy tests to do. The results and conclusions could easily change with the subject and room size. Give it a try and let me know your conclusions.

(But I’ve just heard that good results can be achieved by making a diffuser from a one gallon milk jug placed on top of the flash, so ….)

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