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Old Jan 22, 2004, 1:18 AM   #11
M-O
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Manual mode.

The underexposure is the most obvious with MR-14EX. The built-in flash and my Canon Speedlite 380EX don't seem to underexpose that much. However, I didn't play with the camera extensively yet, and didn't attempt printing my photos. The monitor was calibrated with Photoshop CS's own utility.
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Old Jan 22, 2004, 4:48 AM   #12
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Flash is heavily weighted to whats in the focus box WHEN you take the pic , digital cameras will always expose the highlights well and have little exposure lattitude , thus you get "dim" pics.
If you blow the highlights (the bright bits) you cannot recover any detail at all. Whatever is in the focus box can fool the flash as well as the camera itself , for example if you focus on a pale face , the flash will tend to underexpose.
You can point at a neutral object about the same distance , do a FEL and then recompose focus and shoot.
Or apply FEC
Or set the lens to Manual Focus and this then uses a different metering pattern for the flash which is a full average.
If you want "brighter" pics , rembember your mid tones and shadows will be brighter , but you might lose detail in the bright bits. Most folk can live with that tho.
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Old Jan 22, 2004, 4:56 AM   #13
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Re the MR-14ex , it gives a very "flat" light even if you do use the variable ratios. It should best be used with another flash for modelling lighting , like a 550ex in wireless e-ttl mode.
Problem is with macro , a lot of objects are shiny (like teeth and wet gums) and will fool the flash into underexposure. Try take a pic of yourself in a mirror with the inbuilt flash to see this. Use the histogram to see what the pic will be like , the LCD monitor is useless for this.
The other problem with flash is that if there is bright ambient lighting , the flash thinks it's in fill in mode and automatically applies a reduction ratio (the golden rule of fill in is that flash to ambeint light ratio should be 1:3 and the flash applies a -1 and 2/3rds reduction. On the 10D you can disable this and set your fill in ratio using FEC.
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Old Jan 22, 2004, 11:08 AM   #14
M-O
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Very good points, indeed! Thank you, Doc!

It's just that I routinely used my film-based Canon Elan IIE with the older MR-3 (?) ring flash and all my dental (oral and portrait) slides always appeared perfectly exposed. Despite the reflections, ambient light, partial metering, etc.

Now, with Digital Rebel and MR-14EX, if I can trust the histograms and my monitor, ALL shots are significantly underexposed. I mean each one of them requires adjustment. This doesn't sound right to me.

I experimented a bit more with 380EX flash last night and found a similar problem. And this is with neutral-colored, non-reflective objects situated in evenly shaded locations and with portraits. Built-in flash appears to produce somewhat better results in terms of general exposure (not counting other qualities, of course).

Shall we construct some sort of a standard experiment that would give us a better understanding of what's going on? It would be very interesting to compare our results. Any suggestions?
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Old Feb 4, 2004, 1:10 AM   #15
M-O
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OK. Here it goes.

I extensively tested two new Digital Rebels and two MR-14EX flashes. Canon EF 100mm Macro lens was used to take the pictures.

The setup produces a consistent significant underexposure (1-2 full stops) in macro applications (in my case- dental). The manual mode with the shutter speed of 1/100-1/200 and f-stops from 8 to 32 at ISO 100 was used. The amount of underexposure is directly related to the amount of ambient light. Are you ready? The better the subject is lit by the ambient light, the more severe the underexposure is (?!!!).

The underexposure is less significant when the only source of light is the flash (although the dynamic range remains too narrow). Really good quality shot with wide dynamic ranges are possible too, but only with ridiculously low f-stop numbers (almost fully opened) which is both unacceptable and strange (we're talking only about 1-2 ft. distances). There are two other ways to get acceptable shots: either use of the Flash Exposure Compensation set at +2(!!!) on the flash or cranking ISO to 1600 (no need to comment on the latter, I guess).

Now it's obvious to me that there is something VERY WRONG with the core design of the camera and/or flash.

To tell you the truth, I'm very disappointed.

P.S. On a good note, in a carefully designed experiments, neither camera had any problems with focusing. I checked this just because I've seen quite a few complaints.
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