First the results:
Now some commentary. This car wasn't running right, so I didn't get to put the AF system through the ringer, but overall I like the camera. That said, I do have some concerns with, of all things, the light meter. I don't have a 5DII, so I can only compare it to my 5DC. I almost always keep the metering in evaluative mode. For some reason, I had to bump the exposure compensation up 1 to 1.5 stops all day long. Even in scenes that aren't contrasty by any means, the light meter seems to freak out whenever it seems any whites, grays, or silvers.
I don't expect miracles from a light meter, and as an old film fart, I still bracket. Even so, for my shooting needs, I find the metering on my 5DC is more accurate. The 5DIII seems overly sensitive to highlights as far as metering is concerned, which could be a good thing depending on what you shoot, but I'm not crazy about it thus far.
The same thing plays out when use a couple of 550EXs off camera for fill or accent lighting. In this arrangement, both the ambient and flash output is underexposed. I was cranking up on the flash exposure compensation 1 to 1.5 stops all day. Metering was inaccurate in both AF and manual focus modes. Me no likey
I'll have to play with the different metering modes more until I pass final judgement, but I'm less than thrilled with it so far. Hopefully it's just user error.
Has anyone experience similar issues?
Those are some pretty fantastic shots, V8! Great examples of the 5D III's performance.
Regarding exposure, I am not sure that anything is wrong. If you count dynamic range being from the darkest pixel to the brightest, there is a LOT of dynamic range in those photos. There are some very bright highlights, particularly off the chrome. I am not surprised that you couldn't capture it all in a single shot without pushing down the shadows. If I had to guess, I'd say...counting the very bright highlights...that there was more than 14 stops of DR in those shots.
Regarding 5D III metering, something you might need to learn to work with is the fact that it is no longer monochrome. Until iFCL and the new 100k RGB metering of the 1D X, Canon metering was monochromatic, it did not take color into account at all. The 5D III uses the iFCL metering sensor, which has blue/green and red/green layers. Canon's own official description of iFCL is here:
Exposure settings: iFCL metering
The EOS 7D SLR features an iFCL 63-zone Dual-layer Metering Sensor. The ‘FCL’ stands for ‘Focus, Colour and Luminance’ and hints at the fact that the metering system not only measures colour and luminance data, but also analyses the data provided by each point of the AF system.
The metering sensor has 63 measurement zones and is a Dual-layer design with each layer sensitive to different wavelengths of light. Electronic sensors in general are more sensitive to red light. This means when photographing subjects with lots of red in them – skin tones for example – the sensor receives a stronger signal as it only detects brightness levels. This can lead to the wrong assumption that there is more light than there really is.
The Dual-layer system overcomes this by having one layer sensitive to red/green light and one layer sensitive to blue/green light. Both these layers measure the light in their respective spectra and the metering algorithm then combines the two to provide an accurate light reading. In this way, accurate exposures can be attained in a wide range of shooting situations and irrespective of the colour of the subject being metered.
To work with the iFCL metering sensor, the EOS 7D also features a specific metering algorithm. The EOS 7D always measures focus with all AF points regardless of the selected AF mode. During the exposure reading the EOS 7D looks to see which points, in addition to the selected point, have achieved or almost achieved focus. This information lets the camera know which part of the image is the subject. It then takes metering readings from the zones corresponding to the AF points that have achieved (or almost achieved) focus and combines them with readings from all the other zones. This allows for consistent shot-to-shot exposure, even in complex situations – for example, where there are reflections from a model’s glasses.
I've italicized parts that might be relevant to you. Most importantly is that the previous metering sensors may have assumed incorrectly about how much light was actually available in the scene, as they saw primarily in the red spectrum (monochromatically). The new iFCL metering should be MORE accurate, not less, given that it "sees" full color. It is not surprising that you might have to add more light, for two reasons. One because it meters blue and green now as well as red...silicon is less sensitive to both of those additional colors, and less space is given to red metering. Also for the fact that with a layered system, blue is less sensitive and in the top layer, so the red layer is going to have a certain amount of light filtered out by the layer above, making it less sensitive as well. The lower sensitivity seems like it is by design, though, to produce more accurate, highlight-friendly metering.
Second, the iFCL meter DOES take into account focus, and it will attempt to weight metering around AF points that seem to have focus above those that do not. The backgrounds in some of your wider full-car shots are out of focus, so the meter will probably give them less weight than the car (and all its sparkly highlights) in the foreground. Again, it is not surprising that you need to add more light, since the background is darker than it might have been with a 5DII. I am not entirely certain flash is the ideal solution, though...as that is going to change the lighting characteristics of the car as much (if not more) than anything else, and the way iFCL weights metering....you might just make the discrepancy between dark backgrounds and bright foregrounds worse.