In another forum, a discussion was started by someone trying to understand why four cameras (3 film, 1 digital) had meters which did not agree. He had exposed a roll of film, and had not yet posted scans of the resulting negatives from that camera. In participating in that discussion, I did a quick test of 4 cameras and a handheld reflected light meter, to see if they matched. The results:
- OM-1: ISO1600 1/250 f/2.8
- Minolta Spotmeter F: ISO1600 1/400 f/2.8
- Canon 40D: ISO1600 1/400 f/2.8
- Canon 5D: ISO1600 1/400 f/2.8
- Canon 7DII: ISO1600 1/320 f/2.8
In looking at the histograms in Lightroom (with zero adjustment to exposure) I noted that
- the 7DII exposes so that histogram peaks exactly at the middle of the histogram, whereas
- the peaks on the 40D and 5D are about 0.33EV-0.5EV below midpoint
...so I conclude that my 7DII exposes more as I would expect the reflected light meter to behave...that is, putting the metered surface at the midpoint of the histogram. And if I compensate the 40D and 5D meters to peak at mid-histogram, their meters match the 7DII.
I knew my 5D and 40D matched each other for suggested exposure. I had not compared them to my recently acquired (used) 7DII. It was only in this comparison that I noted the different behavior in the recording by 5D/40D vs. where the 7DII placed its histogram peak. My initial reaction to this is "the 7DII seems to behave as I expect". I had not really pondered about why in LR3 my prior exposures with 5D and 40D all mostly seemed to need +0.33EV exposure adjustment in LR, it was simply 'a fact'...and now I understand why! In installing LR5 to support the 7DII, I had set up some presets for the 7DII starting with 'neutral' (no adjustment) values to various LR settings in LR5.7...and not I can see how this would better work for the 7DII than for the 4D/5D shots!
My point to this post is that prior to this comparison, I had not really noted the placement of the suggested exposure vs. what the camera recorded. It seems to be a very good exercise for others to point their cameras at a uniformly illuminated, uniformly colored wall, let the camera expose where the meter suggests, and then look at a histogram of the shot 'as shot' with no adjustments. You might well become 'enlightened' in doing so, as I was. All Canon cameras do not behave similarly in the 'as shot' results...I knew that from the past, I got verification of that once again.
