EOS-1n metering issues

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I's be interested in other's experiences with the EOS-1n and different metering modes.

Basically I see about 1/3 stop difference between spot metering and either partial or evaluative when metering a uniform target. I presume this could be corrected by Canon for large sums of cash. I'm wondering it it's a common observation.

I see significantly larger differences between spot and evaluative or partial when metering through a #25 red filter, as much as a stop or more. This may be intrinsic to the spectral sensitivity of the two different metering sensors. Again I'd be interested in the experience of others in this regard.

-- Bob Atkins (bobatkins@hotmail.com), August 21, 2000

Answers

Bob: Just curious--in your first paragraph, you don't mention the direction or polarity of the difference. At any rate, did you happen to close the viewfinder shutter before taking your measurements?

My experience with my 1n and 1V cameras has so far been that evaluative and spot metering typically agree when metering off of an entirely uniform surface, and when there is disagreement, this difference tends to disappear when I close the viewfinder shutter.

As for the issue regarding the #25 red filter, I'm still waiting for my ordered B+W Schneider #25 red filter to arrive, so I've not yet been able to experiment with it, using Agfa Scala. But, based on your recent posting which indicated some variation in the sensitivity of in-camera light meters with red filters, I plan to bracket my test shots once my filter arrives.

-- kurt heintzelman (heintzelman.1@osu.edu), August 22, 2000.


It seems to be related to the color temperature of the light source and the color of what you're metering. Everything seems consistant wit the spot meter being more sensitive to red than the evaluative/partial meter. So under tungsten light the spot meter suggests less exposure than the eval/part while under fluorescent light the spot indicates slightly more exposure (1/3 stop). Metering a red card in tungsten light gives an indication of about 1 stop less exposure than eval/part does.

-- Bob Atkins (bobatkins@hotmail.com), August 22, 2000.

I have observed similar behaviour from my EOS 1 (not N). As I recall it was morning and I was photographing flowers using only daylight. After I noticed problems spot metering I used a grey card to check a uniform illumination across the frame and noticed that all metering modes agreed, except spot, which was 1/3 out (but I can't remember which way).

Since that time I have been disinclined to use spot metering, presuming that it may have been operator error on my part. I generally rely on partial metering and footwork as a substitute for spot. It's certainly interesting to hear that someone else has observed this.

-- Paul McSweeney (paulmcs@clear.net.nz), September 06, 2000.


From what I've been able to find out, it seems that the different spectral sensitivity of the fine spot mode is indeed a known effect. To get around it you can set one of the custom functions to link spotmetering with the AF sensor selected. That uses the same sensor as evaluative and partial metering, but it does slightly increase the size of the metering spot. This can be done on the EOS 1n, but not, I presume, on the EOS-1

-- Bob Atkins (bobatkins@hotmail.com), September 06, 2000.

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