In article <4m3gd6$326@elna.ethz.ch>, loeffel@iis.ee.ethz.ch says...

>d_ruether@hotmail.com (Bob Neuman) writes:
>>Methinks you folks have missed the point: with slide films, a
>>consistent 1/4 stop error is evident as a trend toward uniform
>>lightness or darkness of your slides, with a consistent 1/3 stop
>>error showing a near-universal obvious error, and 1/2 stop is enough
>>to make most slides close to unacceptable

>This is not my experience. I bracket every single picture I take with
>my Mamiya on Velvia in a -2/3, 0, +2/3 series, whereas 0 is the >exposure that I came up with, not just the meter's.
>Very often, two of the exposures look equally good to me, especually >when the scene is low contrast. But often, I am glad I bracketed and >just one of the exposures looks right.
>As to 1/4 stop making or braking a picture, I don't quite buy that.

But the experience you recount supports what I said (though, maybe
in a more complete way): Unless the contrast is low, it is unlikely
that two brackets would look good (and if you have equally acceptable slides under low contrast conditions at "0" and "2/3" stop off, the proper "1/3" exposure between those two may have been even better -
and if only one looks right, 2/3 stop was too much of an error for
acceptability. I didn't say that a 1/4 stop would break a slide - I
said that a consistent 1/4 stop error (as from a misadjusted meter) would show as a trend toward lightness or darkness in overall slide exposures. Why fight a call for accuracy in meter adjustment? Without it, we are all guessing. With it, the meter can be used as a reliable aid in making exposures. Or, how can you compensate a meter reading, when the meter reading is unreliable, except by shot-in-the-dark brackets? As I tried to point out in my post, going to the trouble of having accurate meters saves me the time and expense of bracketing (unless the exposure situation is too uncertain) - this
results in being able to get consistently good exposures directly,
without having to resort to the "shotgun" approach. And a 2/3rd stop
bracketing is a recognition that your maximum allowable error is 1/2
of 2/3rds stop, or 1/3rd stop. If your meter is close to correct,
and your metering technique is reasonably good, a 2/3rd stop exposure either side of 0 will likely give you an exposure that is less than 1/3rd stop in error, and probably acceptable.
Hope This Helps