Hi,
It's nice to have some more info on the situation.
In an *average* small bar or club that I shoot, I can get EV 4 or thereabouts on a performer's face. Remember the word *average*! heh heh. I am only speaking from my experience, which is quite a lot with live music in small local venues...but every place is different. Nicely lit places are several stops brighter, and crummily lit places are several stops slower, such as EV 1 or 2, or EV nothing if it is truly dark (what I like to call "no light shooting" instead of "low light shooting"). The average of EV 4 means to make that face middle grey (a perfectly workable value for a face given that you can push that up a bit in development, and also print it up and/or intensify), you must expose 11 stops from sunny 16, which would be '1000 at f/16 with Delta 1000. Go from '1000 to '125 and you add three stops. Go from f/16 to f/3.5 and you knock off 4-1/2 more stops, for 7-1/2 total. Still 3-1/2 stops underexposed from middle grey, meaning that the face is exposed below the threshold of detail, and no amount of pushing or special printing will ever add detail there. Once something falls at a low tone, it cannot significantly be pushed, as
pushing really only works on the midtones and high tones. In my experience, you can get a decent print (albeit rather gnarly to get it) if a face has to be underexposed by two stops. Any more than that, and you have to just find a way to work with it as a block of dark tone in the print, perhaps with a touch of texture there if you are between 2 and 3 stops under.
If you really want to get slick, you can take your brother back to the bar, put him in the same lighting situations, and take some meter readings off of his face with your meter set at EI 1000. Compare the exposures it gives you to the one you actually used the night of the jam session, and you know how underexposed he was in each position onstage.
You were at a disadvantage with a long and slow lens. I find f/2.8 unusable to capture detail in faces in an *average* situation (unless the lens has Image Stabilzation and the person is holding still enough to get a shot with a slow shutter speed, like is this example shot with a borrowed Canon 70-200 2.8 IS at 200mm, f/2.8 at '50, uncropped (love the LONG lens from the front row!):
or this one at '100 at 70mm:
)
(Adjusted on a mac with 2.2 gamma setting, so will look washed out on a standard mac screen. Both shots are of members of the band Savage Republic.)
My lenses for this stuff are my 50mm 1.4s, my 55mm 1.2, my 28mm f/2.0, 35mm f/2.0, 85mm f/1.8 and 100mm f/2.0. I *hate* to say things like this, but a lot of your problem in this case was simply being at a disadvantage equipment wise. Your lens would work fine in a very well-lit venue, but not your average bar.
.
