Doug said:
[One other qualification not yet mentioned is limited depth of field. Alluded to in the comment about camera RF baselength, but you'd want to consider the effect of short DoF in the photos. Desirable or not? [/B]
Doug,
You hit the nail on the head - seems no one else noticed it. Lens speed can be overcome with faster film in many/most cases. Yes, there is a trade-off for quality, but these days, film emulsions are much better than they used to be. You can usually get away with pushing or pulling a stop or two as well. I would not try that with other than color print film or B&W though - slides don't do as well.
The real issue is DOF. At 50mm and 1.4, DOF is pretty short - take a look at this:
http://www.dofmaster.com/dofjs.html
Notice - a 50mm lens on a 35mm camera at f1.4 and 10 feet distance has a DOF of about 1.02 feet. Enough that if you focus of the head shot - the entire subject's head should be in focus, everything behind him or her would be out of focus.
Now, try the same thing with a 1.0 lens - even assuming you get reasonable sharpness with a 1.0 lens at any price...now you get DOF of only .72 feet. Gets a bit trickier to avoid having just part of the face in focus, unless that's the effect you're going for - usually not the case in wedding photography, which is generally less 'artistic statement' and more 'documentary with subtle flattery'.
Does everyone get this? I suspect that DOF is one of the harder subjects to master - some folks seem to be surprised when they get serious OOF effects in their photos. In general, the longer the lens, and the more wide-open the aperture, and the closer the subject, the smaller the effective DOF will be. DOF is defined in general terms as that range that is effectively 'in focus' when the photo is taken. To increase DOF, use a shorter lens, stop down, or take the photo from further away. After awhile it becomes second nature.
One of the reasons it is so important to get a 'portrait lens' that is 'fast' is because the OOF effects one obtains are more pronounced with a 90mm lens than a 50mm lens (shorter DOF for similar f-stop and distance) - it is much easier to throw the background out-of-focus intentionally with a 90mm lens than with a 50mm lens. And with portraits, the accuracy of the lens wide-open is usually less critical than the speed of the lens - people often LIKE the slight softening of a not-so-wonderful lens wide open when it is applied to the cracks and crevices of our faces.
Anyway, that's my 2 cents. Advice? I'd concentrate on getting a really nice 1.4 (or even a 1.8) and stretch the film if required. Better results overall, due to quality of 1.4 lenses wide-open versus 1.0 lenses wide-open and DOF results.
One area where wider is better - the SLR camera when your eyes are getting old and tired like mine. The more light I can get inside the pentaprism, the better! But that's a good part of the reason I tend to shoot more rangefinders these days - lens speed doesn't matter.
Best Regards,
Bill Mattocks