Originally Posted by mcherry
Well, I'm a Nikon guy but I shoot with the 85/1.4 all the time, in studio and out. I prefer sharp glass, even for glamour and especially for digital which softens images a bit anyway.
There are advantages to fast glass over just being able to shoot with a more open aperture.
1) Maybe the most important is that you will have a brighter viewfinder image with the faster glass, regardless of what aperture you are using to shoot at, which makes focusing easier - both auto (as it works through the lens) and manual.
2) Most lenses are sharpest one or two stops down from full open, so with my 1.4, I'm tack sharp at 2.8. (Actually this particular lens is pretty freaking sharp across the spectrum, but still there is a slight difference.)
3) Bokeh. The 85/1.4 has often been referred to as the "cream machine" and for good reason, the bokeh on it is outstanding. While fast glass does not mean a lens will have good bokeh, almost all lenses that DO have good bokeh are also fast.
4) Glass. Usually, the fastest lenses are made with the best glass (hence the sharpness). This should probably be reason #2.
I also shoot at all apertures in-studio and very often shoot at open apertures (>4) in the studio - especially if shooting product, but also for glamour depending.
Well I think this gets a bit into the range of apples to oranges. First of all we're talking about a Canon 85mm f1.8 not 1.4 and a price of less than $400. If we wanted to look a the nearest Canon lens to the one you mention, then we would be talking the Canon 85mm F1.2 L at between $1800-$2400. And you're right, if we were talking about the L lens, then it is the best glass.
Second, the sharpness issue is not really a function of the lens in digital but the way digital works. However, once you sharpen the image either through the cameras parameters or in post processing this "loss" of sharpness goes away. No doubt a top piece of glass will give you an even sharper image, but I generally find that the images are too sharp with the majority of better lens and have to have some softening.
I find very little difference in the viewfinder image between a lens at f1.4 and f4. On the Canon bodies I've used the auto focus seems to work just as fast throughout that range, even in low light. I can't speak for the Nikon, however.
I also find that a high majority of pros I've worked with tend to shoot glamour with a zoom lens simply because it gives you much more flexibility. That's not to say that using a fixed focal length lens is not important in some situations but when dealing with a fast moving subject the zoom allows you capture a wide range of poses. This is especially true in a smaller studio which most Garage Glamour (G1) types seem to have.
Like you, when shooting product, I tend to change my lens requirements and often do want the very sharpest lens I can get for need. I do a lot of product work using the Canon 100mm F2.8 Macro which is a fantastic lens but not of much value for Glamour.