Ultra fast lenses (meaning lenses faster than about f/2.8) in the film era enabled two things:
- Ability to make usable exposures in poor light with modest sensitivity
- Accurate focusing with SLR cameras
in addition to enabling extended control of focus zone with miniature format (35mm film) cameras.
That last is the reason why fast lenses remain viable (and necessary for some purposes) in today's digital camera era with 35mm sized sensors that can achieve eight to ten stops more light sensitivity than 35mm film with good quality results, and with cameras that have even smaller than 35mm format size.
If exquisite control of focus zone isn't needed for your particular photographic aims (and is it certainly not needed
all the time for anyone's!), then there's little reason to spend the additional money for ultra-fast lenses.
The problem is that while you likely don't really need the exquisitely shallow focus zone all the time, on those occasions when you do, if you don't have the ultra fast lens, you can't get it. And the modern ultra fast lens typically performs as well as the lighter, smaller, cheaper lens when stopped down. The disadvantage of the ultra-fast lens, without price consideration, is that it's always a bit heavier, bulkier, and less appealing to carry.
"You pays your money and you takes your chances." I only have a couple of lenses faster than f/2.8 and I only very very rarely find myself wishing for something faster. Most of my photography with most lenses in the wide to short tele range seems to fall out with around f/4 to f/8 lens openings. But every once in a while, a special lens like the Walter Mandler designed Summilux 35mm f/1.4 v2 (circa 1972) used wide open makes its premium price well worth the expense:
Leica M-D typ 262 + Summilux 35mm f/1.4 v2
ISO 320 @ f/1.4 @ 1/30 second
No editing aside from the square crop and border treatment.
Since this particular lens also happens to be small and only modestly heavier than the similar vintage Summicron 35mm f/2, the extra $500 or so price premium I paid was money well spent. I can eat a little lower on the food chain for a month or two and make that up easily.
😀
G
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No matter where you go, there you are.