I don't even think 70-200 f/2.8L IS II is where the sweet spot is. If you shoot a lot, you probably have one of those (I have the 70-200 f/4L, but I'd upgrade sooner if I didn't just do wide angle and macro).
The expensive primes and superzooms and tilt shift and stuff are probably the market, and those are $2000-10000. I've got access to a lens lending program from a manufacturer, and I'd plan a trip around borrowing an evaluation 500mm f/2.8L.
My thesis is: Wedding photography is the biggest market for rental lenses and the lenses REQUIRED for wedding photography are fast lenses that range from $900-$2200. Additionally, there are many people who may shoot a limited number of weddings per year which do not have the cash to spend $2,000 on a lens.
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Once a photographer has a 70-200 f/2.8, a fastish wide angle and a prime or two, they really don't need anything besides strobes to shoot weddings.
Wedding lenses are important for your business for 2 reasons:
1) Non-pros going to weddings are a great market for rental lenses (1 time use, going to get some great shots).
2) It takes a while to transition to wedding photography fulltime and it is the only place to make real money down the road in most cases. During the transition from 1 weddding a year to 20 weddings a year people will need to rent lenses or not eat if they want to use what is basically required equipment for getting quality low light shots.
They will want to own the body first so that they know how to use it.
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I don't have data to support that the sweet spot is $2000, fast lenses, but I'd be shocked if I were wrong.
The expensive primes and superzooms and tilt shift and stuff are probably the market, and those are $2000-10000. I've got access to a lens lending program from a manufacturer, and I'd plan a trip around borrowing an evaluation 500mm f/2.8L.
I'm sure this stuff gets rented too and is probably rented more than bought, but the overall market size (in terms of days used) for people shooting with 500mm 2.8 is far less than the 70-200 f2.8.
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Additionally, those that own the lenses are likely to have them unused 20 weeks a year which provides the other side of the market.
That makes sense. I've never even been to a wedding (except one as security), but wedding photographers seem to be a world apart. It makes sense. It's also a particularly undemanding physical environment for a lens.
It would be cute to do it just for the wedding vertical, to test this theory. Advertise specifically in the wedding market, and try to get weddings to promote "bring your own SLR! Bride's mom covers lens rental of 70-200s for canon or nikon!" Maybe add some other wedding-related stuff (like a free camera check before/after, classes on wedding photography, and resources to hire pros).
The expensive primes and superzooms and tilt shift and stuff are probably the market, and those are $2000-10000. I've got access to a lens lending program from a manufacturer, and I'd plan a trip around borrowing an evaluation 500mm f/2.8L.