The Alpha 575s are some of the oldest-design units in the Alpha
line from
Clay Paky. I was talking to some of the ACT Lighting guys a couple of months ago and they said that since the price of new 575s and 700s was so ridiculously close they were hardly selling any 575s and mostly moving the 700s. I've used the Alpha
Profile 700 and that is one fine
fixture. I know that
Clay Paky optics in general are fantastic, and this
fixture definitely lived up to that. So if you've got a
line on some used units that you know are in really good condition, go for it, but otherwise bump up to the 700s.
I would also like to recommend an
LED solution though. We recently had the folks from Robe in our shop for a demo and they showed us the new DLS/DLX fixtures. DLS has framing shutters, DLD replaces the shutters with a second
gobo wheel. The craziest thing is that these fixtures don't have an arc source lamp - they have an RGBW
LED source. We put a MAC700 (another great
unit to look at for used fixtures, absolutely bulletproof and unbelievably reliable) up against it, and the DLS was brighter in every color except white and very light tints. In white it was brighter than an MSR575-based head. Definitely give them a look (
Robe Robin DLX Spot). The Robe USA office is in Florida, you can have your local Robe dealer set up a demo. I was doubtful at first but left the demo completely sold on the units. And you won't have to keep buying those arc source lamps.
ETA: Looks like the Alpha 575s have been discontinued, so I assume you're buying used. Still, give the Robe DLX a whirl, I'm sure that someone would be glad to bring one out to demo.