Originally posted by Mareket I'd agree with this. A fast prime would be handy, but if you can't get up and move then you want a zoom.
Biggest issue is the K200D, not stellar on high ISO performance, this really puts 2.8's out when shooting indoors with this body, now thinking about it, it probably knocks the DA 35 2.4 I mentioned off of the list.
Originally posted by Neel1 But you also want some very good definition, sharp images. I am working with a K200D
Without a flash, fast primes are the only way to go on this (and you still might not be able to pull it off depending on the lighting). Any lens with an aperture of less than 2.0 (less meaning smaller f/number in numeric terms), you will have to bump your ISO which is going to mean loss in DR loss in detail and noisy photos - sure PP can smooth out some of the noise, but you will end up with plastic looking detail'less photos. The models are going to be moving you will need 1/200 minimum shutter speed OR only shoot when they hit the 1 second photo op stop [which will equate to having photos like everyone else and nothing unique].
EDIT: Your best option may be to rent something like a K5 for the high ISO capabilities, pair it up with some 1.4 ~ 1.8 glass and the shoot would probably be cake work...