I am trying to assemble the lenses I will need for most pet portraits. I am starting a business photographing pets on location (I go to the clients home rather than them coming to a studio).

I use a Canon EOS Digital Kiss (a renamed Rebel Xti) and so far I have been shooting with a standard zoom lens (28-105mm) and a speedlite flash.

My concern: I love my zoom, but the lowest f stop on it is a 4, and I wonder if portraits would be better with a "Fixed" lens: an 85mm or 100mm.

I like the zoom, because when the pet is moving a lot (kittens for example) I can adjust accordingly and I worry about taking successful portraits with a fixed lens, when I can't make adjustments like that. OTOH, I face variable lighting situations; since I go to different homes. Some homes I've been in are really dark, and the fixed lenses have a low f stop (1 or 2) which I uderstand makes them fast and very sharp for portraits. Also, they have the ability to "blur" the background.

I am working on building a business, and would appreicate advice on lenses from pro pet photographers.

Thanks,

Tori