Good-day,

For those of you not already familiar with the environment in which I will be photographing my subjects, a complete description is available under my post "Macro->Nikon, Canon, Pentax->Bodies, Lenses" in this forum (Digital SLRs) (though I do not believe knowledge of this is greatly important for the subject of this post).

Background:

i.) From my understanding, the main purpose of the aperture is for the control of lighting (hopefully I have this much right... ;) ). Now, as my subjects are in a very low light environment to begin with (i.e., the inside of my research furnace), too much light should not be a problem. In addition, I can, and will most likely, add more lighting to my system in order to improve the lighting to a sufficient level.

ii.) It appears the price for a fixed aperture camera is generally more*** than that of a comparable variable aperture.

iii.) I have the impression that a fixed aperture lens is generally of higher*** quality than a variable aperture.

iv.) I am currently looking at acquiring a D100 or D70.

*** Please correct me if this is not the case.

Question:

As I can control the lighting of my system fairly cheaply (i.e., CAN$50-100 halogen lamps) relative to the cost of a better aperture, would it most likely be more inexpensive to get a variable aperture lense with a suitable focal length (i.e., Sigma 70-300mm f4-5.6) and compensate for any difficulties through controlling my lighting?

Thank you for your time.

Auf wiedersehen,

James