Macro Photography and Nikon Metering.

A nice article
http://www.photo.net/learn/macro/

Some excerpts:

- "In short, anyone in the market for a macro lens is already fairly sophisticated and quality conscious."

-"In my humble opinion, the best macro lenses are the latest autofocus mount models made by Nikon (my primary 35mm system is Canon EOS, by the way). Nikon makes 60mm, 105mm and 200mm focal lengths. Each lens will focus continuously from infinity to 1:1. You can shoot the moon and capture the bear claw without stopping to change lenses or screw in filters. How do these lenses work? Do they just have a much longer helical than the 50mm normal lens? Yes and no.
Yes a macro lens helical has much more travel than a normal lens helical. You can watch the front element move an inch or two. However, these helicals aren't just pushing a stack of glass back and forth like the 50mm's helical. Inside one of the elements is moving ("floating") so that the optical design changes to a more appropriate one for close-up photography. Thus you get sharp images at all focussed distances. "

-Rollei probably has the most intelligently designed macro system in the world. costs 3400$

- Taking pictures through a pinhole results in tremendous depth of field but very low sharpness due to diffraction. This is why lenses for your 35mm camera stop at f/22 and don't go to f/45 or f/64. View camera lenses provide these smaller apertures for two reasons: (1) the lenses are longer (f/64 on a 210mm lens is not all that small a hole); (2) the negative won't be enlarged very much.

- the modern Nikons, e.g., 6006, 8008, N90, show you the effective aperture in the viewfinder; the F4 does not; Canon EOS cameras do not. Another reason to go with the Nikon system if you are into macro photography

-g