At 12:06 6/24/02, Ag Schnozz wrote:
I love the 200/4. It, and the 100/2.8 have drop-dead georgeous
bokeh. Granted, it is a bit lacking in wide-open performance,
but drop it down a couple of stops and it is very respectable.
I'm more than happy with the performance of my, albeit black-nose MC,
200/4, except I might want one more stop of speed for a brighter
viewfinder. When using lenses this long, holding them steady enough,
regardless of shutter speed becomes an issue. One must be well-braced in a
very steady stance and use a fast shutter speed (1/250 or faster) to get
away with hand-holding any 35mm small format lens longer than 135mm. I
discovered this several years ago when going through chromes to have them
made into large prints. It's truly amazing the difference in image
sharpness a very sturdy tripod makes! Camera shake is not always
inherently obvious as such unless it's severe enough. It *can* look like
lens softness or improper focusing.
Some comments about numbers of elements . . .
It's not how *many* there are but the lens formulation. In prime lens
designs without floating elements, often fewer elements are required for
longer and slower lenses. Increasing lens speed is a significant driver in
adding more elements to provide for the necessary optical corrections wide
open. Increasing focal length mitigates corrections some due to ray paths
and their angles with respect to the lens axis. The Carl Zeiss evolution
of the 5cm Sonnar is a prime (pun intended) example of lens speed affecting
numbers of elements. To get it from 5cm f/2 to a 5cm f/1.5, Zeiss added a
7th element. When it was resurrected for the 40mm f/2.8 Zeiss dropped back
to 5 elements . . . and yet the basic formulation principles for it remain
unchanged from when it was originally created.
I regularily use it for macro work with around 25mm of
additional extension. With 50mm of total extension you get 1:4
magnification and lots of working distance.
Not only have I used it quite successfully with the 25mm auto tube, but
also have used it for greater magnification of about 1:3 using a 36mm
Vivitar auto tube.
-- John
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