Subject: [Tweeters] What equipment?
Date: Jun 26 19:02:20 2009
From: Jim Greaves - lbviman at blackfoot.net


I suggest, if your interest is in photographing bird groups, larger
birds that are relatively stationary during the time of a foray, and
that you would not be trying deep forest birds at night, that mirror
lenses be considered. They have distinct advantage of fixed f-stop
(no guessing how much light is transmitted), some tend to be
"sharper" than some all-glass non-mirror lenses, and cost much less
than a comparable power (500mm being standard, f-8). PROS: they weigh
down to a tenth what similar high-end all-glass lenses may weigh (a
pound vs 7+ pounds, for instance, my Tamron 500 mirror, versus an f4
or faster 500 by Sigma or Nikon or whoever), they can be relatively
inexpensive. CONS: hard to focus quickly due to not having good low
light transmission (but, best used at dawn or dusk with sun at your
back, on sunny days, when air is crisp and clean), sometimes a
heavier lens actually balances better, may not be as
well-constructed, but I've had not complaints with my Tamron (owned
for nearly 30 years and I still use it). Either type can be
hand-held, but with a camera with image stabilization, a cheap manual
mirror lens can be a great boon! Especially good for shore and water
birds, where sometimes fast focusing isn't an issue. A zoom lens, of
whatever make or alleged quality is not as sharp or well made as a
lens comparable to that zoom's upper power (best 80-400 Nikon is not
as good as the best Nikon 400); cost may be a consideration, and some
zooms are cheaper than that single-focal length lens. My 2 cents to
add to others' comments about cameras - Jim in Montana