At 02:09 20.09.2003, Mike wrote:
a) do I have to leave the blank filter in the rear holder all of the
time, i.e. does leaving the filter holder installed but empty hurt the
performance of the lens?
All rear-filtered lenses will have spherical abberation either with or
without filter. If Tamron has designed their lenses to be used with a
filter, then removing it will introduce s.a. If you're able to detect it is
another matter.
2) What's the rotating ring with the little brass nob located in front
of the rubber focus ring used for? At some position there feels like a
detent.
My take on this: Infinity focus can vary by a small amount with
temperature, and with this ring you can adjust it as needed (or leave it
all the way to the right, and be able to over-focus all the time).
...still no luck finding a drop in CP for this lens. Looks like I'll
have to use the "walt" method. The C*non AF version of the 300/2.8 has a
thumb wheel on the filter holder so that one can rotate the filter while
it is inserted in the lens, unfortunately Tamron says it won't fit in
the manual version. Too bad.
KEH has a filter holder (although more expensive than a new one from B&H)
and they've also got several pol.filters in 43mm. What's the problem?!?
Thomas B.
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