On Sun, 30 Aug 1998 17:56:22 +0200, Dieter Lefeling wrote:

>for some sentimental reasons I am considering getting a Vivitar Series 1
>90/2.5 Macro lens. When it was introduced in the Seventies I just could
>not afford it, but if I can find one now I think I'll get it. I wonder
>if you can help me with two questions:
>
>1. What can you say about this lens' performance? As far as I can see
>many owners of Series-1 lenses rave about their little darling, while
>some more objective sources prove that these lenses usually were "okay",
>while not exactly outstanding.

The Series I lenses I've tried ranged from incredibly bad (two
of the long [-> 500mm] zooms) through so-so (most of the others),
to quite good (the 90mm f2.5). As a line, "Series I" was more hype
than reality, but there were some interesting attempts, and a
few successes, I think...

>I assume I'll be satisfied with the
>sharpness this lens delivers, but what about distortion, flare and
>vignetting at f/2.5 and f/4 ?

This lens is VERY prone to flare, and even a very deep, large shade
cannot prevent it - but the flare seems much less evident in the
macro range... I would rate the lens a tad below the Nikkor 105mm
f2.8 MF macro at infinity (both contrast and resolution), but
up with it at 1/2 life size - and the 90 is really excellent on
its 1:1 adapter (the Nikkor goes only to 1:2, and does not work
well on the 1:1 Vivitar adapter [after modification to fit]).
BTW, many of the insect photos on my web page were shot with
the 90... Distortion and vignetting were not problems I
noticed with the 90. The 90 is beautifully made, and rather heavy.

>2. How exactly does the optical 1:1 adapter work? Does it change the
>lens' focal length? Is the light loss (exposure factor) the usual 4x
>(two f/stops) at 1:1 or more/less than that?

(See Tom Bryant's post...)

>3. What's the usual price for this lens in the U.S.? Over here in
>Germany it's not too easy to find.

I just sold mine, near mint, for $250... (I kept the Nikkor,
which is a better general-use lens, and about equal in
macro at the smaller stops I use, though it is harder to
get the Nikkor to high magnifications...)