Andrew Fildes wrote:
> Which one? I assume that you mean the 90mm Macro. Two versions -
> early metal body with 49mm filter size and later plastic body with
> 55mm filter size. Both versions have a reputation for being VERY
> sharp. Some prefer the earlier because it is more robust - some the
> later because it's younger and a bit prettier. Both have claims to be
> better optically - I don't know who's right.
>
I dunno, but the early one is mighty fine.
> The 1:1 life-size 'add-on' is an automatic extension tube about
> 30-35mm long - hard to find but may cheap auto extension tube sets
> have a 36mm tube which will do just as well - they're optically
> identical! :)
>
That's one of two ways. As with all the 1:2 macros, with the extension
tube on, it focuses only from 1:2 to 1:1. I find that frustrating in the
field, as I tend to like to tkae lots of shots that cross over the 1:2
magnification, which means taking the tube off and putting it back on a
lot. A drag.
Also, you've got the length wrong. With a simple 90 mm lens, 1:2 would
require 45 mm of forward extension by the helicoid and 1:1 would require
a 45 mm tube, for a total extention at 1:1 of 90 mm. With the actual
design of the 90/2.5, the matched Tamron 18F extension tube measures
43.4 mm. For general close-up work, a 25mm or 36 mm tube is quite good.
Doesn't go down to 1:1, but goes further out than 1:2.
The other way to get to 1:1 is to use the Tamron Adaptall 2x
telextender, Model 01F. This makes the lens a 180/5 that focuses
continuously from infinity to 1:1. I don't know how that speed would be
for focusing on an E-thingie. It's very fine on an OM
<http://www.moosemystic.net/Gallery/tech/Tam902.5/pages/wasp.htm>.
Moose
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|