Joel,
I have the Tamron 90 mm f2.5 49 mm filter. I've used it with the T28 a bit.
It is hard to get a bad result on manual. As you know, I'm a 1n bloke all
the way.
I just figure out the magnification in my head. For example, fully screwed
out is 1/2, add a 25 mm tube. This gives 3/4 magnification. There effective
aperture is therefore a bit uder twice what the lens says. (effective
aperture = lens aperture * (magnification + 1).
So now I have the aperture for flash use, and then I set the T28 to the
right value. Generally on 1/4 power (GN 14 metres 100 ASA).
If I set the aperture to f16, I would effectively be a bit under f32. I
shoot Kodachrome 64 (like everybody should be!). So my guide number is about
10 (I think). So I am about 0.3 metres away. This is a simple ball park
estimation, but it comes out OK. As John Shaw says in his books, he shoots
at one or two apertures under these type of conditions.
I either set it based upon the aperture or the distance, depending upon the
subject. I've had a few failures, but quite a few successes.
All this calculation stuff takes about 10 seconds. Numbers round up and down
and I can use one head at full or 1/4 power giving GN @ 100 ASA of 28, 22,
14 and 11. If I were truely desperate I would put a wide angle diffuser on
to drop a stop. But I have never done it. 1/4 power with two or one heads
seems to work fine.
Foxy
----- Original Message -----
Is anyone using the T28 macro twin flash with 90/2 in manual mode? I'm
looking for starting-points for working out manual stops for various
magnification ratios and would love the benefit of someone's prior
experience
with anything relevant.
Joel W.
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|