Alex Wilson wrote:
: I have the Olympus 20mm f3.5 macro lens ( manual diaphragm) which attaches
: via PMTob mount to my bellows / 65 - 116 tube. To use my T10 ringflash with
: this lens, I glued a 49mm filter ring to the PMTob mount so that the
: ringflash could be attached. I have had excellent results up to high
: magnifications, despite the difficulty of the manual diaphragm. Indeed, this
: setup was used to produce full - frame , and larger, images of fruit flies (
: each fly about 2.5mm long) for a commercially - accepted slide set for use
: in education.
Thanks for the idea of gluing a filter ring to the PM-MTob. I've been searching
for two years for a reasonable solution for the flash problem with my manual
20mm
and 38mm lenses, and this is it!
I removed the glass from a cheap thick UV filter, filed a groove in its rear
side
to make it partially slide over the non-slib knob of the PM-MTob, and glued it
with industrial super glue.
The only dedicated macro flash I have is the T28 Twin. It didn't come with the
Macro Flash Shoe Ring, but fortunately I already head an off-brand (Novoflex)
ring
with one flexible shoe, that allows one head to be positioned at the same level
as, or even behind, the front lens. I glued two additional shoes to it, one
fixed
shoe and one flexible shoe. This gig gives me probably even more options to
change
the angles and positions of the two flash heads than the real thing.
The only problem with this setup is that to change the aperture you have to
remove
the flash. So you must select the aperture first (and close it on the 38mm lens)
and then mount the flash. Using the Spacemen screen (1-12) and the modelling
lights of the T28 focusing with closed aperture is still easy.
This evening I did some testings, using a dummy film and trusting the flash ok
light on the T Power Control. I used an OM-2n for the test; the subject was a
small roll of paper with some text on it. I tested both lenses at minimum and
maximum bellows extension, with one and with both flash heads, at different
apertures.
The verdict is: with the 38mm lens there is no problem. At minimal bellows
extension all apertures can be used, with one or with both flash heads. At full
extension it is almost the same, but at F16 you can use only one flash head (GN
28
instead of 22).
With the 20mm lens however the setup only works at minimal extension, with all
apertures and with either both heads or one head. At full extension the lens was
just too close to the subject, and there was only one way to make it work: to
use
an additional handheld T20 flash, connected directly from the T Power Control's
connector to an Auto Connector T20. Holding it in between the two T28 flash
heads,
directly aiming it at the subject I got the proper exposure signal up to F5.6.
So it can be done, TTL OTF flash with the 20mm macro, even at full bellows
extension, but it certainly isn't easy.
H@nz
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