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suitability, materials safety, quality
control, and so forth are being adhered to.
From the owners’ manual for your
specific National f lash unit, there is
no mention of whether the centre pin
is of positive polarity (relative to the
larger outside ring), which is required by
your camera. You’d want to test that for
yourself to be certain. Particularly with
large studio strobes, some manufacturers- for their own reasons – would have leads
with reverse polarity to what was normally
expected on the Prontor–Compur, or
Point Contact, connector, so that is
another aspect to watch out for if using
old equipment.
Even allowing for the loading of the
National PE387S f lash unit’s circuit by
a low impedance digital multimeter, at
a measured voltage of 7.8V it is highly
unlikely that this particular f lash will
have a voltage exceeding 250V. To
provide a more definitive answer would
require testing the f lash unit, both with a
digital multimeter and oscilloscope.
In general, modern cameras are
expensive to repair at the best of times.
It may be the case that a f lash unit
having too high a voltage on its trigger
terminal could cause damage requiring
replacement of the entire shutter
mechanism, thereby becoming an
economically non-viable repair.
If I were in this situation, I’d spare
myself all the anxiety and purchase an
inexpensive, modern, fully compatible
f lash unit, and then enjoy the benefits of
full automation.
For AP readers using cameras with
sensitive circuitry on their camera, for
example, rated at only 6V maximum,
possible solutions would include either
the Wein Safe-Sync Hot Shoe to Hot
Shoe High Voltage Sync Regulator, or,
the Yongnuo radio triggers, for example,
the RF-603N II. These would be possibly
cheaper than the Wein units, and more
f lexible in their usage options.UV filters and
image qualityQ
I recently purchased some
zoom lenses which have filter
diameters of 77 and 95mm. Is
it recommended to attach at least a UV
filter to protect the glass, or will this
affect the final images?
Jim, via email.A
Attaching a filter is a matter
of personal preference but is
generally preferable. A filter will
take the brunt of a severe impact, thereby
avoiding damage to the lens – this could
save an expensive repair bill.
That said there’s also the possibilitythat an impacted filter could cause even
more damage than if there were no filter
attached at all! Broken shards of glass
could scratch the surface of the front
lens element.
Some people have even experienced
being unable to remove damaged filters
due to the threads becoming distorted.
This is probably due to the metal alloy of
the filter being soft, probably softer than
the filter thread of the lens itself!
Discussing image quality is difficult.
It involves knowing what your final
output is. Poster size prints or just for
use online?
It also comes back to the quality of
the image the lens is capable of. Most
zoom lenses are still not up to the optical
standard set by prime lenses.
Lighting and environmental
conditions also play a part in image
quality. If you’re photographing in
the rain, moisture in the atmosphere
between you and the subject will make
the subject look less sharp.
Are you always photographing at the
optimum aperture for your particular
lens? Usually, this will be between two
and three stops down from maximum
wide-open aperture. There’s stylistic
concerns as well. If you’re mostly taking
portraits, you may want to deliberately
introduce some optical softness into the
image as it could be more f lattering than
a very sharp and crisp image.
There are benefits to filters when you
want to accentuate lens f lare and veiling
glare when shooting into strong sun.
The ‘degradation’ introduced by an extra
piece of glass in the optical path – which
the manufacturer never designed their
lens for – can make a notable difference.
It is possible to choose filters which
minimise the loss of image quality. Usually
these aren’t cheap, but you will get less
colour shifts, less colour cast, more light
transmission, reduced ref lections, and
higher contrast for your money. German
filter manufacturer B+W has a good
reputation for these benefits. ❂ABOVE
One situation where
you’d have less
need of a protective
front element filter is
where a substantial
lens hood is already
in place.
QUESTIONS & ANSWERS
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