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Rangefinder
Magazine
December 2002
PROBLEMS & SOLUTIONS
Please accompany your questions with a self-addressed stamped envelope
if you wish an immediate reply. Alternatively, you can email me at: bhurter@rfpublishing.com.
From: Jim Stordahl
stordahl@umn.edu
I enjoy your section in Rangefinder. I have e-mailed Beseler on two
separate occasions with this question, but I have never received an answer.
Maybe you can help.
I read an article about enlargers and I wondered if I could use the inverse
square law to determine exposure time when I change the height of my Beseler
head? For example, if I have determined the proper exposure for a 4x5
print and then change the height to make a larger print, or to crop my
print, can I use this law to determine my exposure time (and aperture)
without making more test strips? If so, can you provide an example? I
realize that I may still want to make test strips, so perhaps this question
is academic in nature.
Secondly, the enlarger that I purchased (a used Beseler 67s Dichro)
has a 6x7 mixing chamber. Is it necessary to use a “smaller”
mixing chamber when I print from 35mm and 120mm negs?
I forwarded your question on to
Bob Rose, who is an RIT grad and a contributor to the Focal Press Encyclopedia
of Photography. He recently formed VMI, a company that helps photographic
and computer manufacturers in product planning and marketing. Here’s
what he had to say…
The simple answer is “yes,”
it’s possible to calibrate the vertical scale on the enlarger to
correlate to different exposure values for a given film size/lens focal
length/color filtration (including VC filters).
In order to do this, it’s critical that your films are absolutely
consistent and there’s no variation in any of the photosensitive
materials and processing. You also have to hope that you’re not
in a range of exposures where the paper’s Reciprocity Law Failure
comes into play. Test strips are starting to sound better aren’t
they? But if you want to try something different you can get remarkably
good exposures from inexpensive enlarging meters.
Anyway, the reason the calibration works is probably easier to explain
if you realize that we all use enlargers sort of backwards. In other words,
we rarely think of the magnification we’re trying to achieve, we
simply raise or lower the head to get the image at the baseboard to an
approximate size before we focus. The print magnification we’re
after is only possible when the enlarging lens is at aspecific distance
from the film plane—andeach magnification can only occur given a
specific object-(film) to-subject (print) distance. Your inverse square
laws calculations have to include a number of factors.
Lots of math you can throw at this if you want, but here’s a practical
way to make it happen:
1) Pick at least five print sizes that you often make from a given film
size (be sure they cover a wide range from the smallest to largest print
the enlarger is capable of making).
2) Make a matching print at each of these five sizes. Keep your lens aperture
the same and only change time. Also note on the enlarger column the indicator
number corresponding to height of the chassis for each of these sizes.
3) On graph paper (or if you like—a computer) make a chart with
print size/enlarger height on one axis and exposure time on the other.
4) Plot the five points and connect the dots with a smooth curve.
You now have a chart that allows you to see the proper exposure time for
any print size/enlarger height. Customize it if you prefer to show magnifications
and/or skip the chart and make a new scale to attach to your enlarger.
The choice is yours!
I hope that sufficiently answers your question and gives you some ideas
how to enhance your darkroom techniques.
From: Michael Alger
Munich, Germany
Michael.Alger@v-pe.de
I understand that a rangefinder’s baselength determines the
precision of focusing, and therefore limits the possibility to cope with
fast lenses. For instance, the Leica M can handle the 50/1.0 while this
is to be questioned with the Voigtlander Bessas.
What I would like to understand: how precise is the electronic distance
metering with the Contax G1 and G2? Is there a hidden reason Contax does
not offer really fast Glenses? Is there a source of information on this
issue somewhere? Thank you for your help!
This one is a little over my head. I have e-mailed the folks at Contax
and hopefully we’ll hear from them right away. I know that the difficulty
in designing a lens that is that fast (f/1.0) and also aberration-free
is considerable and it is extremely costly. These two factors could have
something to do with why there are no lenses faster than f/2.0 for the
G1 and G2.
From: Chad Nichols
chadnichols@earthlink.net
I’m an enthusiastic college junior wanting to exploit my love
of portrait photography in order to keep myself out of a 9–5 office
job. Currently, I cater to just one or two customers per month, mostly
high school senior
portraits. I avoid weddings. However, everything outside of studio work
is fair game for me. As I seek to continue this limited “part-time”
job, what basic equipment should I plan on purchasing? My budget being
as small as it is, I use only a Nikon N- 70 with a 28–105mm lens
and some ingenious creativity. However, in the near future, I want to
be able to offer my customers more. Please help...
My advice to you is not in the area of specific equipment you should purchase,
but information you should acquire. I would suggest you try to attend
WPPI’s Convention and Trade show at BALLY’S Las Vegas from
February 1–6, 2003. You will not only be able to see all of the
equipment that would enhance your part-time business as it transitions
to a full-time business, but you would be able to rub shoulders with the
best photographers in the business and actually ask their opinions. Our
platform and MasterClass speakers— there are more than 60 of them—are
amazingly accessible throughout the days of the convention and trade show,
and I believe you would find it an eye-opening
experience. I do not know from your email address how far you would have
to travel, but many people who are just starting out in this business
find the WPPI show to be an invaluable experience. See the WPPI 2003 section
elsewhere in this issue for more information.
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