Mar. 2002
President's
Message
Focus
On...
Photo FAQs
Photo FAQs
Eric Kissa
Q: What is the best way to mount slides in glass?
A: Slides are mounted in glass for protection, cropping, and to prevent the slide from popping in the projector (The main cause of focus problems in club contests). The slide and a mask can be placed between two pieces of thin glass and bound with mounting tape. This technique is seldom used nowadays because easy to use ready-made glass mounts are available from GEPE, Wess and others. The GEPE mounts are the most popular and come with 8 different openings. The mounts 6002 (24x36mm), 6802 (24x32mm), 6803 (24x28mm), 6801 (21x28mm), and 6805 (17x35mm) are the most useful. The 24x36mm GEPE mounts are available in local photo stores, all sizes can be ordered from RMF Products (P.O. Box 520, Batavia, IL 60510. Phone: (630) 879-0020. E-mail: rmfprod@netcom.com). The AN grade means an anti-newton surface that prevents the formation of Newton's rings (Colored rings caused by interference of light reflected from the opposing surfaces in narrow spaces). The GEPE mounts can be easily opened and are reusable.
Q:
What is the Scheimpflug technique
for increasing the depth-of-field in close-up photography?
A: The Scheimpflug technique increases the depth-of-field by tilting the lens. When photographing a flat field at an angle to the camera, for example leaves on the ground, one can visualize three planes: The plane formed by the subject being photographed, the film plane, and the plane formed by the front of the lens. The Scheimpflug principle states that the maximum depth-of-field is achieved when the three planes meet at a common point. This requires tilting of the lens, something the view cameras can do. The film plane and the lens plane of a conventional lens on a SLR camera are parallel and cannot meet. Hence the Scheimpflug technique cannot be used. However, a special micro lens makes this possible. The Nikkor 85mm f/2.8 PC Micro can be tilted to increase the depth-of-field. The lens has a maximum reproduction ratio of 1:2 at a working distance of 1.3 ft (40 cm) and the minimum aperture is at f/45. The price ($1320 in NY) of the lens may discourage the casual shooter.
Q: What is a quick and easy way to make a slide from a print if a negative is not available?
A:
A slide can be made from a print
either by a photographic or a digital process. The simplest procedure
is to photograph the print outdoors. However, direct sunlight is harsh
and must be filtered with a transparent sheet (diffuser, umbrella) to
reduce contrast. Light is softer in shade but a warming filter (81A or
81B) is needed to prevent a bluish cast.
The color quality of sunlight is not sufficiently consistent and for accurate
color reproduction artificial illumination is preferable. One or two electronic
flashes can e used to illuminate the print at a 45 degree angle. An increase
in contrast is a problem and necessitates a low contrast film (Dupe) or
a slight fogging with a postflash.
The digital procedure allows more control. The print is scanned with a
flatbed scanner into a computer. After making the necessary corrections
the file is transferred to a CD and sent to a digital processing lab.
The cost of a slide made by direct photography is about 30 cents, by the
digital route the cost is at least three dollars.
Q: The Nikon TTL flash remote cord SC-17 is tripod-threaded but my bracket has a flash shoe. How can I mount the cord on my bracket?
A: A flash shoe adapter FSA-8 (Cat. No. 45-0498, $13.95) is available from Porter's, Phone 1-800-553-2001, Fax 1-800-221-5329. Knurled lock rings prevent the head of the cord and the flash from rotating.
Q: The duplicate slides I have made by photographing the original slide from a rear projection screen are yellow. Why?
A:
Like an ordinary light bulb,
the slide projector emits Tungsten light which on a daylight film causes
an orange color shift. You have two options: use a dupe film balanced
for Tungsten light or place a 80A blue filter on the lens. The filter
increases the exposure by two stops but the TTL meter in the camera will
compensate for it automatically.
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Send questions concerning photographic
equipment (cameras, lenses, accessories, filters), photographic techniques
(other than digital), and film, as well as information on international
photographic exhibitions, to: ekissa @aol.com.