Feb. 2002
President's
Message
Focus
On...
Photo FAQs
Photo FAQs
Eric Kissa
Q: Can several close-up accessories (attachment lenses, extension rings, teleconverters, or bellows) be used together?
A: Yes, this is done quite frequently. Two attachment lenses can be combined for a larger magnification, for example, a combination of +2 and +3 Diopter is equivalent of a Diopter +5 attachment lens. Which of the lenses should be mounted closer to the main lens, is a matter of opinion. Usually the attachment lens with more curvature (larger Diopter) is mounted onto the main lens first but the opposite order has proponents as well. It should be kept in mind, however, that attachment lenses and teleconverters degrade the image to some extent, the extension tubes and bellows do not.
Q:
What do the numbers on
attachment close-up lenses stand for?
A: The numbers are Diopter, just like the numbers used in prescriptions for eyeglasses. The Diopter of a lens is the reciprocal of its focal length, expressed in meters. As an example, a +4 lens has the focal length of 0.25 meters or 250 mm. While on this subject I cannot refrain from commenting on the multitude of units used in photography. A focal length of a lens is given in millimeters but the physical length is in inches, e.g. 2 11/16" instead of 673 mm. The weight of the lens is measured in pounds, e.g. 1 lb 1/4 oz, instead of 455 g in the metric system. The distance of the camera to a subject is measured in feet, although the lens has a metric distance scale as well. The film size is 35 mm or 4 x 5", the paper size is always measured in inches. If this is confusing, do not despair. We are not the only country using inches, feet, yards, quarts, pounds and ounces. There is another country, somewhere in Africa, still using the venerable British system, no longer used by the Britons themselves.
Q: How can I attach a mechanical cable release to my Canon camera?
A:
A mechanical cable release can
be attached to Canon EOS cameras via the cable release adapter T3, if
the camera has a T3 socket. Canon cameras with the N-3 type remote control
socket require the remote switch adapter RA-N3 for accepting the T3 adapter.
Unlike a mechanical cable release, Canon remote switches (60T3, RS-60E3,
and RS-80N3) have an inconveniently long (2 ft or 2.6 ft) cord but maintain
all the functions of the shutter release button.
Q:
Which of the zoom lenses have
the close focusing ability needed for close-up
photography?
A:
Most zoom lenses for 35mm SLR
cameras cannot focus sufficiently close to make a large image of a small
subject. By definition, in close-up photography the image of the subject
on film is at least 1:4 (one quarter) of its real size. Only a few zoom
lenses can meet this requirement and provide a 1:2 reproduction ratio:
Nikon 24-85mm f/2.8-4, 28-105mm f/3.5-4.5, and 70-180mm f4.5-5.6*. Sigma
28-80mm f/3.5-5.6, 28-135mm f/3.8-5.6, 70-300mm f/4-5.6, and 70-300mm
f/4-5.6 APO. Tamron 70-300mm f/4-5.6.
* designated as a macro zoom lens with a reproduction ratio 1:1.3.
Several Canon and Minolta lenses border the close-up range with a maximum
1:4 reproduction ratio. With close-up attachment lenses, extension tubes,
or bellows larger reproduction ratios can be achieved.
Fixed focal length macro lenses can provide a 1:1 reproduction ratio,
of course.
Q: Does the autofocus of the Nikon 80-200mm f/2.8 AF lens work with the Kenko PRO teleconverter?
A: The Kenko Teleplus 300 PRO 1.4x converter is compatible with the Nikon 80-200mm f/2.8 AFD lens. I have tested the autofocus of the extended lens and it works well. The converter for Nikon AFD lenses is black and is not compatible with motorized lenses. The Nikon 80-200mm f/2.8 HSM lens has a motor and needs a white Kenko Teleplus 300 PRO converter designated for the Nikon AFS mount.
Q: How can I tell that the diaphragm of the lens is sticking?
A:
The symptoms of this covert
ailment are: (1) The image in the viewfinder does not darken when the
depth-of-field button is operated. (2) The diaphragm does not close when
opened by moving the aperture lever on the lens mount or does it sluggishly.
(3) The film is overexposed when the diaphragm is stuck open.
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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.