Jan. 2003
President's
Message
Photo FAQs
Photo FAQs
Eric Kissa
Q: I am getting into close-up insect photography and have been trying to learn about the Lepp macro bracket. It is not clear to me that the arms can swivel up and down and if so, through what angles? Can the bracket be used to position the flash directly over the lens? Can you clarify? Is the Lepp II an earlier version of the standard and deluxe models currently offered?
A:
The deluxe version of the Lepp II frame has very useful ball heads, otherwise
the standard version is the same. The Lepp frame is extremely flexible.
The rods holding the flashes can be moved in and out through a socket
and rotated. The socket can be rotated around a horizontal and a vertical
axis. The flash can be positioned directly above the lens, if desired.
To hold
the frame vertically is less convenient but the flashes can be properly
positioned for a vertical shot. The Lepp frame is more versatile than
a ring flash (flat lighting!) or macro flashes attached to the front of
the lens, except for extremely short working distances. The ball heads
can hold full size flash units when more fire power is needed. I use two
Micro Nikkor lenses and a sigma APO 70-300mm zoom. The Sigma is not quite
as sharp as the real macro lenses but produces a half life size image
at a working distance of almost three feet, sufficiently long to prevent
frightening of insects. A longer working distance requires more flash
power.
I have equipped my Lepp frame with the Strobonarquick release mount I
use on all of my cameras and tripods. Not necessary, but convenient in
the field.
Q: What is the meaning of 24-bit color?
A:
The word "24-bit"indicates the depth of color. One bit is the
smallest unit of computer information representing binary colors ("0"and
"1"). An 8-bit
color depth per channel corresponds to 256 colors (2 to the 8th power).
The RGB color system used for editing color images has three channels:
red, green, and
blue. The 24-bit color includes three channels with 8-bit color in each
channel. The total number of colors is 256 x 256 x 256 equals 16.78 million
colors. This is the same number as 2 to the 24th power. The number of
colors corresponding to a 24-bit color is the minimum number of colors
needed to make a print look like a real photograph. Some scanners allow
scanning with 14-bit
or 16-bit colors per channel, including 16384 and 65536 colors, respectively,
per channel. A 48-bit color depth, resulting from 16-bit color per channel,
represents a huge number of colors indeed. BecauseAdobe Photoshop uses
24-bit
colors, why is it necessary to increase the file size in order to accommodate
more colors? When editing images, some information may be inevitably lost
and a
large number of colors is a reserve to make up for the losses.
The Nikon Super Coolscan 4000ED
is an outstanding scanner which can produce high quality scans formerly
obtainable only from drum scanners. The scanner is
claimed to have 48-bit color depth but it has only two settings: 8-bit
and 14-bit. Because 3 x 14 = 42 it is not obvious where the 48-bit color
comes from. The explanation
given to me by Nikon is that the 42-bit color is raised to a 48-bit color
by software enhancement. Would not a 42-bit color depth be sufficient?
I guess, more than adequate for making prints and slides but
perhaps defensive in the number game with competing 48-bit scanners. Software
enhancement of color depth is not uncommon although a scanner with a smaller
bit number of real colors may produce a better scan.
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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.