I use a Canon G2, 4.0 megapixel, digital camera for close-up coin
work. The camera has been modified to accept 49mm add-on lenses. An
Osawa 4x macro lens and a ProMaster UV lens are installed to allow for
extreme close-up shots. (The 4x macro lens also has 2x and 1x
companions, but they are unnecessary; I simply use the 4x by itself.)
All photographs are taken in full telephoto macro mode, at f5.6.
The G2 also lets me shoot at ISO 50. This makes the CCD on the camera
less sensitive to light, which increases exposure time and eliminates
"graininess" in the photos.
Good lighting is an extremely important ingredient in getting the proper
color of the coins. I use an OTT-lite, which is absolutely the best
light for coin photography. OTT-lites produce what is called
"natural light," which is a full-spectrum light that closely imitates
sunlight. For coin photography I position the OTT-lite above the coin,
aimed down at the top of the coin at an approximate 45-degree angle.
The camera adjusts the shutter speed automatically depending on the
reflectivity of the coin; lustrous silver coins are shot at a fast
shutter speed (usually 1/60 to 1/30 sec) while dark copper is shot at
a much slower shutter speed (a slow as 1/5 sec).
For darker coins, particularly early copper, the camera tends to
overcompensate for the darkness of the coin, resulting in a slightly
overexposed shot. I correct this by setting the camera to between
-1EV and -2/3EV.
I am beginning to refer to the OTT-lite as the "light of truth." By this
I mean that any problems a coin may have (e.g., hairlines, unnatural
luster, etc.) will be displayed very honestly in the photos.
On the flip side, nice coins will indeed be displayed as what they
are - NICE COINS. (See Photo Samples.)
The camera is mounted on a mini-tripod and pointed straight down at
the coin. To have the coin stand out as much as possible, I use a
pure-white piece of poster paper. One small drawback of the mini-tripod
is that it is not height-adjustable, so I have to raise it up on
blocks. Other than that this gives me a completely stable and
consistent setup in which to photograph coins. (Some additional
photos of the setup are displayed below.)