When to Use a Close-Up Lens like a G-Claron

**Bruce A Cahn** · 21-Jan-2010, 12:40

Though usable as an all purpose lens the G Claron (G stands for graphic arts, I think) is a copy lens, and best used for that purpose.

**Mark Sawyer** · 21-Jan-2010, 15:25

Originally Posted by Bruce A Cahn

Though usable as an all purpose lens the G Claron (G stands for graphic arts, I think) is a copy lens, and best used for that purpose.

A "general purpose" lens is optimized for use from infinity to near 1:1 at the film plane, and is well-corrected for all aberrations.

A "macro" lens is optimized for use at 1:1 and greater magnifications, and is well-corrected for all aberrations.

A "copy/process/graphic arts" lens is optimized for "close distances" (usually about 4:1 to 1:4), and is especially well-corrected for geometrically-distorting aberrations such as pin-cushion and barrel distortion so that "artwork" is not distorted when rephotographed for the printed page. Special attention is paid to making them as apochromatic as possible, though in modern lenses, all are apochromatic for nearly all practical purposes. Keeping the lens to these specifications usually means a smaller maximum aperture.

And I believe (someone correct me if I'm wrong) that eliminating focus shift is also a prime concern in making process lenses.

Any other differences I don't know of that someone can chime in on?

**Drew Wiley** · 21-Jan-2010, 16:16

G-Clarons were made both as barrel copy lenses and as tabletop taking lenses. The
published specification are very conservative because they are linked to the apo standards of copy work. But the proof is in the pudding. For general photography they
excel most general purpose lenses, even at infinity at typical apertures. At close range
they're significantly better. I do big enlargements from these things all the time. They
are damn good lenses for general shooting.