Matt Blaze
9-Feb-2008, 17:35
We all know that general purpose lenses do not perform as well as purpose-designed macro lenses at macro reproduction ratios. I was curious how pronounced the difference is in practice, and so tonight decided put my 240mm/5.6 APO-Symmar up against my recently acquired 240mm/9 APO-Gerogon in an unscientific quick test.
I didn't want to just resolution charts or other measurement contrivances, but rather reasonably plausible subjects to get an idea of how the lenses would perform in practice. So I set up a quick arrangement on the shooting table with a silk map and some dice. Camera was a a 4x5 Sinar P and the film a BetterLight scanning back at 6000x8000. (Yes, digital. So sue me. I wanted as few optical variables between the tested lenses and the screen as possible, and besides, it was quick to do.)
The focus was along the red road from Ryazan to Moscow in front of the dice. I took care to focus and set the swing carefully for each shot. Note that the perspective changes slightly between the two lenses because the two lenses locate their nodal points in different places w.r.t. the lensboard. The reproduction ratio is about 1:1 at the middle of the image.
Here's the full image (downsized to 650x488) for the Symmar:
http://www.crypto.com/private/test/moscow-symmar-650.jpg
... and for the Gerogon:
http://www.crypto.com/private/test/moscow-gerogon-650.jpg
Obviously not much difference visible in these small images, but full resolution crops tell a rather different story. Here's a detail from middle of the Symmar shot:
http://www.crypto.com/private/test/moscow-symmar-crop.jpg
...and from the Gerogon shot (the winner to my eye):
http://www.crypto.com/private/test/moscow-gerogon-crop.jpg
So, in this case, the macro/enlarger/process lens is indeed sharper, although I think the Symmar did respectably well. Not a scientific or controlled test by any means (and the perspective here tells us little about distortion, etc) but perhaps someone will find the comparison useful.
-matt
I didn't want to just resolution charts or other measurement contrivances, but rather reasonably plausible subjects to get an idea of how the lenses would perform in practice. So I set up a quick arrangement on the shooting table with a silk map and some dice. Camera was a a 4x5 Sinar P and the film a BetterLight scanning back at 6000x8000. (Yes, digital. So sue me. I wanted as few optical variables between the tested lenses and the screen as possible, and besides, it was quick to do.)
The focus was along the red road from Ryazan to Moscow in front of the dice. I took care to focus and set the swing carefully for each shot. Note that the perspective changes slightly between the two lenses because the two lenses locate their nodal points in different places w.r.t. the lensboard. The reproduction ratio is about 1:1 at the middle of the image.
Here's the full image (downsized to 650x488) for the Symmar:
http://www.crypto.com/private/test/moscow-symmar-650.jpg
... and for the Gerogon:
http://www.crypto.com/private/test/moscow-gerogon-650.jpg
Obviously not much difference visible in these small images, but full resolution crops tell a rather different story. Here's a detail from middle of the Symmar shot:
http://www.crypto.com/private/test/moscow-symmar-crop.jpg
...and from the Gerogon shot (the winner to my eye):
http://www.crypto.com/private/test/moscow-gerogon-crop.jpg
So, in this case, the macro/enlarger/process lens is indeed sharper, although I think the Symmar did respectably well. Not a scientific or controlled test by any means (and the perspective here tells us little about distortion, etc) but perhaps someone will find the comparison useful.
-matt