Question
IF we agree that precise shimming of a Tech Camera setup within 1/100 can make a big difference
in terms of IQ, why shouldn't we use this precision at any distance?
quote: Jim post 94
brain wandered while i was running a machine...came up with this comparison to jack's findings. I am using Cambo lenses on I assume, Cambo helical focusing mounts
43mm lens: closest focus is 400mm with lens-to sensor calculating to 48.17mm. focus barrel rotates about 110 degrees. that works out to .047 mm (47 microns) per degree of rotation
70mm lens: closest focus is 800mm with lens-to sensor calculating to 76.7mm. focus barrel rotates about 270 degrees. that works out to .025 mm (25 microns) per degree of rotation
120mm lens: closest focus is 2,600mm with lens-to sensor calculating to 125.8mm. focus barrel rotates about 250 degrees. that works out to .023 mm (23 microns) per degree of rotation
Looking at what jack posted, he was getting 170 ticks per full revolution, so each tick is about 2.11 degrees. His result of 14 microns per tick is then 7 microns per degree
So the Arca is 7 microns per degree for all lenses
the Cambos (and probably the Alpa's) are from 47 to 23 microns of lens movement per degree of barrel rotation...
Rod
IF we agree that precise shimming of a Tech Camera setup within 1/100 can make a big difference
in terms of IQ, why shouldn't we use this precision at any distance?
quote: Jim post 94
brain wandered while i was running a machine...came up with this comparison to jack's findings. I am using Cambo lenses on I assume, Cambo helical focusing mounts
43mm lens: closest focus is 400mm with lens-to sensor calculating to 48.17mm. focus barrel rotates about 110 degrees. that works out to .047 mm (47 microns) per degree of rotation
70mm lens: closest focus is 800mm with lens-to sensor calculating to 76.7mm. focus barrel rotates about 270 degrees. that works out to .025 mm (25 microns) per degree of rotation
120mm lens: closest focus is 2,600mm with lens-to sensor calculating to 125.8mm. focus barrel rotates about 250 degrees. that works out to .023 mm (23 microns) per degree of rotation
Looking at what jack posted, he was getting 170 ticks per full revolution, so each tick is about 2.11 degrees. His result of 14 microns per tick is then 7 microns per degree
So the Arca is 7 microns per degree for all lenses
the Cambos (and probably the Alpa's) are from 47 to 23 microns of lens movement per degree of barrel rotation...
Rod