In the
thread on Sony A6000 camera,
Doug Smith made a very helpful post with photo showing a long focal length macro lens (Canon, 100mm) and suggested the longer focal length might
work better than the 30mm focal length macro I
had at the time. The point, well taken, is that the longer focal length allows more 'stand-off' room between the coin and the front of the lens - room to set up and adjust lights. Happy to report that has turned out to be a great recommendation. Turns out it's fairly easy to adapt older SLR film-camera lenses to the A6000 and those lenses can often be purchased very economically. Just did first tests with a Canon FD 100mm focal-length macro lens connected to the A6000 with an adapter. A Sony 90mm macro costs about $1000 and the Canon 'manual only' (which is dandy for copy-stand
work) 100mm macro in excellent condition was only about $100. And indeed the new (actually pretty old) lens allows 'standing off' from the coin by about 10" instead of the 3" range required by the 30mm Sony macro I was using. That 10" or so is
plenty of room for better lighting and the first result is show here. It's an 11.5mm coin and the photo is about 1500 x 1500 pixels, or about 130 pixels
per millimeter (!) and the result with improved lighting is better than similar photos with the 30mm macro that couldn't be lit as well due to being so much closer to the coin. The resolution now is better than 10 microns
per pixel with a
good sharpness and it's much easier to use with the big 10" stand-off (and it
still fits
fine on the copy stand). It was possible to 'fill the frame' with a U.S. cent (19mm) and get about 4000 pixels spanning its
diameter (over 200 pixels
per millimeter, about 5 microns resolution). The 30mm macro by Sony, designed for this camera,
still has its uses but the 100mm 'adapted' Canon lens is going to be the 'go-to' lens for taking pictures of coins. Point of reference - the 100mm Canon lens allows setting of F value from 4 up to 22. Seems F8 works well to get enough depth of
field to make the coin look
sharp throughout its thickness.
Started this as a new
thread because the Sony A6000
thread was so long ago.
PtolemAE