jconey: I really like the on screen scale your setup has. Reading the RPI button info I presume the scale integral to the software not the scope. It says the software is tied directly to the scopes settings but If so how is it calibrated for the surface point regardless of focal distance? Also, how do you re-calibrate if needed? Or did I miss it somewhere.
For a given camera, the image scale is determined by three things for a scope like mine:
- The zoom factor -- this scope goes from 1x to 8x
- The Auxiliary lens -- I have two: 1.0x & 0.63x
- The camera objective -- I have two: 0.32x & 0.5x
When the image comes up in ImageJ, I hit the scale button and it pops up a dialog to collect the three values above. When I say the software is tied to the scope, I mean that I have pre-programmed the values I use into the dialog box pull down menus. The software then knows how convert image pixels to real units like mm or inches. You then can simply draw on the image, and it will measure what you draw. Here is a screen shot of measuring the design size of a WF:
Note: The above image is an old one of me measuring a WF from a scan -- the image is not
from the microscope.
jconey: How much did the microscope itself cost?
The scope is a Leica S8APO. Back when the S8 was being manufactured it was the top of Leica's stereo microscope line, and thus was/is absurdly expensive. I see them going on eBay
from $2K to about $8K depending upon condition.
That said, the RPI camera will work on any scope that can accept a c-mount camera -- from a $200 amscope to a $200,000 Leica.
jconey: Do you also use it for other things or just stamps?
I have two stereo microscopes (Leica S4E and S8APO). The S4E is mostly dedicated to electronics soldering and other messy work while the S8 is my general go-to for the rest. If I were to guess for the S8, I would say 60% stamps and 40% everything else.
Optically the S8APO scope is uniquely suited to philately. It is unusually bright (more on that later). The optical design is fully APO -- no detectable geometric distortion and the colors are true. With correct lighting I can even do color matching under the scope.
On my to-do list is to calibrate the color of the display so that I can do color matching from the monitor.
jconey: Is this microscope front lit and back lit?
Yes. The scope base has full spectrum lighting from top and bottom as well as stage inserts for true dark-field operation. My stamp table is well illuminated by two daylight, LED lamps mounted about 4 feet from the surface. The S8APO is a very bright microscope, and most of the time I don't even turn on the microscope illumination. For example, the image on the screen of the TI circuit board below is a live 30 fps video feed from the microscope illuminated with nothing but my desk lamps.
jconey: Does changing the eyepiece register in the scopes settings and auto adjust the software? Or isn't that necessary?
The image is captured through the scope's documentation port directly from the microscope's primary optics -- it is not passed through the eyepieces. Note that the camera is connected to this port via a "camera objective" that plays the role of an eyepiece for the camera. The FOV for the camera is a function of the sensor size and this camera objective. For the RPI HQ sensor a camera objective of 0.32x delivers roughly the same view as a 10x eyepiece.