NOTE: This is an adaptation of thing 18727 originally made by Boogie, who deserves the credit.
I have attached three different versions for an Iphone, Ipod Touch and an Android which vary according to where the camera lens is located. These were made to fit on a Bausch and Lomb stereo microscope.
While these are technically not a new design, I wanted to share my results and thoughts with anyone who is working on an adapter, and I know there are many.
Microscopes vary from one another, so the first adaptation you need is the diameter of the eyepiece.
Second, depending on the make and model of the scope, you need to determine the optimum distance between the camera and the eyepiece. I did this by simply holding the camera steady and measuring with a ruler the approximate distance that gave me a good clear image without the tunnel effect. This distance was the offset that I used on the adapter. Regardless of what you use for a camera, this distance won't change.
Using a diffuser filter (pictured) eliminated a halo effect from the light source that I was experiencing.
I don't have the capability of producing a parametric model, but if anyone has the time I think this would make a great addition to the open source lab tools. Every student has at least one of these camera devices, they can be printed very quickly and as you can see a pair of rubber bands is all that is needed to secure the camera.