84.5mm dimension is taken from the specs of Meiji. There are 2 important things I want to mention.
1. This surface is important and if machined should be done precisely on milling machine or lathe. the surface should also be smooth clean and lubricated.
2. There is a thing called a tolerance. And 84mm scope body will not fit in 84mm ring.
just wanted to share for everyone's benefit an awesome seller who is a great communicator and can help you figure out what you need and sells heaps of used scopes on ebay. seller name is impers scopes.
also there are some up for sale presently. I'd suggest paypal protection from sellers who have poorer ratings. the ones with good feedback and who sell immense amounts of stuff need to keep everyone happy so I tend to be more comfortable purchasing but paypal makes transactions safe.
handy fact. reducer lenses that screw on to the bottom of the scope to increase the working distance (make the point where it focuses at further away) are called Barlow lenses and a .7 one increases it a bit without reducing as much magnification... a .5 increases it more etc. engravers would generally have enough room with a .7 but if you want more room for swinging beading tools around... hammer and chisel etc for inlay and so forth go for .5.
this is a fun fitting that would allow me to pattach my 4/3 lens mount digital camera to the photo port of a trinocular microscope with a compatible sized port. but... I think you still have to add a tube so that the camera is the right distance away... it's complicated
so what I've leard from shopping ebay for second hand microscopes lately is that a search of smz microscope will doubtless give many results. there are usually a few meiji microscopes for sale. a meiji 5tr takes light from one eye for the camera but a meiji 8tr doesn't... apparently some mount theirs sideways in the stand because the photo port sticks out the back of an 8tr.
Leicas previous scopes included thr a60 but it's not a trinocular scope (that offers filming what you can see). and a previous model to the ivesta 3 is the Leica S9D.
i used an amscope for a few years. then me eyesight went south. bought a leica. happy with it still. the amscope is "ok". some folks say just "ok" aint ok. so, that's ok
if one wanted to mount a digital camera to a scope.... it has an adapter for Canon eos ef or ef-s mount (lens mount type)... and one finds a newer camera that can mount those types of lenses and thereby mount to the scope adapter with the use of an extra adapter.... will the increased distance be a problem? I'm looking at a canon r10 second hand.
For some reason this microscope camera I got off ebay (which has horribly non user friendly software if it is actually fully functional) was not exactly compatible with this scope. I was after lots of staring and thinking and my husbands input able to figure a work around that while I can't move the camera a few mm closer which was what I needed... I could move the eyepiece a few mm further away allowing both to be in focus at the same time. see photos. the other drawback with this scope for trinocular live video purposes is that it totally borrows the light from one eye for the camera so you can only look through one at a time... which gives you no depth of field (ability to tell the distance of something away from you).
ideally one would see through both eyes and your eyes and the camera would be in focus together