The Ergonomics of Microscope Soldering: Direct Optical View vs Camera/Monitor

[Electro Fan]

Since I have been unable to convince anyone to examine the image out of a Amscope SM-4NTP, I have had to reduce myself to arguing like an economist  and have ran a cost analysis on a well regarded stereo microscope head that can be ordered with or without a trinocular photo tube.

It is the Meiji EMZ-5, which I can very well believe is the archetype that Amscope and colleagues copy. According to tequipment.net, the binocular and trinocular versions list for $1260 and $1630, respectively. If Meiji's list prices reflect their production costs, a photo tube adds 29% to the cost. Tequipment sells both at the same 19.75% discount.

The current list (and selling prices) for Amscope's look alikes, the SM745NB and SM745NTP, are $611.99 ($305.99) and $709.98 ($354.99), respectively. Adding a photo tube adds 16% to the price, suggesting that Amscope's supplier is investing only half as much in their photo tubes as Meiji – and cutting corners.

I think it's A-OK for engineers to argue like an economist; I don't think that is "reducing" at all.  In the end I think being competitive with technology (the application of science to business) generally generally requires the efficient use of resources (time, $, bandwidth, you name it).  So I wouldn't look at your approach as anything but positive.

As for Meiji and the EMZ-5 those look like a very plausible next step up.  Seems smart of Meiji to wedgie () it's way in between Amscope and Zeiss/Leica/Nikon/Olympus et al.  Part of TEA is to know what your next bout of OCD will compel you toward as you try to shake the current bout.

[jfiresto]

As for the forecast on likely results, if it turns out that the SM-4NTP is reasonably good with the direct view optics but just so-so with the camera view that's an outcome I can probably live with; it would definitely be better than vice versa.  My goal is to get at least a few Torsten "green"-quality images with the digital view and some correspondingly better views through the oculars.  (Knock on Wood.)

That sounds good to me. The trinocular version does not cost much more, and as far as I can tell, it will only take a little brightness from the eyepieces, a little more focus tension and probably inconsequentially more airspace over the head.

[Electro Fan]

... The market will also be segmented according to what people are willing to pay -  it is a central marketing tenet that you always allow people to pay as much as they want!  Hence, you see basically the same car model sold in different variants, where the difference between the cheapest and most expensive does not reflect the difference in production costs....

So then I would argue that the photo tube fractional price increments reflect the microscopists' marginal utility, that they get nearly twice the value from Meiji's photo tube as Amscope's. Or I better stop before I get silly.

Not silly at all, really - but fwiw if you look closely you might see some 10-15% offs on Amscope.  So now that you have crossed over to the dark side it's good to keep the apples with the apples.   Thanks again 

PS, maybe Dave can go all out and do the Amscope simulfocal teardown in parallel with the Meiji simulfocal.

[jfiresto]

... PS, maybe Dave can go all out and do the Amscope simulfocal teardown in parallel with the Meiji simulfocal.

I would love to see that comparison.

[Electro Fan]

As for the forecast on likely results, if it turns out that the SM-4NTP is reasonably good with the direct view optics but just so-so with the camera view that's an outcome I can probably live with; it would definitely be better than vice versa.  My goal is to get at least a few Torsten "green"-quality images with the digital view and some correspondingly better views through the oculars.  (Knock on Wood.)

That sounds good to me. The trinocular version does not cost much more, and as far as I can tell, it will only take a little brightness from the eyepieces, a little more focus tension and probably inconsequentially more airspace over the head.

jfiresto, you are a mighty fine microscope coach.  I understand appreciate your idea here as a way to deal with the uncertainty of the light path design and performance while preserving the ability to use a scope mounted camera - ie, go with the trinoc rather than the simulfocal.  It would seem that the optical difference between binoc and trinoc should be pretty close to zero, almost without a doubt.  And it would seem that the difference between the trinoc and the simulfocal might be something perceptibly more than zero, I get the thinking.   But I'm hoping (knock on wood) that whatever the binoc-simulfcoal delta is that it's negligible on the direct view, and a reasonable tradeoff for the convenience and flexibility of the simulfocal.  Certainly no one can say you didn't do everything in your power to keep me from erroring on this.  I really appreciate the whole-hearted effort.  Thanks 

[SilverSolder]

... The market will also be segmented according to what people are willing to pay -  it is a central marketing tenet that you always allow people to pay as much as they want!  Hence, you see basically the same car model sold in different variants, where the difference between the cheapest and most expensive does not reflect the difference in production costs....

So then I would argue that the photo tube fractional price increments reflect the microscopists' marginal utility, that they get nearly twice the value from Meiji's photo tube as Amscope's. Or I better stop before I get silly.

Economic theory starts to make a lot more sense as soon as you realize that most people are not rational actors in the market!  Even professional traders are essentially just trend followers...

[Renate]

So where does this leave us for people who are still thinking USB only?
Where should I be looking for something with good refresh (30-60 fps), decent res (2-5 MP) and a decent DoF and working space?

[joeqsmith]

I have an AMSCOPE MU300 camera that for documentation is fine but I can't imagine trying to solder with it.   It's just too slow.   

My scope in its current state.  Don't laugh too hard.

[Electro Fan]

So where does this leave us for people who are still thinking USB only?
Where should I be looking for something with good refresh (30-60 fps), decent res (2-5 MP) and a decent DoF and working space?

fwiw, my impression after all the discussion in this thread is a few things:

1. When looking at the specs for fps, it appears easier to find cameras that do HDMI at 60 fps for a given resolution (such as 1080P) than it is to find USB cameras that get to 60 fps; it appears easier to find USB cameras that do 30 fps rather than 60 fps for 1080P, for example.  Related to this, my personal sense after limited experimenting is that 60 fps is preferred even though previously I would have bet that 30 fps would be sufficient.

2. Finding 2 plus MP will be easy.

3. The hard part, and the key point here, is that there seems to be a consensus that DoF is among the most difficult of attribute to render well with digital cameras* vs. direct viewing optics.  fwiw, I have ordered up a digital camera that I plan to use on the Amscope 745 simulfocal port and I might have enough parts to try it out on a standalone basis this weekend.  I'll see what I can determine about digital only depth of field and post something here but I won't have the 745 with the optical capability probably for a couple weeks so unfortunately it might be a while before I can compare and contrast the two.

As to where to look, you can find cameras, a few C-mount lenses, and some stands on Amazon.  I'm going to try some Hayear products but ymmv.

* I'm talking about entry level cameras that get mounted on microscope tubes for trinocular or simulfocal scopes; perhaps with other dedicated lenses these or other digital cameras will provide enough DoF for soldering.  Obviously 35mm digital cameras with good lenses can provide outstanding DoF.

[rsjsouza]

Regarding USB cameras, a few years ago a company in Hong Kong advertised a microscope camera based on a really good camera from Microsoft. I checked and here is their website:
https://www.diyinhk.com/shop/11-usb-microscope-1080p-for-smt-soldering

I think that Dave did a review of it.

[Berni]

The reason for most USB cameras not supporting 1080p 60fps is that USB 2.0 is too slow for that. It needs to be USB 3.0 to have enough bandwidth to handle it, such cameras are certainly out there but are a lot more rare.

For working under a camera you might actually want to have HDMI anyway due to its latency advantage. Getting a image from a USB camera to the screen jumps trough quite a few hoops. There will typically be some buffering in the camera controller itself to handle hitches in USB bandwidth, then there is some more buffering on the PC side because the CPU might be doing other important stuff sometimes, then once the camera driver gets the USB data it has to translate it into a framebuffer. the camera application has to take this framebuffer and draw it into the display framebuffer on the graphics card (On a modern windows this might be done twice due to the window manager having to move from application framebuffers into the screen buffer), then the graphics cards display output refresh cycle has to come around to the actual pixels that show the camera application and start sending them out to the monitor for display. Each step here can induce some unpredictable latency or cause hitches in the framerate since the camera and display framerate are not synchronized to each other.

On the other hand a HDMI camera simply on the fly coverts the raw data stream coming out of the image sensor into pixels going out of the HDMI output. This involves minimal buffering of perhaps a only a few video lines while the image sensor scan stays perfectly in sync with the monitors LCD scan rate since the monitors timings are driven from the HDMI signal timings. This can significantly reduce average latency and jitter.

So i you don't have an extra monitor to spare for a HDMI camera then think about perhaps getting a HDMI switching box to easily put the signal into your existing computer monitor.

[jfiresto]

My scope in its current state.  Don't laugh too hard.

Laugh at it? I think it looks no-nonsense industrious.

[Mechatrommer]

24" monitors is cheap nowadays.. https://www.amazon.com/24-inch-monitor/s?k=24+inch+monitor if you think its too big, then smaller LCD can be bought from PC shop at fraction of price (or find used market you can get free). if you think they are expensive, Amscope and any other stereoscopes are more expensive, so i cant follow the logic.

[SilverSolder]

The reason for most USB cameras not supporting 1080p 60fps is that USB 2.0 is too slow for that. It needs to be USB 3.0 to have enough bandwidth to handle it, such cameras are certainly out there but are a lot more rare.

For working under a camera you might actually want to have HDMI anyway due to its latency advantage. Getting a image from a USB camera to the screen jumps trough quite a few hoops. There will typically be some buffering in the camera controller itself to handle hitches in USB bandwidth, then there is some more buffering on the PC side because the CPU might be doing other important stuff sometimes, then once the camera driver gets the USB data it has to translate it into a framebuffer. the camera application has to take this framebuffer and draw it into the display framebuffer on the graphics card (On a modern windows this might be done twice due to the window manager having to move from application framebuffers into the screen buffer), then the graphics cards display output refresh cycle has to come around to the actual pixels that show the camera application and start sending them out to the monitor for display. Each step here can induce some unpredictable latency or cause hitches in the framerate since the camera and display framerate are not synchronized to each other.

On the other hand a HDMI camera simply on the fly coverts the raw data stream coming out of the image sensor into pixels going out of the HDMI output. This involves minimal buffering of perhaps a only a few video lines while the image sensor scan stays perfectly in sync with the monitors LCD scan rate since the monitors timings are driven from the HDMI signal timings. This can significantly reduce average latency and jitter.

So i you don't have an extra monitor to spare for a HDMI camera then think about perhaps getting a HDMI switching box to easily put the signal into your existing computer monitor.

That is essentially what I do -  using a "retired" camcorder with a close-up lens, and an external monitor connected using HDMI, to get a minimum latency solution.  This works at up to 60fps and soldering is no problem.  -  That said, I don't think 30fps is a problem for soldering - as long as there is little latency, I could live with even less than 30fps, in all honesty.  Latency is the real "deal killer" and is hardly ever specified...

[Electro Fan]

24" monitors is cheap nowadays.. https://www.amazon.com/24-inch-monitor/s?k=24+inch+monitor if you think its too big, then smaller LCD can be bought from PC shop at fraction of price (or find used market you can get free). if you think they are expensive, Amscope and any other stereoscopes are more expensive, so i cant follow the logic.

Note:  this started out as a short (not my specialty) reply/comment to Mechatrommer; but it caused me to go back and review the Amscope product line - not 100% fully but somewhat quickly - to pick-out the models that seem relevant for soldering (ie, ~3.5x-22.5 using a 0.5 Barlow to give ~8" working space).  So you can zip past the digital camera and monitor stuff and maybe the Amscope model recap below will help someone get beyond decoding the numbering system of the Amscope models and just focus-in (haha) on some of the more interesting models/configurations for soldering.

---

Without a doubt using a HDMI monitor is part of the equation.  With a HDMI camera you can go directly to the monitor and not even need a computer (if one isn't available nearby); you can move the image with a SD card to a computer for post processing if you don't have a USB connection from the camera to a computer.

Dell P2219H
If you are low on space, this might be a consideration; it can sometimes be found for $129 or less:
https://www.amazon.com/Dell-Screen-LED-Lit-Monitor-P2219H/dp/B07F8Z2WFL/ref=sr_1_2?dchild=1&keywords=2219h+dell&qid=1604078410&sr=8-2

Dell U2415
This will provide some extra real estate (1920 x 1200) and a brighter (300cd/m²), better picture and it would be a great general purpose monitor as well as a good microscope monitor.
https://www.microcenter.com/search/search_results.aspx?N=&cat=&Ntt=dell+u2415&searchButton=search

Whatever monitor you choose you can add a digital camera for about $100 plus or minus; with a stand and some other accessories maybe another $100, so all in it's about $200-$250 (if you have HDMI monitor), or about $350-$400 (if you need a monitor) for 1080P 60 fps. (Don't forget some type of lighting.) 

---

Alternatively, for around the same price you could have a pretty nice optical scope (might be able to find these for ~10% off):

Amscope microscope model recap for soldering

SM-3BX (~$400 with discount)
https://www.amscope.com/3-5x-45x-stereo-zoom-microscope-with-single-arm-boom-stand.html

SM-3TX (adds trinocular port)
https://www.amscope.com/3-5x-45x-trinocular-stereo-zoom-microscope-on-single-arm-boom-stand.html

SM-3NTPX (adds simulfocal port)
https://www.amscope.com/3-5x-45x-simul-focal-stereo-lockable-zoom-microscope-on-single-arm-boom-stand.html

Or for 2x $ you could have both optical and digital - either each standalone, or integrated (as trinocular or simulfocal).

Still more possibilities: (same opticals as the SM-3 series; what the SM-1 series gives up vs the SM-3 series is the boom flexibility, but it might be possible to find the ideal location on your bench and leave the scope there; in other words you position the PCB for the scope rather than positioning the scope (with the boom) for the PCB; maybe not much of a give in return for going easier on the budget) :

SM-1BX (~$330 with discount) - maybe just add light and call it a day with this
https://www.amscope.com/3-5x-45x-stereo-inspection-microscope-with-super-large-stand.html

SM-1TSZ-V203 (maybe better yet @ ~$265 with discount) - this could be the sweet spot for entry optical; this would (maybe) make jfiresto happy (with this model, or any of the trinocs (instead of the simulfocals) I think you can close down the 3rd port when you don't need it and (maybe) thereby keep all the light (clearly and reasonably undistorted?) for the binoc view; then you can open the 3rd port when you want an image or video).  I think the only limitation might be the size of the stand: (10" x 7-7/8" x 7/8", allow for some horizontal space taken by the pillar) - will your PCBs fit?  If not, the 1BX (above) with the larger stand might be a solution.  Or maybe go for this SM-1TSZ-V203, ditch the stand, and mount the pillar directly on your bench?
https://www.amscope.com/3-5x-90x-zoom-trinocular-stereo-microscope-with-table-pillar-stand.html

SE400-Z - yet another alternative, at about $200 (with discount) including a light this would seem to give most digital scopes a run for their money
https://www.amscope.com/10x-20x-led-binocular-stereo-microscope-boom-arm-with-gooseneck-light.html


BIG DISCLAIMERS: 
1. Watch out for scope creep; you can start at the entry level and pretty soon walk yourself up the ladder to more features.
2. This is strictly research to help you find some info in one place.  I don't have an Amscope model [anything] yet. 
3. YMMV

Edit:

found another interesting video:


looks like this is the reviewers configuration:
- from the review it appeared to be a simufocal rather than a regular trinocular
- I think MinsVision is what Berni has been using
https://www.aliexpress.com/item/32880372287.html
(it isn't clear if this has a 14" post; it seems to include a 1080P camera but it isn't clear if it's 60 fps vs 30/other fps)
- another Disclaimer:  I have zero experience with aliexpress

[rsjsouza]

I went for the SM-1TSZ-V203 due to the following factors, ordered by importance:
- Price: it is a reasonable cost of entry for a stereoscope to allow better SMD and small soldering
- Bench size: it was the one that used less bench space. Its surface has a reasonable size for 15x15cm PCBs and it is not raised too high from the table, which helps use boards larger than this.
- Replaceable parts and accessories available: one never knows if something falls and breaks... Or add something for the future.
- Trinocular: I still have a desire to add a camera accessory.

[joeqsmith]

It sounds like from what is being posted,  there may not be a good solution when it comes to soldering using USB.  That's been my experience but I would have thought by now with USB3 that there would be better cameras out there.  Do they make HDMI cameras for them or is everyone making their own adapters?

I've used it in a few videos and the slow update rate isn't impressive.   Stills are good enough for me.  I attached a few pictures. 

My scope in its current state.  Don't laugh too hard.

Laugh at it? I think it looks no-nonsense industrious.

Like that custom ring mount I made?      I can swing the head off to the side if I want to work on the bench but have thought about making some sort of sliding boom mount to be able to move the head further away for larger parts.    Still, I like how stable it is. 

[Electro Fan]

phone camera mount
https://www.amazon.com/AmScope-Eyepiece-Mounted-Microscopes-Telescopes/dp/B079TK1YGV/ref=mp_s_a_1_3?dchild=1&keywords=AmScope+AD-TMD+Eyepiece+Mounted+Mobile+Device+Mount+for+Microscopes+%26+Telescopes&qid=1604112609&sr=8-3

[Electro Fan]

AmazonBasics Microscope
https://www.amazon.com/AmazonBasics-Professional-Binocular-Microscope-Magnification/dp/B07TTGZ8NZ/ref=pd_aw_pbp13n_xcat_hcmdp_2/140-8046019-7915028?_encoding=UTF8&pd_rd_i=B07TTGZ8NZ&pd_rd_r=bbff79ce-48cc-42c0-8b8a-1313c81da521&pd_rd_w=Agqbn&pd_rd_wg=LoyWV&pf_rd_p=75686f0f-abfb-4979-8574-9697343cab0a&pf_rd_r=DP3GME0TWG88BA079K6W&psc=1&refRID=DP3GME0TWG88BA079K6W

Looks like Amazon found Amscope’s supplier.  Might become a problem for Amscope.  It can become difficult to sell through a distributor that offers their “own” products that compete with yours.

[Electro Fan]

Ok, doing some digital testing.  The results of this might influence the final choice of optical scope (regular binoc, trinoc, or simul-focal).  Spoiler alert:  nothing in these tests is dissuading me from going with some form of optical scope.

Test bed:

1.   Hayear 3307 (think) 16MP 1080P 60 fps camera (using HDMI)
2.   Hayear 8x-100x 43mm-150mm C-Mount Lens
3.   Hayear stand
4.   Sony 1920 x 1200 U2415 24” monitor (using HDMI)

Preliminary measurements:

1.   The test bed provides about 2” of working distance; doesn’t change much regardless of the lens zoom ring settings.
2.   The lens zoom ring provides a width (fov) of ~5mm – 9.5mm.

Preliminary impressions:

1.   There is little to no lag.
2.   The working distance is of course too small.
3.   The depth of field is extremely small.
4.   My guess is that the monitor and the camera are A-OK.
5.   My guess is that the lens optics are possibly sufficient – but it’s the wrong focal length (it’s too long); it needs to be a shorter focal length to provide a wider fov as 9.5mm fov max is too narrow.
6.   This setup wouldn’t seem to make much sense for soldering but it could possibly be used for inspection.

The problem of course is that as the focal length gets shorter to provide a wider fov, the dof will get still shallower (assuming the same aperture).  So far it doesn’t seem like it’s easy to go shopping for C-mount lenses where you can individually specify focal length and aperture; and in general the whole notion of any sufficient amount of dof with the low end digital cameras for microscope setups seems to be unlikely.

Net, net:  too limited working distance, not enough FOV, too limited depth of field.  Other than that perfect.  (On the upside, what you see on the monitor has enough detail and good color.)

---

Attached are some images taken with a phone camera of the images as they were displayed on the monitor

You can see that when looking at the transistor legs just a tiny adjustment on the focal plane allows the focus to move from leg to leg to leg at the point where they attach to the underside of the transistor – but it’s impossible to get the full transistor can in focus.  In one image you can see that pretty much just the tab is in focus, and the focus runs out on the transistor leg running through the pliers.

Not sure what happens with the 0.5 Barlow but rumor has it that is not going to create a superlative optical enhancement in terms of image quality but it will give a wider fov.  This whole thing is a puzzle. 

[Electro Fan]

PS, waiting for jfiresto say "told you so - you are pushing this whole thing too far; in an effort to easily get some semi-ok digital images you are going to tax the Amscope optics by adding complexity to the light path in order to support a trinoc or simul-focal, and therefore the image quality of the normal binoc will incrementally degrade to the point where everything is marginal when it could be sufficient with the Amscope binoc".  Am I getting this right jfiresto?   (My hope is still that other users who have used the trinoc and simul-focal have reported happy experiences with the optics and it's just hard to capture and display the direct view experience other than with an occasional very good phone camera shot through an eyepiece like Torsten did with his green image.)

What I don't know is how poor to marginal the Hayear lens is (ie, how it compares to what would be seen by the same camera through an Amscope trinoc or simulfocal).

Edit:  added a couple images captured to the Micro SD card rather than camera photos of images on the monitor.

Edit 2:  I tried to upload the two images from the Micro SD card and I got a message back from EEVblog saying that the images had failed a security test....??  So I next ran a scan with some antivirus software on the specific files on the Micro SD card (which had to be formatted by the Hayear camera) and my normally reliable antivirus program just ran and ran with no results until I terminated the program.  Hope Hayear is on the up and up.

So, I took a screen shot of the two images and uploaded those but it's strange that I got the msg from EEVblog and that my software scan didn't like something...  Thoughts on this...?  Thx

Update:  I think the files were too big for the forum and for some reason my scanner seemed to hiccup at the same time; I can't explain why it did, it's kind of unusual.  I happened to this review from another user:

https://www.amazon.com/HAYEAR-C-Mount-Electronic-Industry-Microscope/dp/B07MPY1BHV#customerReviews

So I'm kind of on-watch.  If anyone else uses a Hayear camera, maybe run some scans and let us know if you see anything out of the ordinary.  For now I'm going to move from code red to code yellow.  Thx

.... back to microscope stuff

[jfiresto]

PS, waiting for jfiresto say "told you so - you are pushing this whole thing too far; in an effort to easily get some semi-ok digital images you are going to tax the Amscope optics by adding complexity to the light path in order to support a trinoc or simul-focal, and therefore the image quality of the normal binoc will incrementally degrade to the point where everything is marginal when it could be sufficient with the Amscope binoc".  Am I getting this right jfiresto? ...

I am not sure I would put it that way. The image you view or capture is sourced by the objective and that is all the optics and image processing downstream have to work with. The stuff downstream can only do so much to improve the image; they have much greater latitude to degrade it. Which way things go depends on the resources thrown at the problem.

I noticed for the same price, Meiji Techno also sells a version of the EMZ-5TR I linked to earlier, the EMZ-8TR with 50:50 beam splitters that alway output an image to to all three viewing ports simultaneously. I am sure its image quality is nothing to worry about, so that their customers can freely choose the best version for the things they look at.

When I get a chance I will compare and post the images I get with and without a 0.5X auxiliary lens on a zoom microscope. The lens may win enough depth of field for your transistor.

[Electro Fan]

PS, waiting for jfiresto say "told you so - you are pushing this whole thing too far; in an effort to easily get some semi-ok digital images you are going to tax the Amscope optics by adding complexity to the light path in order to support a trinoc or simul-focal, and therefore the image quality of the normal binoc will incrementally degrade to the point where everything is marginal when it could be sufficient with the Amscope binoc".  Am I getting this right jfiresto? ...

I am not sure I would put it that way. The image you view or capture is sourced by the objective and that is all the optics and image processing downstream have to work with. The stuff downstream can only do so much to improve the image; they have much greater latitude to degrade it. Which way things go depends on the resources thrown at the problem.

I noticed for the same price, Meiji Techno also sells a version of the EMZ-5TR I linked to earlier, the EMZ-8TR with 50:50 beam splitters that alway output an image to to all three viewing ports simultaneously. I am sure its image quality is nothing to worry about, so that their customers can freely choose the best version for the things they look at.

When I get a chance I will compare and post the images I get with and without a 0.5X auxiliary lens on a zoom microscope. The lens may win enough depth of field for your transistor.

Ok, Thanks.  I'm still trying to get it figured out.  My thought is to find exploded part diagrams to show how entry-mid level stereo microscopes work and then move on from the stereo baseline to learn how entry-mid level trinocular and simul-focal microscopes work.

As to how the stereo scopes work I saw this:

http://microscopy.berkeley.edu/courses/tlm/stereo/index.html

a) is Common Main Objective and b) is Greenough, yes?

This seems to confirm that a) is CMO:
https://cdn.shopify.com/s/files/1/1634/0335/files/CMO_Greenough_Diagram.png?v=1591645817

This states the Amscope SM-745 is Greenough:
https://www.amscope.com/stereo-magnification
Optical System   Greenough stereoscopic

Saw this about Greenough and CMO:
https://youtu.be/l3BtJPBJ7Vo
This seems to indicate that for soldering (less than ~22x) Greenough might be ok.

Maybe this is enough on how the baseline (stereo, ie "binoc") works and now it's time to figure out how binoc gets adapted to accommodate trinocular and simul-focal..... in an effort to see what the risk of degradation to the baseline binoc view might be when adding a third port for the camera (which will share some optics with the stereo view but even so will only give a mono view, right?).

At the risk of jumping ahead a couple steps, on a semi-related matter (digital), it has dawned on me that with a USB microscope I can work as hard as I want to get the right combination of focal length and aperture to optimize magnification so as to dial-in the tradeoff between working distance and depth of focus - and while that might include some relatively more vs less depth of in-focus view - it's never going to compete with optical because the larger sense of depth is provided by the fact that the optics of a stereo microscope are by definition "stereo" and stereo (with binoculars) is what creates perspective and a sense of depth much more so than even what is in focus due to lens aperture.  In other words, assuming all the camera sees is mono, by definition stereo (through the eyepieces) is going to be inherently superior to mono for spatial imaging.  This is probably obvious for people who have experience with soldering applications but it has had me a little tangled up when looking at entry level scopes.  So while it would still be good to find the right digital solution, it's the reason why USB/digital scopes (at least at the entry level) just don't compete well with optical scopes for soldering - yes?  But it sort of raises the question of why not make a an entry level stereo digital scope?  I'm curious to know more about this but my main mission is to next run to ground the notion of what degradation might occur to the Greenough stereo configuration when it's adapted to accommodate trinocular and simul-focal. 

[Electro Fan]

Sometimes to figure out why we do it today the way we do it it helps to understand how we used to do it

According to this once upon a time in 1671... and then about 1820....  and then in the 1890s.... and then in 1957 we got Cycloptic (CMO).

https://www.microscopyu.com/techniques/stereomicroscopy/introduction-to-stereomicroscopy
- highly recommended article

CMO or Greenough

"It is a difficult task to determine which of the two designs (CMO or Greenough) is superior, because there are no universally accepted criteria for comparing performance between the stereomicroscope systems. Common main objective microscopes, in general, have a greater light-gathering power than the Greenough-design and are often more highly corrected for optical aberration. Some observations and photomicrography might best be conducted utilizing a CMO microscope, while other situations may call for features exclusive to the Greenough design. As a consequence, each microscopist must make the determination whether one design will be more appropriate for the task at hand and use this information to develop a strategy for stereomicroscopy investigations.

In most circumstances, the choice between Greenough or common main objective stereomicroscopes is usually based on the application, and not whether one design is superior to the other. Greenough microscopes are typically employed for "workhorse" applications, such as soldering miniature electronic components, dissecting biological specimens, and similar routine tasks. These microscopes are relatively small, inexpensive, very rugged, simple to use, and easy to maintain. Common main objective microscopes are generally utilized for more complex applications requiring high resolution with advanced optical and illumination accessories. The wide spectrum of accessories available for these microscopes lends to their strength in the research arena. In many industrial situations, Greenough microscopes are likely to be found in production lines, while common main objective microscopes are limited to the research and development laboratories. Another consideration is the economics of microscope purchase, especially on a large scale. Common main objective stereomicroscopes can cost several times more than a Greenough microscope, which is a chief consideration for manufacturers who may require tens to hundreds of microscopes. However, there are exceptions. If a common main objective microscope is the better tool for a job, the true cost of ownership may be lower in the end."

Photomicrography and Digital Imaging

"Both Greenough and common main objective stereomicroscopes are readily adaptable to image capture utilizing traditional photomicrography techniques (film) or through advanced digital imaging. Often photomicrography is employed as a tool for recording the spatial distribution of specimen details prior to observation and imaging with a higher-power compound microscope. This technique is often necessary for biological specimens, where dissecting, staining, and selective mounts are performed.

The principal concern with digital imaging and photomicrography in stereomicroscopy is the low numerical aperture of the objectives, and the inability to capture on film (or in a digital image) the tremendous depth of field observed through the eyepieces. There are also several limiting factors that should be considered when photographing specimens through a single body tube utilizing a Greenough-style stereomicroscope. Because the microscope objective is positioned at a slight angle to the specimen, depth and resolution seen in the microscope eyepieces is not recorded on film.

Newer stereomicroscopes have trinocular heads or photographic intermediate tubes (sometimes requiring a projection eyepiece) as an option, but these are often limited in use to the camera systems specified by the microscope manufacturer.

The microscope presented in Figure 9 is a state-of-the-art Nikon research-level stereomicroscope equipped for both traditional imaging with Polaroid film and with a digital video camera. The camera systems are coupled to the microscope through a beamsplitter attachment that is attached as an intermediate piece between the microscope body and the binocular head. Both single and double-port beamsplitters are available from Nikon for use with either one or two camera systems. The optical path is directed into the camera ports with a selection lever located on the front portion of the intermediate piece. Standard c-mount, f-mount, and proprietary coupling systems are available to support a wide variety of camera systems. In addition, Nikon offers projection lenses of varying magnification that can be utilized to vary the image size on film or in digital images."

[jfiresto]

Ok, Thanks.  I'm still trying to get it figured out.  My thought is to find exploded part diagrams to show how entry-mid level stereo microscopes work and then move on from the stereo baseline to learn how entry-mid level trinocular and simul-focal microscopes work.

Have you seen Nikon's online, partly interactive tutorials? Here is one to start with.

EDIT: I see you have. Strange, the very-italic post just before this one appeared after I had posted it.

As to how the stereo scopes work I saw this:

http://microscopy.berkeley.edu/courses/tlm/stereo/index.html

a) is Common Main Objective and b) is Greenough, yes?

Yes.

... my main mission is to next run to ground the notion of what degradation might occur to the Greenough stereo configuration when it's adapted to accommodate trinocular and simul-focal.

I would not sweat it. Giving a microscope continuous zoom rather than stepped magnifications probably makes more of a difference. I would choose the camera tube that is best for the things you are looking at: that either takes half the light from and shares the view with one eyepiece, or takes all of it and lets the eyepiece go dark.