Mind-range microscope upgrade? Stemi 305, SMZ-2T, EMZ-5TR, Mantis...?

[lukego]

I have "the usual" AmScope trinocular microscope. I'd like to upgrade the head/objective/eyepiece part at some point. I'm thinking of setting an eBay alert to find a $1000-or-so bargain on something... but what?

The models I've identified are a Zeiss Stemi 305, Nikon SMZ-2T, Meiji Techno EMZ-5TR, or Vision Engineering Mantis. Which one is best and why? How much better is it than AmScope-likes?

I'd like to primarily get better image quality, and I want to run the camera port continuously, and I already have illumination and a stand that I'd be happy to reuse if possible.

SPOILER: Could not find an upgrade path for ballpark $1000 except for taking major risks on eBay. Decided to buy a more expensive new scope instead.

[jfiresto]

My father compared the offerings from the "Big Four" in 1985, when he was setting up his investigative materials science consultancy, bought a new SMZ-2T and happily used it a lot for the next 25 years. Only Zeiss had better optics and they charged a lot more for that. He shot both video and stills. We happened to talk a couple days ago about mounting a micro four thirds camera to bring it up to date. He has the c-mount for a 1-inch video camera and it appears that all he needs is a simple and inexpensive thread adapter.

I also do not think you can go wrong with an EMZ-5TR – just make sure either is in good shape or that you can return a microscope if is not. I would get whatever example is in the best condition and/or best equipped for your projects.

But before going further, why are you thinking about upgrading?

[lukego]

But before going further, why are you thinking about upgrading?

I'm gradually investing in upgrading my soldering/prototyping lab. I've already made some really big improvements by replacing my starter soldering iron, preheater, consumables like flux and solder, microscope illumination, C-mount camera, and so on. I'm now thinking that these aspects are in pretty good shape and asking myself: what's the next upgrade that would provide the most benefit in terms of enjoyment?

Maybe it's the microscope? I hear people talking about their Nikon or Meiji or Mantis and so on but how do they really compare with my one that sells brand new for $129 on AliExpress for the head with eyepieces and objective lens? I'm entertaining the possibility that they are significantly more pleasant to work with and would make a worthy upgrade.

I also do not think you can go wrong with an EMZ-5TR

I'm reading the specs on this now and one concern is that enabling the camera port seems to divert 100% of the image away from the left eyepiece? That would be a problem for me because I want to record with the camera most of the time so that I can review my work sessions after the fact.

Only Zeiss had better optics and they charged a lot more for that.

Zeiss have an intriguing offering now: the Stemi 305 trinocular (https://eleshop.eu/zeiss-stemi-305-trino-microscope.html) that sells for €859.50 brand new (without the stand.) The specs look good although I'm not sure if it has internal electronics (?) that would depend on the Zeiss stand or whether it could be use with AmScope-style stand and ring light. I wonder how this modern entry-level Zeiss compares with the "classic" microscopes mentioned above that sell for a similar price old and second hand on eBay?

[lukego]

But before going further, why are you thinking about upgrading?

Let me answer this a second time trying to be more specific. Issues that I have with my current microscope and don't know whether they can be improved:

• Image quality is not in the same league as some soldering videos I see on Youtube, that I think were shot with normal DSLR cameras or camcorders.
• Image quality degrades towards the edges, especially noticable on the camera port.
• Shallow depth of field on the camera port.
• Focus does not seem very even across the board at least when using 0.7x barlow lens.
• Have to manually adjust focus when changing zoom level which is awkward esp. because camera has shallower depth of field and hard to predict whether "good enough" focus on the eyepieces is also good enough on the camera port (and because I don't have a boom stand and all adjustments are wobbly.)
• Can't easily switch objective lens e.g. casually add/remove barlow lens while working (Mantis seems to have a fast switcher.)
• The 3D depth does not seem especially vivid to me.

[lukego]

Here for reference is an example from my microscope:


I'm struck that the focus is very uneven as seen by the camera. The middle is okay but the edges are very blurry. I assume (?) that this is a property of the lenses.

Maybe an alternative would be to simply buy higher quality lenses for the scope that I already have? Is that a thing one does? This is the one that I have: https://www.aliexpress.com/item/32872196449.html.

[jfiresto]

Maybe it's the microscope? I hear people talking about their Nikon or Meiji or Mantis and so on but how do they really compare with my one that sells brand new for $129 on AliExpress for the head with eyepieces and objective lens? I'm entertaining the possibility that they are significantly more pleasant to work with and would make a worthy upgrade.

The build quality is better and the image quality becomes noticeably better at higher magnifications. But you need to distinguish between new and used microscopes. The models made into the 1990s were built for decades of use, and a clean example generally performs pretty much as it did at the factory. For example, I plopped a 16 megapixel Olympus camera body onto a mongrel stereo microscope I had assembled out of parts from half a dozen, grizzled 40+ year old microscopes. Everything just worked, with zero adjustments, and so well that the microscope revealed the limitations of the camera. They do not built microscopes like they used to, although I understand Meiji is old fashioned and still builds theirs to last.

I also do not think you can go wrong with an EMZ-5TR

I'm reading the specs on this now and one concern is that enabling the camera port seems to divert 100% of the image away from the left eyepiece? That would be a problem for me because I want to record with the camera most of the time so that I can review my work sessions after the fact.

Look at the EMZ-8TR which "offers direct light to all three viewing ports simultaneously."

Only Zeiss had better optics and they charged a lot more for that.

Zeiss have an intriguing offering now: the Stemi 305 trinocular (https://eleshop.eu/zeiss-stemi-305-trino-microscope.html) that sells for €859.50 brand new (without the stand.) The specs look good although I'm not sure if it has internal electronics (?) that would depend on the Zeiss stand or whether it could be use with AmScope-style stand and ring light. I wonder how this modern entry-level Zeiss compares with the "classic" microscopes mentioned above that sell for a similar price old and second hand on eBay?

For that price, I expect it is not built nearly as well as the pre-2000 models, but I am no Zeiss guy!

[lukego]

Look at the EMZ-8TR which "offers direct light to all three viewing ports simultaneously."

I understand from reading now that this Meiji and also the Zeiss are "Greenough" microscopes. Is this a good thing? I'm concerned that it sounds like you can't use the same kind of barlow lenses as on the AmScope for adjusting working distance and field of view. Does this mean that in practice you are "stuck with" the native magnification and working distance quoted in the product literature?

EDIT: Found the product page for the auxiliary barlow lenses: https://meijitechno.com/product-new/geological-24/geological-stereo-microscopes/emz-modular-stereo-microscopes-geological/emz-modular-stereo-microscopes-components-and-accessories/emz-modular-stereo-microscopes-components-and-accessories/emz-modular-stereo-auxilia-1

[jfiresto]

You can design either a Greenough or a CMO microscope to accept an auxiliary lens. You could say that adding a lens to the former makes it a mixed Greenough/Common Objective microscope. Since the added lens somewhat degrades the image, some CMO microscopes only let you change the main objective. That is considerably more expensive, but then so is a CMO microscope, so it is relative. The Amscopes I have seen here have been Greenough designs.

I will try to respond to your earlier posts, but that may have to wait until tomorrow.

[lukego]

Here's how my mental model is developing:

The Meiji EMZ-8TR and Zeiss Stemi 305 both look like "drop in" replacement microscope heads for the AmScope. They all have ~75mm diameter and should all be compatible with the same stands and ring lights. They all support C/CS-mount cameras. (I'm assuming separate lenses.)

Speculating: I'd suppose the optics are high quality in both because Meiji and Zeiss are both quality brands. The Meiji seems to cost about twice as much as the Zeiss (?) due to superior build quality and longer expected lifetime (?). Picking up a Meiji second-hand on eBay might cost the same as the Zeiss costs new.

I'm checking on pricing for the auxiliary lenses. The prices I've seen so far on barlow lenses for the Zeiss have been between $250 and $350 which seems very high to me and potentially increases the effective price of a new unit substantially.

One technical difference noticed on the data sheet: The Meiji seems to come with a 1/3 reducer lens on the camera port (suited to a small image sensor) while the Zeiss comes with a 1/2 reducer (suited to a larger e.g. APS-C sensor.) I'm not sure how easy that it to change but it suggests taking into account which camera you plan to use. I would use the RaspberryPi HQ camera, or Nikon D750 DSLR, both of which support APS-C format and would seem better suited to the Zeiss in its standard configuration.

[lukego]

Amscopes I have seen here have been Greenough designs.

Thanks for pointing this out. I had it backwards thinking that the CMO microscopes were the norm and the Greenough the exception.

[jfiresto]

I'm gradually investing in upgrading my soldering/prototyping lab.... I'm now ... asking myself: what's the next upgrade that would provide the most benefit in terms of enjoyment? Maybe it's the microscope?...

Do you know anyone with a good stereo microscope, that you can try on typical things you look at, to see what you might be missing? You may be pleasantly surprised by the things you did not know about because you could not see them, and decide there is enough enjoyment in that to make a long term investment.

Zeiss have an intriguing offering now: the Stemi 305 trinocular (https://eleshop.eu/zeiss-stemi-305-trino-microscope.html) that sells for €859.50 brand new (without the stand.)

That is a student microscope, I believe Zeiss has made for them in China, that they are also marketing as a low cost laboratory/production microscope you can put under service contract. To make it useful in the lab and on the factory floor, they have made it compatible with a selection of their standard microscope accessories, for example, their boom stands and standard line of microscope cameras and adapters. All charged per their standard price list. To see what that might be like, I created an account at Zeiss and priced out a trinocular system with their twin-arm boom stand and a one-inch c-mount camera mount, part numbers: 491903, 435412, 435411 and 426114. The total: 4660 euros, not including VAT. Somewhat more than half of that is the cost of the boom stand.

[jfiresto]

Image quality is not in the same league as some soldering videos I see on Youtube, that I think were shot with normal DSLR cameras or camcorders.

Even with a really good stereo microscope you will be hard pressed to match a DSLR with a good macro lens at low magnifications. Your Greenough microscope has to fit two objectives in the same space and, compared to the camera's, those objectives are just ridiculously simple, two-element achromats.  The Olympus XA pocket camera, from roughly when the archetype of your microscope was designed, had a fixed, 35mm lens with three times as many elements!

That said the video you should get, with good quality optics from the microscope photo port to the camera, should be much closer to what you see through the binocular eyepieces and suffer from nothing like the chromatic aberrations and barrel distortion you see in your video.

Image quality degrades towards the edges, especially noticable on the camera port.

Even a high quality two-element achromat objective can only be expected to be flat and sharp, at the eyepieces, over the inner 60% or so of the field of view, that is ca. 0.8 x R, if R is the radius of the field of view. The microscope would need semi-plan or plan objectives, each with three to five elements, to be flat and sharp, respectively, over roughly 80% or 95%+ of the field of view.

All that is through the eyepieces. The camera has the added challenge of having a flat sensor that is stuck at the same focus from the center out to the edges. The objective's curved optics project a curved image on to the camera sensor. If the center is in focus, the edges will be at the wrong distance, or vice-versa. Semi-plan and plan objectives, reduce the problem, in that they project an image that is flatter out to a greater radius.

Shallow depth of field on the camera port.

Unlike a pair of human eyeballs, the camera can not change its focus during an exposure and meld what it sees with the mind's eye.

Focus does not seem very even across the board at least when using 0.7x barlow lens.

Getting good images with a barlow lens can be a challenge. The lens may not exactly match your microscope's objectives and it may be slightly out of position if it screws in or clamps on. The objectives also look through the sides of the lens and not through its well corrected center.

Have to manually adjust focus when changing zoom level which is awkward esp. because camera has shallower depth of field and hard to predict whether "good enough" focus on the eyepieces is also good enough on the camera port (and because I don't have a boom stand and all adjustments are wobbly.)

Now that is something I think you should try to fix: it may be causing the issues you see in the video and, personally, it would drive me to distraction. First, do the song and dance to get the eyepieces parfocal. Then immediately after the last step, don't touch the focus or zoom, and try to adjust the camera port and relay lens to get the camera in sharp focus so that it tracks the eyepieces'.

Can't easily switch objective lens e.g. casually add/remove barlow lens while working (Mantis seems to have a fast switcher.)

It is a bit of a hack and may not work that well near maximum zoom, but some folks swap in a pair of 20X eyepieces when they need a quick, closer look.

The 3D depth does not seem especially vivid to me.

At high zoom levels or at all of them?

[jfiresto]

... One technical difference noticed on the data sheet: The Meiji seems to come with a 1/3 reducer lens on the camera port (suited to a small image sensor) while the Zeiss comes with a 1/2 reducer (suited to a larger e.g. APS-C sensor.)...

I may have started from a different base, but I configured the Zeiss with a 1X c-mount adapter for a one-inch sensor. It would produce some vignetting with an APS-C cameras but apparently not too much. I go a bit smaller and use micro thirds cameras. I might ask Meiji if they offer also offer c-mount for a one-inch sensor and let them figure out the magnification.

[lukego]

That is a student microscope [...] compatible with a selection of their standard microscope accessories [...] All charged per their standard price list. [...] The total: 4660 euros, not including VAT.

This is very interesting! Zeiss seem to be doing market segmentation to capture the cost-conscious education market (cheap limited offerings) without undercutting their higher-end sales (premium prices on accessories keeping the cost of a full "professional" setup high) Maybe there's an opportunity here for the semi-professional/serious-amateur to slip between the cracks in their pricing strategy?

I'm looking at the Zeiss Stemi 305 trinocular headpiece with C-mount camera port for €859.50 coupled with the 0.75x barlow lens for €235.70 to match my preferred magnification level and working distance. Total cost: €1095.2 excluding VAT.

Maybe that's a bargin to upgrade my current setup with Zeiss optics? I'm basically satisfied with the setup that I have apart from the feeling that I'm missing out on image quality.

I would be sticking with my current articulating arm stand, ring light with polarizer, and gooseneck lights. That's about $500 worth of AliExpress kit. These all seem to be compatible with the Zeiss thanks to the ~75mm diameter of the microscope head. I would absolutely not be willing to spend thousands of dollars on replacing those components because, unlike the optics, I just don't expect the Zeiss accessories like stands and lights to be that much better.

One slight concern is whether the Zeiss Stemi 305 microscope head can work without the Zeiss stand. I believe that it has some electronics build in (e.g. an LED aligned with the objective lenses) and I hope it can function with that turned off. I would need to confirm that there is not a "DRM" type of feature to prevent people like me being thrifty and picking up Zeiss optics on the cheap to use with third party accessories.

[lukego]

Have to manually adjust focus when changing zoom level which is awkward esp. because camera has shallower depth of field and hard to predict whether "good enough" focus on the eyepieces is also good enough on the camera port (and because I don't have a boom stand and all adjustments are wobbly.)

Now that is something I think you should try to fix: it may be causing the issues you see in the video and, personally, it would drive me to distraction. First, do the song and dance to get the eyepieces parfocal. Then immediately after the last step, don't touch the focus or zoom, and try to adjust the camera port and relay lens to get the camera in sharp focus so that it tracks the eyepieces'.

I will work on this, thanks for the tip!

Good to be reminded that the most important aspect is to use the tools that you have correctly.

The 3D depth does not seem especially vivid to me.

At high zoom levels or at all of them?

I'm not sure that I can defend this observation actually. I suppose that looking through the microscope gives a similar sense of depth as normal vision. I suppose what I mean is that I can't relate to what Vision Engineering users report (Dave in his video IIRC) about being able to vary the perspective of their view by moving their heads. That seems like a feature that's absent on all of these microscopes with ~20mm eyepieces and that I can't judge the value of because I've never tried it.

(Vision Engineering is another whole topic. Maybe those are better for soldering work? I've found it hard to find much details about the difference between their Mantis verses LYNX models and what options they have for third party cameras.)

[jfiresto]

It appears Zeiss has you buy a Stemi 508 to arrange a camera port with a one-inch sensor (system overview drawings, page 2, "Camera adapter 60N-C 1'' 1,0X, part number 426114-0000-000 for 121,00 €+VAT). For the Zeiss 305, you might insert a 2.5X relay lens to fill an APS-C sensor, the same that you used to use to match a 1-inch photo port to a 35mm camera.

[jfiresto]

This is very interesting! Zeiss seem to be doing market segmentation to capture the cost-conscious education market (cheap limited offerings) without undercutting their higher-end sales (premium prices on accessories keeping the cost of a full "professional" setup high) Maybe there's an opportunity here for the semi-professional/serious-amateur to slip between the cracks in their pricing strategy?

As in buy the razor and not the blades, or the printer and not the ink cartridges? Or rather somewhat the opposite.

[lukego]

Even with a really good stereo microscope you will be hard pressed to match a DSLR with a good macro lens at low magnifications. Your Greenough microscope has to fit two objectives in the same space and, compared to the camera's, those objectives are just ridiculously simple, two-element achromats.  The Olympus XA pocket camera, from roughly when the archetype of your microscope was designed, had a fixed, 35mm lens with three times as many elements!

Thank you for making this point. I have to think about this.

I really have two different use cases, working verses inspection, and I've been trying to do both with the same trinocular microscope. Maybe the quality that I have now is adequate for working and I only really need the sharper optics for close-up inspection. In that case it could be more economical to use a separate inspection tool e.g. monocular microscope or DSLR camera with autofocus macro lens?

Much food for thought. Thank you again for taking the time to walk me through the many considerations.

[lukego]

It appears Zeiss has you buy a Stemi 508 to arrange a camera port with a one-inch sensor (system overview drawings, page 2, "Camera adapter 60N-C 1'' 1,0X, part number 426114-0000-000 for 121,00 €+VAT). For the Zeiss 305, you might insert a 2.5X relay lens to fill an APS-C sensor, the same that you used to use to match a 1-inch photo port to a 35mm camera.

Could you please help me to understand this point?

On my Eakins microscope I have similar magnification on the objective lens and eyepieces to the Zeiss and then an "SZMCTV1/2" reducer lens connecting to a C-mount camera with APS-C sensor (RaspberryPi HQ.) This setup seems to be well matched: the camera in full sensor mode captures approximately the largest rectangle possible without going outside the field of view in the corners.

How similar is the Zeiss Semi 305 to this setup? The PDF that you referenced does say the C-mount port is suitable for up to 2/3" sensor which would be much smaller than APS-C. However I've seen multiple descriptions of the Zeiss Stemi 305 (below) calling the C-mount port "0.5x" and that superficially sounds an awful lot like my "1/2 reducer" that seems to work well on the Eakins.

So are the Zeiss and Eakins camera ports really suited to different cameras? How come the Zeiss would need the 2.5x relay lens while the Eakins doesn't? Or am I simply misusing my Eakins today with the wrong lenses on the C-mount port?

Aside: Could you recommend any book on microscopy that would help me understand the lenses? I picked up an excellent book on photographic lighting that has really helped me understand my illumination issues instead of stumbling around in the dark (so to speak.)

References to "0.5x" C-mount port for ordinary cameras:
https://eleshop.eu/zeiss-stemi-305-trino-microscope.html
https://www.microscopeworld.com/p-3298-zeiss-stemi-305-k-edu-bfdf-stereo-microscope.aspx

[jfiresto]

On my Eakins microscope I have similar magnification on the objective lens and eyepieces to the Zeiss and then an "SZMCTV1/2" reducer lens connecting to a C-mount camera with APS-C sensor (RaspberryPi HQ.). This setup seems to be well matched....

Do you have this camera? The description says it has a 1/2.3" sensor with a 7.9mm diagonal. If the camera port projects an image that is sized for a 1" sensor with a 15.9mm diagonal – as many do – the 0.5X lens will give just the right reduction to fit your sensor.

How similar is the Zeiss Semi 305 to this setup?

Apparently the 305 camera port already projects an image that is half as large. You should be able to mount your camera directly to the microscope and not need the reduction lens.

So are the Zeiss and Eakins camera ports really suited to different cameras? How come the Zeiss would need the 2.5x relay lens while the Eakins doesn't?

The old Zeiss microscopes and, I believe, your Eakins, both project an image sized for a 1" sensor. The old 35mm analog cameras needs a 2.5X relay lens to reach the film and fully fill a frame.

Aside: Could you recommend any book on microscopy that would help me understand the lenses?....

I have just started looking. I will let you know if I find something good.

[lukego]

Do you have this camera? The description says it has a 1/2.3" sensor with a 7.9mm diagonal. If the camera port projects an image that is sized for a 1" sensor with a 15.9mm diagonal – as many do – the 0.5X lens will give just the right reduction to fit your sensor.

Yes, this is the camera that I'm using. I seem to have been mistaken in thinking its sensor was APS-C format.

Apparently the 305 camera port already projects an image that is half as large. You should be able to mount your camera directly to the microscope and not need the reduction lens.

This is welcome news! Sounds like the Zeiss really could work as a drop-in replacement.

Having said that, I also have a Nikon D750 DSLR with full-frame sensor that I could use for this application. I have experimented with this on the Eakins using a C-mount adapter but it didn't seem to achieve better image quality, I assume because the optics are the limiting factor. Do you think that with Zeiss/Meiji optics this camera would be likely to provide a much better image due to its larger sensor and/or higher-end electronics? I suppose I would need a relay lens to enlarge the image for fit the 35mm sensor?

[lukego]

I apologize if I'm asking you to repeat yourself while I try to assemble my mental model. Here's how it looks to me now.

Zeiss Stemi 305 seems like a good deal for a drop-in AmScope replacement for EUR 850. Catch is that the barlow lenses run for EUR 250 each and I'd need at least the 0.75x which increases the starting cost.

Camera port should be directly compatible with my current preferred camera (RPi HQ.) This camera should be more than adequate for shooting ~1080p video (using the full sensor in 2x2 binned mode) and for taking stills in the native resolution of the sensor.

In the future I could potentially upgrade with a 2.5X relay lens to use my Nikon D750 DSLR. I'm assuming the quality won't be drastically different for 1080p video but might shine when taking really high resolution stills? That's a lower priority for me though especially since the RPi HQ can take stills at almost 4K resolution.

Could be that eBay alerts would turn up deals on accessories like barlow and relay lenses. I certainly wouldn't be in a hurry to buy too many accessories new at 10x the price of their AliExpress counterparts.

Looking at the Meiji and Nikon alternatives, it really seems like the older models that sell for good prices tend to have trinocular ports that need to be switched with the left eyepiece (e.g. Nikon SMZ-2T) and to have an "always on" camera port requires more expensive models (e.g. Nikon SMZ-U.) So the Zeiss Stemi 305 trino really does look like exceptional value for getting access to high-end optics. I'm not sure how to account for the lower build quality... expect at least five years of life, and potentially a low resale value?

EDIT: I also observe that the Zeiss online shop is selling Stemi 305 microscope head on "passive" stands like a traditional boom that don't have any electronics or power cables. This seems to support the idea that the microscope head doesn't have "DRM" electronics that require it to be used with the more integrated Zeiss stands.

[jfiresto]

I apologize if I'm asking you to repeat yourself while I try to assemble my mental model. Here's how it looks to me now.

Microscopes have their share of complications and it does not hurt to address them sooner rather than later.

Zeiss Stemi 305 seems like a good deal for a drop-in AmScope replacement for EUR 850.

Overall, I am not sure what to tell you. In the past, Zeiss sold some inexpensive microscopes that were not really serviceable. This one might not be the one if you want or need a microscope to use for many years. I wonder if you could talk to Zeiss. Once upon a time, microscopes were sold through a network of representatives, who sold for the long term. They would discuss your applications, figure out what microscope was best and then let you try it to confirm it was the right one for you. That probably has all been eliminated in the name of shareholder value.

... In the future I could potentially upgrade with a 2.5X relay lens to use my Nikon D750 DSLR....

You might want to research that if later you can not roll your own. All the c-mount camera adapters I have seen have assumed a one-inch image.

Looking at the Meiji and Nikon alternatives, it really seems like the older models that sell for good prices tend to have trinocular ports that need to be switched with the left eyepiece (e.g. Nikon SMZ-2T) and to have an "always on" camera port requires more expensive models (e.g. Nikon SMZ-U.)

They are not all that way. Meiji sells both types, for example, the EMZ-5TR and EMZ-8TR, and those two for the same price when I checked.

So the Zeiss Stemi 305 trino really does look like exceptional value for getting access to high-end optics. I'm not sure how to account for the lower build quality... expect at least five years of life, and potentially a low resale value?

I wonder if you could talk to Zeiss, explain that you need a better microscope than your present one, are unfamiliar with theirs and are intrigued by the 305. You could tell them you might need it for, say, 10–20 hours of rework and inspection per week, or whatever it is you might do, for however long. Then see if they think a 305 or something else would be a good or better fit.

[lukego]

Microscopes have their share of complications and it does not hurt to address them sooner rather than later.

Thank you for your patience!

I have done the parfocal adjustment now. I am really happy having the smooth zoom now! It's a testament to my ignorance that I didn't even know this was a thing and had been compensating with constant focus adjustment (and being shy about changing zoom level.)

I've now spent some time looking at the Zeiss Stemi 305. This seems fairly promising but has downsides e.g. lack of reviews, unknown implications of "made in China" aspect, and expensive accessories like $250-$350 barlow lenses.

Meiji SMZ-8TR looks interesting. One issue is that I haven't seen a 0.7x or 0.75x barlow lens listed as an accessory for this model? That's been the sweet spot for me on my Eakins which seems to have the same magnification and working distance range as the Meiji. I would struggle with field of view / working distance / magnification if I only had the 1.0x and 0.5x front optics (and no really quick way to switch between them.)

On eBay now I see a  Leica/Wild M420 Macroscope (https://www.ebay.com/itm/124169002343) for $1199 + shipping. Maybe this is one of the high-quality classic "don't make 'em like they used to" microscopes? I'm reading about this to try and see how it compares in terms of working distance and so on. I'm intrigued by features like the adjustable aperture on the camera port which I suspect would help with extending depth of field for stills. The Wild and Meiji auxiliary lenses seem to be a little more reasonably price that Zeiss, closer to $100 per lens, if I'm browsing correctly.

EDIT: Oh I see now that the M420 "macroscope" is not a stereo microscope and does not provide a 3D view with depth to the eyepieces. So much for that idea!

I wonder if you could talk to Zeiss, explain that you need a better microscope than your present one, are unfamiliar with theirs and are intrigued by the 305. You could tell them you might need it for, say, 10–20 hours of rework and inspection per week, or whatever it is you might do, for however long. Then see if they think a 305 or something else would be a good or better fit.

Maybe so. I have a deep resistance of engaging with the sales pipeline of these companies. Maybe too many experiences of being assessed as a cheapskate who is not worth spending time on

[lukego]

Pardon my continuing to think out aloud...

The objective lenses in the Zeiss Stemi 305 seem to have more magnification (minimum 1x compared with Eakins/AmScope 0.7x) and less magnification range (5:1 for 1x-5x verses 6.4x for 0.7x-4.5x.)

So I suppose it would not be a drop-in replacement in the sense that I couldn't continue to use the same field of view, working distance, and magnification range that I'm used to. That's potentially a real problem because longer working distance is limiting when working over a preheater, more magnification is limiting when placing parts before soldering, and less maximum magnification is limiting during inspection.

Maybe this is an important practical weakness of the Stemi 305. I see that the Stemi 508 has a 1:8 zoom ratio but at the expense of a cost explosion.