LW Scientific Mi5 Overview and Tests

[Scarodactyl]

Well, I said I was done. But just when I got out of the scope buying game, they had to pull me back in with a hot deal on this beauty, an LW Scientific Mi5 polarizing microscope.

I have a masters in geology--hard rock geology at that, and yet here I've been for years without a petrographic microscope. Embarassing. I've watched for years and this was the first real deal I've spotted. Geologists cling to their scopes after all. This one was marketed for use in pathology (particularly for the classic gout/pseudogout differentiation) but it's the same attachments as you'd want for petrology.
Let's hit the basics first. This is a standard Chinese infinity scope, 45mm parfocal. The objectives are not marked with their reference focal length, but I believe it's 180mm. Very similar-looking objectives are sold specifically as fitting on Olympus systems.

Listing for similar-looking objectives on eBay (identical looking really, but you can never be 100% sure if they're the same inside). https://www.ebay.com/itm/254559140731 https://www.ebay.com/itm/322899008968
It has a halogen bulb. I am not sure of the wattage. When I got it it wouldn't start up but when I opened up the lamp hatch in the base it came online after a few seconds, so OK I guess???

Condenser with markings for matching the iris to the objective, and of course a polarizer.


It has a nice petrographic intermediate attachment with a rotatable analyzer, wave plate and bertrand lens. Below is a non-removable nosepiece with five slots (only fitted with 4 objectives on this configuration, 4x 10x 20x and 40x). There is an empty slider above the nosepiece labelled "top", presumably for a polarizer or wave plate if you didn't have one already.
The stage does not have an x-y adjustment(!), just cheap clips. I will need to find one that fits.
The head dovetail is 58mm, 2mm wider than the Olympus BX standard 56mm. The dovetail is also deeper, ~8.3mm vs ~5.9. When an Olympus BX accessory is fit into the female dovetail it fits well and appears well centered--it seems likely that the dovetail is designed to accept male Olympus dovetails but probably not to quite fit into Olympus female dovetails, though I haven't tried it that way since I don't have one.
The head has 23mm eyepieces, and the pair that come with it are particularly cheap-looking 10x/20s. I decided to try out my favorite 10x/22s and compare.

Viewed with one on each eye the view is fine and it doesn't cause any eye strain. No noticeable difference in CA, distortion etc to the eye. Shots with the camera through the eyepiece don't show a significant difference beyond the better FoV.
With the 20x:

10x/20

10x/22
Image quality is not bad, not amazing, except the 10x is rather poor with lots of CA. It's hard to convey that with inconsistent eyepiece phone photos though so I went ahead and mounted an Olympus U-TLU that I'd previously modified for direct projection onto my DSLR. The U-TLU is a non-compensating tube lens, and while there's some minor degradation in the corners compared with a higher end ultrawide olympus tube lens it covers aps-c fine with widefield Olympus objectives.
In what seems to be further confirmation that it's an olympus-based system image quality is good with the u-tlu, maybe slightly better than what I see through the eyepieces.
For these shots I have an overview and then I took crops of the center, sort of the middle and the corners to give an idea of image quality. This doesn't cover planarity since the sample is fairly three dimensional but just from using the scope planarity doesn't seem to be a problem on any of the objectives.
4x with condenser as-is:




Overall, for a cheap achromat it's pretty clean! you do get some lateral CA in the corners and of course the vignetting from the condenser (whstever you'd call that) is bad on aps-c but that's asking a lot more than the scope is specced for. The top element of the condenser can be unscrewed which allows only a small amount of corner darkening with the 4x, though that would not be practical in use.
With the top element of the condenser removed:




Actually the 4x is pretty nice once the condenser isn't holding it back. I might need to get a flip top condenser for this or rig something up.

10x:




The 10x kind of sucks, you can easily see that it's a poor performer through the eyepieces too even within a modest 20mm FN. Not sure if this is a bad design or a bad copy.

20x:




The 20x kind of rocks, it's fairly good even to the extreme corners on aps-c.

40x:




The 40x is a very acceptable achromat.

Overall, it's a really neat piece of kit! I will probably soup it up a bit with a trinocular head (nikon or olympus, whatever I can find a good deal on) and some higher end Olympus objectives someday if I find a deal, particularly to replace the 10x. And definitely x-y controls for the rotating stage. I also need to buy some thin sections, I feel like a fake geologist because I can't even find my own box of them.

[apochronaut]

LW is a company that seems to try to do things right within their means : which implies that they have to source from China and perhaps India and they seem to jump around when it comes to optical systems.
I made a similar purchase for a basic LW 4 objective planachro fluorescence microscope. Under 100.00. It turned out to be a little brother to a 100 watt 5 objective scope still sold in China. They both have 30mm eyepieces with an accessory 23mm f.o.v. trinocular head available. The difference is wattage only. Both are quite heavy and very well made. The one odd thing I discovered was that although the objectives are 45mm parfocal infinity corrected, the optics are patterned after the old AO ( and also in Europe, Reichert) 34mm parfocal infinity system. Those old AO objectives can be directly used in the stand, which broadens out the stands economy possibilities for optical accessories. However it uses a 44mm dovetail, head mount. AO is 50.4mm or 2".

LW may have had some involvement with India at one time, where the end production of the ATC 2000 took place and some subsequent production of microscopes using AO/Reichert systems took place. It gets a little hazy sometimes where Indian design crosses over to Chinese. There are many instances where virtually identical instruments are being sold as made in China and made in India.

I would do some close checking on the optics before you commit to their design principles.

[Scarodactyl]

I did try my best to not make assumptions about the optical system, even with identical-looking objectives being sold specifically as being olympus compatible (though I forgot to add the links I'd found, just edited that into the post). Between testing with a different eyepiece and different tube lens I feel like I've covered what bases I could easily cover. I don't think AO-spec objectives would play well with an Olympus tube lens and no eyepiece corrections but I could be wrong since I haven't tested that.
I suspect LW like most such brands sources plenty of unrelated lines. Honestly most of these whitelabel T-based infinity scopes look about the same to me, but I just tried googling it again and I found another seller of the same model (though with an added epi attachment) and from that I could find Labomed also selling it, and even a listing on Amazon which seems like a solid deal if it's for real. Anyway there are a ton of places listing it including mainstays of Chinese direct sales like Ninbgo/Opto Honyu so I'd guess it's wholly Chinese.

[apochronaut]

Labomed at one time had microscopes coming out of the same factory that the ATC 2000 last exited from.

[Scarodactyl]

Yup, I'm aware they have or had those connections, but a lot of what they sell is Chinese, including their own branding of the 18:1 cmo stereo.

[apochronaut]

The very odd thing is that you can find the same microscope sold in both countries : one marked Made in India and the other marked Made in China. I do know that the BS-2081 ( Bestscope model#) is duplicated out of Radical stock as a base unit carrying a more extensive accessory package and badged " Made in India ".

[Plasmid]

Here's all the upgrades available for it.
I got a couple of quotes from the manufacturer in ( Shenzhen) and the prices are ok , but when you add shipping nit so much. I own the PH objectives and condenser as well as the Plan objectives 4,10,20,40,60&100X. The quality of the optics is inferior when compared to Reichert Plan and Neoplan objectives, have not tested the UplanFL objectives yet, but plan on purchasing a couple.

https://www.cqoptec.com/products/detail/1110.html

viewtopic.php?t=14094

[Scarodactyl]

Cool, thanks for the link! It's interesting that they don't list the polarizer (the one that goes on the condenser) or the petrographic analyzer in their lineup. I'll be very curious to hear how their fluor objectives are.

[apochronaut]

It's odd that most of these systems from China, and I have looked at quite a few similar versions including some based on NIS optics, only supply 1.25 abbe condensers : even when they are offering semi-apos or apos at apertures of 1.3 or higher?
The BS-2081 offers a 1.45 N.A. planapo, 60mm parfocal, presumably made in China because they reported that magnifications other than 20X and 100X were still being developed, yet they only offer a measly 1.25 abbe condenser!