Suggestions for good stereo magnifiers?

[enricosavazzi]

I am gradually kitting up for collecting samples in the field once I retire (within 6 months to one year) and move to a highly promising location for land, fresh- and marsh-water invertebrates and microorganisms (where my wife recently got a job and has already moved). The Quekett Microscopical Club posts have been inspiring in this respect. Most of that club's members seem to be carrying ordinary microscopes for preliminary observations indoors after the field collecting.

As a help for preliminary inspection and selection of samples, I am instead thinking about head-mounted stereo magnifiers to use in the field, of the type designed for watch repair, or the presumably better ones of similar construction for dental/surgical use, for magnifications somewhere between 3x and 10x. Because of the relatively long working distance and hands-free operation, they appear to be far more comfortable to use than a hand-held field microscope or loupe to stick close to one's face.

I can see on eBay a couple of suspiciously cheap watch-repair types made in China, and a handful of surgical/dental types sold at (also suspiciously) extremely variable prices, but I know nothing of their image quality. The dental/medical types seem to inspire more confidence. There are also on eBay the occasional, extremely expensive Leica and Zeiss neurosurgery types of similar design, but I could buy a good field-clinic microscope for less.

I would like suggestions for this type of equipment, in the mid-range of prices above the obvious trash but below the neurosurgery equipment. I am primarily interested in equipment I can buy in the EU, possibly second-hand and possibly through direct import from China if economically advantageous.

PS - The most advanced type seems to use keplerian telescopes with erecting prisms. This type is also likely to have the highest working distance.

[ray_parkhurst]

All I can say is to not buy any of the cheap ones. I've purchased several and none have been satisfactory. The biggest issue is poor image quality, but a nagging issue is convergence. Unfortunately I can't make a recommendation of any that actually work well. Hopefully others have had better luck and can point toward a useful pair.

[rjlittlefield]

Suggestion: ask your dentist what he or she uses.

The last time I did that, I got what seemed like a quite useful recommendation.

But I never did buy a set, and it was a long time ago, so I have no personal experience and whatever details she said are no longer relevant.

--Rik

[Alan Wood]

Enrico

I have only seen one Quekett member using a stereo magnifier, and that is a MagniVisor.



A quick search did not find that exact model, they seem to have built-in LEDs now.

Alan Wood

[Beatsy]

One of my friends is a dentist and he lent me a couple of dental loupes to try out. One cheap Chinese, the other a name-brand German model, but I forget which. It wasn't Zeiss.

They are very fiddly and exacting to set up (for convergence and all that), but once that's done, they both seemed to stay set correctly. Both had a narrower field of view than I expected, and image quality at the periphery was poor in the cheap Chinese one. Centres were OK.

The biggest issue I had with them is the (very) fixed, long working distance. The German one was clearly designed for an orangutan! I had to have my arms AND fingers at full stretch to get the subject in good focus. The Chinese one was a more comfortable working distance, but again, fixed. While this is OK if you're working at a bench, I think it would be a liability in the field that would eventually make them tiresome to use.

As a glasses wearer, the best "hands free" (but not stereo) solution I found was these. Cheap, effective and eminently portable.

[DaveinMpls]

I would like suggestions for this type of equipment, in the mid-range of prices above the obvious trash but below the neurosurgery equipment. I am primarily interested in equipment I can buy in the EU, possibly second-hand and possibly through direct import from China if economically advantageous.

Hello Enrico,
As a surgeon, I have used very expensive custom-made surgical loupes (often sold as "surgical telescopes") mounted in eyegass frames. These have a long viewing distance and excellent resolution but a very narrow field of view, especially at higher magnification. Teaching surgical residents, I was unable to see them about to make a grave error out of my field of view until it was nearly too late.

I went the other direction, choosing a head mounted visor with huge interchangeable lenses. The extremely large field of view makes it easy to scan a large area quickly and repeatedly. I even found them useful for preparing specimens for photography under high magnification. The downside is a somewhat short viewing distance, but the low price is unbeatable. You might try this before investing is something more expensive.

This listing is similar in style to the ones I am using:

https://www.ebay.com/itm/7X-Headband-LE ... itleDesc=0

Best wishes, Dave

[ray_parkhurst]

I have a clip-on pair of 2x magnifiers similar to the linked ones. They do indeed have short working distance, but they have guaranteed convergence, which is nice.

[zzffnn]

Enrico,

I am interested to know what you find usable in the future. A no- compromise product that check all your requirement boxes may not be easy to find (I want one, if you do find one!).

If you can go without stereo, I would suggest a good loupe glued to eye glasses. What is a good loupe will depend on your exact requirements. For example, is 40mm working distance at 5x too short for you?

I have this 5x 4-element achromat loupe with about 40mm working distance: https://www.surplusshed.com/pages/item/L3107.html

It us sharp, almost corner to corner. But I don't know if Surplus Shed would ship to EU for reasonable cost. And they also failed to sent me clean and clear glass twice (1st time they failed to cured the glue, 2nd time they left some fog inside; I had to open it up to clean it off myself). And it is a bit heavy.

Beatsy's solution is probably more practical, if you can find one with quality that satisfy you.

I suspect you may not be able to get to 10x without significant compromise on at least one of your requirements. My good Peak 10x achromat loupe (retail price $90 USD) has WD of less than 20mm.

[Len Willan]

The Standard Binocular loupe used by Watchmakers the world over
Is of this type
Bergeon SA - Depuis 1791

5381-DA02

PDF Description
https://shop.bergeon.ch/Catalogue/PDF/6 ... 206119.pdf


Binocular magnifier with adjustable visor


https://shop.bergeon.ch/index.php?cde=5 ... bart=&new=

[Chris S.]

Useful thread! I’d been meaning to start a thread myself to discuss headband magnifiers. I’ve been plagued by presbyopia—needing to constantly don/doff reading glasses, and frustrated that none of my eyeglasses provided effective seeing for all the close-up things I do. It’s a good bet that other forum members have similar trouble.

Then I found "Donegan Optivisors." I watched a dermatologist use a pair of these to examine a family member; I then looked them up and bought a pair, after noting the many positive reviews. Wow—they made life much easier. Soon after, I bought a second pair of a different power. I use both pairs about equally, depending on the magnification I need for a given task, and find them indispensible for subject preparation, soldering, machining, removing splinters, reading fine print on pill bottles—all sorts of things that previously frustrated my increasingly presbyopic eyes.

I have sets of these in two strengths: Lens LX-3, 3-diopter, 1.75x magnification, 14-inch focal length and Lens DA-7, 7-diopter, 2.75X Magnification, 6-inch focal length. I can recommend both, and easily see myself purchasing a third pair in some other magnification--the ability to quickly switch between magnifications has real benefit.

I would advise against buying magnifiers with interchangeable lenses. I find it useful to switch frequently between magnifications, but would find it frustrating to mount/dismount lenses between views. Quality lenses cost more than quality lens holders. So if one buys more than one set of good lenses, buying a holder for each lens pair is comparatively cheap and makes switching between magnifications quick and easy. And for many tasks, I find it helpful to quickly switch between magnifications.

Also, these magnifiers fit easily over prescription glasses. Since I have prescription safety glasses, this means that I can use these magnifiers, in combination with my safety glasses, to closely observe machining with my mill, drilling with my drill press, and other operations that would not be eye-safe without solid vision protection.

Here is what this brand claims about optical quality:




Here are the range of magnifications offered for this brand:



--Chris S.

[Len Willan]

The Principal consideration is practical working distance with any device.
Magnification is a separate issue, consider Depth of Field
In practical situations, use

2 X -230-320 mm

2.5 X.- 150-250 mm

3 X-80-120 mm

This is well known in watchmaking, and other precision use as a standard.

[Beatsy]

Then I found "Donegan Optivisors."

Thanks for this post Chris. I wondered about headband magnifiers for yonks but have seen no reviews and never got round to properly researching them. Your post re-piqued my curiosity and interest - especially as I'm spending a lot more time mounting dead insects for studio macro these days. So I went looking with a view to buy and try.

One thing to watch for, there are several "Optivisors" offered at infeasibly low prices. E.g. some with headband and all 5 spare lenses for £12. It may be the wrong assumption, but I doubt these are of any quality. Prices for genuine new "Donegan Optivisors" here in the UK range from £40 to £70 a set (single magnification) with a few outliers at >£120 (good luck selling those ).

Anyway, on the strength of your recommendation alone (do you feel "responsible" now ), I just ordered the 1.75x and 3.5x versions. Like you, I wouldn't want to faff with changing lenses either. I'm sure they will prove invaluable in no end of indoor "studio" situations.

Thanks again.

[enricosavazzi]

Thanks to everybody for your replies (and if anyone has more to add, please do so).

After considering the alternatives, I shelved for now the idea of surgical telescopes, and followed Dave's suggestion. I did not order the exact one he mentioned, but a Carson CP-60 Magnivisor Deluxe (see https://www.carson.com/products/magnivi ... uxe-cp-60/ for the manufacturer's description, and eBay item 183280118342 for the one I actually bought). It is more expensive than a direct-order, unbranded item from China, but still cheap enough to chalk it off as research expenses if it does not turn out to be useful. Although I have not tried it yet, I like the idea of having a free field of view at both sides of the lenses, which some of the other types of head-mounted loupes cut off.

It is different in a couple of respects from the item linked to by Dave: (1) the Carson model does not seem to allow the simultaneous mounting of two sets of lenses, but only one, and (2) the LED lamp of the Carson model seems to be smaller (especially the battery compartment) and can be detached to make the visor lighter or to use the lamp separately. The included lenses provide magnifications of 1.5x, 2x, 2.5x and 3x, which is less than my original idea but could be supplemented by a hand-held monocular inspection microscope/loupe if necessary.

I will report back after I have had the chance to try it in practice.

PS - I have been looking at the Mitutoyo 25x portable inspection microscope to get to a higher magnification. Does anyone have a direct experience with this?

[zzffnn]

No direct experience with Mitutoyo 25x portable inspection microscope. However, some inspection scopes use finite tube length and interchangeable objectives and eyepieces (while others do not). WD depends on optics used.

[Steve S]

Just to add some impressions:

I've interviewed a couple of dentists about their optics, tiny Galilean telescopes mounted in eyeglass frames, and seen similar optics marketed at the Tucson Gem & Mineral show. It appears to me that these devices are principally intended to provide very low magnification at very large (~30cm or so) working distance, with the emphasis on comfortable working distance more than magnification. The field of (quality) view is indeed very small.

I've heard museum curator types in the archeological/anthropological racket express widely varying views about Optivisors. Some seem to put them on with their underwear daily, while others swear they cannot get any good out of them at all. I've bought several at yard sales from disaffected rockhounds, and find them very convenient and comfortable when short working distance is tolerable.

I'm also curious about the 25X Mitty, but must admit I bought a nominally ~20X (actually less) hand lens with attached LED light for several dollars at the above-mentioned show and find it surprisingly effective, possibly almost competition for the Mitty handheld -- sacrilege! blasphemy!. Apo, it ain't, of course.