Suggestions for good stereo magnifiers?

[lothman]

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

For higher magnification from greater distance you might try Pentax PAPILIO II 6.5x21. This gives you excellent 3D impression and since you can focus down to 50 cm you can view tiny thinds from a comfort distance. Since we usually lose eyesight AND mobility with age ;-) this could be a solution for some cases.
I own one and it is fun to look at bees or ants (especially also for children) but it is "too strong" for let's say watch repair.

I also had some Russion loupe glasses from old days in the 90ies where they sold everything on flea markets. But the eye distance seems to be very crucial, because if not fitted well using a 4x loupe is rather stressing four your eyes with the time.

[enricosavazzi]

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

For higher magnification from greater distance you might try Pentax PAPILIO II 6.5x21. This gives you excellent 3D impression and since you can focus down to 50 cm you can view tiny thinds from a comfort distance. Since we usually loose eyesight AND mobility with age ;-) this could be a solution for some cases.
I owe ony and it is fun to look at bees or ants (specialy also for children) but it is "too strong" for lets say watch repair.
[...]

It looks interesting. I tried to find out the actual magnification when focused at 50 cm, but did not see any specifications. Magnification at infinity must be the nominal 8.5x, but it is likely different (probably lower) when focused close.

On the other hand, 50 cm is quite a bit far away, a bit too much for looking at a sample in a hand-held Petri dish in the field, for example.

Nikon has/had for several years a 20x plastic stereomicroscope (actually two models, a slightly bigger one with LED illuminator and a folding one without) which looks very interesting, but costs 2-4 times more than an ordinary second-hand stereomicroscope.

[lothman]

It looks interesting. I tried to find out the actual magnification when focused at 50 cm, but did not see any specifications. Magnification at infinity must be the nominal 8.5x, but it is likely different (probably lower) when focused close.

You can wander around with you eyes in a field of view of 5-6 cm diamater fosussed at the closest distance, not like in a tunnel. I'm shure you will love it tack sharp and with good contrast. Take the 6.5x Version not the 8.5. So you have binoculars and stereomicroscope in your pocket, watch out for the newer ii Version.

Got mine from microglobe in UK as the British Pound was very low.

[zzffnn]

I like my little Pentax Papilio 6.5x too. Children tend to like it better than real microscopes, for looking at ants and museum displays, for example.

It has tripod mount (to make it technically hands-free). But yes, probably too much WD for sample collection and examination. That was why I did not mention it previously.

But note some people cannot get used to its incompletely converged image circle (It took a slight getting used to for me, though I don't mind it):

http://www.photomacrography.net/forum/v ... c&start=15

And yes, image quality is very good and the bino is light, small and very portable.

[Beatsy]

Why stereo for field use Enrico? I'd have thought that would seriously limit your choices while being heavier and bulkier than most monocular options. You're obviously happy to make that compromise - I'm just curious why.

[enricosavazzi]

Why stereo for field use Enrico? I'd have thought that would seriously limit your choices while being heavier and bulkier than most monocular options. You're obviously happy to make that compromise - I'm just curious why.

In the field I may want to fish things out from a bulk sample to separate them into small test tubes with scissors, tweezers or a small paintbrush (this applies to things maybe down to 0.5 mm, so not really microscopic). It does not work well for me to do it without binocular vision. I have some past experience from field work in marine biology with predators in a water or disturbed sediment sample eating out all the interesting stuff I was planning to rear once back in the lab, so I may want to separate predators from prey.

For higher magnification, it would mostly be a matter to check whether there are any organisms at all for deciding whether to keep/fix a watery sample or throw it, rather than isolating some of the organisms, so I could give up binocular vision for this use.

The idea of lightweight binoculars for (relatively) long-range observation is attractive to extend my visual reach without (literally) getting my feet wet. It seems however that they would not double as a substitute for a stereomicroscope because the minimum WD is a bit too long, so I have not decided yet about binoculars.

The Nikon field stereomicroscope would be interesting at under half kg, but a bit too expensive, and I don't know yet how durable is the focus mechanism. If it is just a rubber friction wheel, it would not inspire confidence.

[lothman]

just for fun I bought suh a children stereo microscope with battery and led lightning
https://www.amazon.com/Celestron-Micros ... microscope

there are also different other brands selling similar types, they are advertised as children toy (but as an engineer consulting job I took one piece with me to a customer and gifted it to him, what had a huge impact :-) )

surprising good for that money and sufficient optical quality for field work. I doubt the focus mechanism will survive a harcore user but for around 40$ also a nice portable solution.

[Beatsy]

Why stereo for field use Enrico? I'd have thought that would seriously limit your choices while being heavier and bulkier than most monocular options. You're obviously happy to make that compromise - I'm just curious why.

In the field I may want to fish things out from a bulk sample to separate them into small test tubes with scissors, tweezers or a small paintbrush (this applies to things maybe down to 0.5 mm, so not really microscopic). It does not work well for me to do it without binocular vision. I have some past experience from field work in marine biology with predators in a water or disturbed sediment sample eating out all the interesting stuff I was planning to rear once back in the lab, so I may want to separate predators from prey...

Ahh, I see. That all makes perfect sense. Thanks.

[Beatsy]

My Donegan OptiVisors arrived today, 1.75x and 3.5x. The 1.75x ones have an ideal working distance for desk-based tinkering and the 3.5x are just right for close-up fiddly stuff (untangling insect legs and the like). Nice large FoV and good DoF with both and they converge very comfortably too, making them ideal for long periods of continuous use. In short, perfect!

[enricosavazzi]

There might be some useful information in the following papers, but I don't seem to have access to them:

https://www.ncbi.nlm.nih.gov/pubmed/7420328

https://www.ncbi.nlm.nih.gov/pubmed/10842519

https://www.ncbi.nlm.nih.gov/pubmed/2702375

[enricosavazzi]

My Carson Magnivisor Deluxe CP-60 arrived today. First impressions:

Without LED lamp, sufficiently lightweight for extended use. The frame is easily adjustable, and stiff enough to stay lifted up with the lenses out of the way, or down in the viewpath. The height of the lenses can be adjusted a little to look straight ahead or slightly down. My nose is relatively long and the lenses almost circular, so the lenses touch my nose if I try to move them further down.

A positive consequence of the wide (and tall) lenses is that I can move my eyes around quite a bit without moving my head, and still get a satisfactory stereo field of view. The lenses have no surrounding frame. The usable lens surface extends right to the edge of each lens. The two lenses merge together at the center, so there is no "dead" space there, either. The field of view is completely unobstructed at the sides and bottom of the lenses.

Only one lens insert at a time can be used. It clicks in place securely, and is in fact a bit difficult to take out. Hopefully it will get a little easier with time. I can swing the lens toward my face and completely up out of the way, but only if I am not wearing glasses. I can swing it a little outward and direct my eyes downward, e.g. to see where I put my tools on the table.

I am shortsighted (I need no glasses to watch a computer screen, but that is as far as I can focus without glasses). This has a practical consequence: without wearing glasses, when using the Magnivisor I am forced to keep the subject quite a few cm closer to my face than with glasses. With the 3.5x lens, the focus is about 15 cm from the lens without wearing glasses, about 20 cm with glasses. Either way, I have no problem with convergence. Image resolution is good. It does not feel completely natural, but close.

The focus distance is slightly longer with the lower magnifications, but the difference is not that much. It never gets longer than about 25-28 cm.

The LED lamp is a little heavy once filled with three AAA batteries. I think I will use this lamp only when really necessary. A depression is left in the black top of the frame by removing the lamp, but its bottom is closed except for a round hole about 10 mm wide. It is hard to remove the lamp, and pushing a pen or screwdriver through this hole is the only thing that works for me. A plastic cover that completely fills this depression is supplied. This cover might be useful to prevent direct sunlight from entering the 10 mm hole in the field with the sun at certain angles, but so far the cover has not been necessary indoors.

The lenses are housed in a largish plastic box (bigger than a case for sunglasses), and the cover of the box easily falls off. I must remember to use a rubber band to keep this box closed if I take it to the field. It is however more likely that I will take only one lens at a time in the field.

The original packaging is lightweight but not suitable to carry the visor in the field: to store the visor in this packaging I would need to remove the lens and change the length of the headband. I may try to find a lightweight plastic box large enough for this use.

[ChrisR]

My Donegan OptiVisors arrived today, 1.75x and 3.5x. The 1.75x ones have an ideal working distance for desk-based tinkering and the 3.5x are just right for close-up fiddly stuff (untangling insect legs and the like). Nice large FoV and good DoF with both and they converge very comfortably too, making them ideal for long periods of continuous use. In short, perfect!

I don't really get it. Why not use reading glasses from the £1 shop? They go to 4 dioptres.
The lower part of my varifolcals is about +4 that but requires a cranked neck, so I put a £1 pair on top. It's not uncomfortable. They just....work.
I can understand use of higher powers, or when we couldn't get fixed specs cheaply.

[Beatsy]

My Donegan OptiVisors arrived today, 1.75x and 3.5x. The 1.75x ones have an ideal working distance for desk-based tinkering and the 3.5x are just right for close-up fiddly stuff (untangling insect legs and the like). Nice large FoV and good DoF with both and they converge very comfortably too, making them ideal for long periods of continuous use. In short, perfect!

I don't really get it. Why not use reading glasses from the £1 shop? They go to 4 dioptres.
The lower part of my varifolcals is about +4 that but requires a cranked neck, so I put a £1 pair on top. It's not uncomfortable. They just....work.
I can understand use of higher powers, or when we couldn't get fixed specs cheaply.

Tried that and found it *extremely* inconvenient. They fell off more often that not, endangering whatever fiddly and delicate thing I was tinkering with. I couldn't look "under" them when I briefly needed an unmagnified view either (I wear varifocals too). So I while I agree they "work" and are cheap, I don't find them anywhere near as nice to use as a monocular loupe clipped to my glasses, or (as I now have) a stereo view strapped round my head.