Stereoscope vs. Compound Microscope at Given Total Magnification

[J_WISC]

Hello.

This is a curiosity question, not trying to solve a specific problem.

Could someone please describe the expected pros and cons — or direct folks to a website — of using a stereoscope (dissecting microscope) vs. a compound microscope at a given total magnification. For example, both equipped with 10x eyepieces and 10x objectives? Besides the obvious stereo vs. not stereo images.

I hope to actually set up a comparison at some point. What should I watch for?

I hope this isn’t a stupid question. But it wouldn’t be the first time or last time I ask a stupid question.

[Topcode]

Its kinda almost too general of a question to answer super well. A stereoscope can be much better than, or it can be way worse than a compound microscope. If you make everything the same specs to have an accurate comparison, then you arent very likely to have any notable differences, but that kinda defeats the purpose of comparison.

Generally a stereoscope will be better at lower magnification because that's kinda their whole thing, but that doesnt mean high quality low power compound objectives dont exist, and if you compare a high quality to a low quality anything well, its obvious to see what will win.

[Hobbyst46]

Hello.

This is a curiosity question, not trying to solve a specific problem.

Could someone please describe the expected pros and cons — or direct folks to a website — of using a stereoscope (dissecting microscope) vs. a compound microscope at a given total magnification. For example, both equipped with 10x eyepieces and 10x objectives? Besides the obvious stereo vs. not stereo images.

I hope to actually set up a comparison at some point. What should I watch for?

I hope this isn’t a stupid question. But it wouldn’t be the first time or last time I ask a stupid question.

A partial answer:
The purpose of a microscope is not magnification. It is resolution - to resolve tiny objects and see them separate from one another.
To achieve high res, one needs a high numerical aperture. One obvious payment is in working distance.
An important feature of the compound scope is high NA, thus high res and shallow working distance.
An advantage of the stereoscope is deep working distance, at the price of low res.
AFAIK common stereoscopes are equipped with a 1X or 2X or 4X objective, not 10X. The eyepiece may be 10X. In both the compound and stereo, the resolution is determined by the objective. Likely, the stereoscope will yield a less resolved image than the compound. But allow us to visually manipulate the specimen with tools, if so wished.

[J_WISC]

Thank you for answering the question. The choice is depth of field vs. resolution.

I should have chosen a more realistic set of numbers. For context, here is a table from a 1946 Spencer Microscope catalogue.

Screen Shot 2024-02-04 at 2.52.48 PM.png (240.53 KiB) Viewed 819 times

I should have chosen 9x or 10x eyepiece and 3x or 4x objective for comparison. This is a comparison one might come closer to achieving.

(I thought I actually had a 12x stereo microscope objective in a box of other items. It is 6x! I must have been thinking eyepieces. )

Thank you.

[Hobbyst46]

The field of view is the: field number/power of objective. Same calculation for stereo and compound. Also same total magnification calculation.
The table above shows that the Spencer 9X eyepiece has a FN of 19.7 (probably 20?).
For example, on my old Olympus stereo, the eyepiece FN is 22, so for a zoom setting of 4X (equivalent to a 4X objective), the field of view would be 5.5mm, slightly wider than the 4.9mm of the Spencer.
On my old Zeiss compound, the eyepiece FN is 18, and a 4X objective (which I do not have...) would give 4.5mm.

[apochronaut]

If you were to view a subject through one side of a stereo microscope only and use the same magnification objective in a compound stand and with the same type of vertical illumination, that would clarify the comparison. Essentially what you are then comparing is a low power inspection microscope against a low power compound microscope. The quality of the image through the compund microscope will be superior in terms of resolution to that of an average stereo, due to the higher N.A. of the optics but it might lack planarity because planarity is a critical aspect of low power observation through an inspection or stereo scope. but not necessarily through a compound scope. Stereo microscope designers place a high priority on planarity. You have to bear in mind too that once further corrections and field size are applied to a microscope objective , that in many cases the price of one compound objective can exceed that of many good quality entire stereo microscopes. In order for a stereo microscope's objective system to attain the resolution of that of a good compund system, the cost will push the instrument into an elite market because not only will the resolution be high but so will the collimation have to be, especially at high magnifcation. This makes the precision of all aspects of any stereo's construction, higher than that of an average compound microscope. At 100X magnification a compound microscope's objective need not point at dead center in order to produce an image consistent with it's specifications but a stereo microscope's must, or if not, each side must point to the same spot.

Each system is built differently, with different goals, so a direct comparison is difficult but because a stereo microscope is actually two precisely aligned microscopes, an aspect of it's resolution is based on the parallax of the system, so the N.A. is not the whole story. When a stereo has an equivalent N.A. and colour correction to that of a good low power compound system, at say 100X, the view and image quality is far superior to that of a compound scope but don't expect that out of an average stereo microscope with simple achromatic objectives. Most of them cannot be used above 40X total magnification and attain resolution that can equal that of a compound scope. Systems that have objectives above 4X or zoom capability greater than a 4:1 ratio have to be built to higher specifications and that means higher cost. You can't just add a high power, high N.A. objective to any stereo microscope stand.

[charlie g]

Thanks, j-wisc, for this thoughtful/ useful thread, hi all. My stereoscope would only awaken from it's storage shelf...if/when I am introducing novice microscopy ( informal, or formal students) folk to the dimensions of our world ,

of our everyday world ...our important microbe and meiofauna service providing neighbors which share our locale. Stereo microscopy gently leads novice observers to a smaller dimensioned world we exist in..but we still sense the big picture world views.

One needs a stereoscope to deal with your appreciation of bird feathers, scales, the variety of integument appendages..and the fleas/mites/ lice ...observing bryophytes, mosses, lichens, microanatomy of large organs, to appreciate

the 'tissue/ organ status'...gemology, stamp collecting, finger prints, forensic sciences...etc., etc. .

As has already been posted into this thread...stereo microscopes are optics for: 'hands on/ instrument manipulations' of materials , or of patients being treated by manipulations.

Usually cmpnd microscopes require special 'long working distance optics' to permit similar: 'hands on/instrument manipulations' ( think invitro egg fertilization, cell manipulations, a diatomist constructing a collection of diatoms frustules

into a deeply charming prepared slide, etc., etc.,.)...with much smaller tools ( think micromanipulators, micropipetts, all radically smaller than tools for stereo microscopic manipulations.

So, my burning question for this thread is: are image captures/ camera recordings from stereo microscopes less demanding for say an image capture of: intact honeybee? Does the 'deeper field of focus' with a stereo microscope, permit

image captures with oh so much less constraint of: narrow depth of field which a cmpnd microscope Plan 2X objective offers?

At my suggested: Plan 2X cmpnd scope objectiveX10X occular...will a reasonable stereo microscope '20X' magnified image be easier to image capture due 'deeper field of focus ' with the stereo stand?.

thanks again, j-wisc, for this thread, charlie guevara