Comparison/Review

Ken-A-Vision Professor vs. Leica EZ4

by Dave McShaffrey

I recently purchased a Ken-A-Vision Professor Microscope from BioQuip. I planned to use the unit, which was very inexpensive, as a field stereoscope. However, upon receiving it I was pleasantly surprised by the quality of the image and we are considering buying several more to supplement our existing Leica EZ4 stereoscopes.

Overall: The scope is very small - 5.5 x 4.5 x 9.75-11.5" (depending on focus height). It is binocular, with 20x illumination. It weighs about 1.25 pounds, and appears to be mainly plastic construction (except for the base, lenses, screws, electrical components and stage clips), however the build quality is impressive and I found myself using a magnet to determine if some parts were metal or plastic. Although it is light weight, it feels solid to use (though it does slip around a bit on the tabletop). The oculars are 10x and the objectives 2x for a total of 20x; this seems to be correct as measured against the Leica. It does not have as wide a field of view as the Leica, however.

Illumination is provided by a single LED mounted on the frame supporting the objectives, that is, it travels up and down with the objective. It is fixed in orientation, and provides usable light, though it is not particularly bright (at least by comparison to the Leica which has 5 LED's). There is no provision for substage lighting. The stage is a circular piece of plastic, reversible white to black. If the stage were removed and the scope placed on a light table with a piece of glass for the stage (say a small petri dish or even a microscope slide) then viewing could be done with transmitted light. There are two metal stage clips.

Power for the LED is provided by two included AA batteries; battery life is claimed at 300 hours. There is a simple off/on switch; no provision for dimming (not that dimming would be necessary).

The oculars are apparently 19mm; an odd size. They rotate but do not fall out; they are held in place by a small straight-head screw (eyeglass hinge screw size). I am not sure if the scope is adaptable to a eye-tube mounted camera. There are no rubber eyecups supplied. Eye relief is good without glasses, adequate with glasses. The short height of the scope means it will be usable by small people sitting at a normal height table; taller folks will have to bend over a bit more than usual. The stage size is small and hand rests might be desirable for prolonged manipulation of specimens under on the stage. The body of the microscope is fixed in the mount and cannot be rotated so that someone sitting across the table can look; the entire scope would have to be moved.

There is no fine focus, but the rack-and-pinion focusing mechanism is reasonably precise. With only a 2" focussing distance it is quick to focus; however large specimens may be too tall to be viewed.

The image is remarkably clear, although the limited illumination is a problem. The scope is better if there is sufficient ambient illumination, and very good if an additional microscope lamp is supplied. The single LED gives a definite bluish cast to colors. Low-incidence illumination to provide relief is not possible with the fixed LED, but an external lamp solves this problem as well. Resolution is actually comparable to the Leica at least at the center of the image, but even at the edges it isn't bad. The image below is unlabeled; it shows occiput of a yellowjacket at comparable magnification with both the Ken-A-Vision and the Leica. Hand-held digiscope with Canon G-11, ISO 1600 (hence the grain). I used the high ISO because of the low light levels on the Ken-A-Vision; in order to get a reasonable shutter speed (1/6 second) I needed 1600 ISO. Illumination on the Leica was adjusted to use only the LED's mounted high on the mounting bracket and at a lowered illumination level to match the output of the Ken-A-Vision (in this case actual shutter speed was 1/5 second). No processing was done other than to convert the image from Raw and adjust the highlights to correct the overexposure of the highlight near the center ocellus. Both images were also cropped to the center of the image.

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Can you tell which scope is which? Scroll down for labelled image....

 

 

 

 

 

 

 

 

 

 

 

 

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As you can see in the image above, the Leica is on the left and the Ken-A-Vision on the right. In both, one can see individual ommatidia of the compound eye (top of screen), some detail within the 3 ocelli, and at least discern the presence of various hairs on the vertex. The Leica has slightly better resolution, wider field of view, vastly better illumination, zoom, is more flexible, heavier, more stable, has substage illumination, etc. The Ken-A-Vision is smaller, lighter, battery powered and about 1/10th the cost of the Leica. We are debating purchasing 10 or so to supplement the Leicas for use in class in situations where higher magnification and better illumination are not necessary, and for field use. Optically, they are fine for many purposes, and we will see how they hold up. Uncropped images are shown below at smaller size - you decide which is which.