Bob's Rock Shop Product Review
Raynox Video MicroExplorer
I've been contemplating some content and coverage on microminerals and micromounting at Bob's Rock Shop, and I came across this interesting and facilitating video accessory during the '97 Tucson Show when I visited with Don Parsons, of Parsons' Minerals and Fossils, at the Executive Inn. The Raynox Video MicroExplorer(tm) VM-3000 is a $220.00 lens adapter and stage system which enables a 'standard' compact video camcorder to be used for viewing small and microscopic objects. Using a camcorder rather than a conventional film camera provides some obvious advantages, such as the ability to acquire and present images in real time to a classroom or club audience viewing a TV, monitor or video projector. Video can also be readily frame grabbed as still images suitable for display on the WWW, and the ramifications of that for generating digital micromineral images really pushed my buttons.
The heart of the MicroExplorer system is three special, auxiliary, rare-earth optical glass lenses which mount in front of a camcorder's regular lens to increase its effective magnification. They are shown at right with the nice protective case and lens caps which
accompany them. The lens barrels and screwthreads are fabricated from plastic and appear to
be molded parts with some machining as necessary.
Also supplied is an illuminated stage and stand, which provides a means to mount the camcorder as well as vertical adjustment to accommodate various height specimens and focusing. The bulk of the stage and stand components are injection molded from ABS plastic. A battery powered fluorescent lamp is built into the base and can be used to provide light table illumination for subjects that benefit from backlighting. In addition to the camcorder, you must supply a suitable TV or monitor and of course, your own micromineral and other microscopic
specimens. You'll also need a frame grabber and some image processing software if you want
to generate digital stills from your video like I've done to illustrate this review.
The Video MicroExplorer includes a multilingual manual in English, French, German and Spanish.
It provides clear and detailed instructions for setting up and using the Video MicroExplorer with your camcorder, along with some tips, cleaning instructions and cautions. The manual also explains and provides an example of how to calculate the overall video system magnification. Raynox provides a 1-year warranty against manufacturing defects for the MicroExplorer.
Don had a unit all set up for doing video microscopy demos in his room at the Executive, and after just a minute or so of playing with it, I asked and Don obligingly swapped out his camcorder for mine. (I was raised in Missouri - the 'Show Me' State.) The auxiliary lenses all use a 37mm male thread to attach to the camcorder, and one thing I learned right off the bat was that none of the 3 thread adapters supplied with the MicroExplorer system fit the 46mm filter and accessory mounting thread on my Canon ES3000. However, Don had the necessary adapter to fit my camcorder on hand, which can also be readily obtained through a number of video and photographic mail order businesses. If your camcorder has 34, 37, 43 or 52mm accessory threads, you're all set right out of the box.
Imaged at right is an aesthetic specimen of endlichite (vanadinite) crystals on orange descloizite from a pocket at the 510 level of the Chalk Mountain mine in Churchill County, Nevada. This image was frame grabbed from video taken with the '140x' lens and provides a system magnification of about 28x if you're using 800x600 video resolution and a 15" monitor.
Raynox labels and refers to the auxiliary lenses as '35x', '70x', and '140x'. However, the calculation and specification of those powers is somewhat arbitrary, and also rather misleading in conventional optical terminology for component lenses. Raynox calculates these effective magnifications as total video system functions, to which the zoom setting used on your camcorder and the size of your display screen contribute as direct functions. Their system calculation assumes you are displaying the video on a 21" screen, and that your camcorder has a zoom lens which is set at 10x.
It's the zoom lens in your camcorder which actually contributes the lion's share of the optical magnification. By Raynox's terminology and methodology, if you used a 12" TV with a given lens and then swapped out the 12" for a 48" bigscreen, magnification gets quadrupled. I'm afraid I'm somewhat cynical and I suspect a bit of specsmanship may be at play here... While the image on
the 48" screen would be enlarged, it would not display any increase in resolution or detail.
I'll concede Raynox's method of specifying magnification makes some sense from a total video system perspective, where magnification has been defined to be the size of the output image divided by the actual physical size of the subject, as Raynox does. However, I feel those accustomed to using cameras, microscopes, telescopes and similar devices employing compound lenses would appreciate and understand a more conventional, 'optical' component quantification of the lenses' powers - consistent with terminology used to characterize magnifying glasses, telephoto extenders, oculars, objectives, etc. If you think of the zoom lens in your camcorder as a variable ocular in a video microscope, the Raynox lenses function as three separate, switchable objectives.
If the video screen size, camcorder zoom setting and distance from the subject are all held constant, it becomes a straightforward test to determine the conventional optical component power of each lens by simply switching them and comparing the results. That's just what I've done in the test described below.
Click each of these thumbnails to view the full size test images.
The test image marked 'None' was taken with my camcorder alone as a baseline reference. One
of the things I appreciate about my Canon ES3000 Hi-8 camcorder is it has a very nice 20:1 optical zoom with good macro focusing capability. I adjusted the distance to the subject and zoom for the most magnified, in-focus image I could obtain unaided, and then frame grabbed it as a 640x480 image. The actual physical distance shown on the specimen from one side of the frame to the other in the 'None' reference image is just under one inch. Leaving my camcorder's zoom setting and distance to the subject fixed, I then did successive 640x480 grabs to generate each of the test images marked 'With 35x, 70x and 140x', using each of those lenses to generate the corresponding images.
With all of the other variables affecting system magnification held constant, the relative amount of optical component magnification contributed by each Raynox lens is readily determined by measuring a selected feature, such as the length of a particular crystal, on each image. The relative difference in optical power between lenses and the baseline reference are simply the ratios of the selected crystal's lengths, as measured on each image.
The length of a prominent crystal in the center of the baseline test image without a Raynox auxiliary lens measures about 1.3" on my 15" monitor at 800x600 video resolution. Relatively, this is 1x, of course. With the '35x' lens attached the image of that same crystal measures about 1.6"; about 2.0" with the '70x' lens; and about 3.7" with the '140x' lens. Allowing for a little slop in my measurements, the actual component optical magnification contributed by the Video MicroExplorer lenses is approximately 1.25x for the '35x', 1.5x for the '70x', and 3x for the '140x' lenses. Compare that to my GemOro binocular microscope, a fairly optimal device for viewing microminerals, which comes outfitted with 10x oculars and turret selectable 1x and 3x objectives. The total optical magnification provided by the scope is calculated as ocular power times objective power - 10x when the 1x objective is selected, and 30x when the 3x objective is used.
If you've followed this video system magnification Vs. optical component magnification discussion so far, then you won't be confused when I also tell you that the particular crystal I used as a constant reference has an actual, physical length of .142" and therefore, if you view the full sized test images at 800x600 video resolution on a 15" monitor like I used, the baseline test image taken without a Video MicroExplorer lens provides a system magnification (displayed image to actual size) of 9x. That increased to a little over 11x with the '35x' lens added, to 14x with the '70x' lens, and to 26x with the '140x' lens.
By the way, in case you're wondering, the specimen in component magnification test images is a nice little cluster of pyromorphite crystals on matrix from the Pschelojad mine in the East Rhodopa Mountains of Bulgaria.
Shown at left are some more pyromorphite crystals from a different locality, the Bunker Hill mine in Kellogg, Idaho. This image was frame grabbed from video acquired using the '140x' lens.
It provides a system magnification of 26x when viewed using 800x600 video resolution with a 15".
If you do find yourself confused over the difference between component and system magnification, you don't need to worry about it too much if your principle application for the MicroExplorer is micromineral video photography. Assuming your camcorder has a zoom lens which you can set to 10x or thereabouts, the three lenses supplied with this system will put you right in the ball park for viewing and video photographing most micromineral specimens. The majority of them are best viewed at total optical magnifications between 10x and 30x, with few requiring more than 60x. If your thing is looking at or photographing bacteria, this is not the product for you, and you are going to be very disappointed if you interpret the '35x', '70x' and '140x' as literal component powers and think you are going to get an effective optical magnification of 1400x when you compound the '140x' MicroExplorer lens with a 10x zoom setting on your camcorder.
You may be wondering since your camcorder zoom lens functions as a variable power ocular in the video microscope, why 3 lenses, why not just one - the most powerful one, and just zoom up and
down with the camcorder? The reason is that each lens is designed on the assumption you'll be using something near a 10x zoom setting with it. Shown at right is an example of what happens if you zoom down too much (about 3x here) - vignetting and distortion of the image result. Multiple lenses are required cover a range of magnifications and allow for optical optimization.
That's galena dusted with pyrite from an unknown locality. An interesting specimen to view with just a 10x hand loupe. By the way, if your interest in microminerals and micromounting is still at the casual level or you're on a really tight budget, do not underestimate the enjoyment
to be had with 'just' a good quality 10x hand loupe. If you can afford it and can hang on to
it, invest in a 'triplet'.
If I've got bones to pick regarding the Video MicroExplorer, one is over the stability of the
camcorder support arm. This injection molded part is mostly hollow with the
gear rack for the height adjustment and reinforcing ribs molded in. The support arm can be adjusted horizontally to center the optical axis of your camcorder width-wise on the stage, a nice touch. Unfortunately, the support arm and its mounting are somewhat lacking in the rigidity and damping department. Raynox cautions not to mount camcorders weighing more than 2.6 pounds on the arm. Mine weighs 1.7 pounds. Each time I manipulate a camcorder's control button, even with the lightest of touches, it sets the camera oscillating on the end of the support arm and it takes an annoying amount of time for the oscillating to damp out. This problem would be very annoying if you were using the Video MicroExplorer for live group presentation work, such as in a classroom or lecture situation.
Imaged at left are some striking turquoise colored, botryoidal clumps of rosasite from the Silver Hill mine in the Waterman Mountains in Arizona. This image was frame grabbed from video acquired using the '35x' lens. It provides a system magnification of 8x when viewed using 800x600 video resolution with a 15" monitor.
Another bone of contention concerns sponginess and spring in the height adjustment knob, which directly drives a relatively coarse, plastic pinion gear engaging the molded rack on the support arm. This height adjustment is used in conjunction with the camcorder controls for focusing the image. Depth of field is inversely proportional to magnification, and when higher magnifications are employed, the focus becomes a chore to adjust with this knob.
There is a simple, clamp-type height adjustment friction control/lock mechanism provided, but even when it is adjusted to provide minimum friction for the height adjustment control, there is a springy action to it. You'll turn the knob to achieve optimal focus, and when you release it, it springs back slightly, throwing off the focus. You wind up having to overturn a guestimated amount to compensate for the spring-back, and then releasing the knob to see the result of the adjustment. Plastic... you can't live with it, and you can't afford not to.
While the auto focus on my camcorder performs admirably with the MicroExplorer lenses, it is possible to get into situations where manual focusing is required. Both the zoom and manual focusing controls on my camcorder are uncomfortably fast for fine focusing chores using the Raynox lenses. An additional, mechanical fine height control is really needed to help facilitate critical manual focusing at higher magnifications. A KISS implementation with a mounted specimen
might be adding or removing a sheet of paper under its mount.
These problems with the support arm and height (focus) adjustment manifested themselves right
away when I demoed the Video MicroExplorer in Don's room at the Executive Inn. I complained about them then, and Don was the first to agree that they could certainly be improved. I asked
if it was possible to purchase just the glass, as a set of lenses or even separately, but I'm
afraid if you want only them, you'll have to buy the same box for the same price and get the
stand for free. That's what I did. ;)
At right is a dolomite crystal on galena from the Westfork Mine in Reynolds County, Missouri, imaged with the '140x' lens. When viewed with 800x600 resolution on a 15" monitor, the system magnification is 24x.
I do have a large, rock steady, home brewed video copy stand that I could use to support the camcorder while using it with the lenses, but it's really too cumbersome to drag out and set up for convenient use. I keep resolving to fabricate a custom stand and camera support scaled to MicroExplorer use. But you know what? While the stability of the support arm and height adjustment with standard hardware could use some improvement, after nearly a year, I'm also still using it. It is usable as supplied and I guess these problems irritate me enough to notice and complain, but not enough to spend the time to do something about it. Life is a compromise, eh?
I do find the light table built into the base of the Video MicroExplorer to be downright handy.
Shown above are reduced versions of three images made using backlight provided by it. Click them to view the full sized images. At left is a rutilated smoky quartz crystal. The full size image provides a system magnification of 10x when viewed at 800x600 video resolution on a 15" monitor. It was frame grabbed using the '35x' lens. Center is a "fire quartz" crystal from Madagascar that's included with lepidochrosite and hematite. It was also made using the '35x' lens and the full sized image provides a system magnification of around 20x when viewed at 800x600 resolution on a 15" monitor.
At right is a three phase (gas, liquid and solid) inclusion inside an enhydrous channel in a long, thin selenite blade from Durango, Mexico. It was grabbed using the '140x' lens and the full sized image provides about 160x system magnification when viewed at 800x600 on a 15". In case you're wondering how I managed that, I used a nearly full power (20x) zoom setting on my camcorder. The depth of field is shallow at this high magnification and you can only focus a rather narrow cross-section of the gas bubble at any given time. The irregular, striated surface of the selenite crystal contributes significantly to the fuzziness of this one.
I don't use the light table lamp nearly as much as external sources for top and side lighting opaque specimens, but a jack to supply 6 volts DC for that lamp from a line powered, 'wall mounted' type transformer would be an appreciated improvement. The fluorescent lamp is pretty efficient as light sources go, but it takes 4 AA alkaline cells a pop to replace the batteries. Raynox does supply the first set. You can be sure if I ever build a custom microscopy stage and mount for my camcorder and the MicroExplorer lenses that the light table will incorporate a line powered supply for the lamp.
I guess I don't need to tell you the Raynox Video MicroExplorer works for me! It has proven to
be a valued addition to the toys, er... tools that I employ for creating Bob's Rock Shop. The Raynox MicroExplorer provides a convenient and expeditious solution for adapting a camcorder to image microminerals and of course many other small and microscopic subjects, such as scorpion stingers, fly wings and cockroach eyes...
Is this product for you? If you're just getting started with micromounting, on a tight budget, and don't yet own a binocular microscope, my advice is to save your money and acquire one of those first. An entry level binocular scope, such as the GemOro, will dramatically outperform the MicroExplorer for as a portal for personal viewing of microminerals. However, if your needs and applications entail video acquisition or presentation and sharing of micromineral or other microscopic subject images with an audience, here is a product that definitely merits your consideration.
While I've voiced several gripes with the ergonomics of some of the Video MicroExplorer stage mechanics, it might help to put them into perspective by relating that I spent some years doing technical and product development work for Boeckeler Instruments, a world class manufacturer and OEM of precision microscopy metrology and video measuring devices, serving scientific, medical and many other industries. There I became accustomed to working with extremely fine (and expensive) precision mechanics and I'm still somewhat spoiled from the experience. And yes, I griped about some of Boeckeler's stuff too... that was part of my job.
The Raynox Video MicroExplorer can be ordered from:
Parsons' Minerals and Fossils
2808 Eden Lane, Rapid City, SD 57703 USA
Phone: (605) 348-0937 Email: email@example.com
Don is also a dealer for other Raynox products, 35mm SLR micro and macro add-on lens sets, and wide angle and telephoto lenses for most of the digital still cameras including the Apple QuickTake 200, Sony, Kodak, Olympus, Ricoh, Casio, Epson, FujiFilm and others. If you're
interested in photography and digital imaging accessories of this nature, you may find a visit to the Parsons' Minerals and Fossils Web Pages engaging.
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