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Optical Tools to Get “Up Close and Personal” with Bugs, Plants and Rock...
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I want to share some experiences with optical tools that bridge the gap between distance viewing and microscopy. These offer a lot of natural history appreciation on clear or cloudy days, and cloudy nights. There are several ways to see the details we usually associate with ‘macro’ photography, at magnifications that bring us closer than inspection with the unaided eye but fall short of those used with typical prepared slides and medical-purpose microscopes.
The Spotting Scope as “long range microscope”
The Celestron C-90 is a compact and lightweight 90mm f/11 Gregory-Maksutov-Cassegrain. My first impression of a yard-sale C-90 was its roughly 3-pound weight that can ride well on many camera tripods. The aspect that impresses me more over time is the close-focusing ability. With a 1.25-inch Plossl 30mm or 32mm eyepiece in the 45-degree correct0iamge diagonal, the C-90 operates around 35x and offers almost 1.5 degrees field of view. Focused at 20 feet or less, that view shows the detail in the iris of a rabbit’s eye, the feather details of a perched bird, the fur and whiskers of a packrat, or pollen clumps inside a flower.
The C-90 used at the close end of its focusing range is a long range microscope. Focused at 100s or 1,000s of yards the C-90 is a nice spotting scope for water birds or bighorn sheep. The C-90 holds up well compared to an 80mm refractor for astronomy use; the same ~ 33x low power view at infinity focus nicely frames the Pleiades or the Double Cluster, and lunar detail is very nice up to 100x or so with a 12.5 or 9mm eyepiece with a 90 degree star diagonal.
I doubt that the C-90 is the only ‘scope to offer such close-up views. There are other small “Maks” and small achromatic or “ED” refractor scopes from 50 to 80mm that are just as compact. The small Cassegrain designs achieve close focus in part because their moving primary mirror focusing system provides what is in effect a very long focuser travel. Traditional spotting scopes that use a short-travel helical to move the eyepiece in and out may not have such a close-focus capability. Owners of the smaller ‘sparrow hawks’ 50mm to 80mm interchangeable eyepiece finder from Stellarvue, or the current smaller achromat and ED refractor scopes, might want to check out close focus views in daytime. Closer focusing (via longer focusing travel) could be achieved with these small refractors by adding an extension tube before inserting the eyepiece or diagonal. A correct image diagonal is recommended, of course. The only drawback of the extension tube is that infinity focus may be lost while the extension is in place.
I keep the C-90 on an old camcorder tripod to allow for grab and go day-time nature or white-light solar filter use, and lunar observing. The Bogen ‘micro-fluid head’ 3126 can handle the C-90’s light weight fine and makes for an easy one-hand grab and go setup with the light 3001 tripod. The stock 5x24 finder is sharp but I seldom use it at night. I prefer a small red dot finder as a night time finder for the C-90, and learned to sight along the OTA well enough, or use the inverted image finder in daytime.
Papilio binoculars get closer than other models
Compact roofs may focus close to let you watch a floating butterfly, but the Pentax Papilios will show you a bee’s stinger and even smaller creature’s features. The Papilios focus by moving their 21mm objective lenses, and the objectives converge to maintain field overlap at close distance.
6.5 Papilio experience –
I use these more than any other daytime binocular, largely due to their light weight and ease to carry along for a hike, in addition to the ‘bonus’ of their close focusing ability. The ~ 50 degree FOV is pretty sharp and with the sharp field edge does not feel restrictive. Although not waterproof, they survived a whale-watching cruise with some spray wiped off with a sweatshirt. At closest focus the 6.5x magnification is increased, and these are like looking through a ‘macro’ lens for an SLR camera, with a greater than life size view showing the pollen combs on a bumblebee’s legs, or the multiple eyes of bees or spiders.
Some other roofs or reverse Porros that focus to about 3-5 feet would allow for insect ‘behavior’ observations at somewhat lower, just less than life-size magnification. The Papilios allow for a closer look up to 1.6 feet, which requires a steady had for the depth of focus but shows impressive detail. The Papilios could serve as a low power stereomicroscope if attached to a device like a photographic copy stand.
8.5 Papilio feedback sought –
I’d like to read on the CN forum discussion from people who have used both the 6.5x21 and 8.5x21 Papilios. I seen several readers ask “which should I get 6.5 or 8.5?” and some people like me may wonder “is it worth the outlay to have both?”
I like the brightness of the 6.5 and wonder if I would be put off by the smaller exit pupil of the 8.5, and if the 8.5 suffers any when sharpness is compared since they have a wider FOV of 60 degrees or more (the 8.5 provide nearly the same true FOV as the 6.5). Eye relied might be another important factor in choosing, because of the necessarily different eyepieces of the 6.5 and 8.5.
Monoculars and Pocket Microscopes
Swift combination monocular/microscope Model 777 –
This is a decent vintage Japanese-made coated optics 8x30 monocular with over 8 degree true FOV. I’m not a monocular fan so I only gave this some backyard use to appreciate a pretty good image day and night, relative to our windowsill Porro binoculars. Since then, the 777 remained paired with the supplied close focus adapter, a positive achromat that screws on to the front of the monocular and has a sturdy clear plastic skirt that serves as a stand. Some care is needed since the device is tall and narrow when assembled (you wouldn’t want it to fall off a table). I estimate the magnification to be between 30x and 40x with the adapter. The monocular and adapter both fit in a leather belt-loop carry case that could go on a hike, but I’ve only used this for tabletop science exploration in the house or in the backyard.
The Swift recently let us explore a dead beetle the kids found, showing the segmented antennae, the tiny gripping claws at the end of each leg, and the patterns of its compound eyes and of the pores or reinforcing corrugations in its exoskeleton. This shows the small crystals seen in some volcanic local rock well too, making a sparkling cave out of a tiny bubble in the rock. I’m impressed by the brightness and apparent sharpness of the view through the Swift compared to smaller and/or more powerful pocket microscopes that I’ve tried. If an object will inside the 1.5-inch diameter base, you’ll get a great close-up view with the Swift 777.
Close-Focusing Monoculars –
There are similar devices to the Swift that I’ve seen over the years. Some are hybrid monocular/microscopes like the Swift and others are close focusing monoculars.
Lately I noticed the Brunton ‘Macroscope’, a close-focusing 7x42 monocular with a tripod mounting block. It might perform like a brighter, one-eyed Papilio in use, allowing very close focus to the life size ‘ballpark’.
Edmonds and other gift catalogs sometimes show monocular/microscope combinations. The 8x30 Swift is larger than most of these, which seem to have lower power and smaller objective diameter monocular components. I’d suggest finding reviews or trying out at a store.
Edmund 50x pocket microscope -
This is a classic from at least the 1960’s. The Edmund Scientific 50x pocket microscope is the size of a fountain or thick ballpoint pen, and its overall construction is reminiscent of the green 30mm Balscope spotters from that era. It’s a compound microscope with fixed 50x magnification. At the object end a polished tapered chrome mirror serves to focus light on the subject, protect the objective, and provide a support point on which the microscope can be rocked back and forth to achieve focus.
This provides a narrow focus plane view of a field at most a few millimeters across. Compared to the Swift, the view is darker – a bright light source is needed, a small ‘high intensity light’ desk lamp indoors or the sun, with one’s eye kept in shadow, outdoors. While the sharpness is impressive for the size of the device, the apparent sharpness isn’t quite up to the view perceived through the Swift. Carefully cleaning the tiny objective helps achieve top performance – just a couple of dust fibers seem to make a difference in the view. I have two of these; one is from a day-trip to Edmunds in Barrington, NJ that my dad provided with several rocket-building and star-gazing friends along. The other example was a yard sale find, and it has a nice clear plastic skirt with locking height adjustment, that also allows the microscope to rotate within the skirt to best position the reflector.
Next Step – the Stereo Microscope or ‘dissecting’ microscope
I’ve been intrigued by these since college geology and biology classes, and have followed occasional discussions on Space Rocks and Cloudy Days forums with interest. A stereomicroscope adds a 3-D view, with the comfort of binocular viewing, to close-up examination. There are imported models that seem to be sourced from the Far East and perhaps Russia. The only one I’ve looked through in recent years was the Celestron 20x-40x, which has fairly wide angle (I’d guess over 60 degree AFOV) 10x eyepieces and a turret with 2x and 4x objectives. Eye relief seemed like it might be close for eyeglass wearers. It had a good built-in illuminator and uses 120 V AC wall outlet power. I hope to read more feedback about these types of scopes, as the discussion found searching on CN has been a little sparse.
Improvise and Explore
Years ago my dad helped me sandwich thin metal flashing between washers, in turn held between filter rings, to grip the eyepiece threads and allow afocal photography with the 50x pocket microscope. After working out focus, 3” x 4” Polaroid film packs produced nearly-sharp but exciting photos of insect eyes or wings, leaf veins and mineral crystal subjects at about 75x on film. Making an adapter ring to try this with a digital camera would cost much less per shot today, and probably be much easier to focus!
Before I paid top dollar for a geology loupe I used an eyepiece from pawn shop binoculars to make one that seemed to work as well at about 15x, with a larger eye lens and eye relief than some of the specialty catalog triplets. Then I found that the two objectives held in a PVC fitting made a large ‘symmetrical’ magnifier for lower power use.
Even kid’s microscope kits are likely to offer better views than van Leeuwenhoek saw (much as we can tell people at astronomy outreach, comparing binoculars or modest telescopes to Galileo’s tools). The close focus limits of our astronomy telescopes may offer up new daytime views of small wildlife. So try taking a close-up look at the “macro “world around you while outside, or study a few small treasures from it on a cloudy night.