Another Entry Level Microscope

The Bausch & Lomb Standard Teaching (hereafter ST) microscope is hardly the finest instrument one may buy, though it is a true and reliable stand. Carrying on the great tradition of simple and rugged construction begun with consumer microscopes designed for both student and arm-chair scientist the ST is descended from the FL (For Learning) of decades prior. For a look at a far earlier version see this previous post.
Immediately recognizable by its B&L slate-gray enamel one will always know an ST or FL upon sight. Telling one from the other is simple as well, meerly glance at the fine focus. If it’s located at the inclination joint it’s of the ST line. A fine focus on the arm above the joint is indicative of the FL line. There are a number of less immediate means of identification, the contruction of the foot, the mechanics of the coarse focus, the presence or abscence of a focusing stop, and the finish of the stage, to name a few. This is about the ST though, so on with that.

As with most B&L lines there are more variations on the basic ST stand than one would expect ranging through optical components to convience features. Apart from the regular ST there is also the Inclined model (IST) which carries a two piece body tube with prisim adjusted angled ocular tube. It’s called the ST for a reason though and the versions that could be had ranged from the very modest too three objective, condenser equipped models with mechanical stages suitable for entry level bacteriology, and other oil-immersion work. The most advanced models made use of the same objectives as the flagship Dynoptic line, their compromise was the slide focusing condenser. A slide focus condenser is not to be sneared at, but when used with an external illuminator one may be hard pressed to secure Khler illumination. Pressing a simple substage to its limits and restricting the user to a monocular system the advanced end of the spectrum is not where the ST shines.

At the lower end one finds the ST in its element. The not quite there, complecated yet inexpensive condenser set up is replaced with a simple rotaing disct diaphragm and either concave mirror or Optilume lamp. It’s worth mentioning that B&L with the ST line once more holds to the concave mirror only (for condenserless substages). The Optilume is well suited too, offering a bright field of view and on/off simplicity.
Perhaps the most laudable feature is one that more advanced users will never make use of. The ST microscopes take seriously the inexpert focusing of the student or novice microscopist. However much one drives home the importance of the microscopists obiesence there are those who will insist upon obtaining coarse focuse with eye at the lens, all such marksmen should be forced into carears as snipers. The ST line repesents the first standard Prefocusing Gage from B&L.

This simple addition has doubtless saved more than a few slides from the hazards of crashing objectives. The Prefocusing Gage is a humble projection from the body tube through which a theaded hole has been bored. A hexagonal set screw is fitted through the hole and a smaller flat headed set screw penetrates from the side to lock it in place. In use one need only to place a slide between the gauge and arm and gently rack down the coarse focus until contact is made. Removing the slide to the stage one will then find the specimen in rough focus and need only touch the fine focus knob until examination is complete. As with most every microscope of quality the objectives are parfocal so the utility of such a device should be obvious.

If one has other stands at their disposal one may see quickly where costs have been saved on the ST microscoscopes. The fine focus mechanism is mechanically identical to that of the Dynoptic but there is not graduation upon the adjustment. The body tube has been cast from a single mould so that nosepiece and ocular tube are permanently in place. The stage likewise is cast as one with it’s mount and may not be exchanged without likewise replacing the entire substage.

For those people out there who have and use an ST or IST here are some useful measurements from the manual (I’ll get around to uploading a scanned copy of it sometime).

First the table of approximate equivalent size of the pointer in the plane of the specimen:

Then the table of magnifications with the same 10x Huygenian eyepiece:

Mosquitoes Part II: Larval Breeder

Ask someone where to find mosquitoes and they’ll likely answer with some clever little quip. “On my patio” or “wherever I hang my hammock” they might reply, doubtless referring to the bites of adult female mosquitoes out for a blood meal. When asked where to find mosquitoes larvae these same comedians may be stumped. Finding mosquito larvae in areas where they are endemic is surprisingly simple, just find the water.

Look for standing swatter, without fish, even tiny ones. Don’t think just because the garden lacks a pond there aren’t mosquitoes breeding surprisingly close to home. A bloodbath, a puddle beneath the garden spigot, the terracotta base of a potted plant, all may be home to scores of squirming mosquito larvae. Even if it hasn’t rained in weeks one might find that condensation from a window air conditioner has built up in a clogged rain gutter to provide a tiny oasis for breeding mosquitoes.

During their aquatic stage larval mosquitoes eat by filter feeding. They’ll feed on aquatic bacteria, fungi, algae, and nearly anything else that they can strain out of their battery habitat. However clear that water in the dogs bowl in the garden one may rest assured it contains enough microscopic food for the larvae to developers so don’t think it isn’t worth checking. Additionally don’t overlook a potentially rich breeding sight simple because it doesn’t seem as if it could contain enough water. The cup-like bases of numerous plants accumulate water in which a number of mosquito species may breed, and the Asian Tiger mosquito has been introduced to the United States via the scant water held in automobile tires shipped from overseas.

Housing the larvae is really a simple matter. Any wide-mouth clear vessel will do in a pinch, but a special breeding vessel is simple to make and removes the difficulty of capturing adults without them escaping.

Gather the supplies:

  • 2 identical plastic containers with lids.
  • 1 fine mesh screen (just a few cm square)
  • 1 99 cent store plastic funnel
  • Hot glue or silicone caulking
  1. Cut a hole in the bottom of one plastic vessel. Make it as big a hole as you can while still leaving enough flat surface for gluing the screening.
  2. Glue the screening over the hole and set aside. This part will be the top of the breeding chamber.
  3. Cut out the center of the two lids, leaving a small amount (2-4mms, 1/8-3/16in)of flat surface.
  4. Cut the top (inlet) of the funnel so that it is of a size to rest on the rim remaining of the lid.
  5. Cut the bottom (outlet) of the funnel to remove the stem. If the remaining opening is smaller than a flying mosquito, cut it larger (about 1cm, 3/8in).
  6. Place on lid right-side-up on the work area and place the up-side-down funnel upon that. Connect the two using hot glue or contact cement.
  7. Fit the second lid up-side-down over the funnel cone and glue the whole together.

With the whole thing assembled and the glue dry the only thing remaining is to place the collected water and larvae inside and wait.The vessel with the t is the top of the breeder, while the unaltered vessel is the reservoir. When placed in a Northern window (for those in that hemisphere) the microorganisms on which the larvae feed will thrive and in a matter of days develop into adults. The adults will fly up into the cone of the funnel and become stuck in the upper chamber. At this point the upper chamber and cone can be uncoupled from the bottom and briefly frozen to stun the adults for transfer to a suitable killing vessel.

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Large vessel in Northern exposure window.

I like to use containers that have a bit of a recessed lid, the inexpensive plastic food storage canisters sold at most grocery stores work great. With those sorts of lids it’s important to fill in the area where the funnel passes through the second lid so that there is no area in which adults may become stuck. This sort of breeding vessel is suitable for many aquatic dipterans. In the case of mosquitoes it could be a good idea to first paint the top half (when assembled) of the vented vessel black. A number of mosquitoes are known to be attracted to black preferentially and it can serve to speed their transition through the funnel trap into the top vessel. If a large number of breeders are going to be assembled it could be a good idea to purchase a large roll of fine, stiff, mesh. Using the mesh one can form a significant number of funnel traps at exceedingly little expense.

Mosquitoes Part I: The Zika Vector

For residents of the United States it’s been hard to ignore the alarmist “news” about the Zika virus this spring and summer. Like a number of tropical diseases it’s mosquito borne and the particular vector is Aedes aegypti.

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Zika? No! This is a male and it’s the wrong species!

Individuals in northern areas may feel somewhat reassured by the fact that vector insect population data from the Centers for Disease Control shows only a scant few places where A. aegypti have become established. Well… that information is out of date at best and flat out wrong at worst. After all, this is the yellow fever mosquito we’re dealing with. Remember yellow fever, they used to all it the American plague, no one should be surprised that this particular mosquito is all over the place in North America.

Want some specific location data? I’ve been sampling populations in my area (at two locations one 30 miles East of Rochester, NY, the other a further 10 miles East of that) for a few years now just for fun. Wonder of wonder, there’s several species around, including A. ageypti. What’s better than my word? Your own hard data, lest we give in to the complacency of ignorance lets find out what mosquitoes we have in our own backyards!

I should point out that one doesn’t need a microscope to identify mosquito larvae, nymphs, or adults; but in each stage of development they’re wonderful subjects for the microscopist. Larvae (eggs too if you find them) and nymphs make wonderful live or preserved specimens. Newly killed adults may be examined nicely in temporary mounts. Permanent whole mounts in resinous media are only a little more involved. Unlike with other flying insect species, prepared slides of the mosquito life cycle are widely available, but they’re so simple to do at home anyone who isn’t in a mad rush should really consider it.

Obviously one will first need to get a quantity of mosquitoes. Before rushing outdoors to wait for a hungry little vampire in search of a blood meal to land on an arm (which is an option for the impatient) consider: a feeding mosquito will be female, will probably be damaged during capture, and must be suffered to bite. It’s a great deal simpler to collect mosquitoes with a live trap (for adults) or a turkey-baster (for larvae and nymphs). In fact, anyone with an empty jar can run out and collect hundreds of mosquitoes in an few hours, if they consider the aquatic larvae sufficient; and they are! Those larvae will become adults in short order.

This isn’t a series about how to prepare permanent mounts of the specimens, this is about how to get them, and observe them in temporary mounts. Some other time we’ll get into permanent mounts of mosquitoes for now the goal will be simple and three-fold:

  1. Locate a likely source of mosquito larvae, and collect some.
  2. House those larvae in a vessel in which they may mature through all stages of development.
  3. Sample and observe specimens from that vessel representing each stage.

Hey check it out I can be topical! -K

B&L Photomicrographic Apparatus VI: AX-1

The final development, before the microscope camera went from still-chemical photography to motion/still digital photography is equal parts groundbreaking and re-purposing. Like the System II the new version maintained the same basic layout and universality, it was made compatible with all the camera backs of the System II. It retained the focusing knob (to date all those known are marked at 3x, 5x, 7.5x, and 10x) but departed from the consumer camera style shutter speed selector and remote shutter release; the new camera was automated.

Since the earliest days of photomicrography it was just assumed the the microscopist would be the darkroom technician as well. Those seeking to record images of their work were expected to practice and understand the skills needed not only for obtaining a clear, useful image at the eyepiece, but at the imaging surface of their camera, and final media as well. Books from the golden age are filled with detailed information on how to properly compose and sequentially expose test images. Entire chapters in books on general microscopy are devoted to the proper taking of photomicrographs. In detailed texts on photomicrography extensive chapters describe the best way to salvage (and in future avoid) over or under-exposed films. The AX-1 changed all that.

 

For a generation that grew up (or like the author, grew complacent) with the automatic exposure and aperture cameras of the “Kodak Moment” era, the AX-1 no doubt seems unduly complex. A two variable analog meter, no less than six buttons-two thirds of which light, two additional indicator lights, four tumbler set values, all run off of a grounded AC plug in a package the size of a lunch box and weight of a bag of sugar is understandably daunting. The space-hogging controller is only half the unit and like it’s counterpart is entirely useless without the automatic shutter assembly camera. As previously mentioned it is superficially like the System II but in place of a release bears a nine pin cable and connector that conducts light data from its integrated sensor to the control box and carries the exposure signals back. A small electromagnet actuates the simple shutter, and the photo-sensor is positioned to one side of a right angle partially silvered reflector.

To allow for the proper calculation of required exposure one must set a few parameters on the controller before beginning. Film speed is dialed in using A.S.A. units and it’s worth noting that the controller uses the 1960 revision (from what I can tell in use, I’ve not been able to locate anything in the documentation). One must also select the desired reciprocity, which is best left set to “OFF” for most uses. Setting the level of magnification to the nearest value marked on the shutter informs the photo-sensor of the general range of light intensity and is vital for achieving accurate exposure times and light levels. One may also set the desired exposure to a fixed value darker or lighter than the calculated exposure which may be useful for those who want to avoid pushing or pulling during processing.

Once properly set up the user is ready to set the focus of the shutter assembly, load film, power up and begin taking pictures at the push of a button! Imagine, no need to shoot and develop costly trial exposures or to calculate required shutter speeds/exposure times by hand with based on light meter readings. The device can serve as a light meter only and exposure may be done manually at the press of a button. The controller can be put on a separate table and the only source of vibration limited to the movement of the shutter itself. That’s probably the chief point in the AX-1’s favor these days, but it may still be worth while for those more willing to give it the space than to learn about shutter speeds.

-K

Housekeeping

As I’m sure someone (apart from myself) has noticed posts have been becoming increasingly wide-spaced. In no small part this has been due to the continuing demands upon my time made by life. Unwilling to part with time spent at the lens I apologies that sharing this enjoyment has been the aspect to suffer. An inexpensive recent acquisition may help in correcting the issue, and it is the device used to compose this post.

The new tool is a strange thing, the Alphasmart Neo2. Little more than a keyboard with monochrome liquid crystal display it has the valuable feature of a year long battery life (honestly 700 hours is the claim) and instant on/off with no need for tedious file-management. It’s felt that this will enable the composition of posts without the need for booting up or toting around the laptop. If need be I can even transfer the text directly to the WordPress application on my cellular telephone. Tragically, editing is an impossible task for this device but composition is a breeze and exceedingly convenient. In future, if the device proves an asset, posts may be less orderly but no less verbose-I’ve chosen to embrace my tendency to wordiness.

On a final note, to the woman who attempted to contact me with a question concerning the sort of microscope used in the 40’s; the email address you provided was not apparently accurately typed and my response was bounced back. If you are still at a loss you know how to reach me.

-K

B&L Photomicrographic Apparatus V: System II

A Re-design

The System II represents a fundamental change in B&L integrated photomicrographic cameras. Sleeker than the early DynaZoom camera but far more substantial than the later versions, the System II is a step back to the design principles that required a focusing system. It was necessary for the System II to feature a focusing lens system because the unit was intended to be a new universal device for all (camera ready) professional B&L lines, including the earlier DynaZoom/DynOptic lines. Despite maintaining the compatibility of the system with earlier stands, once more the camera backs required are not compatible with previous versions (although they do come in all previous formats).

New Features

The opticians behind the System II seemingly asked themselves ‘how can we make this the last camera a microscopist will need?’ and set about answering it. The systems chief major departure is the coupler, specifically its diameter. At 7/8ths it’s a full quarter inch larger than the previous model DynaZoom camera, and a return to the large size used with focusing DynaZoom cameras. Care was also taken in the design of the coupler, it was made to be removed and a number of versions of the coupler were made, some making allowance for the use of a manual exposure meter.

Once more the camera back attachment point was redesigned. The new male dovetail fitting was made a bit smaller than those used previously and unlike previous models did not feature an alignment screw that required the female dovetail camera back be fixed in relation to the camera. Additionally, where earlier camera backs used two thumb screws the new versions used only one; making it a simple thing to orient the photosensitive surface however one wished without being forced to suffer an inconvenient shutter release or winder position.

Couplers and Camera Backs

Three couplers are known of: the silver Bal-Coated male dovetail, the black lens-less male dovetail, and the eyepiece mount. The silver dovetail makes good use of a Bal-Coated lens to eliminate errant reflection which can prove frustrating with uncoated optics and both it and the black dovetail carry a small slot in the dovetail that mates with the camera. This slot may be turned to align with a similar slot in the System II or turned so as to exclude all light. The purpose of the slot is to permit the insertion of the B&L Cat. # 421240 exposure meters sensor.

Versions

The versions are discrete rather than explicit, which is to say there is not any particular model number to distinguish them that is official but they are readily identifiable. One sort is focusable from below 3x to over 10x. On these models only four magnifications are marked: 3x, 5x, 7.5x, and 10x. Two versions of this sort are known, one having an all black shutter speed selector and the other having a silver ring. An additional version, and perhaps more desirable (if less common) one has the same range but is marked in one unit increments from 0-25x with every fifth mark being numbered.

Accessories

Apart from the previously mentioned camera backs a number of accessories were produced. Special viewfinder adapter plates and eyepieces were available for the various camera backs. It should be noted that these eyepieces were not the film area viewfinder eyepieces that would show the field that would be covered by various popular film sizes. Extension tubes were also available that would extend the distance between the final lens element of the shutter assembly and the camera back. Tubes were made in 2.5x and 5x lengths were produced and could be used in various combinations where special needs required.

Notes:

∗It should be noted that the connection to the shutter in all cases is a male dovetail and the designation here refers to the connection to the microscope photo-port.

†I’ve seen one in use during the course of a museum visit although I’d be hard pressed to say if it were an actually B&L item or the product of a machinist and a tight budget.

B&L Photomicrographic Apparatus III: Integrated Cameras

Microscope Stand Design

Around the halfway point of the last century (1940 or so) microscope design began to change drastically. Modern manufacturing and engineering, together with the proliferation of compact, bright, electric lamps contributed to an opticians ability to design microscopes which provided a new option for the photomicrographer. Contemporarily advertised as tri-nocoular (but more properly referred to as photomicrographic) microscopes began to become available with specialized camera ports that did not require interchanging a binocular body for a monocular body, or the occupation of a standard eyepiece tube by a cumbersome attachment camera.

At the time this was a considerable advance and as photographic process became more accessible and streamlined so too did the process of making ones microscope ready to capture an image. In many cases a microscope could be used visually as normal and simultaneously outfitted with appropriate apparatus capture images on a variety of media. Ones microscope could stand ready for either photomicrography or visual use and a great many sights that were only previously fleeting could be captured.

Regrettably, while some mechanical aspects such as the Royal Microscopical Society (RMS) thread, or 23.2mm eyepiece have become standard, the same can not be said of photomicrographic apparatus. For obvious reasons apparatus from one manufacture may not be compatible with another. Infuriatingly, apparatus from a given manufacturer may not be immediately compatible with a different line or generation of microscopes.

The Systems

It can be impossibly difficult to find information on the integrated camera systems of Bausch & Lomb, so forgive any inaccuracies and permit the establishment of two broad categories; the DynOptic/DynaZoom (hereafter DynaZoom camera) and the Integrated Camera System II (hereafter System II). Each was available with a range of formats and in a variety of styles with various interchangeable or permanently fixed accessories.

The DynaZoom camera was created specifically for the so named line of microscopes and was available throughout the life of that line. When the black finish stands were replaced by the slate finish models the cameras followed suit but maintained the established standards and are interchangeable with the earlier versions and vice versa.

The System II was in simultaneous production with the DynaZoom but was created so as to be compatible with a wide range of microscope lines and to offer improved options and forward compatibility. While still compatible with both the black and slate DynaZoom microscopes it could also be fitted to StereoZoom, and BalPlan microscopes as well as Bausch & Lomb Bench Metallographs, and inverted microscopes. System II also saw the introduction of automatic shutter control with electronic light metering.

One may immediately identify the camera system because in the DynaZoom cameras of every sort there is no independent magnification (focus) control. System II cameras of every sort feature a vertically oriented magnification (focus) control which may be marked from 0 too 25 or from 3x too 10x.

Sorry for the long silence, computer failure and a new job have eaten up a great deal of my time lately. I promise the next post wont be so far away. -K

B&L Photomicrographic Apparatus II: Attachment Camera

The Attachment Camera

The attachment camera as designed by Bausch & Lomb remained primarily the same over its production life. Changes to the apparatus itself were minor and all components have proven interchangeable if one is faced with assembling a complete working device from multiple units purchased separately for parts. The shutter features the following speed settings: 1/10, 1/25. 1/50, 1/100, 1/200, B, and T, and uses a standard cable release. There is no prism release as may be found on attachment cameras from other manufactures. This is a bit of a trade off, as without the prism release one can not direct 100% of available light to the camera. Fortunately, absence of a prism does eliminate its motion as a source of vibration during exposure. In place of a swing out prism a preferential beam splitter is fitted which directs 85-90% of available light to the camera and from 10-15% to the viewer. Aside from the camera itself (see below) the part most likely to be missing is the ocular sleeve which is a metal collar that slips over the tube of the microscope prior to the fitting of an ocular. The sleeve holds the shutter assembly in alignment with the optical axis of the microscope and holds the beam splitter at the exit pupil of the ocular.

This design requires a vertically oriented microscope tube. If used with a classic style B&L Dynoptic binocular microscope one will need to obtain the interchangeable monocular body. When attached the viewfinder projects horizontally towards a seated microscopist. There are two varieties of viewfinder both projecting significantly from the axis of the microscope so that the microscopist need not lean in uncomfortably when using the camera. Each sort makes use of a ground glass screen which the older version views through a large fixed focus condenser. The newer variety uses a spiral focus condenser that improves the clarity which one obtains to a certain extent, but does require that the user lean in towards the lens for proper viewing. Focus is entirely via the controls of the microscope.

Cameras

The camera bellows and bodies that are available for the unit run the gamut. Most common of the camera attachments is the 35mm camera body. The camera itself is often quite diverse and might be any of a half dozen different models. As of this writing the author has found the following 35mm camera bodies: Argus (stripped down, unknown model), Kodak Pony (without view finder), Kodak ColorSnap (complete with permanent lens mount). There are two lengths of bellows tube for the 35mm camera, one providing a 5x enlargement, the other 10x. Each tube is equipped with a dark slide.

Less common is the 2¼ x 3¼ cut film holder which is not equipped with a dark slide. The fixed enlargement factor metal bellows cone is felt lined internally and is confirmed as compatible with Kodak film holders and plates. There may or may not have been a ground glass focusing screen but considering the standard size of the film holder it is simple enough to obtain one from a third party source. Thankfully, a ground grass screen is not necessary as the film plane is parfocal with the fixed focus ground glass viewer. Film is only infrequently available from a limited number of suppliers but may be desirable if one has access to a dark room and a willingness to cut down more commonly available film stock. It is not compatible with the common 120 roll film Graflex camera backs without modification to the camera back or a homemade light seal.

The 2¼ x 3¼ Polaroid instant film pack camera backs may be found and makes use of the 10 exposure peel apart film now produced by Fuji. Although the images obtained are very nice, and provide an easy introduction to medium format photomicrography, the difficulty of pulling film from the camera (so that the chemistry is applied to the film) will require verification of alignment between exposures. The commonly available backs compatible with Graflex cameras are not compatible with the above described bellows. An additional model permanent camera is fitted to a plastic fixed enlargement factor bellows cone and is not outfitted with a dark slide. Unless one has a Polaroid back that is known to be interchangeable with a Kodak film holder it is advisable to obtain the permanent Polaroid version if one is set upon using that format.

The 4 x 5 camera bellows is infrequently seen but provides the best option for those interested in medium or large format photomicrography. A scaled up version of the 2¼ x 3¼ camera, it is metal and felt lined and like it’s smaller counterpart, also does not have a dark slide. The cone is compatible with 4 x 5 camera backs, of all sorts including cut film, film pack, and plate holders. Off the shelf 120 roll film backs from Graflex are compatible and the ease of using such a system can be an economical way for the beginner to get involved with large and medium format chemical photomicrography. Depending on the winder it may be necessary to remove the metal spring that holds cut film plates in place. Ground glass focusing screens are simple to find or make with a bit of glass and a dab or carborundum grit, but the original screen features a thick rubber frame.

Use

No doubt everyone can picture the attachment camera in use on a classic monocular microscope. In the interest of displaying something one might not have considered, below is an image of the attachment camera (with Polaroid back and spiral focus viewfinder) in service on a Phase Contrast DynaZoom as well as two detail images of the difficult to find ocular sleeve.

 

Notes:

∗Images in reference works term the apparatus the “Model N” attachment camera but I have not been able to locate the appropriate B&L catalog or manual to confirm the proper name.

†The camera back is slightly too wide and thick. A few minutes with a hobby grinder or similar tool is all that is needed to permanently adapt a roll film back. If one is unwilling to dedicate a camera back, a thick felt gasket may be glued to the back and cut so that it projects slightly into the bellows cone to prevent it from being jostled while in use.

‡The hardest part is cutting the glass to the right size and it isn’t even that hard if one has ever cut glass.