The Bausch & Lomb Model R part: III

The question of the determination of a microscopes magnification has a distinct tendency to be treated in either a profoundly technical way or only the most basic terms, never mind the source. On the simpler end of things it’s often put similarly to this: the magnifying power of a microscope is determined by multiplying the power of the objective by that of the ocular. Well, lovely. That certainly buttons that up doesn’t it, no? There may even be a few lines here of there on the power of an objective or ocular but all such texts take it as given that the optical components will be marked. At the opposite end of the spectrum one will find page after page of complex optical formulae and jargon like principle poster focus and Ramsden disc. Fortunately those formulae that are printed can be made rather more meaningful to most people by simply substituting words for symbols, as such:

Magnifying Power = Tube Length x Distance of Distinct Vision / Focal Length of Objective x Focal Length of Eyepiece

Which is great, if you want to muck about in physics class and measure the focal length of your lenses. One could of course forego that in favor of a little bit of basic math, if one had an eyepiece micrometer and an object micrometer, but then the Model R uses non-standard diameter optics so the chances one has an reticule of the right size for the narrow ocular is slim, and in any case it’s a closed system-not something one would easily disassemble. So what if you haven’t got anything, not even a stage micrometer? I mean the Model R was made for kids right, what kid just happened to have a hankering for a stage micrometer first thing when they got a microscope? Alright, maybe a lot of us did, so we’ll use one but bear in mind we can do this with any object that has a known diameter, like a human red blood cell (7.2 microns at the widest point) or a human hair (in the neighborhood of 70 microns is diameter.

All the physics used to determine magnification is well and good but pales as a practical exercise for the microscopist to comparing the known size of a particular object to the magnified size of that object. In order to do that with math one needs to know a great many things about the lenses to begin with, most of which is best suited for classwork in physics only. In order to make the same comparison in an almost exclusively practical way one need only set up the Model R (or any microscope) as below.

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  1. Place the object of known size (be it a blood smear or stage micrometer) on the stage and focus the microscope.
  2. Incline the joint so that the microscope is horizontal The Model R hasn’t got an inclination joint but the body and stage comes off from the foot and may be mounted horizontally.
  3. Use a rule to position the exit pupil of the microscope 250mm from a sheet of paper taped to a wall or other support.
  4. Position a bright, high intensity light source so that it may be focused on the specimen from below the substage.
  5. Turn out the room lights.
  6. Mark the locations of several divisions of the micrometer or a few red blood cells on the paper.

Now that the paper has been marked only one further measurement is required. The marks made by projecting the specimen on the paper are of a known division. They are also of a size that may be easily measured with convention means.

  1. Use a rule marked in millimeters to measure the divisions marked on the paper.
  2. Line up carefully and note the number of divisions on the paper that are needed to span the distance perfectly between any given number of either.
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Yes, I did chose to awkwardly lean over the entire setup rather than walk to the other side of the table!

Now for the math, in this case the formula is much simpler than one might expect. One need only divide the distance as measured on the ruler by the known measurement of the magnified and enlarged divisions marked on the paper. Therefore if the divisions of the stage micrometer are 0.01mm, and at the Model R’s most powerful magnification (draw tube fully extended) they measure precisely 4 divisions in 12mm the formulae would be 12/0.04 = 300 diameters of magnification. It’s pretty nice to see that that confirms the marking on the draw tube. Repeating the process with the draw tube fully retracted one finds that 2 divisions as marked on the paper span 3mm exactly, 3/0.02=150 diameters of magnification.

With this knowledge one can accept that the marked powers on the draw tube are accurate, but that doesn’t inform on the individual power of either the objective or ocular. One will of course recognize that removing the front element serves to reduce the power of the entire system by half as that is what the markings indicate. Unfortunately this does not enable one to know the power of the individual elements. One need only repeat the process without the ocular to find the power of the objective alone. It then becomes a simple matter to know the power of the ocular, power of the entire system / power of the objective = power of the ocular.

Repeating the steps above, except to this time measure 250mm from the rear of the objective lens provides the following measurement. Twenty divisions (marked in intervals of 5 each) measures 4mm on the paper. Such that, 4/0.2=20 meaning the power of the objective is 20x and the ocular is therefore 15x which further indicates that removing the front lens element reduces the power of the objective to 10x.

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The Bausch & Lomb Model R part: II

It’s time to see how the optics of the original B&L Model R perform. To begin with a few common test objects, beginning in this instance with the wing of a fly, will be evaluated visually. Then, the next visual test will be the scales of a Podura springtail followed by the more finely striated Pleurosigma angulatum. The ability to resolve the features of these objects once served the same descriptive needs that the numerical aperture measure serves now.

It’s worth mentioning that no special effort will be made to ensure perfectly clean elements, so although this microscope is in exceptional condition for a stand of its age one could expect to see a not insignificant improvement in resolution should the effort be made. All photomicrographs taken will be made with a ring-stand supported iPhone camera. To avoid putting up an over abundance of images that will will only be given a cursory place only two images of each test object will be provided. The lowest power is that marked on the Model R microscope as 75 while the highest power is that marked as 300. It’s worth noting that to configure the Model R to provide the lowest power one must remove the front element of the objective lens and set the draw tube to its shortest length. To achieve the highest power one must use both elements of the objective and set the draw tube to its greatest length. Lighting is provided by a high variable intensity condensed B&L illuminator.

In the low power photomicrograph we can see that there is some indication of markings on the various cells of the wing and make out a pattern of hairs on the costa. At the high power end of things we can clearly see the individual hairs of the costa, they are not the toothy spikes represented on the first photomicrograph. The pattern of hairs on the marginal cell is clear but the individual definition is somewhat obscure. It is not immediately clear that they are in fact raised hairs, easy enough to determine with a bit of back and forth of the focusing knob. All things considered the imaging abilities of the microscope are surprising. The axial third of the field of view is surprisingly clear and sharp, even when viewing so comparatively thick a specimen as a fly wing. Except at the lowest power, without the complete objective in place, there is very little evidence of chromatic aberration.

In the low power image of the podura scales we are able to discern some implied texture on the surface of the scale, it’s obvious it is not simply a color gradient. Again it is clear that there is some chromatic aberration, more in evidence due to the slight misalignment of the illumination source, but one should expect that when using a divisible objective. Turning to the high power photomicrograph the texture becomes a clear pattern of lines although, one could certainly not make any secure judgment as to the nature of the texture in cross section. It should perhaps not be surprising that the Model R can make no clear statement on that count, there was in fact profound disagreement on the form a podura scales texture would have that was unsettled until the rise of electron microscopy. As a side note, these scales are not intact lined but rather feature a pattern of lines composed of fine hairs.

Although the Model R did not provide the performance of a professional stand on any of the test objects thus far it certainly stood tallest on the fly wing. It’s then somewhat pointless to set it against the Pleurosigma angulatum as there’s little reason to expect it to resolve the finer points of the diatoms test. Fortunately, one would hardly expect someone to put such a difficult object before the Model R. It is gratifying though to note that if hard pressed one could certainly enjoying viewing diatoms with the stand, clearly it’s not the ideal object one might chose to observe but it certainly performs far better than one might expect. The red and blue fringes of an achromatic objective are obvious on the photomicrographs of the diatoms; they are by no means reason to disregard the Model R. It would be a great thing if a microscope of this quality were put before every elementary school student rather than the sort of needlessly complicated and overly ambitious toy one can find at any of the “science” themed stores that exist in shopping malls and digital marketplaces.

In part III, a few simple tests one can perform to find the powers of the optical elements. -K

Large Format Photomicrography part: IV

Photography Basics / Darkrooms

Not having a darkroom doesn’t mean giving up on large format photography; there is a darkroom solution for every problem out there, ranging from fully equipped professional quality spaces all the way to under a comforter, with the lights out, at night. One could run over to a site like localdarkroom.com to see the spaces available in ones area and, if fate is kind, find out a nearby space can be had for a nominal fee. If everything is hopelessly far away or self reliance is more ones style it’s just a question of expense. Free solutions can be as simple as waiting for nightfall and putting towels over every bit of light in evidence in a darkened bathroom, or cleaning out a little space in a closet.

Buying a photographic changing bag or darkroom tent is certainly an option. A changing bag is essentially a darkroom, for ones hands. A fairly large changing bag may be found in the $25.00-$40.00 USD range on any of the countless “we have everything” web-stores, just search for “changing bag.” If going that route don’t try and save a little cash by purchasing an undersized bag that’s really only useful for 35mm work, unless of course that’s ones ambition. Except in cases where every penny must be pinched it’s generally good advice to buy the largest changing bag one can afford; something about darkness turns a meter into a millimeter.

Photography Basics / Holders for 4×5

With some sort of perfectly dark place, a box of film, and a film holder one’s all set to load some film. The assumption here is that one will be loading up 4×5 film into a 4×5 holder.

If working in an improvised dark room take a moment to lay everything out that will be needed in an orderly way. It’s imperative that the box of film be fully reassembled as the final step; it’s no fun at all to have the lid of a box go missing as a result of a cluttered workspace. Where at all possible bring everything that is needed and only what is needed into the darkroom, whether that darkroom is a closet or a changing bag. It’s a good habit to open up the dark slides of the film holders as shown before going dark; closing the holders then only after film has been loaded. In this way one avoids both failing to load film and wasting time trying to load a sheet in a full holder.

Before the actual business of loading a few notes on film holders and loading 4×5 film. Holders usually have two sorts of indicators to avoid loading film incorrectly and double exposures. The first indicator is less universal and is based on two colors, white and black. One side of the dark slides handle is apt to be painted white or molded from white plastic. By convention this side is placed facing out when the film is un-exposed; it’s ready to see the light. After exposure the dark slide is placed back with the opposite (black) side facing outwards, indicating that the film has been exposed and should only be removed in the blackness of the darkroom.

Vintage or antique film holders are liable to have plain metal dark slide handles (or to have had all their paint worn off). Moreover, one can hardly observe the color on the dark slide when working in a darkroom or changing bag. All film holders thankfully have a second indicator which most commonly takes the form of  one or more raised or recessed dots on the upper right hand corner of the dark slide when viewing the un-exposed indicating side.

In addition to indicating the exposed or un-exposed state of a loaded film holder the raised dots serve as a reminder of how to properly load film. Every sheet of film has two sides, the emulsion side and the back. The emulsion side is the side which has been coated with light sensitive material and is the side which should be exposed to the light from ones camera lens. Unlike 35mm film which can only be loaded in one direction (as a result of the cartridge construction) 4×5 film can easily be loaded backwards. To address this issue every manufacturer includes a small indicator on each sheet of 4×5 film.

The indicator takes the form of one or a series of shaped notches in on corner of the film. Different patterns of notches indicate different types of film, speeds, manufacturers, and emulsions. Explanations of the notches is beyond the scope of this post, see the film makers documentation for details. Just as the raised dots of the dark slide should be in the top right when the film is un-exposed so too should the notches in the film be in the top right when loaded. If the notches are loaded such that they are in the top right, whether one loads the film by sliding it up from the bottom of the holder or down from the top, it is not possible to face the emulsion side away from the lens. Thank goodness for chirality.

Photography Basics / Loading 4×5

One should prepare for loading 4×5 film holders by giving them a good clean up. Take a clean, 2″ paintbrush, just the sort one would use for painting trim or moulding, and brush out the film holders. In a similar vein it’s frequently recommended that one use some sort of air duster for the task. The thought of so powerfully propelling dust into the air at a time when it would rather be settled seems enough to proscribe that practice. Pull all the dark slides out only so far as to expose the channels into which the film will be slid. Don’t pull the dark slides out all the way, doing so only serves to clutter up the work-space. At the same time do not think to simplify the task by only pulling out the dark slides a very minimal amount; one should be able to bend the partially loaded film slightly upwards to tell that each side is uniformly slid into its channel, a task that’s impossible if the dark slide itself is holding down the film.

If a picture is worth a thousand words I own at least one now.

Well there it is, enough to get anyone loading 4×5 in no time at all.

The Bausch & Lomb Model R part: I

The microscope is something of an emblem of science. Unlike similar fetishes of science such as the test tube, the microscope stands as well as a banner for the curiosity of scientific pursuit. It’s an amazing thing and has had an impact on the sciences similar to that the automobile has had on transportation. Fortunately, while the automobile exists in a state of age restricted licensure, the microscope is available to all-or is it? What about price? What about the availability of something serious but attainable? What of something in between a fly swatter and an atom bomb?

Over the years the optical company Bausch & Lomb has broken new ground any number of times in the world of microscopy. Growing up outside Rochester, N.Y. it was something of a given that the microscopes in school would bear that prism-shaped logo and great treasures would be hidden away in the attics and sitting rooms of my childhood. These were all, however, great heavy things of cast iron and brass, replete with fragile glass elements and cases bigger than any bread-box. There was something else though, something different, and it started with the Model R.

Sold in the 1930’s during the years of the world-wide economic downturn popularly called “The Great Depression” the Bausch & Lomb Model R had a retain price of twenty-one dollars in the United States. Depending on the precise year one elects to compare that equates to anywhere from $300.00-$400.00 in todays currency. This was a time when the average factory worker was earning some $0.40 an hour and could expect a weekly paycheck which would only just cover the cost of the Model R. It was accessible but surely out of range of anyone without the willingness to sacrifice to obtain it.

The styling of the Model R was such that considered on it’s own it would not seem out of place beside a professional instrument from its day. Black enamel paint and bright nickel plating were the norm. The look is replicated in the Model R with a glossy black Bakelite stand and shiny metal body tube. A few points that quickly stand out are the lack of an inclination joint, the single focusing knob and total lack of a fine adjustment.

Then there is a draw tube… What? No! To dispense with the need for a nose piece and multiple objectives, a pair of which would cost more than the entire Model R, this microscope made use of a varifocal lens system (rather like but distinct from a zoom lens system). With this simple change the microscope was enormously reduced in price.

While today one might expect a plastic snap-case if any were provided at all it’s well to remember that in the 1930’s when an item came with a box it was as likely to be wood (perhaps more so) as pressboard. So if the look of the Model R were a product of it’s time, what can be said of it’s utility?

For that, watch this space for part II where the Model R will be put through it’s paces -K

How The Posts Get Made

In the somewhat vain hope that anyone wonders about how this blog gets written, I thought I’d write about it. In the present state of things I write the actual content out on paper, yes paper. The paper is an A4 pad on top of my Wacom Bambo Slate. The Slate syncs the writing over Bluetooth to my phone where it is exported as text via the Wacom Inkspace app (or website) then into the Pages word processing app or even directly into WordPress. From there I do a bit of editing, add pictures or what have you and call it a post! The process is a bit convoluted but it allows for me to do my writing while traveling for work, as I am now, or in the lab where I might not want to set up a laptop. I find it particularly appealing that I do end up with a paper copy of whatever notes I may take as well as an automatically synced copy in the cloud. I’m sure its not a process that would work for everyone, but it works for me.

-K

Large Format Photomicrography part: III

The Homemade Camera

At this point I’ve got everything I need to shoot some 4×5 film. I could load some film into a holder, and start shooting without any delay. I wonder though, what about everyone else? What if I didn’t have a trinocular BalPlan, a working System II shutter assembly, the proper camera body, and the right adapter? What if all I had was was a basic monocular microscope and dreams of shooting 4×5? Could I get away with something simple and homemade or would that be too impractical. Thinking about the preceding one is apt to consider the old standby of shoe-string photography: the pinhole camera. Such a camera need be nothing more complex than an opaque box with a pinhole at one side. It should then be entirely possible to use the same principles in the task at hand; replacing the pin-hole with a microscope wouldn’t do though. One would need some way of determining focus. Depending on what’s to hand it may prove more or less feasible to solve the problem of focus by building two cameras; the one for focusing only a screen of some sort in place of a sheet of film. Two identical carers could be easy (perhaps two identical shoe boxes) or nearly impossible at a moments notice (the recycling picked up yesterday). In any case I have a ground glass and a film holder so a single camera seems easier. A student should be able to borrow both from the art department or one could buy a holder second hand and make their own screen easily enough.The question now becomes how to attach the box that will be our camera to the microscope. With a basic monocular microscope with inclination joint, using it in a fully horizontal arrangement seems ideal. One needn’t bother with standing on a chair to view the screen or precariously balancing the “camera”. So far, no consideration has been paid to the question of a shutter. The simplest option would be to ignore a shutter in the traditional sense and merely block out the light source with a bit of light opaque material, tin foil, for example. Then we need only consider the need to ensure that the only way light may enter the camera is through the microscope. Easy enough, a hole only just the size of the ocular tube is made in the camera and the connection masked with a bit of gaffer tape. All that remains is to consider how the film holder will be held to the box. This being the most complicated aspect of construction it has been left for last. One need cut away enough of one end of the box so that the light may reach the film. This hole may be made large enough to utilize the entire film or it may be masked so as to provide a circular photomicrograph. With the hole cut one should then glue a few layers of soft dense material to the area the film holder will press against. This material will serve as a light seal. A few layers of dark colored fleece or soft foam insulation will do nicely. To hold the film holder in place one has a number of options, the first that occurs to me is to poke four holes through the box and insert through the same a pair of dowels or pencils, mask the ends with tape for a tight fit, and then stretch rubber bands from end to end to hold the film holder tight against the light seal.

1. Place the specimen on the microscope stage and position the “camera” at the ocular.

2. Affix the focusing screen to the camera.

3. Turn out the room lights, turn on the illuminator, and focus the microscope.

4. Taking care not to move anything, remove the screen.

5. Place the loaded film holder in position.

6. Block the light of the Illuminator with foil.

7. Pull out the film holders dark slide.

8. Briefly remove and replace the foil in the illuminators path to control for exposure.

9. Replace the dark slide with the exposed film indicator facing out.

10. Process exposed film as per developer instructions and enjoy!

Large Format Photomicrography part: II

Preparation of a Ground Glass

Using the integrated camera system II means that one will be correcting for parfocality between the camera and oculars with the shutter assembly optics not the cameras tube length. The process is the same for any of the Bausch & Lomb integrated camera systems and the effect is functionally identical to increasing the cameras tube length. This may not be immediately clear to anyone using the device because on a number of models the adjustment is marked with an “x”. Rest assured that focusing the knob to “15x,” is not going to provide an increase in magnifying power of 15 times over the obdective magnification. Provided this little endeavour is successful, I’ll look into calculating the power of the lens system when in focus. Unfortunately, before any of that a method of obtaining clear focus in the plane of the film will be required. An ideal method of obtaining focus would be inserting a ground glass in place of the film holder. The ground glass would need to be in some type of frame so as to keep the ground surface at the same position the film would occupy. It would at first seen expedient to place a piece of waxed (or oiled) paper onto the camera back and this would work in a pinch. A far better opption would be to cut a sheet of glass to size. If one hasn’t got a sheet of glass to hand a quick trip to the nearest second hand shop or discount store (where a picture frame can be had very economically) will provide the needed material. If one hasn’t got a glass cutter or is not confident in their use of one, a stiff sheet of lexan or transparent acrylic that may be cut with a hand saw will do. If one intends to use glass a finely ground surface may be quickly achieved with a bit of carborundum powder. One must take care to cut the glass to size before grinding. For determining size I have considered two methods. First one may trace out and cut the glass to match the outside dimension, of the plate holder. Alternatively, one may trace the dimensions of a sheet of film and cut to that size. The former is likely the easier option, but if one is careful and has a spare or broken film older the later may prove a more secure and attractive option. In the first case, one will later be supporting the glass with shins to bring it into the film plane. It may be easier in the sense that one may make alterations with little trouble if initial results are not all that one could hope for. Another option would be deconstructing a film holder so that it provides an empty frame into which one may fit the ground glass. Originally sold with a frame supported ground glass, I have never seen a 4×5 body for the Integrated Camera System on the market together with the glass back and feel it likely that most were either broken or lost track of over the years since the apparatus was in active production. It may be worth noting a few points concerning focusing with a ground glass. Focus is limited in sharpness by the fineness to which the glass in question is ground. To obtain an area for perfect focus, one should then cement a cover slip in the center of the ground glass or leave a small area unground. When the clear area is observed using a hand lens or small focusing magnifier one may observe the quality of image that will be captured on film. To leave an area unground one may mask it with a layer of heavy tape (or even a cemented cover slip) which must then be removed after grinding. To grind the glass one need only introduce a little carborundum grit in water to one side of the glass. A second piece of glass (a plain slip works well) is then sanded over the grit under light pressure.

The gallery below demonstrates the process.

Above may be seen my poor abilities in cutting glass, and two ways to go about creating a ground glass for focusing. First a 4×5 piece of glass salvaged from a broken window is inserted into a film holder that had irreparably damaged dark slides. The solid film holders were removed and the glass is supported by the top and bottom of the holder rather than the sides. As an alternative I cut a piece of 1/8th inch acrylic to the size of the film holder. Rather than grind it I simply left in place the frosted protective film on one side. It should be noted that in each case the frosted surface is the one which should be held in the film plane. This means that the in the wooden holder the frosted surface is facing down and in the case of the acrylic it is facing up.

Large Format Photomicrography part: I

Scope and Intent

This series is going to be a bit of a departure from the usual around here, by which I mean that I’ll be covering something I know perishingly little about; namely photography. The practical upshot of which being that I learn something, while the corresponding hazard must necessarily be that I spend a great deal of time, well, screwing up! It’s not even going to be my intent to avoid failure, which can be as enjoyable as success if one has the right attitude. Rather, my goal will be simply to end up with a 4×5 print. I’ll of course shoot for a properly exposed, in focus negative, but in all honesty I fully expect to end up with a blurry, underexposed, wretchedly vignetted negative and an overdeveloped, streaky print if I end up getting that far at all. I’ll claim right now that either way I’ll be throughly enjoying myself. Here’s hoping someone or other out there does as well!

Right, so I’ll be doing an insane amount of referring to R.M. Allen’s monograph Photomicrography I’m sure, anything else is liable as not to be found here or there on the web. I’ll try and link to the sources for the materials and chemistry as they come up and at the end I’ll mock up a quick one-sheet for the practicum and supplies; something without my tedious verbosity! This is apt to be a long one as multi-part series go so don’t be surprised if I toss something else in here or there. All the photos on this site aside, I’ve never really gotten the shutter “bug” and still much prefer an awful little sketch in the margins of my notes to roll after roll (or card after card) of whatever full color high resolution photos I manage to snap. If I ever need a belt of good photography I’ll pop over to Dr. Robert Berdan’s site, see what someone who enjoys it can do!

For this series I’ll be using the BalPlan, and I’ll spare a few lines to say why. I’ve got the equipment to shoot large format on either the BalPlan or the phase contrast DynaZoom, I don’t have the space or the chemistry on hand to process or print color though. It seems a shame to pass up phase contrast, but I just haven’t got a clue how that would look in black & white. The other factor is field flatness. The BalPlan has a full compliment of planachromat objectives; just the thing for a 4×5 negative right? Maybe not though, how much of the visible field transfers to the negative, would spherical aberration be noticeable if I used an apochromat, a fluorite?

Once I end up with a negative I’ll process it. I haven’t got a dark room, and can’t be bothered to take over even my own bathroom for the purpose, so drum processing it is! Then I’ll try and contact print it onto some very slow paper and drum process that. I’ll try not to act like I know what I’m doing (because I don’t) and I’ll look at how to rig something up from available materials so anyone with the photography resources (but maybe not the same microscope collection) can maybe get something out of this.

Opaque Object Microscopy part: IV

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This last installment will be a look at the B&L STM Electroplater’s Microscope. A refinement on the Standard Teaching line, this Metallurgical microscope is designed for simplicity and easy of use. Superficially it resembles any of the other stands of the ST line, enamel grey with an integral, two-position nose piece, it manages to provide all that is needed and nothing that is not. A single intensity transformer powers a Nicholas style light source that is fixed to the side of the stand just above the nose piece. The light path features a filter holder but is not equipped with either field or aperture diaphragm, rather the light path is permanently restricted to a degree appropriate for the two supplied objectives.

3ca50003-f562-435a-95e7-fbda76ccfc37-649-000000960bbb8e15_fileEach objective is of 215mm tube length construction and is corrected for use without any cover glass. One is a low power finder (5x) and the other a higher power (40x). One will quickly notice that neither is of the power one expects to find on a student microscope; 10x and 43x being the usual combination. The reason for this quickly becomes apparent when one calculates powers in consideration of the characteristics of the stand. A 215mm tube length, correction for no cover glass and the nessecity of a short working distance. At right one may see the working distance of the 40x objective.

In place of a standard eyepiece it features a filar micrometer ocular as for most all metallurgical work one would desire the ability to take measurements. In that same vein the fine focus adjustment is graduated as well. Although the stand features an inclination joint, there is no adjustment for the stage and no arrangement to provide for transmitted light work. Internally, the light source is directed downwards by a half silver mirror which is not adjustable without tools. This was no doubt done so that it may be aligned once and may then be employed without a further thought to the matter. When I first acquired this stand the reflector was shattered. No matter, it was easily replaced and enabled me to have this delightful little stand for no more than $40 USD plus shipping!

In the interest of providing a little eye-candy I placed the seemingly polished brass surface of a pocket knife in a bit of putty on the stage. Putty or a specimen holder of the standard sort is recommended for most specimens for the sake of stability. A photomicrographic ocular of 7x power and a Pentax microscope camera adapter was used to take the photomicrographs.

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Pentax Microscope adapter in place on STM Electroplater’s Microscope

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Low Power

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High Power

In the above images we may observe the compromises made in the STM Electroplater’s Microscope. The low power photomicrograph shows that the apperture size employed in the illumination system is such that slightly less than the entire field is evenly illuminated. In normal visual use with the 10x filar micrometer eyepiece this is only very slightly noticeable. The 7x photomicrographic eyepiece exaggerates the defect because of the larger field of view it provides. It would be possible to artificially crop out the uneven area by using a greater photomicrographic tube extension, but the one I use is perfectly sized as to be parfocal with the eyepieces when employed on a trinocular stand.

In the high power image we will immediately notice how the curved portion of the specimen surface falls out of focus and quickly devolves into a mess of chromatic aberration. This is why flat surface polishing is such an important part of metallurgical microscopy! Luckily enough, the (exceedingly self-congratulatory) microscopist managed to place the specimen such that the two larger scratches (dark marks slightly left of center in the low power photomicrograph) remained in the frame under the higher power objective. Note how the formerly dark high contrast scratches are now fully illuminated and visually interesting.

Next time: Adventures in Large Format Photomicrography! -K

Significant B&L Library Update

As the result of a thoughtful donation by an excellent person who I won’t embarrass by naming outright, the B&L library will shortly be doubling in size. I’ll be doing my best to get as many of the new materials as I am able to scanned and uploaded in the coming days. Some of the materials have already been added, eight new documents as of last evening. With so many more documents available, and so many more to come, I’ve put a little (regrettably very little) effort into making the library page a bit more attractive. Gone are the clunky columns of cover and download link! Now each document is merely a cover, that cover linking of course to the corresponding document. While at some point I may look into putting them into some sort of order, I have no planes to attempt that now.

By far the primary use of these documents, at least for myself, is in properly identifying a stand or component so that it may be restored and used appropriately. I have on occasion made use of them in that capacity while assisting others in identifying just what they have, or what they may be considering for purchase. At the very least they are an aid in determining the completeness of an apparatus or compatibility of a component. I won’t pretend to know how they are used by the many people who download them, I’m simply happy to share with anyone who may need them all the free Bausch & Lomb puff manuals and guides which I have been fortunate enough to have at my disposal.