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.