Brief history and development of ground glass focusing loupes
May 17, 2021
Brief history and development of ground glass focusing loupes
This post is dedicated to a very helpful yet often-overlooked photographic accessory. After scouring the web, at this point, I have only been able to find few brief entries dedicated to those devices, so I hope my writing will be found helpful by inquisitive minds interested in the history of photo equipment.
Tintypes Made Using Focusing Loupes as Lenses is a companion post to this one. Capturing images in this exact manner is something that to my knowledge has not been done before, though of course, I am always ready to be proven otherwise.
My passion for vintage large format focusing loupes was sparked by a visit to Will Dunniway’s home about seven years ago. A pillar within wet collodion community, Will Dunniway was kind and generous, with a real passion for history and craft of wet plate process. During my first very brief visit to Will’s, I noticed a display cabinet on his wall, which was filled with beautiful little brass gems. At that point I only had one loupe, acquired in early 2013 from the estate of late Ernst Purdum, who was famous in photo circles for his extensive knowledge of photographic shutters and their history and mechanical development. After his passing, Mr. Purdum’s massive estate ended up in a second hand retail shop. It was from there that I picked up my first loupe by Taylor Taylor & Hobson loupe.
My main interest has always been in producing images, and knowledge of equipment needed to fulfill particular results is therefore essential but not central; other than admiring it’s minty finish, didn’t think much of my first little loupe, until my eyes caught sight of that cabinet at Will’s place. When I got home, I searched about the web to see what was available on this topic, but my inquest came up woefully short. This lack of information acted to further strengthen my resolve to learn as much as possible, and to share my findings with the world. Through the years, I visited Will’s place a number of times, and purchased or traded for more than a few choice pieces from that cabinet. Sadly, Will passed away on April 8th of this year. I was thinking of waiting to make this post until I reach 10 years of collecting, but decided to rather do so now in memory of Will Dunniway, may he rest in peace.
Challenges of gathering antique brass loupes and information about them are as follows. First off, they are generally small, and to someone who is not an avid large format photographer it’s not obvious what they are, so vast majority of loupes must have gotten lost or tossed out when someone died and their relatives wouldn’t know what they were. Lets face it, half of that small percentage of photographers who even shoot large format today would likely not recognize some of these for what they are. Secondly, most of them have no engraving or stamp, and those that do vey rarely mention anything other than the maker, so sellers have a hard time describing them precisely. More than one maker made not just different iterations of their loupes, but in each generation there would have been 3 or more various sizes offered, and so there’s thin hope for assembling an entire line of 6 or 9 variants. Add to that the fact that there are a myriad other types of loupes out there, and the fact that a lot of other small optical pieces could easily be confused for loupes and would actually function as such to some degree. Even in Will’s cabinet pictured above, of 36 objects seen 10 are in fact not loupes at all, but this will be addressed later.
Just what is a ground glass focusing loupe, and how is it different from other similar objects? By definition, ground glass focusing loupes are made specifically to aid photographers with bringing the image upon their large format camera ground glass to critical focus point. To ease this crucial task, photographers at times use a countless number of DIY magnifiers and gadgets, but nothing beats a well-made loupe designed for that exact job. These loupes should be able to focus sharply at a distance of about 2mm from the bottom edge. A ground glass focusing loupe also has a completely opaque body, which blocks stray light and brightens the image. Their magnifying power varies from around 4x to 8x and even 10x, though most seem to be at about 6x. Since the ground side of the glass is perfectly flat, most makers went through the trouble of making sure their loupes have a relatively flat field of focus, something that isn’t as crucial in botanical magnifiers for example.
I’ll quickly note here that as far as actual use a lot of other things can replace an actual true ground glass loupe; loupes made for negative examination are nearly identical in all respects, map reading magnifiers and even hand-held loupes can be used. 19th century magnifiers for botanical specimens often also very closely resemble focusing loupes, and can focus in the correct plane. I have used center group from Canon 28-80mm lenses as high power magnifiers, and with one camera I purchased came a thing someone made from a film canister and a single element with some enlarging power glued into it, and that thing also worked to show the image larger. I feel that a lot of photographers may actually resort to using all sorts of substitutes simply because they may not even be aware that specific focusing aid loupes do in fact exist, and so I hope this post helps out.
Variety wise, photo loupes seem to have been not as plentiful as lenses, cameras, and other equipment; after all, they were meant to do one thing only, and how many ways can one achieve that rather straightforward task? Still however, there’s more than enough to explore and marvel at.
Simplest photographic loupes have no focus adjustment at all, or basically a minimal capacity for that, with top glass on a thread, which can be unscrewed a bit. These loupes usually have just one element, and image quality is not exactly great. Next level up have a way to slide central part up or down, to adjust for personal eye sight of each photographer, as well as to change focal plane to ground glass of different thicknesses. Better ones will have either a sliding or turning central adjustable part, which is then locked in place.
Simplest way to have a loupe be able to focus of course is one tube sliding within another one; only simple precise machining is required for a fairly tight fit. For more control, some companies made that central part have a spiral or even a full-fledged thread; this makes adjustment more precise, but the finer the thread is more turns it takes to get it to where you want it. A more complex mechanism involved a guiding pin placed on outer surface of inner barrel, and a slightly spiral channel in outer body part for that pin to ride inside (though of course that channel was hidden buy outer skirt). This is a very smooth and exact way of achieving focus, but indeed it required a whole bunch more machining and assembly, so not a lot of loupes exhibit it.
To lock that central sliding part in place of correct focus, most loupes have a threaded ring on outer part of the body. As that ring is screwed down, it presses inward upon carefully cut wings, and that locks central column in place. Some makers resorted to a simpler setting screw. Yet others had their loupes focus via a long thread that had a stop-ring on same thread.
Glass configuration varied drastically; from simple one-glass magnifiers akin to hand-held reading aid, to complex systems with cemented crown and flint glass elements. Most good models have a single element on top, and a cemented double at bottom. More complex loupes had complex achromatic groupings of elements both on top and bottom. Below at left are elements with a spacer from Waterbury loupe, and at right are three cemented elements by Goerz.
Just like lenses and cameras, loupes were also rebranded, and multiple retailers often sold exact same ones. Some loupes may have been sold without company engraving, while others were finished differently. For example a Hansa loupe is identical to Zeiss Ikon, except Hansa has an incredible enamel finish and is made of brass rather than aluminum that Zeiss went with. Did Hansa buy rights for that deign or did they have Zeiss make them a batch from a metal they considered better, and then enameled them in Japan? Hard to tell now, but they surely are related. Dallmeyer seems to have copied Ross loupes almost completely except for making them shorter, Montauk ones are identical to those marked Waterbury, Busch loupes were also sold by various retailers engraved with their own labels, etc.
It’s usually rather difficult to determine date of manufacture with these objects. They are rarely marked in any way, and of those that have an engraving few have a serial number, which is also near impossible to trace for vast majority of vintage manufacturers. Endlessly searching though old catalogs can at times give a glimpse of which configuration of the loupe was made in which decade by which company, but some makers kept their loupes the same for decades, while others have no catalogs available for search online. After a while of working with antique brass lenses, one can start seeing similarities in progression of types of brass and lacquer used by makers, and that can be used to place a loupe within this decade or another with relative degree of accuracy.
I believe one of the oldest loupes in my collection is probably the Scovill Focusing Glass pictured below at left. It seems that they haven’t changed their form from early 1860s through 1880s, and so this loupe in theory can be from any year in that period, but basically it’s the same ‘60s loupe. In the middle is a loupe seen in LaVerne catalogs from France, and it seems it was imported and sold by Edward Anthony as well; it dates from mid-1870. Judging by machining and type of brass and lacquer used, Darlot loupe on the right is also likely from either late 60s or early 70s. I’m not certain when Ross or Dallmeyer started making their loupes, so I didn’t include those in this group of old-timers.
Parisian lens maker Hermagis is credited with inventing spiral shaped central columns, which make the process of tuning the loupe to your eyes very precise. Some of their loupes have no spiral, but instead employ the guide-pin system; I’m assuming those are later type, but am looking for find even one of those in an actual catalog for verification. Some of their models are plain brass finish, some black lacquer, and some bodied came covered in leather.
The spiral central column design was copied endlessly through Europe, and no-name examples of these are probably the most common of all loupes to come up for sale. All spiral loupes I’ve seen sport a single element on top and cemented double at bottom. It’s possible that the central spiral tube was bought in standard length, and then, if top and bottom glass needed to be moved apart a bit more, a ring of appropriate height was soldered onto the spiral. Occasionally an example with much finer thread is seen in the wild, but for the most part the spiral is nearly identical through many models and makes.
Darlot loupe design was kept around almost unchanged for at least 30 years, and it also sprung a bunch of nameless copies. Other companies even advertised their loupes as ‘Darlot Type’. Darlot brass type and lacquer finish changed through the years, very much consistent with their lens bodies from same time periods. Below are a Darlot loupe that was likely made around mid 1880s, and three examples of other makers copying same general design.
Most loupes are between 40mm and 60mm when closed, and extend by 10-20mm, average weight of about 100-150g. Space is often a consideration for photographers on the go though, so some loupes were made in miniature sizes. This makes them even more susceptible to being lost of course and the image is tiny, but in a pinch they work quite well. Below example of an early E. Krauss loupe is only 30mm tall, and weighs 54g. If space is in fact of absolutely no concern, and if one really wants to get the widest field of view while having a marvelous object in their hand, then the obvious only choice is the Grande Model loupe by Hermagis. This mid-188s giant weighs in at 235g, and stands 105mm tall when extended.
Hermagis deserves another quick mention here. Ground glass can be scratched by the bottom metal edge of loupes. To prevent this, on one of their models, Hermagis inlaid a ring of whale baleen in most careful and beautiful manner. This is the only example lined with baleen I have seen. Later loupes were made of plastic, but among brass-bodied loupes this may have been the only meaningful effort to protect the glass from scratches, and what an elegant effort it was.
For clear focus, bottom edge of loupe is placed squarely against the ground glass, with line of sight being at 90 degrees to glass. At times, the spot you want to check focus on is a bit lower or higher than the angle you can comfortably bring your eye to, and a few companies gave their lopes the ability to tilt, so you can look into it from above or below. Notice that they tilt around the central axis of bottom plane, because that is where the focus is adjusted for ground glass depth; if you just keep one point of the edge on the glass, focus plane will be lifted, and your loupe will be totally out of focus.
Another problem one sometimes encounters in the field is checking critical focus along the very edge of ground glass, because it is usually sunken into the wood or metal frame around it by a millimeter or two, so edge of your loupe hits that edge. This sole example by Taylor’ Taylor & Hobson, with its lovely patina, combats this problem by having a small cutout in bottom edge, which allows it to stay perpendicular to the glass while going over the frame wood. In theory, tilting loupes seen in above picture can also answer the call, because their center can also be brought closer to the edge than most.
I think that the first time anyone who ever glanced upon the ground glass of a regular large format camera, they may have been a bit confused by the image being upside down and left to right reversed. After having worked with LF cameras for over 20 years, I now see what my college professors were saying about the benefits of this. Having an image reversed serves in some subliminal way to detach the ground glass image from what is actually happening in front of the lens, so lines, tones, and other compositional elements stand on their own, uncoupled from reality by being inversed. Not everyone shares this sentiment, and so we all know of those large reversing prisms that go behind ground glass and orient the image correctly from at least top to bottom by the use of a mirror. Some loupe makers attempted to offer photographers that same solution by adding an extra element between the two groups, and having that element reverse the image in both directions.
Using a loupe like that is actually not as fun as it may seem. First off their magnifying power is really high, so you end up seeing too much of the actual gran structure of your ground glass. Plus area of view is also rather limited, so you have to move it around lot to find where those point of interest are. When I tried using these loupes, I could not for the life of me get used to having the image slide upward as I’m moving the loupe down, and also it makes you want to move it in the wrong direction to begin with. Still, it’s a novel innovation worth mentioning.
With the advent of smaller cameras in late 1890s and through 1930s, there came to be a lot of folding cameras that still had a ground glass on back, but were meant to be hand-held. Holding the camera, focusing it, and also holding a loupe against the glass is a trick that only select Hindu gods can perform with ease, but for those of us with only two hands, some companies had a bright idea to make tips of their loupes into little rubber suction cups. I imagine this worked pretty well when they were new, but those early forms of rubber would become hard and very brittle after a while, and so all those loupes now have that rubber either missing completely, or it’s hard as a rock, and usually with cracks and chips missing.
Those smaller cameras also often had a leather hood that would pop up to reveal the ground glass and shield it from stray light. In more modern cameras, Graflex has a metal shade in back. Getting your hand with a loupe in there is nearly impossible, and so a longer loupe is very handy in those situations. Aside from the collapsible example shown above, 1950s Ednalite answers the task very well, though I can’t say it’s the sharpest loupe on the shelf. There are also quite a few examples to be found by Wista, and, provided that the glass is reinserted correctly after cleaning, which wasn’t the case with mine when I first received it, it’s actually a very sharp loupe.
Some loupes came with a provision for their own little ground glass, which would slide onto or screw to the bottom side. Turn that ground glass toward you, and you can actually focus on the scene in front of you, which basically serves as a quick preview viewfinder. Provided that you’re shooting with about a ‘normal focal length’ lens, this can aid you in selecting a good spot to set up the camera. It’s a bit of a gimmick, as the image is small and not easy to see, but it’s the nifty thought that counts. Seeing the first loupe with such attachment is what gave me the idea of making a series of images by using loupes as lenses.
Loupes are among the smallest of objects in a large format photographer’s bag, but it’s also pretty handy to always have it by your side without fear of losing it. Hence the old solution of putting a neck strap on whatever you need rapid access to. Surprisingly, not a lot of loupes actually came with neck strap provisions, and in those that did the string loop is often missing.
Vintage focusing loupes are hard to find in general, and so to come upon them with original carrying cases is a great treat. Only about 10% of my collection have original cases, and below are a few examples. Some were supplied in a Moroccan leather cases akin to those for Waterhouse stops cases, others made paper or pressed board boxes. At some point in time, TT&H chose to make their cases from thin wood veneer. Some cases were hard and lined with velvet in a formed shape, while others were but a suede satchel. Limpet loupes, which originally had both a rubber end and a circular ground glass that could be inserted into that rubber, came in a thin tin canister.
Being worried about losing one of the vintage ones, in the field I use a Nikon 7x and in studio my go to is this Sima, made in West Germany back when there was such a country. Both of them are exceptionally sharp, though some of the better antique examples aren’t far off quality wise either. In the past I’ve tried a few Peak and Wista loupes, and they were very well made. I assume Horseman wouldn’t have made a bad loupe, but I never did hold one in hand.
I think this about covers most all loupe variants I came across. For the sake of those who are just learning, I feel I should add a brief word of caution. In the past few years, interest in loupes seems to have grown tenfold. Not sure if this is due to some great influx of large format photographers with poor eyesight, or maybe the fact that over that time every once in a while I would put out open calls for them on social media. Either way, prices have tripled if not more, though some sellers actually don’t try and gouge and keep things at reasonable prices.
In latest development, careless sellers are misbranding things that aren’t loupes at all, whether knowingly or not. For example, it’s relatively easy to see that a toy magic lantern lens isn’t a loupe, but with just a bit of an imagination stretch, their ability to focus on needed plane of ground glass can spell Euro signs as far as sales. Meant for eventual destruction by playful and maybe less than attentive children, these objects are cheaply made of very thin metal, with simple glass being held in place by a spring. They do happen to focus on the ground glass, but aren’t lockable and the image is much more poor than in good examples of actual ground glass loupes. Microscope eyepieces also sometimes happen to focus just in the right plane to work. I actually wrote here that I have so far not seen those sold as loupes, but right as I was editing this post, indeed one shown in a collage below appeared on eBay; it’s not brass, it’s not a loupe, and that seller should know better. A seller in France appears to have a monocular mislabeled as a loupe, and it’s been on eBay for at least a few years now. I tried multiple times to confirm whether that’s a loupe or not, but he never did answer his messages.
I would like to extend a great deal of gratitude not only to the late Will Dunniway, but to all those who helped my collection through the years. I couldn’t have done this in such a relatively short time without the support of dedicated loupe hunters scattered around the globe. Their selfless generosity stands in stark contrast to blind competitiveness observed elsewhere. You know who you are folks, and the world is a better place with you in it. Thank you!
Oh, and a good collection is never finished. I wouldn’t want to give an impression that I am done hunting for examples that I don’t yet have. In fact, I ask any kind reader who thinks they may have a vintage loupe that I don’t have to email me, and I would be glad to talk of possible purchase or trade.
Thanks for reading, and again, here’s a link to the post about Tintypes Made Using Focusing Loupes As Lenses.
About the Author
Anton Orlov is an analog photographer from the US. He is the man behind The Photo Palace Bus, a traveling darkroom dedicated to the art of traditional photography. You can see more of Anton’s work on his website. This article was also published here and shared with permission.
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