Emil Busch Glaukar 7.5cm f/2

13. July 2024In Fast, Germany, PortraitBy Espen Susort

This is one of the most mysterious lenses I own, at face value you wouldn’t think this, it looks like any normal vintage lens with a normal looking leaf shutter. And you’d be correct. But for some reason I can find absolutely no mentions of this lens from various sources. Emil Busch would write extensively about their famous Glaukar f/3.1 series, which are simple Cooke triplet lenses from as early as 1910. The Glaukar f/2 lens series is another matter completely. You’d think they’d advertised this lens at least once, I’ve found plenty of mentions of other brands Emil Busch made before the war.

I looked for the lens in “A lens collector’s Vade Mecum” where they write:

“Glaukar f/2 85mm for movie and an example has been noted in a USA list as such. It was also mounted for M39x26 (coupled). A post 1918 lens (not in Frerk’s 1926 list), near sharp in the center, seemingly with a 1+2+1+1 layout. Rare, these are normally high priced items. Iris is to f/5 only, so these do seem to be portrait lenses. An example in M39x26 was seen at No322,72x while a plain one was No322,76x in movie mount.”

Apparently the author found some sources, I haven’t, so it remains a mystery what Emil Busch actually wrote about this lens.

This is actually the only mention I could find about this Glaukar f/2 series. It’s an ad from a different company selling new Glaukar lenses. The ad was found here dated 1936:

Busch Lenses f/2, 8cm Glaukar with iris diaphragm, shutter, new, only M 29,-
Zeiss Monocular Binoculars 2.5 fixed tube M 5.-
Leather case for binoculars M 1.50 unused
Army stock. Cash on delivery
Charlottenburg Motor Company, Berlin – Charlottenburg 2, Bismarckstr. 105

Even trying to estimate a date of production is hard, because of the lack of historical records. I tried everything from trying to find information on the bellow camera some of the lenses came with. The shutter seems to be a standard Ilex Universal shutter with a small wheel to change the shutter speed. I found the exact same model, which was only used by Ilex themselves for their own lenses. I couldn’t figure out exactly how old this shutter type was, but it seems to come from the early 1930s, maybe even late 1920s. So I assume this Glaukar f/2 lens is also from the same period. It is kinda strange a German optical company wouldn’t use a German shutter, especially in the 1930s.

To look further I tried finding the camera store that had sold the camera with the Glaukar on. I managed to trace it back to one of two stores only some hundred meters from each other in the middle of Berlin that seemed to have been in business around at least the 1930s. So the dates make sense.

Lastly I tried to construct my own serial number list of different Emil Busch products, but I’m not quite sure they used a simple serial number listing technique. I know they had totally different serial numbers for binoculars, so they might have used different serial numbers for each brand or each type of optical equipment.

Glaukar f/2 optical design

Tessar f/2.8 optical design

Glaukar f/3.1 optical design

The lens design stated in the source mentioned above states it uses a 1+2+1+1 layout, which is incorrect. When I found this lens I really had hoped it was this kind of lens, resembling a Primoplan f/1.9 more than anything. The actual optical design surprised me immensely. It was more complex than a simple Cooke triplet, which can hardly ever go under f/2.5 or so. But this f/2 Glaukar lens is in fact a reversed Tessar design. I had no idea a Tessar could achieve this low aperture, maybe it has something to do with reversing the design, or maybe Emil Busch decided to push the design to its limit. Whatever the case was it was a little bit disappointing it wasn’t a Primoplan-like design.

The Glaukar f/2 series is not even mentioned in this 1939 book about different current lenses.

Lens adaption:

But my disappointment didn’t last long, because I can use this lens on my GFX camera, the 35mm lens equivalent being then 59mm f/1.6. I can also use it on the Kipon M645 0.8x speedbooster on the GFX for closer focus, making it a 47mm f/1.25 lens, which is absolutely amazing! The lens in my eyes is totally unique because of these factors. Max focus with speedbooster is around 3 meters, which is enough for portrait photography.

Adapting this lens wasn’t completely straightforward, especially not when using the speedbooster. The lens has screw threads, I thought it was 48×0.75mm, but it seems to be some american standardized threadings (because the shutter is american), so no ring I tried on fit. The 49×0.75mm step down ring had the best fit, but it wasn’t perfect at all. So instead of finding an obscure american adapter ring, I instead bought a 49mm to M52 clamp from eBay. And from there I used a normal chinese made M52 to M52 focusing helicoid and lastly M52 to GFX G-mount.

To adapt it to the M645 mount with the Kipon 0.8x speedbooster I had to remove the shutter mechanism and only work with the lens components. I made and 3D printed a lens barrel to replace the shutter mechanism, matching the necessary measurements. I did this to get enough space for a focusing helicoid. Of course this operation is easily reversed as the shutter and lens can easily be put together as there’s no screws and things. It’s strictly not necessary to adapt it to M645 because at that point you’re already pushing the limits to how big the image circle is. I did it more out of curiosity.

Lens characteristics and performance:

An early worry I had was the image quality, from the few samples I’ve seen it looked pretty bad. Maybe the photographer had a bad copy, whatever the case is my lens performs very well for such an old lens. Of course being f/2 and a reversed Tessar design it’s not my sharpest lens at all. The main weakness is definitely its corners, which start to show field curvature and become unsharp relatively early. Maybe the lens was originally designed for smaller formats like S35 cine format? So you can imagine the lens is not that good for shooting landscapes at f/2. When you step down the corners become a bit better, but far from perfect.

The lens is overall a bit soft, but I kind of like that for portrait photography, it gives a very nostalgic feeling to the images. The lens has some strange lens flares, being very big and very round. For not being coated there’s not much loss of contrast, even when shooting toward the sun or having a strong light source nearby.

Due to the field curvature the bokeh shows slight hints of swirling at the edges of the frame. Other than that the bokeh isn’t that special from any other Tessar design I’ve tried, meaning it doesn’t take much attention away from the photo in general.

Conclusion:

For me this is a one of a kind lens, I still don’t know why Emil Busch didn’t market this lens at all and why no other company tried making a reversed Tessar from what I’ve seen. It’s a good lens, not the best lens I’ve tried, not the worst. It gives a mature image, similar to the more available Glaukar f/3.1 lenses.