Sunday, July 7, 2013

The 50mm Kern Macro Switar lens

Legends of photography:
Photographing with the Macro Switar on a Leica M and Fuji X-Pro1

The f/1.8 50mm Kern Macro Switar lens was made in Switzerland by Kern Aarau exclusively for the Alpa 35mm cameras. It was introduced in 1951 and reached legendary status for its precision optics and hand-crafted elegance. In 1958 the model was modified with the introduction of the Visifocus depth-of-file indicator shown on the lens in this blog post. As the aperture ring was turned, yellow dots appeared in the ring below to indicate the depth-of-field for the selected f/stop. In 1968 the design changed again with the addition of better coating of the  lens elements and a decrease in the maximum aperture to f/1.9.

Early camera lenses did not have the sophisticated anti-reflective optical coatings we have today. Early lens designs had fewer optical elements to control aberrations and so did not require coatings to control reflective glare.  As optical elements were added to lens systems creating more glass surfaces, they also created more problems with reflective glare from the increase of internal glass surfaces. In the mid-1930's a non-reflective coating was first discovered and used to coat the lens surfaces to reduce glare. This was not widely applied until after WWII. It took decades for the development of the sophisticated, multi-lens coatings we use today.

Early lenses have a muted, low contrast effect when used on modern digital camera sensors, which are more demanding than film. The original sharpness of these lenses remains unaffected.  I seem to remember reading somewhere that for the film "Saving Private Ryan" the cinematographer had the lens coatings removed from the Nikon lenses used to shoot the film in order to simulate the effect of contemporary optics.

The electronic view finders and "live view" mode of mirrorless cameras has made it possible to mount many older camera lenses on them. So I decided to try the 50mm Switar on my Leica M and also the Fuji X-Pro1. Interestingly, it is a very small lens for having been intended for SLR use. In fact, it is not much larger than a regular Leica M lens. This, plus its ability to focus close, made it very appealing to try.

The focusing ring has a long throw -- a really long throw.  It focuses down to 1.8x magnification at 11" but takes 2 3/4 turns of the focusing ring to get there. Note the Visifocus depth-of-field scale of yellow dots.

The lens shade for the Switar has an unusual, and innovative way of attaching by means of a single, thin, spring wire that runs along the inside of the hood and protrudes out the bottom. Pressing the bottom loop loosens the tension on the spring so it fits over the lens. As soon as you release the spring tension, the hood is attached. The design is not exactly graceful with the metal loop sticking out from the bottom, but it is very functional and speedy to use.

First thing I noticed about this lens was the low contrast due to its lack of modern anti-reflective coatings.
The images are definitely sharp, but lacking in color punch -- a direct result of the low level of lens coatings.
Normally, the colors in this photo and the one above would be very vibrant. I could have punched the color some more in Photoshop, but decided to keep it as it was to illustrate the muted color palette of the lens.
My preliminary lens tests led me to realize that I should not be working against the grain. If the lens exhibited a low contrast, muted look, perhaps it was better to exploit this quality rather than mask it with some post-processing punch. With that in mind I did the three still life photos below, thinking they would be a little more in keeping with the natural characteristics the lens had to offer.

For all of the above samples, I used a very wide open lens aperture of f/2 and a filtered window light for illumination to enhance the softer color palette of the lens. The muted colors are a product of the age of the lens and its minimal anti-reflective coatings. There is no other post-processing going on here.

The main reason I enjoy using older lenses on modern digital cameras is for the inherent optical effects they offer due to the less sophisticated technology of their age. I find this extends the options of my creative palette.

Here the Switar is mounted on a Fuji X-Pro1 where it acts as a 75mm close-up lens. The pleasing look of the match of camera to lens almost appears as if they were made for each other.
A Metabones Speed Booster adapter is also available to connect Alpa lenses like the 50mm Switar to Fuji X-series.  The adapter preserves the same 50mm focal length when the lens is attached to the Fuji camera.

Taken with the Switar on the X-Pro1, this shot demonstrates the beautiful bokeh in the out of focus areas when working in close at a wide open f/1.8 aperture.


  1. If we use kipon adapter for M mount, are we able to close focus?

  2. On 36mm wide sensor the lens produces 1/3x magnification.

  3. will a 75mm Switar cover the corners on a full frame sensor?

  4. The Switar 75mm was made for the Bolex movie film camera. It might work on micro 4/3 but not full frame.