Carl Zeiss S-Sonnar 62mm f/2.5 2.5/62 M1:2,12 Lens
The Carl Zeiss S-Sonnar 2,5/62 M1:2,12 is a technical lens optimized for film duplication at a specific reproduction ratio of 1:2.12 (0.47x reduction) for reducing film format sizes. The lens was part of a group of lenses sold at auction by a film duplication company in Los Angeles (along with a large collection of Printing-Nikkors). Industrial Zeiss lenses like this were designed for use in the graphics arts industry and lenses like the S-Sonnar 2.5/62 were very expensive when sold as new.
The S-Sonnar 2.5/62 has a high level of fit and finish, and is a small but solid feeling lens. The iris housing is all-metal, glossy black body with 9 blade iris. The aperture ring is step-less (no click-stops or half stops) and there are no front accessory thread. This lens has a nice purple coating that looks similar to other industrial lenses I’ve used but don’t expect this lens to full multicoating so I recommend a lens hood for best results. See this PDF for a lengthy in-depth story of Zeiss lens coatings: https://lenspire.zeiss.com/photo/app/uploads/2022/02/technical-article-about-the-reduction-of-reflections-for-camera-lenses.pdf
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Carl Zeiss S-Sonnar 2.5/62 M1:2,12 Copy Lens
S-Sonnar 2.5/62 TECHNICAL SPECIFICATIONS
Carl Zeiss S-Sonnar 2.5/62 M1:2,12
Lens application: industrial film duplication
Focal Length at infinity: 62mm
Nominal maximum Aperture: f/2.5
Aperture Range: f/2.5 - f/16 labeled effective f/3.6 - f/22 on the lens (see notes below)
Mounting threads: M26 x 0.75 (see the how to mount section below)
Accessory threads: none (see the how to mount section below)
Barrel type: all metal
Optics: 4 elements in 4 groups
Design includes sensor cover glass: no
Iris design: 9 blades
Optimization reproduction ratio: 0.47x (1:2.12) mounted forward and 2.12x when mounted in reverse
Image circle at 1:2.12: 15mm
Image circle at 2.12:1: 28mm
Compatible sensor size: APS-C
Dimensions: ⌀ 37.9 x 51.5mm
Typical used price: asking prices are over $700 USD
Lens source: made in Germany
Notes:
Forward mounting in this case means lens label towards the subject and threaded mount towards the sensor.
For best results use a deep hood with this lens, due to the lack of accessory front threads this isn’t easy but you can roll up a small section of black (flocking material is ideal) paper and tape to secure it in place.
The lens is not labeled with the standard nominal f-number but instead with the effective aperture unfortunately. Wide-open, which is f/2.5, is labeled f/3.6 which is the effective aperture. Using this simple formula Effective aperture = (mag + 1) * nominal aperture, the number should be f/3.675 or f/3.7 rounded. EA = (0.47 + 1) * 2.5 = 3.675 or f/3.7 rounded up.
The Carl Zeiss S-Sonnar 2.5/62 is optimized to work at 1:2.12 duplicate film to a smaller format
S-Sonnar 2.5/62 Image Circle
Image circle is easy to measure with a ruler placed diagonally across the image field. This lens will fill a full frame sensor but sharpness drops off near the corners. At 0.47x I measured a 15mm image circle (IC), at 2.12x the IC measured 28mm. See the diagrams below to see what the image circles look like compared to a full frame and APS-C image circles.
S-Sonnar 2.5/62 2.12x Test Results 28mm IC (Sony APS-C sensor)
2.12x TEST SETUP
S-Sonnar 2.5/62 lens reverse mounted, mounting threads facing the subject.
Camera: Sony α6300, model # ILCE-6300, also known as: A6300
Sensor size: APS-C 23.5 × 15.6 mm. 28.21 mm diagonal. 3.92 micron sensor pitch
Flash: Godox TT350s wireless flash x 2 with one Godox X1s 2.4G wireless flash transmitter
Vertical stand: Nikon MM-11 with a Nikon focus block
The camera sensor and wafer were aligned by adjusting subject stage. Next a stack of images in 10 micron steps was made at each aperture. The sharpest frame was then chosen using at 100% actual pixel view. Separate images were selected for center, and corner if needed. Each image was processed in PS CC with identical settings with all noise reduction and lens correction turned off, all settings were zeroed out (true zero) and the same settings were used for all of the images. All images are single files, image stacking was not used.
Click on any image below to open a larger version or right click (two finger click on Mac) to open in a new tab or to save to look at the images in the app of tour choice. All web browsers render images slightly soft by design.
Test area outlined in blue on the 100mm test wafer. Silicon wafers provide an extreme level of fine details like nothing else out there. The micro-lettering, micro-numbers, shapes and fine lines make differences in sharpness very easy to see. High contrast edges on the surface of the disk results in red or pink color fringing with most lenses. A wafer is also perfectly flat and will stay perfectly flat and will never warp or bend during test as natural targets can.
Click on any image below to open a larger version or right click (two finger click on Mac) to open in a new tab or to save to look at the images in the app of your choice. A web browser will render images slightly soft by design.
This is the uncropped test area image out of the APS-C sensor downsized to 2500 pixels across.
Center and corner crop areas highlighted above.
Image quality is best closed down one stop with a good balance between sharpness and chromatic aberrations. Overall very good image quality with just some mild CAs.
I am not showing crops made at maximum aperture since that is not a working aperture, the lens was not designed to be used wide-open. There are issues with excessive red fringing.
Image quality is not as good closed down two stops, with some loss in sharpness. Image quality is good closed two two stops also. Closing down more than two stops results in an additional drop in sharpness.
S-Sonnar 2.5/62 Lateral Chromatic Aberration Test at 2.12x
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Wide open you can see some mild red fringing but CAs are pretty well controlled and disappear when stopped down so not really visible in real world images.
S-Sonnar 2.5/62 LONGITUDINAL CHROMATIC ABERRATION Test at 2.12x
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LoCAs will be invisable in real world photos wide-open and closed one stop. But closing down two stops LoCAs clean up and are no longer really an issue in photos. Closed down three stops the LoCAs are almost are not visible.
Final verdict
The S-Sonnar 2.5/62 lens is an interesting and unique lens and I would recommended if it fits your lens budget. I really enjoyed shooting with it thanks to the small compact size, magnification range, and good IQ when stopped down slightly.
This lens is not corrected at the same level as a true apochromatic lens but I don’t think someone in the market for a Zeiss lens cares about that anyway.
S-Sonnar 2.5/62 PROS AND CONS
What I really like
All metal body
9-blade iris
Compact size
Useful range of conjugate ratios
Mounting threads compatibility with SM1 (close enough)
What I could do without
Non standard size mounting threads
Click-less aperture ring
Lack of available lens information
Aperture ring marked with effective aperture for some reason
What I don’t like
Used market prices
No half-stop detents on the aperture ring
No front accessory threads
Uncommon mounting threads
Small image circle
S-Sonnar 2.5/62 2.12x 2500 pixel image samples
S-Sonnar 2.5/62 lens reverse mounted, mounting threads facing the subject, lens front facing sensor.
Camera: Sony α6300, model # ILCE-6300, also known as: A6300
Sensor size: APS-C 23.5 × 15.6 mm. 28.21 mm diagonal. 3.92 micron sensor pitch
Flash: Godox TT350s wireless flash x 1 with 3 diffusion layers.
The images below were made handheld with a diffused single Godox flash. Iris was closed one stop and 1/160th of a second at 1/32nd flash power at ISO 100 in manual mode.
Unfortunately the day scheduled for in-the-field images with the lens was a poor day for macro photography in sunny Southern California. The morning was was windy, rainy and dark so I was not able to get as much shooting done as I had hoped.
Click on any image below to open a larger version or right click (two finger click on Mac) to open in a new tab or to save to look at the images in the app of your choice. A web browser will render images slightly soft by design. To make sure the image is full size check the URL, it should end in format=2500w. If not change the number to 2500 and hit enter.
At 2.12x the S-Sonnar 2.5/62 coverage is not bad at all on an APS-C sensor camera. Be sure to open the above photos in a new window in your browser or better yet download the image to view in a real photo viewing app.
The S-Sonnar Design
The name "Sonnar" is derived from the German word meaning sun and the design was known for a fast maximum aperture. The S- prefix means either "Sonder" or "Spezial" , both German for special. There are lots of other specialized industrial lenses with similar designation like the S-Planars, S-Orthoplanars, S-Tessar, S-Distagon, and S-Biogon. The classic Zeiss Sonnar design, usually 7 elements, and optimized for use wide-open, it’s a very old dating back to 1929 where it was the leading technology at that time, but the S-Sonnar is a special design. This 4 element S-Sonnar has the large f/2.5 maximum aperture but this lens is at it’s best stopped down one or two stops.
How To Mount the S-Sonnar 2.5/62
The M26 x 0.75 mounting threads used on the S-Sonnar 2.5/62 are not very common. Nikon BD, LU and MM objectives share this thread size so there are Chinese adapters on eBay that will work. Thankfully Thorlabs SM1 (1.035"-40) threaded mount adapters are available online and are compatible. SM1 pitch is slightly different but it’s close enough to thread on more than 5 turns so it works. You can see some of Thorlab’s adapters below.
Optical Component Threading Adapters with SM1 (1.035"-40) Threads:
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=1524
For this test I used Thorlabs SM1 > SM2 flat adapter with lock ring. This allows forward or reverse mounting with the same adapter.
SM2A6 - Adapter with External SM2 Threads and Internal SM1 Threads:
https://www.thorlabs.com/thorproduct.cfm?partnumber=SM2A6
RafCamera offers an M42 mounting clamp style adapter for the S-Sonnar 2.5/62.
30.5mm clamp to M42x1 male thread adapter for reversed Zeiss S-Sonnar 2.5/62mm:
https://rafcamera.com/clamp-30-5mm-to-m42x1m
The same adapter is available on RafCamera’s eBay store and is for reverse mounting.
Link For More Information
Very interesting information on Zeiss industrial optics on Marco Cavina’s site: