The MAKRO-SYMMAR is a special 8 element macro lens optimized for 1X magnification or 1:1 reproduction but the range is given at 1:2 to 2:1. This lens covers a huge image circle, something like 5 inches at 1X. In my experience, a lens designed for medium format coverage, usually will not be a good match for a modern digital sensor with a small pixel pitch. The M-Componon 4/80 is a good example of a medium format dud on digital. But this lens covers medium format and is designed to work with a 5 µm sensor (the D810 has a 4.88 µm pixel size, the D850 is 4.35µm).
The 120 Makro-Symmar HM has been discontinued on the Schneider Germany site but the large format version 120 Makro-Symmar HM is still listed as still available on the US Schneider distributor, Schneider Optics. In Europe the 120 Makro-Symmar HM has replaced by newer models called the Apo Macro Digitar 5.6 / 120mm or Apo-Digitar 5.6/120 M, depending where you find the info. It would be interesting to see how this model compares to the newer models that, supposedly have been re-designed for digital backs, or are they just re-badged?
So the 120 Makro-Symmar HM is available in a few other mounts and designs, these are a few that I know of:
Makro-Symmar HM 120 f/5.6 B-0 Mount
Makro-Symmar SR 120/5.9 Makro Iris mount industrial 12K Line Scan Lens: https://schneiderkreuznach.com/en/industrial-optics/lenses-v38-line-scan-macro-system
Apo Macro Digitar 120/5.6: https://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=203&IID=1928
Apo-Digitar 120/5.6 M (Macro)
Apo-Digitar 5.6/120 mm M (Macro) Distributed by Alpa: https://www.alpa.ch/en/article/apo-digitar-5-6120-m
At 1X magnification, compared to the Schneider Componon, APO-Componon, M-Componon, and Componon-S the Makro-Symmar has much better chromatic aberration control, even better than the APO-Componons, and tons better in corner sharpness on a full frame sensor. (These lenses are usually better suited to higher magnifications)
For this test at 1X I used a Nikon D850 camera mounted vertically on a stand, Manual mode was used at ISO 64, and to avoid any sharpness loss due to vibration, a Nikon SB-R200 flash was used. RAW NEF files were processed in PS CC with all noise reduction and lens correction turned off, all settings were zeroed out and the same white balance setting used for all the images. For more on this test and to see results for 15 other lenses see the test page: https://www.closeuphotography.com/sharpness-test-1x/
This is the entire frame at 1X on the D850 with the crop areas, center and corner highlighted.
Schneider Makro-Symmar HM 120mm f/5.6 vs Sigma 150mm f2-8 EX OS APO Macro, both at f/5.6
Be sure to click on each image to see it in the full size view. Between these two in the center there isn't much of difference, they both have great detail and sharpness.
In the extreme corner it's a different story, the Schneider lens pulls ahead with better acuity and better control of lateral chromatic aberrations. The Makro-Symmar crop is so clean, the lack of CAs really makes the image appear sharper. Be sure to click on each image to see it in the full size view.
Schneider Makro-Symmar HM 120mm f/5.6 vs Voigtlander 125mm f2/.5 APO-Lanthar, both at f/5.6
The Schneider and Voigtlander also both very sharp in the center. To be fair I should mention that the Voigtlander is sharper at f/2.5 and f/4, but, the f/5.6 crop of the APO-Lanthar is a lot cleaner, so it's a better match for the Schneider in the corners. Be sure to click on each image to see it in the full size view.
In the extreme corner the Makro-Symmar has better control of chromatic aberration. so the image has a lot more acuity and fine detail. Although, the APO-Lanthar has good CA correction, next to the Schneider, the purple and green fringing really stands out.
Be sure to click on each image to see it in the full size view. Look closely at the tiny wavy circuits in the upper left corner to compare the difference in micro-contrast.
Image Quality: Across the frame, edge to edge, clean and sharp at 1X.
Consistent edge to edge performance on a DSLR
All metal lens body
Don't like so much:
Odd-ball mounting thread
5 blade iris
Mounting the Makro-Symmar
Type: Macro lens / line scan lens Focal length: 120mm at infinity Aperture: 5 blades
Aperture: f/5.6 nominal, f/5.9 effective
Magnification range: Optimized for 1X, recommended range is 0.88X - 1.13X
Coverage: Full frame Working distance: Good.
Image circle: 250mm at 1:1
Chromatic Aberration (CAs) control: Zero visible Lateral CAs.
Lens mount: B-0 Iris mount threads - M32.5 x 0.5 Front mounting threads: M40.5 x 0.5
Optical design: symmetric 8 Elements in 4 Groups, ULD, ultra low dispersion glass used in the design.
Notes: This model in the B-0 mount is discontinued, but is easy to find on the used market. There are still the V-mount versions available as new.
This lens is in the B-0 iris mount, and like the CPL-#0 mount version, unscrews into 2 cells. The problem is that, the rear cell is 37mm OD, which is larger than the 32.5mm mounting threads. So the easiest way to mount the lens, would be to use a M32.5mm to 42mm adapter, you can order one here, on Ebay:
http://www.ebay.com/itm/32-5mm-M32-5-x0-5-To-M42-X1MM-For-Roedenstock-schneider-enlarger-Lens-shutter/322536975453 (seller seems to be okay, I have used them in the past).
With this adapter in place you have 42mm outer threads that would allow mounting the lens inside of a 42mm extension tube. To mount the adapter you would have to disassemble the lens, install the 32.5mm adapter, than reassemble the lens cells with the adapter in place. Now the lens will thread into the 42mm extension tube. Now, you can mount the lens on a bellows or directly to the camera with a 42mm to camera mount adapter.
When I bought my Makro-Symmar I got really lucky. I picked up a machine vision camera mounted on a servo motor linear stage setup that came with a 42mm extension tube with a M32.5 x 0.5 > M42 x 1.0 adapter mounted on the end attached to the lens.
External Links for more Info
Schneider Optics site for more info on the CPL # 0 mount version https://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=167&IID=1845
Schneider Optics site specs: https://www.schneideroptics.com/pdfs/photo/LensCharts.pdf
Schneider Optics PDF with illumination and distortion specs for the 120 makro-symmar: https://www.schneideroptics.com/pdfs/photo/datasheets/macro-symmar/macro-symmar_56_120_1.pdf
Schneider Optics site 120 Makro-symmar MTFs: https://www.schneideroptics.com/pdfs/photo/datasheets/macro-symmar/macro-symmar_56_120_2.pdf
Schneider Optics site specs on the V-mount version of the 120 Makro-symmar: https://www.schneideroptics.com/Ecommerce/CatalogSubCategoryDisplay.aspx?CID=1353