The 6 element Schneider 50mm Componon S is a one of the better enlarger lenses. This lens is an easy way for someone with a normal macro lens that wants to move beyond life-size or 1X magnification up to about 4X for a reasonable cost of less than $100.
You can find the 50mm Componon S in a few different versions, the unit above with the green stripe is the most recent version, which is still in production, and is the most common. You will also see all black metal barrel versions which are nice, and also a non-variable aperture version that I would avoid. Also there are very old chrome barrel versions which are great but the glass condition can be a problem with those since they are so old so shop carefully. There is also a really good all-metal industrial Makro-Iris body version. All of these versions are the same optically so they should have similar performance.
Late model BV-L (plastic) barrel Componon S on the left and the all-metal body B-V Makro-Iris industrial version on the right share the same optics and image quality.
Rating
Like:
Image Quality
Low used prices and easy to find
Working distance
Can live with:
Plastic lens body
Disappointed with:
5 blade iris aperture shape
Corner sharpness is not as strong as the center
Don't need:
Aperture ring being a little too close to the end of the lens sometimes causing clearance problems with adapters.
Image Quality: This lens is one of the better enlarger lenses. Flare is not an issue. The only weakness with this lens is that the corner sharpness is not as strong as the center.
Example
Shell spiral at 2X with Schneider 50mm f/2.8, Nikon D500, 1/60s, f/4.5, ISO 64, manual mode on MM-11 microscope stand.
This is the same shell to show scale
Technical Details
Type: Enlarging lens Focal length: 50mm Aperture: 5 blades
Magnification range: 1X to 4X and sharpest at f/4 to f/5.6.
Coverage: Full frame Working distance: Good, a little less than 2 1/2 inches at 2X, or about 60mm.
Chromatic Aberration (CAs): minimal no problem with either CAs or LoCAs. There are two types of chromatic aberrations; lateral CAs, also called color fringing, and longitudinal color, LoCAs, also called Bokeh CAs.
Lens mount: 39mm mount and
Filter threads: 43mm filter threads that can be used for a lens hood or for reverse mounting for larger than life-size magnification ratios.
Normal or reverse mounting: For best image quality this lens should be mounted in reverse beyond life-size or 1:1.
Cost: These lenses are easy to find on Ebay and expect to pay about $50 for a good copy with prices ranging from $20-100. I was able to pick up one of these new in the box, old stock, for $99 on Ebay so I would not recommend paying anything over $100. This lens is available at retailers for $500+ and is still being made in Germany.
For a more money you can buy the all-metal Makro-Iris version for about $100-190, I was lucky to find a misidentified Makro-Iris lens for about $50.
Notes: Schneider and almost all other enlarging lens brands offer different quality grade lenses. For Schneider you have the budget line of Componar with 3 elements in 3 groups, the higher quality Comparon lenses with 4 elements in 3 groups, then the highest quality Componon with 6 elements in 4 groups with the S added to Comparon and Componon indicating the highest level of correction for flatness of field, contrast, and color. There are also M-Componon 50mm lenses available on the used market but these are specialized large format lenses that are expensive and don't perform so well on small sensors so they are not worth the extra expense.
Mounting
This is my easiest and least expensive way to mount an enlarging lens. You only need a set of extension tubes and 2 adapters, these are the parts I used, left to right;
Enlarging lens - mounted in reverse.
Step-up ring - 43mm to 52mm. This ring mounts the lens using the female 43mm filter threads to the reverse adapter's male 52mm threads.
Reverse mount adapter - this unit has a male 52mm threaded mount and a male camera lens mount on the other side.
Extension tube set - This tube set is all metal and has male and female lens mounts. Tube length is adjustable changing the number black metal sections.
Lens magnification is controlled by the amount of extension. For less magnification you can mount the reverse adapter, step-up ring and lens to the camera directly. For more magnification you can add more extension tubes.
Notes: Ebay has the lowest prices and largest selection of adapters but it can take some time to actually receive the items if the seller is overseas, you can filter search results and find sellers in the country you live.
Schneider 50 Componon S with Canon 39mm extension tube serving as a lens hood
Since the lens was not designed to be used in reverse I use a 25mm Canon 39mm mount rangefinder extension tube to serve as a lens hood and to protect the rear of the lens. The front of the lens has well protected recessed front element but for high magnification work you want to use the lens mounted in reverse which exposes the rear unprotected side of the lens to stray light which can cause flare issues.
Technical data sheets on the Schneider Optics website: https://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=176&IID=1979
Lens test at Coinimaging.com: http://coinimaging.com/s50comp.html