Schneider Makro Apo-Componon 60 mm f/4
Schneider Kreuznach has a long tradition in industrial, camera and enlarger lenses. Since the pervasive acceptance of digital photography, enlargers and enlarger lenses have largely become obsolete, and mainly of interest as collector's items. Photographers dealing with macrophotography and photomacrography have long known that some enlarger lenses give very good results for these applications, and this interest in the best enlarger lenses continues in the digital age. However, these applications are a specialty niche, unlikely to generate major lens sales. Consequently, most lens producers have entirely abandoned the production of enlarger lenses. A few, however, including Schneider Kreuznach and Rodenstock, have attempted to remarket some of their best lenses originally designed for darkroom enlargers as macro and photomacrography lenses.
While several enlarger lenses (e.g., most of the Nikon El-Nikkors) perform well in photomacrography (usually reversed with their front elements pointing toward the camera sensor), only the best of these lenses give truly excellent results. These include mainly the apochromatically corrected models, and especially the Nikon Apo-El-Nikkors, Rodenstock Apo Rodagon and Schneider Apo Componon. The Apo-El-Nikkor series commands extremely high prices and is out of the reach of most buyers, while second-hand Apo Rodagon and Apo Componon lenses can be found at relatively reasonable prices. Although most of these lenses have been designed as enlarger lenses, a few are optimized for photomacrography. These include the Apo Rodagon D (with models optimized for 1x and 2x magnifications) and Apo Componon HM (= High Modulation). The older M-Componon are also good, but were designed mainly for medium- and large-format film, and are not on the same level as the apochromatic models.
The Apo Componon HM series is still currently marketed in a variety of lens barrels, of which the series labelled Makro is mounted in all-metal barrels with a proprietary V-groove mount at either end of the barrel. This series includes also several focusing helicoids, extension tubes and adapters for a few types of DSLRs. They are quite expensive if purchased new, but occasional second-hand specimens like the one shown above can be found.
The lens itself has a male V-groove mount at either end of its barrel, with the front groove normally protected by a removable sleeve (mounted uppermost in the above picture). Three grub screws are used to tighten a female mount onto a male one. The main advantages of the V-groove mount over a threaded mount are that components can be aligned as desired with respect to each other, and that they are less likely to accidentally loosen. The grub screws, however, require an Allen key for tightening and untightening (one key is supplied with most components). Grub screws of a different type (with a rounded, rather than pointed inner end) are present on the aperture and focusing rings. They can be used for locking a ring at the desired position. A small thmbscrew is also supplied for these rings, as an alternative to a grub screw.
My specimen of the lens came with an additional helicoid focusing ring with a travel of 12 mm. This can be used for precision focusing or for manual focus stacking. It varies the camera-to-lens distance and therefore slightly changes the magnification, so it should not be used in applications where the magnification must be documented with precision. Unfortunately, the 60 mm requires an extension ring with a length of at least 8 mm between the reversed lens and the helicoid, so I could not include the helicoid in this test. This lens can mount directly on the helicoid when used in forward orientation for close-up photography.
The following quick test was carried out with the three above lenses mounted on Nikon PB-6 bellows, a Nikon D300s camera and a Bowens Gemini 500R studio flash. Each pair of images is a reduced version of the picture and a 1:1 crop of its lower-central region. The magnification varies, as a consequence of the different lens focal lengths. The higher extension of the Schneider lens results in a higher magnification (approximately 3.5x) and further increases the difference in magnification among the images. A moderate amount of gamma adjustment (of approximately similar amounts among the three test pictures) was carried out. As a whole, the best "image brightness" is subjectively displayed by the Macro-Nikkor, followed by the Micro Nikkor. The Apo Componon displays a less lively color but a more effortless rendering of high-contrast areas and very fine detail. All three images, when considered in their whole character, are quite similar. Because of the different magnification, it is not possible to directly compare the fine resolution, but the Apo Componon seems to display a slight edge on the two other lenses. It is probably the first time I see a photomacrographic lens that exceeds the resolution of the Macro-Nikkor 65 mm (the only exceptions I already witnessed are infinity-corrected systems using apochromatic Mitutoyo microscope objectives, and the overall performance of the Apo Componon reminds me of these). Opening the diaphragm by one stop does provide a slight improvement in resolution in all three lenses (with a corresponding decrease in depth of field, which negatively affects the present subject), but the slight differences among the three lenses remain.
The diaphragm of the Apo Componon has a clearly pentagonal shape, which betrays its original design as an enlarger lens. In some cases, this results in out-of-focus pinpoints of light being rendered as pentagons. The two Nikon lenses have octagonal apertures, slightly less likely to produce this bokeh problem. In the present test, no image displayed such a problem.
As a further comparison, I used a reversed Rodenstock Apo Rodagon N 50 mm f/2.8, with aperture stopped down to f/8 (unfortunately, the framing and focusing are slightly offset because I had already changed the camera setup). This is an enlarger lens not particularly optimized for photomacrography. Nonetheless, results are very respectable. Overall, the color and contrast rendering are quite similar to the Apo Componon sample above. Resolution seems a little lower than with the Apo Componon. Given the substantially lower price and higher second-hand availability of the Apo Rodagon N, the latter lens would be a satisfactory alternative.
So, does the above mean that the Apo Componon is the best lens I tried so far? The answer depends on a few factors. For instance, the above tests were carried out at magnifications around 3.5x -4x. The following crops, instead, were shot at 1x with the reversed Apo Componon and the Zeiss S-Planar 74 mm f/4, which is a rather old copy lens designed for maximum performance at 1x. The results are clear: the Zeiss S-Planar has a far better resolution than the Apo Componon at this magnification. The Apo Componon is obviously outside its optimal magnification range at 1x. However, the Apo Componon displays a superior contrast and color rendering, while the Zeiss S-Planar clearly "hits the ceiling" in the rendering of the brightest areas, probably because of its dated lens coatings.