Best results in photomacrography can be expected with lenses specifically designed for this application. However, these lenses are expensive, and almost all of them are no longer manufactured and are difficult to obtain in good condition and at reasonable prices. Therefore, one may look for alternatives that are easier to obtain and cheaper, while still providing good results.
Based on theoretical considerations, good quality lenses designed for use on darkroom enlargers should be suitable also for photomacrography. These lenses are optimized to enlarge a negative (usually 24 by 36 mm or larger, depending on focal length and other design parameters) by projecting on paper an image magnified, in most cases, roughly between 3 and 10 times. These lenses are designed to provide a high resolution and a low field curvature. They are also chromatically corrected throughout the visible range (and sometimes even in the near-UV). Several users report excellent results when using these lenses for copy and close-up applications (in which typically they are used within their optimal range of magnifications).
When used in photomacrography (i.e., at magnifications exceeding 1x), enlarger lenses should be reversed, in order to work within their optimal design conditions. This brings the back of the lens (designed to be placed close to the negative), now pointing forward, at a comparably close distance from the object. The camera film or sensor is placed at a higher distance from the (reversed) front of the lens, at a distance hopefully similar to that the lens is designed for.
Other than reversing the lens by means of adapter rings, the use of enlarger lenses for this application requires essentially the same technique and accessories as true photomacrographic lenses. Both categories of lenses usually have manual stop rings that must be turned to focus and shoot, and must be used on extension rings and/or bellows. A potential problem with enlarger lenses is that they are supposed to project an image on paper that is much larger than the sensor of a DSLR, while photomacrographic lenses are designed to cover very small images at both their front and back. Therefore, enlarger lenses may sacrifice high resolution in order to provide a large image. However, in the best cases the resolution at the centre of the image should still be high enough for photomacrography. Thus, it is legitimate to ask whether enlarger lenses of good quality can be an alternative to expensive specialty photomacrographic lenses like the Zeiss Luminars.
In this page, I compare the following lenses:
- Zeiss Luminar 63mm f/4.5 (above picture, leftmost).
- EL-Nikkor 63mm f/2.8 enlarger lens (second from the left). This lens is reversed onto Nikon bellows by using an EL-Nikkor reversing ring (shown at the bottom of the lens) of appropriate size and an M39-to-Nikon adapter ring.
- EL-Nikkor 50mm f/4 enlarger lens (second from the right), similarly reversed (because of the different diameter of its filter attachment, it requires a different EL-Nikkor reversing ring, also shown in the picture). The chrome-plated ring at the bottom is an M39-to-Nikon adapter.
- EL-Nikkor 50mm f/2.8 enlarger lens (not illustrated; see here), similarly reversed.
- EL-Nikkor 75mm f/4 enlarger lens (not illustrated; see here), similarly reversed.
- As a term of comparison, also a Micro Nikkor 60mm f/2.8 D (rightmost) was tested. This lens was reversed with a 62 to 52mm filter adapter and a Nikon BR-2A reversing ring (this setup can be seen here). An E2 extension ring was mounted at its back to make it easier to use the reversed lens. Like in my test of photomacrographic lenses, all lenses on this page were tested at the maximum extension of Nikon PB-6 bellows (209 mm flange-to-flange).
The Luminar 63mm is generally regarded as one of the best photomacrographic lenses ever made. I reviewed it here, and compared it to other lenses specifically designed for photomacrography. EL-Nikkor lenses are generally regarded as among the best enlarger lenses. There are at least three series of EL-Nikkor lenses, and at least two categories of optical designs. The EL-Nikkor 63mm tested here belong to the newest series (the N series, multicoated, with partly plastic barrel) and consists of 6 elements in 4 groups. The EL-Nikkor 50mm f/4 tested here, on the other hand, belongs to an earlier series (with all-metal barrel and scalloped aperture ring). It has a simplified coating and a simpler and cheaper optical formula consisting of 4 elements in 4 groups. It is regarded as moderately good in its optimal magnification range, but clearly inferior to 6-element designs. A still-earlier series of EL-Nikkors has a finely knurled aperture ring and all-metal barrel, and it is rarely seen, except in focal lengths exceeding 100mm. Given a choice, I would not select one of these early EL-Nikkors because of potential contrast problems with the lens coating. Exotic Nikkor lenses of other series were also made (e.g., Apo Nikkors, Ultra Micro Nikkors) and some of them certainly are better than EL-Nikkors, but they are definitely rare, especially the shorter focal lengths. I don't have any of them to test.
Like in my test of photomacrographic lenses, the subject used for this test is representative of real-life, three-dimensional subjects illuminated with an SB-800 flash in iTTL mode and manual exposure compensation if needed. Results are shown at apertures of f/8, which seem to be the best for all these lenses. Reduced full frames are shown for all tested lenses, and for most of these also a 1:1 crop from a detail slightly outside the centre of the picture.
The two pictures above show the results with the Luminar 63mm at f/8. The full frame is at the top, and a 1:1 crop of a portion at the bottom. As you can notice, the sharpness of the details is not comparable with what you can expect in a landscape or close-up picture taken in optimal conditions (see here and here for a iscussion and detailed tests).
Above are the results with the EL-Nikkor 63mm at f/8. The resolution is slightly lower than with the Luminar, and a slight chromatic aberration is also visible in the 1:1 crop. However, the performance is still very good.
The EL-Nikkor 50mm at f/8 (and any other aperture) is clearly disappointing. Magnification is higher because of the lower focal length, but the lack of detail is obvious even in the reduced full-frame.
I initially used the Micro Nikkor 60mm with the focusing helicoid focused at a reproduction ratio of 1:3. My thinking behind this was that, the lens being reversed and providing a magnification around 3x, focusing it in this way would make its floating elements effectively compensate for aberrations in the way they are designed for. The practical result is that the working distance was extremely small. I was forced to dismount the E2 ring, and even without this there was very little room available for illumination.
For this reason, I re-focused the lens helicoid to infinity and re-focused the bellows by moving the front standard only (pictures at the left). The magnification is somewhat lower, but the working distance increased threefold. As far as I can judge, the sharpness is unchanged. It is difficult to judge which picture, if any, is sharper, because of the different magnification. Possibly, there is a better flatness of field and higher contrast in the first picture. The increased working distance, however, may make it worth using the less optimized settings.
There are several other enlarger lenses potentially useful for this purpose. The EL-Nikkor 50mm f/2.8 (left) is much better than the 50mm f/4 (both specimens tested are from the same, older, metal-barrel series with scalloped aperture ring). The 105mm f/5.6 and 135mm f/5.6 come to my mind as additional alternatives, although they need very long bellows. Perhaps the 80mm f/5.6 is also a good performer.
I should expect that EL-Nikkors of the N series (the last produced) are optically better than earlier ones, in spite of their plastic barrels. At any rate, their optical formulas have been re-computed, and their coatings are better. It may be mentioned that there is an older EL-Nikkor 63mm f/3.5 which is expensive and difficult to find. This lens is often mentioned as useful in near-UV photography, because it is corrected down to 350 nm, and this rumour is probably responsible for it having been hoarded by collectors (although, in my opinion, probably it does not differ substantially in this respect from a few other lenses of the same series, like the 50mm f/2.8 and 80mm f/5.6). I don't have a 63mm f/3.5 to test, but my guess is that the newer EL-Nikkor 63mm f/2.8 N is at least as good for photomacrography, and probably better. I have no experience with enlarger lenses of other brands and series (a few of which are said to be "the best" by their respective users, e.g., Schneider Componon S and Componon M, Minolta Rokkor, Apo Rodagon, Rodagon G). There is ample room for further tests, and possibly there are quite a few surprises in store.
One last note about the N series of EL-Nikkors is that they have aperture markings illuminated through a translucent window in the lens mount (when mounted on an enlarger). The window is visible when looking at the mount. This portion of the mount can be removed by unscrewing three small screws, and rotated to another position before reassembly. This eliminates the possibility that stray ambient light entering the gap between lens barrel and aperture ring may pass through the translucent window and cause flare. Earlier EL-Nikkor series do not have such a window.
As expected, the Luminar 63mm is the best in the present test. This lens turned out to be the best also when I tested it against other photomacrographic lenses. The EL-Nikkor 63mm f/2.8 is slightly worse than the Luminar, and the Micro Nikkor 60mm f/2.8 slightly worse than the EL-Nikkor 63mm. Both last lenses are fully usable as substitutes for photomacrographic lenses, if a Luminar or equivalent is not available. The EL-Nikkor 75mm f/4 and 50mmf/2.8 are also acceptable, albeit slightly worse than the above. The EL-Nikkor 50mm f/4, instead, is clearly inferior. Don't use it for photomacrography.
