Lens: Nikon El-Nikkor 50mm f/2.8N
Vintage: Current.
Lens Mount: M39.
Needed Adapters: Reversing ring (for your camera), 40.5 to 52 step up ring. The size of the step up ring depends upon the size of the threads on the reversing ring.
Preferred Mounting: Reversed.
Filter Thread: 40.5 mm.
Street Price: $50-$100 in good used condition. Prices vary a lot online, shop around.
Controls: Aperture setting.
Aperture: 8 blades.
Basic Function: Requires a bellows to set focus and magnification
| Extension | Magnification | Working Distance |
| adapters | 0.66 | 110 mm |
| 25 mm | 1.17 | 76 mm |
| 5 cm | 1.50 | 63 mm |
| 9 cm | 2.27 | 51 mm |
| 13 cm | 3.04 | 46 mm |
| 19 cm | 4.25 | 43 mm |
| Est. Focal Length: 51.2 mm | ||
Appearance:
Resolution vs. Aperture:
This lens shows it's sharpest aperture at about f/5.6, about typical for a lens of this focal length. It's highest resolving aperture is between f/4 and f/5.6, also typical for a 50 mm enlarging lens.
I use this lens at an aperture of f/5.6.
Corner Sharpness vs. Aperture:
There is quite a lot of peripheral fuzziness at lower aperture settings, being quite visible from about f/2.8 through f/5.6. This graph was obtained at a magnification of 1.5:1, so these number will worsen at lower magnification and improve as the magnification increases.
If you want the sharpest image you will want to use f/5.6 - but that only applies to the center of the image. Because of the moderate peripheral fuzziness at f/5.6, you may want to use f/6.7 or f/8 at lower magnifications and then switch to f/5.6 at higher magnification. You will lose a little sharpness and resolution with the smaller apertures, but will gain significant sharpness in the corners.
In comparison with other enlarging lenses that I own and have tested, the corner sharpness seems to be a little below average. This was a little disappointing for me as I normally expect enlarging lenses to have relatively sharp corners.
Sharpness and Resolution vs. Magnification:
This lens shows slightly above average resolution and sharpness in the center of the field compared to other 50 mm enlarging lenses - I own 6 at present.
The corner sharpness is the one limitation of this lens. As the green line on the graph shows, the corner sharpness is relatively good from 2:1 and higher (at f/5.6). Below 2:1 magnification, the corner sharpness at f/5.6 become a bit of a mess. That is why I suggested using f/6.7 or f/8 at lower magnifications in the previous section.
Performance: Sharpness vs. Magnification:
I have 4 lines that represent levels of performance from outstanding (top) to fair (bottom). This shows where this lens fits into the hierarchy that I have created.
The El-Nikkor 50/2.8N shows sharpness performance varying from very good to fair across it magnification range.
Performance: Resolution vs. Magnification:
I have 4 lines that represent levels of performance from outstanding (top) to fair (bottom). This shows where this lens fits into the hierarchy that I have created.
The El-Nikkor 50/2.8N shows resolution performance varying from very good to fair across it magnification range.
Resolving Power vs. Magnification:
This graph represents the smallest details that are able to be resolved by this lens at various magnificaitons. If the number doesn't get smaller as the magnification rises, there is little benefit to going up in magnificaiton with this lens. This situation is also called empty magnification.
Good resolution, no problems.
Chromatic Aberration:
This lens show minimal color fringing in the center (about 0.10 - 0.30 pixels) and fairly severe on the periphery (1.0 - 5.0 pixels), worst at lower magnification.
Image Contrast: Image contrast is good, typical for an enlarging lens.
Flare: This lens shows no significant flare during testing.
Distortion: This lens shows no significant distortion during testing.
Image Samples:
About 1.5:1 magnification, f/5.6, cropped and resized:
Pixel level crop from the image above:
The pixel level detail is really quite good, although slightly fuzzy. With appropriate sharpening, this lens' resolution capabilities at this magnification are close to that of the detector.
About 3:1 magnification, f/5.6, stack of 22 images, resized:
Pixel level crop from the image above:
Good detail at the pixel level, but starting to get a little fuzzier as you would expect at high magnification.
Conclusion:
This enlarging lens works very well as a bellows lens although the corner sharpness isn't its strong suit. That is a problem that can be fixed by proper choice of aperture, so it isn't a deal-breaker, but it is a disappointment for me. That being said, this decrease in corner sharpness is not particularly obvious with typical images. If corner sharpness is important for you, other 50mm enlarging lenses may be a better fit. I will need to do more corner testing on my other 50 mm lenses to find out they compare. My gut feeling is that they will do a little better.
This lens is best used in a reversed configuration when used above 1:1 as reversed most closely approximates the image and object distances that it is designed for.
These lenses are relatively cheap and plentiful in new or used condition. There are always several available on eBay, and they are commonly seen at used camera stores. All-in-all it is a good lens for imaging in the range from 1:1 to 4:1.