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Lens: Nikon El-Nikkor 105mm f/5.6

Vintage: probably 1950's or 60's.

Lens Mount: M39

Needed Adapters: M39 to F-mount (or any other camera mount). This lens is easy to mount in reverse as the ring that says "made in Japan" is removable and when removed, it reveals an M39 thread on the front of the lens. The back is also removable to reveal an M32 thread. That adapter can be useful as some enlarging lenses come with M32 mounting threads.

Preferred Mounting: Enlarging lenses are typically mounted in reverse configuration. One could make an argument for mounting this lens normally below 1:1 magnification. My own evaluation of this is that the lens has a little better resolution in reverse, but has a little better corner performance mounted normally.

Filter Thread: 34 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
9 cm 0.34 400 mm
13 cm 0.73 231 mm
16 cm 1.03 187 mm
19 cm 1.31 165 mm
Est. Focal Length: .103.3 mm

Appearance:

el-nikkor 105 top view el-nikkor 105 side view

aperture graphResolution vs. Aperture:

The sharpest aperture is f/8 and the most resolving aperture is also f/8. Having f/8 as the sharpest aperture is typical for a lens of this focal length.

corner sharpness graphCorner Sharpness vs. Aperture:

The corner sharpness of this lens is very good. At the preferred aperture of f/8 it is extremely good above 0.7:1 magnification and decent at lower magnifications.

(Testing done at 0.7:1 magnification. Numbers at each aperture setting will tend to improve as the magnification is increased and worsen as the magnification is decreased.)

resolution graphSharpness and Resolution vs. Magnification:

This lens shows good sharpness and resolution across its usable magnification range of anything below 1.3:1. Compared to similar 105 mm bellows and enlarging lenses , it has good resolution and sharpness, outperforming a few lenses out there. When you compare this lens to a modern 105mm macro lens, the resolution and sharpness are not quite up to those standards, but the difference is fairly small.

The corner performance is comparable to most bellows lenses in this focal length range although maybe a little lacking in the lower magnification ranges (not much though). Compared to a modern 105mm macro lens, the corner performance tends to be a little better overall.

performance:sharpness graphPerformance: 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 Nikon El-Nikkor 105 shows sharpness performance that varies from very good at low magnification to fair at its upper end of about 1.3:1.

performance:resolution graphPerformance: 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 Nikon El-Nikkor 105 shows resolution performance that varies from very good at low magnification to good at its upper end of about 1.3:1.

resolving power graphResolving 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 to very good resolution.

Chromatic Aberration: This lens show minimal color fringing in the center (about 0.0.2 - 0.30 pixel) and minimal on the periphery (0.40 - 0.60 pixels). Anything below 1.0 pixel is good.

Image Contrast: Image contrast is good across the magnification range.

Flare: This lens shows no significant flare during testing.

Distortion: This lens shows no significant distortion during testing.

Image Samples:

About 0.3:1 magnification, f/8, cropped and resized:

sample image

crop imagePixel level crop from the image above:

There is very good pixel level detail, no problems.

About 1:1 magnification, f/8, resized:

sample image

crop imagePixel level crop from the image above:

There is good pixel level detail, no problems.

Conclusion:

This is an easy to find lens that can make a decent macro lens substitute (as long as you have a bellows). It can be found inexpensively on eBay and from used camera stores.

The resolution and sharpness are good (comparable to other 105 mm bellows lenses) although not quite up to modern macro lens standards. It has very good corner performance and minimal chromatic aberration.

It has a built-in reversing adapter and M32 - M39 adapter, so it will be easy to mount reversed or normally. As I stated earlier, it has slightly better resolution when mounted in reverse and slightly better corner performance when mounted normally. One could easily make the argument that this lens should be mounted in reverse above 1:1 and normally below 1:1 as the lens would working closer to its designed conjugates in those situations.

The biggest drawback that I see with this lens is that it can be a little tough to focus as the maximum aperture is f/5.6. Modern macro lenses have a large aperture that allow for a bright viewfinder and easier focusing.