• Ultraviolet Photography

Nikon 50mm f/2.8 EL-Nikkor: old metal version

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#1 UlfW

    Ulf W

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Posted 18 February 2021 - 10:09

Finalized: Work in progress.
Last Update:

Nikon 50mm f/2.8 EL-Nikkor:. old metal version

Manufacturer: Nikon
Manufacturer's lens designation: EL-NIKKOR 50mm f/2.8
Currently manufactured: No
Lens type: Enlarger lens for film up to 24mm x 36mm ( Ø43.2mm )
Focal length: 50mm
Aperture range: f/2.8 – f/45, Manual, 8 blades
Design: 6 elements in 4 groups
Flange Focus distance: 44.8mm
Recommended magnification range*: 0.05x – 0.5x.
Optimal magnification *: 0.125x
Mount: M39 x 26tpi thread.
Sensor format/coverage: up to 24mm x 36mm
Front filter: 40.5 mm x 0.5 mm
Introduction year: pre 1960?
S/N of test object: 343805
* Definitions reversed from normal enlarger definition, referring to the motif not the negative-plane

Lens review (VIS), on the web:
Lens Manual on the web: http://www.savazzi.n...El-Nikkor_2.pdf

Image of test object:

Attached Image: IMG_2582.jpg Attached Image: IMG_2584.jpg Attached Image: IMG_2585.jpg

Transmittance Summary

Definitions of the parameters below
  • Range: The El-Nikkor 50/2.8 Old Metal lens transmits 0-80% in an increasing slope from 332 nm to 400nm.
  • TVISmax(%) = 84%
  • T400nm(%) = 80%
  • T365nm(%) = 56%
    This percentage is an indicator for moderately short exposure time under typical UV-pass filtration peaking around 360 nm.
  • λUV HMvis(nm) = 357nm
  • λUV HM400(nm) = 356nm
  • λUV Zero(nm) = 332nm
  • These three values indicate that the lens is primarily UV-capable in the UV-A range using UV-pass filtration peaking around 365 nm or higher.

Spectral transmission graphs:

UV-NIR, EL-NIKKOR 50mm f/2.8, old metal version
Attached Image: El-Nikkor 50mm f:2.8, Old metal Full.png
The transmission measurement accuracy into the end of NIR range is less good due to limitations in the light source.

UV, EL-NIKKOR 50mm f/2.8, old metal version
Attached Image: El-Nikkor 50mm f:2.8, Old metal UV.png

UV-Log, EL-NIKKOR 50mm f/2.8, old metal version
Attached Image: El-Nikkor 50mm f:2.8, Old metal UV Log.png

Filters and how to use them on this lens:
The front filter thread is common and can be adapted to other filter sizes buy a simple step ring.

It is also possible to use rear mounted filters, either in lens mount adapters for mirrorless cameras like Sony A-series etc, or placed directly in the camera.

An alternative, if space in the camera allows, is to putty-mount a filter directly against the lenses rear element mount ring.
The rear lens element is recessed and thus safe and the ring provides a good reference plane for orienting the filter normal to the optic axis.

My Omega 330W80 Improved Ø25mm, is mounted in a 27mm-filter ring and works well to mount as it is.

Handling and focusing:
This lens needs to be combined with a helicoid or macro bellows to set desired magnification.
With short enough minimum length of a short helicoid it is easy to obtain focus at infinity with mirrorless cameras.
However the standard adapters for M42-lenses to mirrorless cameras will not give focus at infinity.
However these lenses are designed and optimised for short focus distances. At infinity the result will not be optimal.

Edited by UlfW, 06 April 2021 - 06:26.

Ulf Wilhelmson
Curious and trying to see the invisible.