Thursday, January 16, 2014

Lens Review: Nikkor 2.5cm f/4 Rangefinder Lens

One of the rarer lenses in the Nikkor S-mount lineup with only about 2,000 made, the 2.5cm (25mm) f/4 is a lens that is rarely seen "in the wild." Despite being so rare, they seem to be readily available on eBay or at KEH, with usually about half a dozen for sale at any given moment.

I finally got my hands on one of these this month for a price I was willing to pay. I got a pretty good deal since it didn't come with the auxiliary finder - but I already have the Cosina-Voigtlander 25mm f/4 in SC mount and its finder, so I was covered. Plus, I generally can visualize the image based on the 28mm finder built in to the Nikon SP.

Self-Portrait in Shadow, Leaves - Nikon SP, Nikkor 2.5cm f/4, Kodak Elite Chrome 400
This vintage lens design, first seen in the early '50s, is a clone of the Topogon design - which itself is derivative of the Goerz Hypergon, dating from 1900 (1). These types of lenses are not used in (D)SLR cameras due to their design which has a protruding rear element that sticks deep into the camera, which would interfere with the mirror mechanism. Further, even with mirrorless cameras being more common, these lenses cause problems due to the light coming in at such an angle to the sensor. So they are best used on film cameras.

VSU Campus Scenes - Nikon SP, Nikkor 2.5cm f/4, HP5+, Acufine

But this design, despite being over 80 years old, is also its raison d'ĂȘtre. The symmetrical design gives superior sharpness and astonishingly low distortion, with little to no chromatic aberrations, which even today is only rivaled by the newest and most expensive lenses. The retrofocus design required for SLR-style cameras is the reason for lenses needing to be so complex to achieve the same level of quality.

Sunset Cemetery - Bessa R2S, Nikkor 2.5cm f/4, Plus-X, Acufine
Sunset Cemetery - Bessa R2S, Nikkor 2.5cm f/4, Plus-X, Acufine
Enough about the history and background of this lens - how does it perform? Well in a word, excellently! Of course wide-open the lens is not performing at its best, but at f/8 through f/16, resolution and detail is superb. The one major fault of the lens is vignetting, which some may actually enjoy. The lens vignettes so harshly at the extreme corners that it seems that the image circle is actually too small to cover at infinity (see the above b&w examples especially). Additionally, the outer 1/3 of the image is vignetted probably 2/3 of a stop or so until about f/11 or f/16. This is of course exacerbated when using contrasty slide film.

VSU Campus Scenes - Nikon SP, Nikkor 2.5cm f/4, Kodak Elite Chrome 400

This vignetting though is just something to be aware of and can be used for creative effect if desired. The other issue with this lens, common to most lenses from this time and earlier, is a slightly low-contrast look. The harsh contrast of modern lenses with multicoated optics will not be achieved with this lens - which can sometimes be a good thing (see the back-lit cemetery photo as an example).

One of the things this lens excels at is flare resistance. Despite not having modern coatings, flare is almost none-existent, even shooting right into the sun. This performance is quite good in comparison with some other optics from this time period.

Sunset Cemetery at Sunset - Bessa R2S, Nikkor 2.5cm f/4, Plus-X, Acufine
One thing to note when considering this lens - it has no focus ring. The lens is focused solely by the razor-wheel on the top plate of the camera. This is a bit of a pain, but not a huge issue for me - but for others it might be a deal-breaker. The aperture is set inside the front barrel, near the glass. I have read that the aperture leaves are very thin paper, so do be careful changing the aperture - do it slowly! The lens also sadly has no filter threads, but instead supposedly uses Series VII filters. I don't have a VII adapter on hand so I have yet to try that - but considering the vignetting, I think filters might be impossible to use. Disappointing, as I like to use yellow, orange, and other filters.

Scene Shop - Nikon SP, Nikkor 2.5cm f/4, HP5+, Acufine
This lens is the second widest lens in the native S-mount system, with only the even rarer 2.1cm f/4 Nikkor and Cosina-Voigtlander 21mm f/4 lenses being wider. If you are looking for a super-wide angle for your Nikkor rangefinder, this is a great choice. However, one can generally find a 2.8cm f/3.5 lens for about half the price. I have also recently purchased one of these to test, which I will discuss at a later date - but if you like wide-angles, this 2.5cm lens will not disappoint. It also pairs well with 3.5cm and/or 5cm lenses.

Despite some of its flaws, it is definitely a stellar lens and I am quite happy to have it in my lineup. I'll finish up this review with one more image from Sunset Cemetery:

Strickland Facing the Mill - Bessa R2S, Nikkor 2.5cm f/4, Plus-X, Acufine

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