Data sheet: Revuenon Auto 50 mm f/1.4 MC (Pentax K)

Pekka Buttler, 02/2024

Note: This lens partook in the JAPB comparison of fast fifties and did rather well. See details here.

Specifications

The table below summarises the lens’ key specifications (measurements based on pictured sample):

Brand:	Revuenon	Lens name	Auto MC 1:1.4 f=50mm
Focal length(s) 1	50 mm	Angle-of-view 2	46,8 °
Maximum Aperture	f/1.4	In Production	≈1975–1985
Lens mount	Pentax K	Subfamily (if applicable)	K-type (see details)
Length 3	40,3 mm	Diameter 4	61,8 mm
Filter ring diameter	49 mm	Weight	259 grams
Lens element count	?	Lens group count	?
Aperture blades (S/R/C) 5	8 S	Focus throw	210 °
Minimum focusing distance	45 cm	Maximum magnification	1:6,9
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops 6	1.4-2•2.8•4•5.6•8•11•16-22

Further notes:
• This lens was Revue’s fast fifty to be used with those Revue SLR cameras that used the Pentax K mount.
• Importantly, there is an almost identically named lens (The “Auto Revuenon MCF 1:1.4 f=50mm” – the only difference is MC vs. MCF) differs radically from this lens in that it is a Mamiya Z mount lens (a rebrand of the Mamiya fast fifty for the Mamiya Z mount).
• There is no clear information regarding manufacture date (or original manufacturer for that matter, but Cosina is a strong guess). The guesstimated range (1975-85) of manufacturing dates is based on the years during which Revue sold Pentax K mount cameras (and lenses).

A mystery wrapped in an enigma
• As with many lenses outside of the big-name manufacturers, there is a lack of hard data, which in turn has led to a lot of online speculation based on low sample sizes. Let me try to tell what I know:
• Based on hundreds ⁷ of 4sale listings on eBay and elsewhere:
➡ There are clearly at least two versions of this Pentax K mount lens, that both are named “Auto Revuenon MC 1:1.4 f=50 mm”.
➡ The most obvious and concrete difference is that some of the samples have a 6-bladed aperture whereas others have an 8-bladed aperture (pictured sample). Both aperture designs are roughly as common.
➡ Some samples have a narrow aperture ring grip (the ridges do not go all the way to the mount), other samples grip is less pronounced, but reaches the mount (pictured sample). Again, there is no distinct difference in frequency.
➡ Importantly, while there is a strong correlation between narrow aperture ring grip and 6 aperture blades, there are enough exceptions (9 samples of 112) to cast doubt on the connection.
➡ To add consternation to confusion, there seems to be no clear correlation between the serial numbers of samples (observed range between C601nnn and C668nnn) and either the number of blades or the aperture ring design.
➡ According to several online accounts, there are also two optical designs out there – one based on 6 elements in 5 groups, and another based on 7 elements in 6 groups. The latter would be more typical for a fast fifty.
➡ However, while some accounts link the 8-blade version with the 6e/5g design, others do the opposite. I have insufficient data to present any guesses, except to say that if there are indeed two different optical designs, they are more likely to go hand-in-hand with the number of aperture blades than with the aperture ring design.
➡ And, BTW, the confusion is not yet at an end: there are two other rebrand lenses that share many if not mist of the characteristics with the Revuenon:
➡ There is an Auto Chinon 50 mm f/1.4 MC [data sheet] that – while having two clearly different designs on the name ring however is consistently using a 6-bladed aperture and a narrow aperture ring.
➡ There is also a (somewhat rarer) Agfa Color Multi-Coated 1:1.4 f=50mm lens (see image on Flickr) that harkens back to Agfa’s short-lived attempt to market a prosumer SLR. These evidence the same range of alternatives as the Revuenon (narrow and wide aperture ring grip; 6 or 8 aperture blades)

A brief history of Revue/Revuenon

Pleas see the JAPB company profile of Foto-Quelle (the originator of Revue and Revuenon marques)

Adapting

If you want to natively mount this lens you need to find a functioning Pentax K mount SLR (or a dSLR) camera. Luckily that should be relatively easy as Pentax K film bodies were produced in their millions and most of them – especially those manufactured by Pentax – have a good reliability record. Alternatively, you can use this lens natively on any Pentax dSLR.

Adapting this lens to a mirrorless, full-frame digital camera is a breeze thanks to the lens having full manual controls (aperture ring, focus ring). You simply need a dumb adapter from Pentax K to your mirrorless system.

Due to the medium flange focal distance used by the m42 mount (45,46 mm), whether you can adapt this lens to other than Pentax’ dSLR mounts depends on which dSLR mount: Canon EF, and Four Thirds can mount Pentax K lenses using a simple adapter ring. Minolta/Sony A and Nikon F on the other hand are not as problem-free, and – to retain anything near infinity focus – the adapter will necessitate corrective optics. In all cases, your camera will work only in stop-down metering.

Footnotes

1. Focal length is (unless stated otherwise) given in absolute terms (not in Full-frame equivalent), and according to the manufacturer’s naming practice (which does not always reflect the lens’ actual field of view). For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
2. Picture angle is given in degrees and concerns the diagonal picture angle. Rule of thumb:
   > 90 ° ==> Ultra-wide-angle
   70–90 ° ==> Wide-angle
   50–70 ° ==> Moderate wide-angle
   40–50 ° ==> ‘Standard’ or ‘normal’ lens
   20–40 ° ==> Short tele lens
   10-20 ° ==> Tele lens
   5-10 ° ==> Long tele lens
   < 5 ° ==> Ultra-tele lens ↩︎
3. Length is given from the mount flange to the front of lens at infinity. Measured unless stated otherwise. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. Measured unless stated otherwise. ↩︎
5. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
6. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
7. These 112 samples over time may contain minor duplication (as the same item may have been sold and later re-listed as all listings do not show serial numbers) ↩︎