Data sheet: Chinon Auto 135 mm f/2.8 multi-coated (Pentax K)

Pekka Buttler, 03/2026

Specifications

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

Brand:	Chinon	Lens name	Auto Multi-coated 1:2.8 135mm
Focal length(s) 1	135 mm	Angle-of-view 2	18 °
Maximum Aperture	f/2.8	In Production	≈1975–1985
Lens mount	Pentax K	Subfamily (if applicable)	K-type (see details)
Length 3	77,8 mm	Diameter 4	62,4 mm
Filter ring diameter	52 mm	Weight	381 grams
Lens element count	?	Lens group count	?
Aperture blades (S/R/C) 5	6 S	Focus throw	210 °
Minimum focusing distance	152 cm	Maximum magnification	1:8,9
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops 6	2.8-4-5.6-8-11-16-22

Further notes:
• This lens was one of Chinon’s portrait primes during the period when its SLR cameras used the Pentax K mount.
• I have been unable to find trustworthy details on production dates, but Chinon quickly saddled over to the Pentax K mount after its introduction (1975) and largely lost its ambition in manufacturing SLRs after Minolta’s introduction of autofocus (1985). The actual production run might be significantly shorter.
• Problematically, there is little hard knowledge about the lens’ optical design (elements & groups).
• Chinon is not known for having manufactured the lenses it sold under the Chinon brand. Hence, the lens likely originates with a Japanese OEM manufacturer (Cosina is a relatively strong bet).
• This lens features an integrated, pull-out lens hood that however does not extend by much.

Versions

There are three fundamentally different 135 mm f/2.8 lenses that were sold as Chinon lenses for the Pentax K mount.

One is the pictured lens that is characterised by a 52 mm filter thread and that also being sold as the Revuenon MC 135/2.8 and the Agfa Color Multi-coated 135/2.8. While most of the samples of this lens version have a similar aperture ring as the one pictured above, there is also a variant where the ribbing of the aperture ring extends to the base of the mount.

The other two versions both share a 55 mm filter thread, but are easy to distinguish as one carries a prominent green diamond shape in the depth-of-field scale and the other’s aperture ring is viewable through an opening (see below).

While I have no hard information on the origin of the second version of the Chinon 135/2.8, the 3rd (rightmost) version has strong commonalities with a series of lenses that Tamron manufactured for third parties.

Chinon company profile

Chinon is known to still photographers as one of the more advanced 2^nd tier Japanese cameramakers. From 1971 to the late 1980s Chinon was known to enthusiast photographers the world over for combining technological advancements in cost-effective cameras bodies. See more details in the Chinon company profile.

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. ↩︎