Data sheet: Topcon RE. Auto-TOPCOR 135 mm f/3.5

Pekka Buttler, 06/2026

Specifications

The table below summarizes the lens’ key specifications (measurements based on pictured, last version of the lens):

Brand:	Tokyo Kogaku (Topcon)	Lens name	RE.Auto-Topcor 1:3.5 f=13,5cm
Focal length(s)1	135 mm	Angle-of-view2	18 °
Maximum Aperture	f/3.5	In Production	1963–1977
Lens mount (this lens)	Topcon/Exakta	Generation	RE.Auto-Topcor3
Length4	86,7 mm	Diameter5	62,9 mm
Filter ring diameter	49 mm	Weight	405 grams
Lens element count	4	Lens group count	3
Aperture blades (S/R/C)6	6 S	Focus throw	290 °
Minimum focusing distance (measured)	150 cms	Maximum magnification (measured)	1:8,8
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	auto	Aperture click stops 7	3.5••5.6•8•11•16•22

Further notes:

• In an era when most lenses were uniformly black (and when even silver rings were going out of fashion), Topcon initially went in the opposite direction in the styling of their Topcon RE. Auto-TOPCOR series of lenses. These lenses were initially matte silver, with black rubber grips giving a contrast. • However, after the 1971 introduction of the Super D, Topcon also started offering most of its lenses in black. The pictured lens is one of the earlier samples, especially as it still has its focal length indicated in centimetres.
• The filter threads do not rotate on focusing.
• The lens offers a telescoping, two-segment lens hood that extends a total of 41 millimetres, offering – for once – decent protection with a built-in hood.

Versions and variations

When the groundbreaking Topcon RE system was introduced in 1963, so too was the RE.Auto-Topcor 135 mm f/3.5 lens. This was not an entirely new design as it was based on Topcon’s earlier 135/3.5 designs that were available for the Topcon R camera.

The RE.Auto-Topcor 135 mm f/3.5 remained in the lens lineup all the way until the 1977 introduction of the Cima Kogaku 135 mm f/2.8 lens. During the 14 years this lens remained in production it was manufactured in silver (from 1963) – initially with its focal length reported in centimetres; later in millimetres – and also in black from (1972). I have found nothing to indicate that there would exist any optically significant variations.

History of Topcon

Unless you know your camera lore, you might not know that Topcon was once – between 1957 and 1976 – one of the foremost camera companies in the world.

You can read more details in the Topcon company profile.

Adapting

When intending to adapt Topcon/Exakta lenses keep in mind that most Topcon/Exakta lenses have control pins in the lens flange that vanilla Exakta lenses do not have. Hence, there is a theoretical possibility to that some old-time Exakta adapters have been manufactured that do not accommodate these pins. When procuring an adapter, make sure that it explicitly is compatible with Topcon lenses, or visually inspect the adapter regarding whether it makes room for the Topcon control pins.

With that caveat, the following applies to all Topcon/Exakta mount lenses.

This lens cannot be used natively on any current SLR or dSLRs. To use it in its native environment, you will need a Topcon RE Super film body or one of the subsequent Topcon cameras with the Topcon Exakta mount. While these were never produced in immense numbers, they seem to have stood the test of time reasonably well, and can still be found in perfectly serviceable condition.

Thanks to being a fully manual lens (manual aperture, manual focus), the lens can be adapted to all mirrorless cameras using a suitable ‘dumb adapter’. Moreover, due to the popularity of the Exakta mount, special adapters (helicoid adapters, tilt/shift adapters) are readily available.

Using Exakta mount lenses on dSLRs can also be an easy option, depending on the marque of dSLR. 
• Canon EF has the shortest flange focal distance among full-frame dSLR’s and Canon’s wide range of dSLRs are able to mount Topcon/Exakta lenses perfectly using a simple adapter ring. 
• Minolta / Sony A dSLRs, Pentax K and Nikon F mount dSLRs do not have a short enough flange focal distance to enable reaching infinity focus without an adapter that uses corrective optics.

Footnotes

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1. Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
2. Picture angle is given in degrees (based on manufacturers’ specs) 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. See more about Topcon lens generations in Topcon Company profile. ↩︎
4. Length is given from the mount flange to the front of lens at infinity. ↩︎
5. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
6. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
7. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎