The classic Pentax 135mm f3.5 exists in several versions — mainly the M42-mount Takumar models and later K-mount SMC Pentax / Pentax-M versions — but they all share a similar reputation: compact, extremely well built, sharp for the money, and one of the best-value vintage 135mm lenses around.

Best-known versions

• Super-Takumar 135mm f3.5 (M42)

• S-M-C / Super-Multi-Coated Takumar 135mm f3.5

• SMC Pentax 135mm f3.5 (K mount)

• SMC Pentax-M 135mm f3.5

The later SMC-coated versions are generally the most desirable because of improved flare resistance and contrast. (Pentax Forums)

Optical performance

Sharpness

This lens is known for being surprisingly sharp even wide open at f3.5.

Review testing found:

• good center sharpness at f3.5

• very good to excellent performance from f5.6–f11

• softer corners wide open, improving stopped down (pentaxuser.com)

A lot of vintage-lens users describe it as a “sleeper” lens because it performs better than its low market price suggests. Reddit users consistently praise its sharpness and contrast. (Reddit)

Rendering & character

The Pentax 135 f3.5 has a classic vintage rendering style:

• warm color reproduction

• smooth, calm bokeh

• strong microcontrast

• gentle highlight transitions

It is less “dreamy” than some old Soviet or Canon FD telephotos and more neutral/clean overall.

The SMC versions especially have strong color and contrast for a vintage lens. (Pentax Forums)

Build quality

This is one of the biggest strengths.

Most versions are:

• all-metal construction

• buttery smooth focus rings

• long focus throw

• compact for a 135mm lens

The Takumar versions in particular are famous for exceptional mechanical feel. (Pentax Forums)

Weaknesses

Slow aperture

At f3.5, it is not especially fast for a 135mm lens.

Compared with:

• 135mm f2.8

• 135mm f2.5

• 135mm f2 lenses

…it gives less subject separation and weaker low-light performance.

Chromatic aberration

Some versions show purple fringing and CA in harsh backlight, especially on modern high-resolution digital sensors. (pentaxuser.com)

Long minimum focus distance

Most versions only focus to about 1.5m–2m, which feels limiting today. (Pentax Forums)

Adapting to mirrorless

This lens adapts extremely well to:

• Sony E

• Canon RF

• Nikon Z

• Fuji X

• Micro Four Thirds

Mirrorless is honestly the ideal way to use it today because focus peaking makes manual focusing easy.

On APS-C bodies, it behaves like roughly a 200mm equivalent field of view.

Best uses

The lens works especially well for:

• portraits

• compressed landscapes

• street candids

• nature detail shots

• vintage film-style rendering

It is less ideal for:

• sports

• fast action

• low-light handheld shooting

Which version should you buy?

Best value

SMC Pentax-M 1:3.5 135mm

Tiny, sharp, cheap, and easy to adapt.

Best rendering/coatings

Pentax SMC Takumar 135mm f3.5 M42

The SMC Takumar versions generally have the nicest contrast and flare control.

Collector favorite

Asahi Pentax Super-Takumar 3.5/135mm

Beautiful all-metal construction and classic Takumar handling.

Verdict

The Pentax 135mm f3.5 is one of the best low-cost vintage telephoto lenses you can buy.

It is:

• sharp

• compact

• mechanically excellent

• inexpensive

• full of vintage character

Its biggest limitation is simply the relatively slow f3.5 aperture. But if you mostly shoot outdoors or don’t need ultra-shallow depth of field, it offers outstanding value — especially compared with much more expensive vintage 135mm lenses. (Pentax Forums)