Author: | | Loyal Site Supporter Registered: November, 2012 Location: Jasper, AR Posts: 3,325 | Lens Review Date: September 9, 2020 | I can recommend this lens: Yes |
Price: N/A
| Rating: 9 |
Pros: | Handling, sharpness, image quality | Cons: | Aberrations | Sharpness: 9
Aberrations: 6
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K-1 mII, K2, K1000
| |

Two versions were introduced, one in 1975 and a second in 1977 which differ only in the name plate. Mine is the older version with "SMC PENTAX 1:2.5/135" on the nameplate. The newer version appears to differ only in the name, which adds "MM" at the end. The lens has 6 elements in 6 groups and 8 aperture blades. Minimum focus distance is 150cm (59 inches) with a maximum magnification of 0.11x which can of course be enhanced with diopters or extension tubes. Speaking of diopters, the front filter threads are 58mm. The lens is 86mm long (3.4 inches) and weighs 500g (1.1 pounds).
The lens is somewhat heavy but handles very well on the K-1 full frame DSLR. On lighter or smaller cameras, it may be slightly front heavy, but on my all metal film units it handles well. Focus action is well damped as the lens extends when focusing close. The aperture ring goes from f/2.5 to f/32 with half-stop indents between all but the last two apertures, each click stop is audible and clear. There is a focus distance window at the top that crops out of range measurements, showing only those distances that should be in focus at available apertures. 
The lens is sharp wide open and fairly easy to focus with the stock K-1 focus screen. Image quality improves as you stop down, where sharpness increases and aberrations decrease. Aberrations are easily noted at wide apertures or high contrast areas, however Lightroom's latest "defringe" function works excellently at removing this defect. Just use the eyedropper on the worst parts of the image and watch it disappear!
What to use this lens for? Anywhere a medium telephoto lens has an application. It's a great travel lens and a decent single-lens solution to shooting candid street photos or architecture. I use the lens for all purposes, including portraits, outdoor photography including macros and landscapes, pet portraits, and miscellaneous things like architecture and still life photography. Rating the lens on a scale of 1-10 for Sharpness, Aberrations, Bokeh, Handling, and Value.
The lens deserves a 9 for sharpness. I'll give it a 6 for aberrations and only because they are easily correctable in Lightroom. Please remember that this lens was introduced 30 years before digital SLRs, and the problem does not show itself as readily on film. Smooth transitions and pleasing out of focus areas garner the lens a 10 for bokeh. I personally like the beefy feel of the lens and enjoy using it, so it gets a 10 for handling. The lens is an exceptional value also, usually setting you back $200 plus or minus $50, so I'd call that a 10 for value. Overall, that averages exactly 9.0. The lens is almost as old as I am and still very competent on a DSLR, and of course it is fun to use on film too.
Thanks for reading, and please leave a comment on my site! 
Wide open example (on K-1 mII)
See more here. Thanks for reading and looking!
| | | | | New Member Registered: June, 2020 Posts: 2 2 users found this helpful | Lens Review Date: June 25, 2020 | I can recommend this lens: Yes |
Price: $140.00
| Rating: 6 |
Pros: | Colors, bokeh, resolution after f4, object separation from background (3D look) | Cons: | Hard to use for close-up, color fringing in some situation | Sharpness: 7
Aberrations: 4
Bokeh: 7
Handling: 9
Value: 7
| | I bought this lens a month ago, paid it 140 USD (imported it from Japan). It is in mint condition. Focus is soft and precise, aperture blades are dry and clean.
Below are few pictures. Second is using Kenko 2X extender.   | | | | Loyal Site Supporter Registered: September, 2017 Location: Medellín Posts: 1,284 | Lens Review Date: December 23, 2019 | I can recommend this lens: Yes |
Price: $260.00
| Rating: 10 |
Pros: | Separation, bokeh, f/2.5-32 | Cons: | | Sharpness: 9
Aberrations: 8
Bokeh: 9
Handling: 10
Value: 10
Camera Used: Film cameras, K-5
| | I paid a little more for the later version, which included the original case, caps, clip-on plastic hood and a B+W protective filter. Definitely shoot it with the hood on if the sun, or bright lights are in the frame or just outside of it while shooting high contrast scenes. It really benefits from it. Then again, some veiling can be used creatively, too. A longer 58 mm collapsible rubber lens hood works well, too. Compared to the Takumar (Bayonet) it's a world of difference. The coatings and better optical design really are worth the price. It's a lens that really shines in low light wide open.
| | | | Site Supporter Registered: November, 2015 Posts: 272 1 user found this helpful | Lens Review Date: October 14, 2019 | I can recommend this lens: Yes |
Price: $125.00
| Rating: 10 |
Pros: | beautiful bokeh , super sharp | Cons: | none | Sharpness: 10
Aberrations: 9
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K3
| | my favorite lens or one of favorite . excellent image quality and beautiful bokeh .
photo straight from camera jpeg with out PP | | | | | Site Supporter Registered: June, 2013 Location: Utrecht Posts: 58 | Lens Review Date: October 11, 2019 | I can recommend this lens: Yes |
Price: $75.00
| Rating: 10 |
Pros: | Sharp, bokeh, beautiful rendering, build quality | Cons: | Abberations wide open | Sharpness: 10
Aberrations: 8
Bokeh: 10
Handling: 10
Value: 10
Camera Used: K2 to K1ii
| | Most is said about this lens, it's sharp and has a "special" rendering and bokeh. Yes, there is some fringing at the edges and corners wide open, but from F4 this almost disappears.
Because of the narrow DOF wide open, while the sharpness is already there, manual focusing goes quick and accurate.
I compared this with the M135 F3.5. At wider apertures the K is sharper (much sharper in the corners on full frame), stopped down the M comes close. Big difference is the amount of aberations, the M shows noticeably more purple fringing at the edges and corners. On APS-C the differences are less.
I always use the metal hood from the Takumar era for the K 2.5, it never comes off...
All pictures here K1ii :
Following pictures develloped in RAW, day light AWB, auto settings, no sharpening | | | | New Member Registered: November, 2014 Posts: 3 1 user found this helpful | Lens Review Date: March 29, 2019 | I can recommend this lens: Yes |
Price: $183.00
| Rating: 9 |
Pros: | sharp, beautiful colours, outstanding bokeh | Cons: | tricky to properly focus | Sharpness: 10
Aberrations: 10
Bokeh: 10
Handling: 7
Value: 8
Camera Used: K-5 IIs
| | I didn't believe the reviews how unique and wonderful the K series is - I should have. This lens makes outstandingly gorgeous pictures, especially when it comes to colour rendering in bokeh.
My only issue is the handling, and not for the manual focus part. While the size and weight is lovely from the carrying point of view, it's difficult to handle: it is too short to use your palm to support it, too long not to support it, the focal length (135x1.5=202) is way too prone to micro movements to get the subject out of focus wide open.
This results in a lot of images where you think you've tackled a sharp focus, but in reality, it's a teeny bit off - once you do have an actually sharp image to compare it becomes obvious.
Despite this, the lens is recommended, but either have a rock solid hand or consider a tripod.
| | | | New Member Registered: June, 2018 Location: Houghton, Michigan Posts: 1 1 user found this helpful | Lens Review Date: December 28, 2018 | I can recommend this lens: Yes |
Price: N/A
| Rating: 9 |
Pros: | wonderful optics and nice bokeh | Cons: | somewhat strong CAs, especially wide open | Sharpness: 10
Aberrations: 7
Bokeh: 9
Handling: 10
Camera Used: K-1
| | This lens is extremely well built and extremely sharp, even wide open. It can be really hard to MF accurately as your DOF will only be a couple inches in a portrait situation. Live view can help this somewhat. The only drawback is somewhat strong CAs, but they are easy to remove in PP.
Higher Res: https://i.imgur.com/6bjkeca.jpg | | | | Senior Member Registered: July, 2018 Location: Stockholm Posts: 214 | Lens Review Date: August 28, 2018 | I can recommend this lens: Yes |
Price: $60.00
| Rating: 10 |
Pros: | Sharpness, bokeh, colour rendition | Cons: | Weight | Sharpness: 9
Aberrations: 8
Bokeh: 10
Handling: 9
Value: 9
Camera Used: Ricoh XR-1
| | This lens was my go to telephoto lens, handled perfect on my camera, I preferred using a winder mounted for speed and handling and that works very well with this lens.
Focusing is smooth and easy to learn to get in focus.
Image quality is great as the brightness of the lens (f/2.5) was good for the time.
I used to pair it with Agfa CT 18 film for wonderful dreamy landscape photography and that was a super lens for getting a bit closer.
Harsh light in the frame was handled very well by Asahi Pentax Super MultiCoating, I always used a hood for maximum contrast.
I recommend this lens in a heartbeat!
| | | | New Member Registered: January, 2018 Location: Paris Posts: 8 3 users found this helpful | Lens Review Date: January 26, 2018 | I can recommend this lens: Yes |
Price: $150.00
| Rating: 9 |
Pros: | COLOR rendering and iQ, 3D pop at 2.5 | Cons: | Manual but easy with k1 and the smooth ring | Sharpness: 9
Aberrations: 7
Bokeh: 9
Handling: 8
Value: 10
Camera Used: K1 K5
| | Why I bought this lens ?
First when I bought my k1, I found my FA77 short as I was used to shoot with my crop k5 sensor so quite a 115/120mm equiv range
This old lady as such great optics (plus it’s a pleasure to watch such a big front piece of glass and the build)
On my K1 I shoot only at 2,5 For subject isolation because of such a mix of great IQ/contrast/COLOR rendering which seems very close to my fa77 on k5.
Notice if you want to stp down With this =M mode +use of green button metering And you have to set -0,7 manual exposition correction (because over expo And contraste loss)
IAM not fond of the green button mesuring ... but
This K2.5 is a gem for the pic rendering with isolation . It’s a fame lens and it deserves it
Don’t worry of the manual focusing even if you dislike, at the first pic at 2.5 you will have big smile.
Knowing this lens now I can tell you it worth easily a 150/200€ bill average with no discussion and suit the k1 lovely
Be careful of the m135 3.5 you can find everywhere on eBay. I bought it 4 years ago for my k5 and resold it 1week after. Absolutely not not the same league.
| | | | Veteran Member Registered: November, 2010 Location: London Posts: 309 | Lens Review Date: October 27, 2017 | I can recommend this lens: Yes |
Price: $100.00
| Rating: 10 |
Pros: | Sharpness, Colours | Cons: | Fringing wide open in certain light | | Really impressed with this lens though it has taken a while to get used to it as I rarely shoot over 55mm. Yes it is heavy-ish, but beautifully built and a joy to focus when you have an EVF. I love the colours I get out of this lens and actually being able to stand back a bit and compose due to the longer FL is an experience that is growing on me.
Lens is very good at F2.5 but really shines when stopped down to F8.
If you can find it for £100 or less, Id say go for it, as you won't regret it...
| | | | Site Supporter Registered: April, 2015 Location: Lower Saxony Posts: 181 3 users found this helpful | Lens Review Date: July 24, 2017 | I can recommend this lens: Yes |
Price: $140.00
| Rating: 9 |
Pros: | Sharp and rich contrast wide open, mostly soft Bokeh, long focus screw, colors | Cons: | OoF little cyan to magenta fringing wide open, sometimes rough Bokeh depending on background | Sharpness: 9
Aberrations: 8
Bokeh: 9
Handling: 9
Value: 9
Camera Used: K-30, K-5 IIs, K-1
| | Owning it more than 2 years i rediscovered this lens summer 2017
for its FL, its 8 blade aperture and its plastic rendition
- and it was sticky then on my K-1 for three month - until i found a K 1:1.8/85....
My Dobi Koma
K-1 + K 1:2.5/135; @f/2.5; linked to original out of camera jpg 
Mrs 3586
K-1 + K 1:2.5/135; @f/2.5; linked to original ooc jpg 
Mrs 3586 II
K-1 + K 1:2.5/135; @f/2.5; linked to original ooc jpg 
Lord of the Flies
K-1 + K 1:2.5/135; @f/2.5; linked to original ooc jpg. 
Halfshadowfax
K-1 + K 1:2.5/135; @f/2.5; linked to originl ooc jpg.  ...and 257 more ooc shots with this lens @f/5.6...a german doberman show 2017.08.06; a flickr album... | | | | Pentaxian Registered: October, 2011 Location: British Columbia Posts: 325 2 users found this helpful | Lens Review Date: July 17, 2017 | I can recommend this lens: Yes |
Price: $180.00
| Rating: 9 |
Pros: | Sharp wide open, pleasant soft bokeh | Cons: | Size, flare resistance, bokeh past f/5.6 gets geometric | Sharpness: 9
Aberrations: 8
Bokeh: 10
Handling: 7
Value: 10
Camera Used: K-1 (digital), K-2 (film)
| | Superb lens. I'm quite fond of the colours that this lens produces and the bokeh it creates both in the foreground and background are some of the best I've seen from a 135mm lens. It's worth noting, however, that the specular highlights can become rather geometric (octagonal) when stopped down past f/5.6. This lens is not the lightest of the pack when it comes to Pentax 135mm primes, but is hardly a burden to carry. I reach for this lens when I want more compression in the frame than the FA 77mm can grab.
Having owned the M-135mm f/3.5, this K-135mm f/2.5 is quite an upgrade in terms of sharpness, bokeh, and contrast.
Although focusing can be challenging, the lens itself is very sharp wide open. See unsharpened photos below @ f/2.5 with 1:1 crop. | | | | New Member Registered: July, 2017 Posts: 1 | Lens Review Date: July 5, 2017 | I can recommend this lens: Yes |
Price: $40.00
| Rating: 8 |
Pros: | built like a tank, compact, sharp wide open | Cons: | purple color fringing | Sharpness: 9
Aberrations: 8
Bokeh: 10
Handling: 10
Value: 10
Camera Used: canon 5dc
| | Beautiful lens, buttery long focus throw, solid metal and glass and the best bokeh of all my pentax lenses (I have 6)
I was very surprised how sharp it was at f2.5 but when I stopped it down to f5.6.... BOOOM! it seemed to turbocharge my Canon 5dc
Purple fringing is a problem, best to stay away from contrasty shots but many programs can deal with 90% of it
I paid just $40 US so I'm an extremely chuffed ole fellow!
| | | | Site Supporter Registered: December, 2014 Location: Colorado Posts: 481 | Lens Review Date: April 29, 2017 | I can recommend this lens: Yes |
Price: $160.00
| Rating: 9 |
Pros: | Sharpness, build, bright aperture, | Cons: | Difficult to nail focus | Sharpness: 10
Aberrations: 8
Bokeh: 10
Handling: 9
Value: 10
Camera Used: K1
| | I used this lens for some time on K-1. Very nice build. As to sharpness I give it 9.5 which is rounded to 10. The only complaint that I have is the razor-thin depth of field, making it difficult to focus. With some patience, however, you will get amazing photos.
| | | | New Member Registered: July, 2016 Posts: 4 2 users found this helpful | Lens Review Date: December 28, 2016 | I can recommend this lens: Yes |
Price: $180.00
| Rating: 9 |
Pros: | Build quality, bokeh, flare resistance, sharpness | Cons: | CA, long minimum focus distance | Sharpness: 8
Aberrations: 9
Bokeh: 10
Handling: 10
Value: 9
Camera Used: Sony A7s, Sony a6000
| | Good lens with excellent build quality and handling. Sharp enough wide open with beautiful bokeh and good contrast and colours. Some CA wide open, and could focus closer than 1.5m, but otherwise excellent.
Check out my detailed review of this lens with lots of image samples at http://www.theweekendlens.com/pentax-135-f25-smc.html | | |