PENTAX-A SMC 50mm F1.2 Review

Pentax-A SMC 50mm F1.2 is an interesting lens. It’s one of those lenses that you either love or hate. Being an F1.2 prime, it’s not the cheapest vintage lens out there and even in comparison to other 50mm F1.2 vintage primes it’s quite pricey (average price is around $550), so it’s better be good, right? Let’s find out!

Before we start I want to point out there is also an earlier, slightly different looking version, which can be bought for under $300. I’ve only had access to the updated (improved?) “A” version, so this is the one we’ll be taking a closer look at.

Build quality & usability: Like most vintage lens, this is a solid, pretty much fully metal lens, built to last. Focus ring is smooth with about 200° of rotation, which is great for video use. Same as with Nikon lenses, Pentax SMC lenses focus clockwise from foreground to infinity, which for me is a bit of a problem because I’m so used to opposite direction of focusing, but Nikon users will feel right at home.

Character: Pentax SMC lenses are well known to produce saturated, high contrast images. Even wide open it produces higher contrast images than many vintage alternatives. When pointed at a light source it of course loses contrast, but again, not as much as most vintage 50mm primes I’ve tried. All of this can be a good & bad thing depending on the look you’re are going for or lenses you are trying to match it to. It will match to modern lenses better than some lower contrast lenses like Olympus, Minolta or Canon FD, but high contrast potentially has its own downsides too. I’ve been wondering for a while now about how contrast of any particular lens could affect the perceived dynamic range of the camera. Obviously actual sensor does not gain or lose any more dynamic range, but it appears that it’s possible to squeeze in more image information into the same dynamic range when using a lens with slightly lower contrast as demonstrated below. Both test shots were shot with Sony NEX6 at pretty much standard settings and it’s obvious from both, the image and histogram that Pentax pushes the sensor beyond its ability to record the full tonal range of the image, while a slightly lower contrast Canon FD 50mm F1.2 does a much better job, not clipping the highlights and also leaving a bit more room to play with in shadows. It’s almost like shooting with a flatter picture profile and seems to help with limitations of a digital camera sensor. Of course if high contrast was a negative characteristic, no one would use modern lenses, so again it all comes down to what you are trying to get out of your camera/lens setup.

Pentax at F1.2 (100% crop)
Canon at F1.2 (100% crop)

Bokeh: Flares produced by Pentax-A SMC 50mm F1.2 are nothing to write home about, but let’s not mistake it for a modern lens alternative; overall it still has that vintage feel, most of which actually comes from the bokeh it produces. There’s plenty of it, but I find it extremely difficult to describe. It’s both, super smooth and busy, depending what the out of focus area is. I like that it’s a bit swirly and painterly but unfortunately it’s negatively affected by CA, often making it appear busy and unpleasant.

Performance: For me optical performance is the deal breaker when it comes to expensive F1.2 lenses, especially when compared to slower and/or cheaper alternatives. As far as sharpness goes Pentax-A SMC 50mm F1.2 is just about usable wide open (my test video above was all shot wide open to see how usable it is). Questionable performance wide open ia not a surprise for me, because I haven’t yet tried a 50mm F1.2 lens that performs well wide open. Unfortunately that is not my main gripe with this lens. It’s the very obvious purple fringing and chromatic aberration in general, which really disappoints me. Although by F2.8 is completely gone, there are plenty of cheaper 50mm lenses that also perform perfectly by F2.8, so it begs the question, why pay so much money for one? See my conclusion below.

Mount: Pentax K mount has quite a good compatibility with camera mounts including Sony-E, M4/3 and Canon EF, although protruding pin at the back will hit the mirror on FF Canon DLSRs (APS-C Canons should be fine).


  • Introduced in 1984
  • Closest Focusing Distance: 45cm
  • Optics: 7 elements in 6 groups
  • 14 click-stop aperture settings from F1.2 to F22
  • Filter thread side: 52mm
  • Weight: 345g

Let’s now round up the PROS and CONS to get a better idea of what this lens is actually offering us for the money.


  • Fast aperture (great for low light)
  • High contrast, saturated images (good match to modern lenses)
  • Smooth focus ring with hard stops & multiple M/FT marks
  • 200° focus throw (perfect for video use)
  • 0.45cm closest focusing distance for nice close ups
  • Quirky Bokeh wide open (subject to taste)


  • Expensive
  • Soft wide open
  • Very strong CA and purple fringing wide open
  • Bokeh might not be to everyone’s taste
  • Clockwise focus rotation not ideal for anyone used to Canon/Cine rotation

Conclusion: My reviews are usually very positive and concentrate on what can be achieved with a certain lens. It’s particularly interesting when I try out a super cheap lens that you wouldn’t expect much from, but I’m having to be much more critical with a lens like this, which is not exactly a bargain. Although I found more pros than cons to list, I feel that cons are much stronger than pros, generally found on most vintage primes, like the excellent Canon FD 50mm F1.4 or magical Helios 44-2. Considering its price, I expected more from it. I generally found that F1.2 50mm primes are not worth their price against the F1.4 alternatives because performance at F1.2 is usually very average and by F2/2.8 many times cheaper F1.4 primes perform pretty much the same. Saying that, there are many people who will still choose this lens over a slower alternative if they can afford one. A Pentax user building a set would probably love to add one of these to his/her collection and after all it does perform quite well from F2 and becomes pretty much perfect by F2.8, so if you are a Pentax SMC user and you can afford this lens, why not. However I can’t justify the price of this lens, therefore I sold mine to a Pentax user who probably will be very happy to own one.

Click to find this lens on ebay

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One Response to PENTAX-A SMC 50mm F1.2 Review

  1. you should have a look at the upcoming SLR MAGIC 50mm f1.1 :). preorder price is 349$. seems a good alternative to old overpriced lenses.

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