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SMC Pentax-FA 50mm f/1.4 Review

John Riley reviews the classic Pentax 50mm f/1.4 prime lens on the the full-frame Pentax K-1.

|  Pentax SMC-FA 50mm f/1.4 in Interchangeable Lenses
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Handling and Features

Pentax 50mm F1,4 On K 1 Body

Although the ubiquitous 50mm standard lens has largely given way to the kit zoom as a first purchase, it still has a very important role as a light, bright optic with a special value in low light photography. The SMC Pentax-FA 50mm f/1.4 is one of the few survivors of full frame Pentax lenses from the film era. It has been reported as discontinued many times over the years, but has continued to be available. Now it has a new lease of life with the K-1 full frame body, so it will be very interesting to see if this 1991 design is up to scratch compared with the excellent new zooms now appearing.

SMC Pentax-FA 50mm f/1.4 Handling and Features

Pentax 50mm F1,4 Front Element View


First made available around 1991, the SMC Pentax-FA 50mm f/1.4 lens is fundamentally a much older optical design, stretching back perhaps even further than the F series lenses that preceded it. Nonetheless, its seven elements in six groups design is a well tried and tested one that is capable of high grade results.

If we start at the front of the lens, the bright f/1.4 maximum aperture results in a very easy to focus viewfinder image. It is an AF lens, but if the camera body is switched to MF then a thin focusing ring at the front of the lens can be used to focus. The image snaps in and out very cleanly, so manual focusing is not a problem if needed.

A plastic window reveals the focusing scale in feet and metres. There is also a depth of field scale inscribed on the lens barrel. Finally, closest to the camera body, is an aperture ring. This should be set to the “A” position to fully utilise the features of the DSLR range.

The diaphragm has eight blades, the filter thread is an economical 49mm and the lens focuses down to 1.5 feet (0.45m), giving a maximum magnification of 0.15x. Weight is a modest 220g.

Pentax 50mm F1,4 Oblique Front View

One missing feature is QuickShift, the ability to tweak focus manually whilst using AF. With this lens, manual focus must be set on the camera before the manual focusing ring can be used. There is also no inbuilt focusing motor, so AF is by screw drive. This is fine and works quickly, but is inherently more noisy than the DC or SDM lenses.

Another feature that is absent is Weather Resistance, although the construction of the lens does not seem to offer too many avenues for water ingress.

The beauty of the 50mm lens is its relatively low cost, its high quality and its ability to be abused with the use of extension tubes, close up filters, bellows and any other accessories that might be found. These lenses are also generally very bright and f/1.4 is a useful maximum aperture. With the higher ISO values now available, hand held shooting can continue as the light fades, to remarkably low levels.

It is a shame that no lens hood is supplied as standard, but it was the norm in the days when this was first released. There is a dedicated square Pentax lens hood available, a very convenient clip on design, the PH-SA49. This is now priced at a more palatable £24.99 after many years at around £60. There are also plenty of lower cost third party hoods available. Even with current coating technology, a lens hood is always a good idea.

Pentax 50mm F1,4 Oblique Rear View

SMC Pentax-FA 50mm f/1.4 Performance

Of particular interest is how a film-era lens design will cope with the requirements of digital sensors, especially with high pixel counts. There was little thought with lenses made for film cameras of making telecentric designs, so it is reassuring to find that this lens is definitely up to the standard of the latest Pentax high quality zooms. (Telecentric design results in the exit light rays from the back of a lens being parallel, thus improving the peripheral illumination with a digital sensor. Film can accept more oblique rays without problems.)

Centrally, sharpness starts off quite soft at f/1.4, is of a good standard by f/2 and is very good from f/2.8 through to f/22. It peaks at f/5.6.

The edges also start off soft at f/1.4 and f/2, reach a good standard by f/2.8 and are very good from f/4 to f/8. There is a drop to good sharpness at f/11 and f/16 and a softening of detail at f/22. Again, performance peaks at f/5.6.


Pentax 50mm MTF Chart
MTF Chart

How to read our charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. 

The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance. 

For this review, the lens was tested on a Pentax K-1 using Imatest.


Distortion is a respectable -1.22% barrel, which is good for such a fast, bright lens design. CA (Chromatic Aberration) is very well controlled centrally, down to about one quarter of a pixel and resulting in no fringing being apparent. The edges do show some CA, but it is easily dealt with in software.


Pentax 50mm CA Chart
CA Chart

How to read our charts

Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.

For this review, the lens was tested on a Pentax K-1 using Imatest.


Images are bright and contrasty and have plenty of punch. There is an almost total resistance to flare, even with the sun just on the edge of the image area. In even the most demanding shots there is no loss of contrast because of flare. The colour balance of all Pentax lenses is excellent and this one is no exception. I would describe it as slightly warm natural colour. Colour balance across a lens range is desirable for consistency and the lens blends closely with even the newer HD coated optics.

The conclusion is that this lens still holds its head up high and can compete with the latest high quality full frame lenses as an equal. An excellent result for a well established design.

Pentax SMC-FA 50mm f/1.4 Sample Photos

Value For Money

In the Pentax range there are some options for a bright full frame standard lens. The SMC Pentax-FA 50mm f/1.4 costs £339. The SMC Pentax 43mm f/1.9 Limited lens costs £629. Alternatively, the slower SMC Pentax-D FA 50mm f/2.8 Macro lens is priced at £319. Although not as fast it does offer 1:1 magnification.

To see how this relates to the cost of other marques, Canon offer the EF 50mm f/1.4 at £232, Nikon the 50mm f/1.4 G AF-S at £349 and Sony the 50mm f/1.4 AF at £299.

This suggests the Pentax is about at the right price level for a high quality, fast standard lens. There are of course some very low cost options, but these are usually 50mm f/1.8 designs. Sadly, the SMC Pentax-DA 50mm f/1.8 is for APS-C format only.

For more options have a look at to Top 10 Best Pentax Lenses, or the Top 27 Best Portrait Lenses.


SMC Pentax-FA 50mm f/1.4 Verdict

There is still a case for the fast standard lens. Zooms have convenience and avoid too much lens changing, but the fast prime lens is smaller, lighter and sometimes even of better quality. The quality issue is perhaps of less relevance as the results from zoom lenses have become so good, but the bright maximum aperture and small size do give us freedom to continue shooting in much lower light.

The 50mm lens was at one time the lens of choice with a new camera, and it is still a very versatile option today. Many photographers will carry such a lens as well as a bag of zooms, and the SMC Pentax-FA 50mm f/1.4 is an excellent choice. The quality is high, the lens handles well and it is an unobtrusive addition to any camera kit.

SMC Pentax-FA 50mm f/1.4 Pros

High sharpness levels
Low central CA
Excellent colour
Low flare
Compact, light lens

SMC Pentax-FA 50mm f/1.4 Cons

No QuickShift
No Weather Resistance
Some edge CA


The SMC Pentax-FA 50mm f/1.4 is a robust, high quality standard lens for Pentax DSLRs.


Pentax SMC-FA 50mm f/1.4 Specifications

Lens Mounts
  • Pentax K SMC-F
Focal Length50mm
Angle of View0 - 47
Max Aperturef/1.4
Min Aperturef/22
Filter Size49mm
35mm equivalentNo Data
Internal focusingNo
Maximum magnification0.13x
Min Focus45cm
Box Contents
Box ContentsNo Data

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8 Jun 2016 2:44PM
Photos are very disappointing
JakubS 6
28 Jun 2016 12:04PM
Good news. The DA 50 1.8 works on fullframe too. Marketed as DA but really a fullframe design.

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