Friday, May 24, 2024

Comparing vintage 28mm lenses

I love the 28mm field of view and wanted to update my insights now that I've returned to using a full-frame camera. Here I will compare five different 28mm film-era lenses, namely:

  • smc PENTAX 1:2 28mm (1976) 
  • Carl Zeiss Distagon T* 28mm f/2.8 (1978) for Contax-Yashica mount
  • Kino Precision Kiron 28mm f/2 MC (1981)
  • Vivitar 28mm 1:2.0 MC Close Focus (1983) made by Komine
  • SMC PENTAX-A 28mm f/2.8 (1984)

This article is the result of months of work shooting in real-world scenarios and staged tests. Hopefully of interest to other photographers... like you!


I have a history of dedication to 28mm focal length lenses. Back when I was using a Pentax DSLR with an APS-C sensor, 28mm corresponded to a useful "perfect normal" field of view. There was a plethora of such lenses available for the K-mount. A series of random bargain-basement purchases alerted me to those marketed under the Vivitar brand name. With the help of photographers on the Pentax Forum, I began compiling information. The result was The Great Vivitar 28mm Bestiary, first published in 2009. This compendium grew to include 38 variants... and that's only counting those Vivitar lenses compatible with Pentax! There are even more models for other mounts.

Today I use a full-frame camera on which a 28mm focal length renders a 74° angle of view. This wide angle maintains a naturalistic image without perspective distortion calling attention to itself as a "special effect". Of course many wonderful photographs can be taken with much wider lenses, but these are of niche interest... to me at least! Whereas 28mm is a useful focal length every day.

I find it strange that in the contemporary digital market, manufacturers commonly produce a 24mm prime for their systems, but many brands (including Panasonic Lumix) do not provide the classic 28mm focal. Of course any number of zoom lenses can be pressed into service. But I prefer the ergonomics of vintage primes with aperture dials. The experience is simply more satisfying. 

Circa 2008 I leveraged my growing collection of 28mm lenses to publish test articles on this blog (itemised in an appendix below). But lenses that might perform admirably on a smaller sensor face a greater challenge on full-frame, where the entire image circle is used. So I decided to update my aged APS-C sensor tests. This has taken some work!

The Lenses

In this section I will provide an overview of the lenses. For convenience I've named these the Pentax Distagon, Zeiss Distagon, Pentax A, Vivitar by Komine, and Kino by Kiron. This saves you reading the full name each time. 

Pentax Distagon

The Carl Zeiss Distagon T* 28mm f/2.0 was released for the Contax-Yashica mount in late 1975. Designer Erhard Glatzel collaborated with Pentax, who were planning the launch of their first K-mount camera, the K1000. They needed an excellent line of lenses to accompany this milestone. And so the Zeiss Distagon 28/2 was also released as the "smc PENTAX 1:2 28mm".

This optic utilises 9 elements in 8 groups, including floating elements that maintain excellent performance down to the closest focus distance (30 cm). Like many Zeiss designs, the lens is unusually large and heavy (length 69mm, mass 423g, 52mm front filter). Pentax produced this lens from 1976 to 1981 in two variants that are identical except for their markings.

This first line of K-mount lenses are referred to as "K", even though this letter does not appear on the markings or in the official lens designations. But this nomenclature helps distinguish the "K" line from the subsequent "M" series (which are marked "PENTAX-M") and A series (marked "PENTAX-A"). The M line were all re-engineered from the K, following consumer demand, to fit a smaller form factor. This is where Pentax and Zeiss parted ways! The A series are so named because they had an automatic aperture setting... though this is not relevant when they are used on contemporary digital cameras. Many but not all of these A lenses were optically identical to their M predecessors. But the K line are unique and often highly prized by Pentax fans.

Note that the official Zeiss specification sheet measures the focal length at 28.8mm for a 74º diagonal angle of view.

Most Zeiss lenses have minimal distortion, low flare, insignificant chromatic aberration, good contrast, and accurate colours. This Distagon is no exception.

Zeiss Distagon

The Carl Zeiss Distagon T* 28mm f/2.8 was released for the Contax-Yashica mount three years after the f/2.0 version (1978) as a more compact (52mm, 280g, 55mm filter) and more affordable option. The optics use 7 elements in 7 groups. Though it can focus closer (25cm) than the f/2 lens, it does not include floating elements. The official specification sheet measures the focal length at 28.5mm for a 75º diagonal angle of view.

It is worth mentioning that the name Distagon indicates a retrofocus design, where "the distance between the last lens surface and the film plane is longer than the focal length, allowing unobstructed motion of the reflex mirror" (Zeiss spec sheet).

Pentax A

The SMC PENTAX-A 28mm f/2.8 was produced from 1984 to 1988. It's more compact than the Zeiss designs at 37mm long, 170g, 49mm filter. The 7 elements in 7 group optic is the same as its predecessor (the second version of SMC Pentax-M 28mm f/2.8) though optical performance is generally thought to be slightly better. Reviewers note its sharpness and dimensional rendering. Close focus is 30cm.

For completeness I list the full line-up of manual focus Pentax 28mm lenses:

SMC Pentax 28mm F2
SMC Pentax 28mm F3.5
SMC Pentax-M 28mm F2
SMC Pentax-M 28mm F2.8
SMC Pentax-M 28mm F3.5
SMC Pentax-A 28mm F2
SMC Pentax-A 28mm F2.8

Vivitar by Komine

For this comparison I selected two of the best lenses from The Great Vivitar 28mm Bestiary. The Vivitar 28mm 1:2.0 MC Close Focus was manufactured by Komine circa 1983. It is distinctive for the high magnification (1:5) made possible by the 23cm minimum focus distance. It's similar in size to the Distagon f/2.8 at 50mm long and 280g, with 49mm filter thread. I very much enjoyed using this lens on APS-C sensors. Details and photos here.

Kino by Kiron

The "Kino Precision" Kiron 28mm f/2 MC was released in 1981 for K-mount. It's 51mm long and 270g with 55mm filter and 30cm close focus. It was included in the Bestiary since it's similar to some Vivitar variants and performs well. Details and photos here.

I note that my copy appears to have hazy elements. This might be something that's developed in the last decade!

Other remarks

All the K-mount lenses have the widest aperture to the right and stop down with a clockwise rotation. They include half-stop clicks that are firm and decisive.

The Zeiss Distagon, like other lenses for Contax-Yashica mount, have the widest aperture to the left and stop down with a counter-clockwise rotation. It has only full stop clicks that move easier than Pentax lenses. Hence the aperture is quicker to change but does not permit the same fine control over exposure.

All these lenses focus from near to far by rotating the barrel counter-clockwise.

Test Method

At the outset I should declare that I'm not a technician and do not have calibrated test equipment. I compare lenses by shooting them in controlled circumstances, but also by taking them out for real-world encounters. This article is hence less a "test" and more a "comparison". I make no claims for scientific validity.

Numerous test shots were made over several weeks, in part because I didn't believe the initial results. I present a useful subset of tests in this Flickr album. Other results not reported here are nonetheless consistent with these.

I shot using the excellent Panasonic Lumix DC-S5, a hybrid photography and video camera. The S5 has a 35mm full-frame (35.6 x 23.8mm) CMOS sensor with 24.2 effective megapixels. All photos were taken on a tripod, with shutter timer and IBIS set off. Sensitivity was kept consistent for each set, at either 100 or 640, these being the base ISO values of the sensor in Natural profile. Lenses were set to four aperture settings: f/2 (if available), f/2.8, f/4, and f/8.

The raw (RW2) files were batch converted to JPG using Affinity Photo. I did not apply any of my usual development processing.

The shared results are from two scenarios.

The first subject was my bookshelf at a distance of 60cm. I used 14x magnification on the LCD screen to focus on a region 80% of the way to the right-hand border, this being the closest to the edge of the frame that I could manage. This region corresponds to the "DM" of "BIRDMAN" on the spine of the book. I cropped a 1000 pixel square out of each image, arranging these in a grid for ease of comparison. The first column is at f/2, second column f/2.8, and so on.

books border (crop)

Here is a comparison of the centre and edge of the frame at f/4.0. Again, these are magnified crops.

books at F4 (crop)

The second subject is a bunch of yellow roses. Focus is on the centre, with the flower in the top-right also falling into the focal plane. View these in the Flickr album already mentioned.


The Pentax Distagon acquits itself very well. At f/2 the results are usable, even at the border. The bokeh is smooth and delightful. Vignetting is obvious, as was expected. Improvements in sharpness and contrast are seen when stopping down, resulting in a wonderful f/8 image across the frame.

The results from the Pentax-A f/2.8 will not surprise any Pentax fans. From wide open the bookshelf images have improved micro and macro contrast compared with the Pentax Distagon. At f/2.8 the flower image is lovely, with smooth bokeh typical of Pentax. Vignetting is less than the Distagon. The slightly wider field of view is more true to the claimed 28mm focal length.

If we turn to the Kino by Kiron it's obvious that border clarity is lacking, though OK at f/8. I had already noticed this while shooting, since it was difficult to nail focus. In the flower image the outer bloom is soft and dreamy. The Kino could be used as a specialty lens for when this effect is desirable. But personally I'd be shooting a longer focal length and wider aperture if subject isolation was my priority. I prefer my wide lenses to be useful for wide shots!

The Vivitar by Komine lens proved a winner on a cropped sensor and has a good reputation. But here I found it washed out and hazy, with ridiculous vignetting, hence useless wide open... and not much better until f/8.

I was surprised to see that the Zeiss Distagon f/2.8 performed as poorly as the off-brand lenses. Border detail is blurred, especially in high contrast areas. Vignetting is significant. It doesn't appear to handle contrast or colours well. No doubt there is a reason why the Distagon f/2 sells for five times the price.


Any lens you have will take decent photos. Your gear is not as important as your subject, lighting, knowledge of photography (both technical and aesthetic) and other factors. That said, there is obvious value in using the best tool at your disposal. 

This test revealed the Pentax-A f/2.8 as the superior option among those lenses tested. This was quite a surprise! But it's been backed up by continued shooting over many months. 

Equally surprising was the inferior quality of the Zeiss Distagon f/2.8. And though the Vivitar lens worked well on my old Pentax camera, performance here is poor. This could be because of infinitesimal differences in the mount adapter. Or perhaps this demonstrates the effects of aging (misalignment, haze on lens elements, etc.).

I absolutely adore the usability and aesthetics of Zeiss lenses, which is why I also own 50mm, 60mm, and 85mm focal lengths. For me Zeiss has perfect ergonomics while producing clear and accurate images without the colour cast of, say, Leica. Though the ergonomics are different from a true Zeiss, I have very much enjoyed using the Pentax version of the Carl Zeiss Distagon T* 28mm f/2. Though it may not be as sharp as the Pentax-A, images justify its legendary reputation. The following photo demonstrates the incredible rendering which the plain old Pentax-A does not possess. View more examples in this Flickr album.

A notable characteristic of the Pentax Distagon is the significant field curvature: corners are focused behind the centre of the frame. With the subject near the image centre, this provides greater isolation of foreground from background, that characteristic "3D pop". (See my article on that phenomenon.) Another lens that demonstrates this effect is the Pentax Limited 43mm... also a favourite of mine.

But this quality might make the lens less suitable for edge-to-edge sharpness (e.g. landscapes). Though I haven't made strict tests of this performance, in practice I've not encountered this problem once stopping down to f/8.

Of course there are other considerations when choosing a lens, namely price and availability. A Pentax-A f/2.8 can easily be found for €100, making it a bargain for such a compact performer. But the Distagon T* 28mm f/2 is closer to €1500, once you've paid import fees from Japan (where most stock seems to be located). If you get lucky you might find a copy for €1000... but then you are taking a risk that the lens will not perform to par. 

For my part, I will continue to shoot with both Pentax branded lenses and put aside the Vivitars and other brands. 


For reference, these are my original 28mm lens reviews.


1 comment:

MarcW said...

Very interesting post! Including the Hollywood, quite impressive! Still looking for that one...

Post a Comment