Three months ago I compared five vintage 28mm lenses. Based on those results I've obtained one new lens and dug up an old M42 from my archives. Here are the lenses in today's comparison, with their official designations:
- smc PENTAX 1:2 28mm
- smc PENTAX 1:3.5/28
- SMC PENTAX-A 28mm f/2.8
- Vivitar Series 1 28mm 1:1.9 VMC Auto Wide Angle
- Carl Zeiss Distagon T* 28mm f/2.8
Why do I keep doing these comparisons? Mostly for fun and to make up my own mind about what to take out for a shoot. I also realise that few photographers have access to my distinctive collection. My comparisons might benefit your own purchase decisions.
The salient features of each lens are summarised in the following table. For completeness I've included two lenses from the previous test.
| year | aperture | length (mm) | mass (g) | filter (mm) | focus (cm) | optics | mount | |
|---|---|---|---|---|---|---|---|---|
| Pentax-K 28/2 | 1976 | 2.0 | 69 | 425 | 52 | 30 | 9 in 8 | K |
| Pentax-K 28/3.5 | 1976 | 3.5 | 47 | 260 | 52 | 30 | 8 in 7 | K |
| Pentax-A 28/2.8 | 1984 | 2.8 | 37 | 170 | 49 | 30 | 8 in 7 | K |
| Vivitar 28/1.9 | 1978 | 1.9 | 62 | 335 | 58 | 30 | 9 in 8 | M42 |
| Distagon 28/2.8 | 1978 | 2.8 | 51 | 280 | 55 | 25 | 7 in 7 | C-Y |
| Kino Precision 28/2 | 1981 | 2.0 | 51 | 270 | 55 | 30 | ? | K |
| Vivitar 28/2 Close Focus | 1983 | 2.0 | 50 | 280 | 49 | 23 | 8 in 7 | K |
Please read the previous article for details on the first three lenses.
Two lenses are new for this test. The Pentax-K 28/3.5 was recently reviewed on this blog, alongside many sample images. I'll add another below. Remember that compressed images viewed online always appear softer than they should. You can click each image for a full-sized version.
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| fern hill |
The second addition is the Vivitar Series 1 (Vivitar Bestiary entry), manufactured by Tokina to high standards. Physically it's quite a monster, almost as big as the Pentax-K 28/2. Like that lens it includes a floating element for improved near field performance.
Today's test was conducted using the Panasonic Lumix S5 with K&F adapters for each mount. A tripod with two second timer was used, so IBIS was turned off. The ISO was 800 and distance from bookshelf 70cm. It can be difficult ascertaining that the camera is oriented parallel to the subject, but I used a liquid level to assist.
For each lens I used a range of apertures from maximum to F8 in single stops. While there may be further optical improvements after F8, I find that most lenses will render very similarly in that regime.
Development was in Affinity Photo using my usual RAW defaults, which do apply some standardised adjustments.
Comparing results
Toggling between the full frame images (not included here) a few observations can be made.
The Pentax-K F2 and Vivitar F1.9 have slightly less field of view than the other lenses.
Pentax-K F3.5 has significant vignetting wide which is noticeable until F8. The amount wide open is similar to the Pentax-K F2 which is of course significantly faster. The Pentax-A F2.8 and Distagon have less vignetting. The worst performer wide is the Vivitar F1.9 though it clears at F5.6. Vignetting may not be seen as a terrible flaw, since post-production correction is easy. However on the Pentax-K F3.5 it is enough to darken the entire image.
The Pentax-K F3.5 has the least distortion, near zero in fact. The Carl Zeiss Distagon is almost as fine, followed by the Vivitar and the remainder of the Pentax lenses, which do bow a bit in the middle of the horizontal extent. (I guess about 1%.) This distortion might not always be noticeable, but can be corrected in post where important.
We now turn attention to the crops. There are three of these, assembled below. Two sequences were shot with the centre of the image (word "Sound") in focus. The first crop is from the centre, the second from the top-right corner.
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| centre focus, centre crop |
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| centre focus, corner crop |
The third crop was taken by focusing to the right side of the image, as close to the edge as possible (word "Sonic"). This test will indicate the absolute performance at the edges, without the effects of field curvature.
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| edge focus, edge crop |
Here we discover just how remarkable the "Hollywood" Pentax-K F2 is. Even wide open, it produces an entirely useful image, especially when focused near the centre of the frame. Contrast is good and sharpness sufficient. Colours are slightly muted but that could look nice for portraiture. Stopping down to F2.8 tidies up the rendering with increased contrast, saturation, and sharpness.
Notice that the corner crop is out of focus and lacking until F8. But if we focus on the edge it is already decent at F2.8. This is indicative of significant field curvature... but this is not the problem it might first appear. In fact, the combination of a wide aperture (sharp in centre) with a field curvature that further isolates the subject can produce amazing images. Especially near the close focus distance, backgrounds will be rendered in a lovely smooth bokeh while subjects pop.
I have a number of examples in my previous article. But here's one more.
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| two resting cats |
If we compare the Pentax-K F3.5 wide open to the Hollywood at F4 we discover something remarkable. This lens gives up little in image quality. And since we have already determined it to have the least distortion of the bunch, it's perhaps the better choice for any image where a blurred background is not the priority. However this lens also has field curvature. In practical use I have not noticed this effect to be as bad as demonstrated here, though the lens certainly likes to be stopped down. This difference is likely due to the fact that I typically use this as a landscape lens. I don't focus as close as 70cm but instead at a distance of many meters.
The Pentax-A F2.8 is a compact build that equals the performance of the previous two lenses. I honestly can't distinguish the centre performance at F2.8 from the Hollywood. But the corner crop is a revelation. By F4 it's already usable and at F8 the image is as good as the centre of the frame! This is by far the best result here, if we judge the entire frame.
The fast Vivitar F1.9 has made significant sacrifices in quality to attain that aperture. Wide open the image has the typical haze of uncorrected aberrations. Some people like to use this for effect but I have never been in that camp. Quality improves stopped down to F2.8 but only in the centre. The edges remain dark and messy throughout the aperture range tested. The Vivitar has significant light transmission loss due to the accumulated effect of aberrations.
Finally, the Carl Zeiss Distagon F2.8. This did poorly in my last test and I wanted to rule out user error. In this retest the centre the image is fine but the corners are still not usable at F8. Even when focused on the edge there is nothing special about the performance. While this is not a bad lens it cannot compare to Pentax optics.
Conclusions
So, which lens should you buy if you are interested in the 28mm field of view? Back when I was shooting on an APS-C sensor I got good results from various Vivitar lenses, including the two models tested in my last report. But these do not hold up on a full-frame sensor.
There are certainly many other brands that have produced good wide angle lenses for film camera. But I can honestly say that I have little interest in Canon, Nikon, Olympus, etc. after using Pentax glass. This is not to claim that those products are any worse. Only that I cannot see them being any better. Pentax lenses have a nice feeling in the hand and hold up very well over the decades since they were made. The aperture blades stay snappy and lubricants don't dry up. These are important practical factors when buying lenses that might be 50 years old.
For the ultimate in subject isolation and bokeh (two aspects not tested here), the Hollywood lens (whether the Carl Zeiss Distagon or Pentax-K varieties) cannot be beaten. It is renowned among stills photographers and film-makers alike, so you'll be paying circa €1300.
Is that lens too big and expensive for you? For a fraction of the price (around €100) the Pentax-K F3.5 performs very well and still has wonderful haptics.
But the absolute star of the show is rather unexpected. The lowly Pentax-A F2.8 has excellent performance to the edges and at F8 is already wonderful for landscapes. Here's an image wide open that demonstrates that the bokeh is not bad at all.
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| obstacle no. 1 |
You can find this lens for €100 at online prices or perhaps less at your local junk shop. Note that the prior Pentax-M F2.8 has identical optics and works the same as the A on a mirrorless camera. (The automatic aperture coupling is only relevant to Pentax SLRs.) So put that model on your radar as well.
Finally, the Carl Zeiss Distagon F2.8 is not to be ignored. If you already have a commitment to Contax lenses, this is an obvious choice. Indeed, I find the usability of this line to be second to none, ranking Pentax and Leica in second place. But in comparison to my other Contax Zeiss lenses (Planar 50, Planar 100, Sonnar 85) the Distagon 28mm F2.8 is underwhelming.
I recognise that shooting a bookshelf is boring and cannot demonstrate every quality of a lens. Neither is it scientifically rigorous. For me this formal exercise is an adjunct to the many shots I've taken with these lenses. The test confirms some of my impressions while revealing a few surprises.
Can I say this is my last 28mm comparison? I do think so. But... never say never!
Revised 14 August for better language and flow. More images added.
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