At the start of the millennium, we were pleased with the performance of the recently-launched Pentax 645 FA 35mm f3.5, which we used for shift movements and stitching on Canon DSLRs via the Zörk PSA. We found it improved on the sharpness of the best 28mm shift lens (Schneider PC Super-Angulon), which in turn was better than the best 24mm shift lens of the day: the Olympus Zuiko 24/2.8 Shift.
During a bout of gear indecision that somewhat mirrored the state of the industry, we adopted – then bailed on – medium-format digital, returning to the next generation of higher resolution 35mm DSLRs, and jettisoning our medium format glass and adaptors. The Pentax 645 FA35 had mainly been used to shift-stitch 17-20mm FOV-equivalent letterbox-format landscapes but, with all those extra pixels to play with, we no longer felt such a fiddly approach was worthwhile.
Which is why, when we reviewed the Olympus, Nikon 35mm shift lenses in 2007, we didn’t compare them to the Pentax 645 FA35. I lazily promised to, one day – and I’m happy to report that in 2023, we finally did. It’s still a fine lens.
But times change, and so has the Pentax 645 35mm. There are now three versions. For a more in-depth comparison of the first two, please see the Pentax 645 35/3.5 v Olympus 35/2.8 articles.
Pentax-A 35mm f3.5 SMC
The first wide angle prime for Pentax’ 645 film body was launched with the system in 1984. It’s a timeless, no-frills design: simple, practical and well wrought. It’s a relative lightweight, too, at just 470g. The focus mechanism is beautifully damped and weighted, which makes shooting with it via an adaptor a much nicer experience than the herky-jerky FA 35/3.5. It’s a nine-element lens in eight groups, with an unusually flat, thin front element. The diaphragm is a curved eight-blade type that presents a flat polygon stopped down. Coatings are first-generation SMC: ahead of their time in the early 1980s, but ineffectual compared to current optics. However, direct light is handled quite gracefully, with uniform flare and minimal ghosting. The Pentax round hood for this lens is rarely seen, which is surprising, because contra-lighting is poorly handled, making a good big hood essential rather than optional.
Sharpness is excellent at smaller apertures (f5.6-11), but tapers off rapidly in the outer image circle, making it better suited for unshifted use on smaller MF sensors like the Fuji GFX. There is some kinky moustache distortion but CA issues are surprisingly slight. It remains the cheapest option on the used market, but prices have increased with the growth of the GFX community, among whom it currently has a strong reputation.
Pentax FA 35mm f3.5
It was evidently Pentax’ intention to present an autofocus version of the A 35/3.5 with the new 645N at it’s peri-Christmas launch in 1997. However, it’s absence from launch catalogues indicates that the FA revision didn’t land until around 1999, and even when it did, there was sufficient demand for the older, cheaper, manual focus version for the two to co-exist in production until at least 2005.
The FA put on a little weight (now 510g) but somehow feels lighter: the longer barrel distributes its ten elements in seven groups and externally comprises hard plastics and soft rubber. Ergonomically, the cool metal heft of the A is a pleasure – but it’s a different animal: it doesn’t autofocus on Pentax bodies. While the FA is a more sophisticated design – optically and mechanically – it’s not superior to the A in every respect.
It is considerably sharper wide open, and retains a clear resolution advantage in Zone C throughout the aperture range. However, the A resolves slightly more strongly in Zones A and B at common working apertures.
Light handling is a mixed bag: the FA has improved coatings and renders cleaner sunstars, but the additional elements bring with them internal reflection issues: green ghosts – and the bulbous front element is prone to catch contra-light in situations the A better copes with. Mostly the hood rescues the lens, but not always.
The FA suffers from worse chromatic aberration in the outer zones – although partly this is because the A can’t deliver sufficient contrast in those areas to be an issue! We can’t really credit that as a bonus. The FA is also consistently less ‘punchy’ than the A, with slightly lower contrast and more muted saturation – although this will vary according to age and condition on a sample-to-sample basis. Geometrically, the FA is less problematic: there’s still moustache distortion (though less), but it’s straight into the corners rather than kinky.
The clearest improvement of the FA is its rendering: the A’s bokeh is inelegantly attention-seeking: there’s strong mechanical vignetting (cat-eye distortion) until f8, and ‘nisen’ soap-bubbles. Foreground bokeh is particularly ugly. The FA smoothes all this out and allows for much more effective subject isolation.
Pentax evidently set itself the brief of improving the A’s Zone C performance and refining its drawing style, adding better coatings. The brief was met: the FA is a more sophisticated and desirable lens than the A, but it’s also more expensive. It’s easy to see why adaptive digital shooters on a budget, cropping out the A’s badlands, might not see the benefits of the FA – especially when the older lens is so pleasing to use, and slightly crisper in the central zones at f8 – but the subtler and more mature rendering of the FA – in particularly its much more refined bokeh – is worth paying a little extra for.
Pentax-D FA 35/3.5
Production of the FA ran until 2015 when the lens was finally ‘recomputed for digital’, designated Pentax-D. Typically, that means better resolution and fewer aberrations. The broad formula was unchanged (10 elements / 7 groups) but the new (expensive) 35/3.5 has improved aspherical elements and better coatings – combining to give better correction and improved flare resistance.
We’ve not tested this lens in detail, but samples viewed online suggest that the trajectory of development is predictable: the Pentax-D appears to improve slightly on resolution across the frame, correct the CA of the FA, and provide smoother bokeh highlights in the f5.6-16 range with its new curved nine-blade diaphragm.
Doubtless it’s the best of the bunch, but at £1000+ on the used market, the somewhat unloved FA and the evergreen A will likely retain their appeal to budget-conscious photographers for a while longer.
Originally published in 2007, during the period in which Pentax was unsure whether to commit to their newly-launched medium format digital line – a sentiment that seems hard to fathom writing fifteen years later.
Elegy or Eulogy?
Given the present uncertainty as to whether Hoya/Pentax have axed the long awaited Pentax 645 Digital, the undervalued Pentax 645 range of medium format optics remains practically homeless.* While Mamiya 645 users are exploring the realms of possibility opened up by the ZD back and body, rediscovering the excellent lenses in the Mamiya line, an even better range of optics has tragically been orphaned.
If we’re talking about the sharpest medium format optic, we naturally think of the Hasseblad 120mm Makro. Mamiya users have already discovered that their new AF 120 Macro is very close to its equal. What remains under-publicised is that the Pentax version is at least as good. Until the very recent release of the Mamiya 28mm which, at the time of writing, is suffering a number of teething / compatibility problems, Pentax’ mould-breaking 33-55mm zoom was the widest rectilinear lens available for medium format: a sorely needed commodity with the present generation of undersized MF sensors. However, the true star of the range is the autofocus FA version of the Pentax 645 35mm f3.5. This is truly the Zeiss 21mm f2.8 of the medium format world, towering above its peers. Using medium format lenses on 35mm can be a bit of a lottery but the Pentax FA35 is a safe bet.
Consider the following data extracted from PopPhoto’s tests, back in the day when they used to do the job properly, publishing lpmm figures for centres and corners. Here’s the quoted data for the state of the art, brand new Hasselblad IF FLE 40mm f4, set alongside the current AF Mamiya 35mm f3.5 and the Pentax equivalent. The strongest performer at each aperture is emboldened:
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|
Hasselblad 40mm IF FLE
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Mamiya AF 35mm f3.5
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Pentax FA 35mm f3.5
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|||
|
|
Centre (lpmm)
|
Corner (lpmm)
|
Centre (lpmm)
|
Corner (lpmm)
|
Centre (lpmm)
|
Corner (lpmm)
|
|
f4
|
74
|
47
|
70
|
35
|
68
|
34
|
|
f5.6
|
74
|
47
|
74
|
39
|
76
|
38
|
|
f8
|
74
|
52
|
62
|
35
|
76
|
54
|
|
f11
|
59
|
42
|
62
|
39
|
76
|
54
|
|
f16
|
59
|
42
|
60
|
39
|
68
|
43
|
|
f22
|
52
|
37
|
49
|
35
|
48
|
38
|
|
f32
|
–
|
–
|
–
|
–
|
43
|
34
|
Ask an impartial observer to nominate the best MF wide angle and chances are they would say Hasselblad – especially an all-new design – but overall the wider Pentax 645 lens easily outresolves the ‘Blad. Crucially it’s really on form at typical working apertures. True, the IF 40mm is outstanding wide open, especially in the corners, but the Pentax glass owns f8 / f11. The gulf here between it and the highly regarded Mamiya – and the Hasselblad! – is telling.
At f8, the Mamiya is way off the pace but by f11, there is little choose between the Blad and the Mamiya at f11 and f16. But at f11, the Pentax is out on its own. And when you consider the price of the Hasselblad lens, the Pentax FA35’s performance becomes even more impressive.
But will the difference be visible on the big, lazy Dalsa chip in the ZD? After all, there are many happy Mamiya 35mm f3.5 users . . . ? But then again there are no Pentax 645 / ZD users out there yet – happy or otherwise. Do the maths: the Mamiya’s 39lpmm corner resolution is not enough to resolve adequately on a 56.1mm wide 22MP chip, whereas 54mm is pretty close. I think the difference would be clearly evident.
Given that the pixel pitch of the Mamiya ZD back is almost identical to that of the 5D, we can use a Zörk shift adaptor to gain a fair idea of how this lens would perform if adapted to the 22 megapixel Mamiya 645 AFD/ZD combo. From my experience with the lens on 5D and 1Ds II bodies, I am far more interested at this point in adapting the lens for use on the ZD than downtrading to the Mamiya equivalent.
**Update:**
Having spent considerable time looking at the adaptation of the Pentax FA35 for the Mamiya mount, I can see that it is feasible, but may require a minor mirror mod to the Mamiya body. It also entails the removal of the FA35’s rear mount and it’s not easy to disentangle the aperture and AF mechanism from the bits you need to discard. Wearing a donor Mamiya mount, the rear element needs to protrude beyond the flange to provide correct infinity focus. Somewhere along this conversion, I decided for other reasons to abandon the Mamiya body altogether and use selected lenses from the range on the excellent 1Ds III. I can’t therefore report from the front, as it were, but I got close enough to see that it’s a viable concept that I would have seen to completion had I stuck with the body.
* One year after this was written, we can amplify with greater authority the statement that the system is dead and buried. RIP Pentax MF.
