The Pentax 645Z review, part III: SDM lenses and long exposures

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Exif data is intact for all files – click through to flickr to view it, and larger versions of the images.

Having a bit more time with the relatively new Pentax 645Z under my belt has given me the opportunity to try a couple of things I’ve been curious about: long exposures, and a more thorough evaluation of the three SDM lenses currently available for the 645 system. The former is probably only of interest to landscapists, architectural photographers and people who have severe allergies to controlled lighting, but I feel the latter is probably a critically important topic in itself. Let’s start there.

Compared to other medium format system contenders – really only Hasselblad, Phase One and Leica – Pentax has about 13 lenses currently available; unfortunately this is somewhat misleading as most of them appear to be much older designs that date from the heyday of the film system in the late 80s or early 90s. For the most part, they are body-driven, plastic-barrelled (not the nice kind of crinkle finish plastic that Nikon uses, for instance, but the smoother, slightly cheaper/ more brittle feeling kind of older lenses) and have manual focus on sliding clutches rather than permanent override or switches. Build quality leaves something to be desired, and they were designed for the resolution of film – not the 645Z. Of the four contenders, I’d say only the Leica S glass gives me the confidence to use it at any aperture and any subject distance and be assured of consistently excellent results – the rest all have stars and dogs, caveats and cautions, even for the best of the lenses.

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Pentax 645 lenses come in three flavors: A, which are manual focus; FA, which are autofocus, and D-FA, which are accompanied by built in SDM motors, weather sealing and full time manual focus overrides. SMC is super multi coating, something analogous to the various other branded coatings on other lenses; Aero Bright is their new equivalent of Nikon’s Nano Coating – as far as I can tell. Again, I believe this is only present on the D-FA lenses. There are a plethora of A (discontinued) and FA (still available new, and recently in the USA too) lenses; from a 35mm wide (28mm-e on the digital bodies) to a 400mm telephoto. D-FA lenses are only three: the 25/4 (19mm-e), 55/2.8 (43mm-e) and 90/2.8 SR Macro 1:2 (70mm-e), which is the only medium format lens with optical image stabilization. Confusingly, there’s also a DA version of the 25mm, which I believe is the same except for a slightly longer hood. Pentax’s own roadmap shows a couple of zoom updates due later this year or early next, which will presumably be D-FA, have SDM focusing, Aero Bright coatings and hopefully also optical stabilization. Leaf shutters would be nice too, but at this point I feel I might be pushing it.

My experience with most of these lenses suggests a few things: firstly, if you have patience and don’t mind possibly having to try a few samples, don’t buy them new. There are an abundance of them available second hand online and from various dealers as holdovers from when people quit the film days. There are bargains to be had – though probably not after this article is published – up to 60-70% cheaper than new glass, for excellent plus/ mint-minus grading. Second hand FA lenses start from $300 or thereabouts; on the other end of the scale, a new D-FA 25/4 or D-FA 90/2.8 SR will run you close to $5,000. Secondly, there definitely is sample variation: AF tolerances in the past might have been responsible for a number of these lenses acquiring undeserved reputations for being soft or inconsistent; the truth is helicoids can not only drift out of alignment, but body driven AF (or any non-lens-based coreless direct driven DC motor system) is going to have some backlash and free play that will result in zero movement for small changes in subject distance even if the AF system and motor in the body commands it. It would be impossible for the gear train to move without binding otherwise.

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Since film emulsions have some thickness, the focal plane has some tolerance of movement before the image appears to be decidedly out of focus. This is not the case for digital, and small changes can make the difference between pixel-crisp and ‘might as well use a FF DSLR – or less’. This difference in tolerances, AF backlash etc. basically means that a lens which will not focus properly on one body even with maximum AF fine tune may well do so on another body with none whatsoever. (My partner and I actually pooled FA lenses to mix and match which would work best on which bodies – the 75/2.8 that would still backfocus on my body at maximum -10 fine tune adjustment focused just fine on his with zero fine tune. And all of our SDM lenses require +/-2 or less adjustment – go figure. I imagine it’s a lens thing, not a body thing.) Finally, not all of these lenses have weathered the ages well – there’s no easy way to tell the age of a lens without tracing the serial number as there don’t appear to have been many cosmetic changes throughout the lifetime of most of the optics, so guessing age this way can be tricky. Sticky or stiff actions are probably not a good sign, to say the least. And be weary of fungus and heavy internal dust. Remember that A and FA lenses are not weather sealed if you intend to use the camera in harsh environments.

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Performance-wise, I have not yet encountered any FA lenses that are outstanding performers wide open on the 645Z other than the FA 120/4 Macro 1:1; most are very good one stop down and excellent by two stops, but by that point you’re at f5.6 or f8 and very much into tripod territory or elevated ISOs. Some lenses like the FA 200/4 are frustrating: it’s possible to get surprising results even at f4, but AF backlash means that most of the time you’re at f8 on a tripod for insurance. I find there’s a slight difference in color transmission between the D-FA and FA lenses; the D-FAs are neutral and moderately saturated; the FAs skew slightly warm and have both lower contrast and a slightly odd-feeling spectral transmission. I put it down to the difference in coating technology.

D-FA 25/4 (and presumably DA also)
Beware sample variation on this one. If you get a good sample, it can be quite spectacular, even into the corners. I’ve handled four lenses: the first wouldn’t focus to infinity with or without the drop in filter (new lenses include special thin CPOL and skylight filters) in place and was very astigmatic; the second demo unit was slightly astigmatic, and the third and fourth units were fine. I suspect alignment of elements in this lens are very sensitive to impacts and the first two may well have been dropped or bumped; #3 and 4 were new lenses. Wide open, center resolution is excellent; you get a bump in microcontrast and edge performance one stop down, and the corners are not far off the center by f8, but there is some lateral CA. There’s surprisingly little distortion for a lens this wide. Enabling the default ACR correction profile cleans this up nicely and restores corner performance. What I find most impressive about this lens is the way it renders: it simply doesn’t feel anywhere near as wide as it actually is; the Zeiss 2.8/21 Distagon on my D800E has more geometric distortion/ stretching towards the edges as a wide ‘signature’ than 25/4, even though the 25/4 is a 19mm equivalent. Advantages of medium format, I suppose.

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D-FA 55/2.8
The standard kit lens for both 645D and Z; it’s easy to see why. 55mm is a very natural feeling focal length for the 33x44mm format; much in the same way 80mm feels and renders on 6×6. I suspect it’s got something to do with this ‘natural’ diagonal of 43mm-e; Pentax has made a number of ‘limited’ lenses for their 35mm cameras around this range. Central sharpness and resolution is excellent at f2.8; there’s definitely some field curvature on this lens as focus and recompose too far off axis requires some compensation. The edges and corners require f5.6 to come up to central standards. Bokeh is smooth and it doesn’t quite have the microcontrast bite of the 90, but it’s not far off. All in all, much to like here: light, small, reasonably affordable – and probably the one must-have, in my book.

D-FA 90/2.8 SR Macro
In my opinion, only the D-FA lenses perform at maximum aperture on the 645Z; the 90/2.8 SR Macro is probably the best of the three, with an unqualified shooting envelope – any aperture, any distance, subject anywhere in the frame. There is some slight field curvature as there’s a clear difference in sharpness wide open between focusing with an edge AF point and recomposing slightly, or using live view (even with AF fine tune perfect). This goes away by f5.6. Resolution and microcontrast are excellent at every aperture, with almost no noticeable lateral CA and only trace amounts of longitudinal CA. Both are easily cleaned up by the lens’ default ACR profile. Bokeh is smooth and vignetting minimal. This is perhaps the best of all of the lenses available for the 645 system, and an excellent optic by any standard. On a relative basis, I’d put it somewhere between the Zeiss 2/100 Makro-Planar and 2/135 APO-Sonnar. A note on the optical stabilization technology: it seems to be not quite as effective as Nikon or Canon’s latest and is slightly noisy in operation, but it definitely welcome. It clearly reduces the ‘danger zone’ speeds by about 1.5 stops (as compared to about 2-2.5 on Nikon VRII, regardless of what the manufacturers claim). We can only hope this is incorporated into future lenses.

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Long exposure performance
I have to admit, I was quite blown away by the 645Z’s long exposure behaviour; with dark frame subtraction (‘long exposure noise reduction’) set to auto, it almost never uses a second frame below 4-5 minutes. 2-3 minutes at base ISO appears to have no penalty to the noise floor or dynamic range; there’s no amp noise at the edges, either. You start to see a bit of luminance speckling in the lowest couple of stops of dynamic range up to the 5 minute range, and frankly, I haven’t found anything dark enough to require much more than that.

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This image is remarkable for the amount of dynamic range it retained at two minutes, and above base ISO – nothing is clipped at either end in the original, from the deepest shadows in the upper balcony, to the brightest highlights in the lower one.

Cranking the ISO a couple of stops on longer exposures appears to have no more penalty to noise and dynamic range than increasing for a shot of more normal duration. This is one of the most impressive performances I’ve seen; even my D800E requires some cleanup above 30 seconds. Coupled with the wireless triggering app and automatic mirror lockup with self timer, it makes for very fluid and easy long exposure work. Battery life is also equally impressive – after 50 test exposures of several minutes, using live view – as a sort of torture test for both battery life and thermal-induced noise – performance at the start and end of the test was the same, and the battery indicator hadn’t budged. Using a rough approximation by recharging time, I’d say I’d used somewhere between a quarter and a third of its capacity. Again: impressive.

My next installment in this series will come after a few months, trips and assignments and using the 645Z as a documentary/ available light camera; this will be the mid term report. MT

The Pentax 645Z is available here from B&H, and the respective lenses are here: 25/4, 55/2.8, 90/2.8 SR, older legacy lenses.

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Comments

  1. Ming, many thanks from Down Under for the three informative articles on the Pentax 645Z. Much appreciated. Having shot MF film for years, I’m keen to move to MF digital once the tech and my bank balance line up. Best of luck with your endeavours.

  2. First of all: thank you so much for your detailed, professional and always very friendly source of information.
    One little questions: do you ave any experiences with the Pentax zoom-lenses. Or do you hesitate using them?
    Thank you, tom

  3. Leaf shutter lenses soon to be available from Pentax for the 645z according to Luminous Landscape.
    All that’s needed on top of that is a firmware update to to sort of the flash sync speed and include 16-bit colour. Hassy and P1 don’t stand a chance.

    • That’s fantastic news for studio shooters.

    • Hi Ming – just bought a 645Z and there’s a page with side bar in the manual referring to “645LS lenses” with do’s and dont’s….tried my new ‘Z’ with an old 67 (but unused) 45mm lens (via 67/645 Diox adapter) , but the images look ‘mushy’ even on tripod, low ISO etc etc…..also have an old 67 165mmLS lens to try…..bought a used mint FA 120 f4 macro , and although image is very good after Lightroom processing , out of the camera it also looks rather ‘soft’ and a tad milky….seems to confirm what you said about having to “bite the bullet” and invest in the new D-FA lenses to get the image quality I expected , unless I have been unlucky with the quality of the older lenses I have…
      Regards,Ian Moore (in UK)

      • Most of the older lenses were not designed to have this level of resolving power, especially the 67 glass. Some 645 A series lenses are much better though – the 35 and 150 for instance.

  4. Quick question – and sorry if I have missed this in this excellent review – but how doss live view function on the 645Z with regards…

    1 Mirror Up – when in LV and you take the shot, does the mirror remain locked up, or is it dropped and then raised again to take the shot, basically giving a double hit of possible vibration?

    2 DOF Preview – I understand that the LV displays based on a fully open aperture. If so, how do you judge the DOF on the LV screen?

    Many thanks

    Phil

    • 1. The mirror cycles. But if you use the 2s self timer, it stays up and only the shutter fires.
      2. Press the DOF preview button.

      • Ha – 2 was so obvious :-)

        Re. 1 – so you are saying that normally the mirror will drop and then flip-up again before the shutter is fired – BUT if you have the 2s self timer on, then the mirror will not drop and the shutter will close, open for the image, close and then open back for Live View?

        Sorry to still ask, but the 645D was so much simpler – without this new Live View technology :-)

        Phil

  5. Hi Ming,

    i have a technical question and i’m not sure if I’m right so…Sadly, the flash sync of the 645z is limited to 1/125 but there are only two Pentax native Leaf shutter lens out, the 75mm f/2.8 LS and the 135mm f/4.0 LS which would allow you to use 1/500 flash sync?

    Could I increase the flash sync limit of the Pentax 645Z up to 1/500 when I am using these two lens??

    Hopefully it does that would still close the gap a lititle bit to P1 and Hassy….with their wonderful 1/1600 and other advantages 16 bit etc but that is may what you have to pay more for….you get what you pay….;)

    Thanks!

    • Yes they would let you use flash to 1/500s.

      • plevyadophy says:

        Earlier today I was reading through the Pentax 645Z brochure, and was just blown away by all the technology and features they have crammed in the camera (although some of them are a bit naff, like those Instagram-type filter effects)…………….. and at such a remarkably good price. Of course my excitement at what I read is relative; relative to the primitive feature sets hitherto available in medium format land (I doubt such features excite APS-C and 35mm format users as they’ve seen it all before :) ).

        And the more I read it, the more convinced I became that Hassy will soon go bust unless they can, as the saying goes, “pull a rabbit out of the hat” at Photokina or within the next 18 months, or better stil, within the next year.

        Anyway, moving on from my preamble, how does the Pentax utilise the LS lenses? I thought for a camera to do that it has to have a switch or something to tell the cam to not fire the normal shutter curtains and to expect exposure from the lens attached. I haven’t noticed any such feature on the Pentax Z.

        Also, are those LS lenses from the film era? And if so, will they be any good on the Z?

        Regards,
        plevyadophy

        • They’ve got electronic contacts, as far as I know.

          No idea on the optics. Frankly, the older lenses have been very disappointing…so I’m not expecting much.

      • Hi Ming,

        I think there is a possibility that you could even increase the common flash sync limit of 1/125 or 1/500 of the 645Z Pentax…..it works with other cams as well (Canon 5dmark III, 1dx, nikon d4(s), d800e/810 etc.)

        Have you ever tried and heard sth. about the supersync method (e.g. http://www.infocus-photo.de/blog/2013/04/29/supersync-how-to/?lang=en) ….???

        You will need at least Pocket Wizard Flex tt5 or Pixel kings triggers and the jinbei FL-II 500 Porty Flash (400 watt) set including standard flash head or even stronger, powerful strobes if sometimes needed but you probably have to reduce their power for the supersync method…

        The only problem that may will be resisting despite using this method is to freeze action/movements WITH flash sync above 1/125 limit (maybe the much more expensive Elinchrom Set Ranger Quadra Hybrid Li-Ion Set with an action flash head not the standard head/version could be the solution for this purpose??)

        Best regards
        Fred

        • You will land up losing one stop of power for every stop of shutter speed you gain, which means 1/500 costs you two stops – not ideal…

          • Okay, thanks for clarifying…but if Pentax would create new Leaf shutter lens would theoretically the Pentax 645Z been able for higher flash sync??? As plevyadophy stated / was asking you….”Anyway, moving on from my preamble, how does the Pentax utilise the LS lenses? I thought for a camera to do that it has to have a switch or something to tell the cam to not fire the normal shutter curtains and to expect exposure from the lens attached. I haven’t noticed any such feature on the Pentax Z.”

          • plevyadophy says:

            Hi Ming,

            Maybe I am being a bit dim but I don’t quite understand how, using that sync trick, you will lose a stop of flash power for every stop of shutter speed gained. Can you please explain?

            Thanks

            • You can’t shorten the physical duration of the flash; the shutter curtains move at a certain speed and the sync speed is the fastest speed for which the whole frame is exposed. The sync trick fires the flash multiple times, which means no time to recharge between shots. The Nikons already offer high speed FP sync up to 1/8000, but the tradeoff is one stop power loss for every stop speed gain. Also, you can get odd artifacts with moving subjects as the flash fires twice. Finally, the last solution would be an electronic shutter…which may be implementable in firmware.

              • plevyadophy says:

                Ming,

                I think you are misunderstanding how the sync trick works.

                Let me explain how I have done it.

                1. When using flash, I know my cam will not allow my shutter to go faster than 1/250 unless I have a Canon compatible flash atop the camera AND I have enabled the HSS feature.
                2. The Speedlite is the one repeatedly flashing but ………..
                3. I don’t want any light from it, I am simply using it to trick the camera. So…………
                4. I either dial down the flash output to minimum or turn the flash head away from the scene.
                5. That’s my sync prep done.
                6. Now I set my studio strobe (or off-camera Speedlites at high power settings) at the power level I want.
                7. I also set the strobe to fire when it sees a pulse from my Speedlite. The strobe will fire on seeing the first of the many Speedlite pulses.
                8. For me to get the strobe’s light to work in the image, I am relying on a the strobe having a somewhat long and powerful light duration.
                9. It’s this long light duration, sometimes the tail end of it, that is being captured in my image. The Speedlite may simply not have the power to light the scene, hence why I introduce the bigger strobe. I can stop motion either by shutter speed but HSS leads to low light output, or I can rely on powerful fast duration (and super expensive) packs but the problem there is that you are asking the light to do all the work so ambient light has to be minimal and that won’t work for you if you want ambient to register AND stop motion AND add flash. So that’s where the sync trick comes in.
                10. The strobe light doesn’t pulse, it just fires once as per normal (the Speedlite is pulsing but what it is doing is of no importance other than to trick the cam into allowing shutter speeds faster than X-sync).

                That there is one variant of the sync trick/hack. The other variant is to use devices like the Phottix Odin that have a “hyper sync” feature (which, from my quick perusal, seems to be the method used in the technique pointed to in the post above).

                So you are not really losing a stop of light from your strobe. Rather, what you might find is that you are losing a “stop” of battery life due to having to fire the strobe at higher power settings so as to avail yourself of that long light tail. :)

                I hope that makes sense?

                I should add, that I am no expert on the technique as I have only used it once (but my personality is such that I like it, and reading about variants of the trick, because I like doing things annoying systems try to prevent me from doing) :)

                Regards,
                plevyadophy

                • I assumed you were using speedlights, but the same applies for the studio strobes here. There are three things in play: the duration the frame is exposed and the curtain is open; the duration of the flash; how much power the flash can dump out in that duration, and of course how the relative timings work. Max sync is the fastest exposure duration for which the frame is fully exposed – the bigger the frame, the bigger the shutter, the more distance it has to travel, and there are speed limits for these things due to mechanical constraints. Speedlights all have maximum durations much shorter than the sync speed; they have to fire multiple times as the curtain crosses different parts of the frame to provide full coverage. Studio strobes typically (though not always, Elinchroms and Profotos can be very, very fast) have longer durations.

                  The syncing flash (not a native TTL one) may or may not fire at your higher speeds; if the studio strobes have a longish flash duration, then you can’t freeze motion. If this doesn’t matter it may work, depending on the above…some cameras will not fire at all above the sync speed if they detect a return on the hot shoe central pin.

  6. plevyadophy says:

    Michael Reichmann and Nick Devlin on the Pentax 645Z

    An interesting read with sensible commentary

    http://www.luminous-landscape.com/reviews/cameras/pentax_645z_first_impressions_review.shtml

    • I can’t say the images blow me away though – too much processing. That said, the B&W portrait of Michael is excellent.

      • plevyadophy says:

        Well, you and I have had this conversation numerous times :o)

        I know you are never happy with review images. :o)

        Those of us who want poetry (the eloquent writing of you and Tom Liles) and eye candy (your images) accomapanying a review simply come to this site. ;o)

        As for that B & W pic of MR, doesn’t suprise me that you like that image (oh, and by the way, I saw some images from a photographer and at first sight I thought that the photographer was you; I will send you the link later).

        The review of the cam is pretty good, no? Very reasonable and pretty much supports what you say.

        Regards,
        plevyadophy

  7. Max Spann says:

    Good review. There is a new lens coming out at Photokina which should be interesting: HD Pentax DA 645 28-45mm f/4.5 AL SDM AW SR

    • I’m waiting…definitely sounds like something useful!

      • plevyadophy says:

        As I am not following Pentax news and views as much as I perhaps should, could you tell me, does it appear, especially with this new zoom, that Pentax are doing with the 645 what they do with APS-C, which is to produce lenses with focal lengths that make sense for a crop sensor? Or are they just sticking to standard full frame focal lengths?

    • Hi Max, where did you get the info? That’s exactly the lens I’m waiting for…

      • Max Spann says:

        The development was announced a while ago, and it has been on the road map. A prototype was shown at CP+ and a presenter revealed the specification as I listed above. The specifications look very unique and attractive. Shame that the cost of the medium format system is beyond sensible level for an amateur (well me level of sensible anyway).

  8. Hi Ming Thein, when taking long exposures, did you use the 645z internal noise reduction options or did you use the noise reduction of ACR? In fact a similar questions is about the lens correction settings that the camera offers. Did you use those or rely on ACR? What is your recommendation?

    Thanks

    • No NR of any sort, but I used the adobe profiles. The pentax provides do not affect the raw files – only jpegs as far as I know.

      • thanks for the quick answer! I wasn’t sure whether the internal camera NR etc affects only jpegs or the RAW files too.
        So far I have switched off all camera settings for NR or lens correction and completely leave it up to the ACR profiles as well. The results are good so far, but I wanted your view too ;-)

  9. Ming, while I am still enjoying the relatively new concept of affordable full frame (FX) cameras and the image quality they are capable of – I have always been tempted by the allure of medium format cameras. I shoot predominantly landscape photography, and am very happy with the image quality I’m getting from my Nikon D800, Leica M9, and Sony A7R … but I’m always curious how much better IQ would be with something like the Pentax 645 D / Z?

    Would you have to blow an image up the size of a wall or billboard to appreciate the difference between FX & MF, or would it be noticeable on smaller prints – and even your desktop screen?

    I apologize in advance if you’ve answered this question elsewhere on your site, I visit as often as I can, but don’t get the chance to ready every post.

    Keep up the great work!

    • Second question: if I did move up to medium format, what MF lenses are available that would be a wide angle equivalent to my
      Nikkor 16-35mm? I know there is a reverse crop factor from MF to FX, but is Pentax making wide glass for their 645 series?

    • It’s actually not an obvious question. I see the difference on my 27″ monitor and in a 10×15″ Ultraprint, but that assumes your technique and shot discipline are bang on – if you throw away anything anywhere in the process, all you have is DOF/ rendering style as the difference – which is not always obvious. The same applies for any medium format camera, though…

  10. I would be very intrigued to know how the Pentax 645Z mirror vibration holds up to the D810 in terms of acquiring the best resolution possible in normal shooting conditions : 1/25 to 1/4000 shutter speed with mirror on, and with MLU. On the other side, the Leica S offers leaf shutter lenses which allows higher flash sync speeds and reduce the effect of the mirror slap, which is a huge asset with high resolution cameras.

    • Somebody will have to send me a D810 if they want the answer to that!

      The Leica S still has mirror slap with the leaf shutter lenses anyway because there is no way of framing without the finder.

      • plevyadophy says:

        Eh?
        Ming, you’ve confused me.
        Can you not, on the Leica S2, use mirror lock-up, then pause for a second, and then fire the leaf shutter and thereby eliminate shutter and/or mirror induced shake?

        • How would that be any different to mirror lockup on any other camera?

          • Eh?

            I am still confused.

            The point I am making is that I don’t quite understand your remark re the viewfinder as I would have thought that mirror lock-up in addition to using the in-lens shutters on the lenses that have them, would make the Leica S less prone to shock/vibration.

            I am not quite understanding why the optical viewfinder viewing method is detrimental to the Leica S? Surely, with mirror lock-up the mirror return sequence takes place after the exposure has already finished and with the shutters being in the lens there isn’t much vibration going on, no?

            • 1. If you’re locking up the mirror beforehand, you can’t see the frame.
              2. Hassy V and Leica S both have leaf shutters. What’s the advantage of Leica S if you’re already locking up the mirror on both?
              3. It isn’t the shutter that causes most of the vibration usually; it’s the mirror.

              • plevyadophy says:

                1. Yes, that’s a pain and it’s where the Pentax with its Live View and tiltable LCD has a massive advantage. But I guess if you are tripod mounted and shooting a static scene, not having live view isn’t that much of a problem when you use mirror lockup.
                2. No advantage I guess other than perhaps the mirror on the Leica S being smaller and I am assuming better damped than the mirror on the Hassy V?
                3. Yes

  11. yes but we are still losing lens speed, a huge asset of 35mm for faster/less noisy work. I’d really like to see a comparison of legacy zeiss glass, like the Zeiss 55 Otus, shot between F1.4 and F7 and compare it to an equivalent fast Pentax lens like the 55 2.8 DF-A to compare the separation between the subject and the background as well as sharpness and micro contrast. It would be awesome if you could set up such a test with full size samples.

    I think that the pixel pitch of both sensors D810 and 645Z are comparable, so I wonder why the 645Z offers a wider dynamic range megapixels put aside.

    Are they any Mamiya 645 adapters on the market for the Pentax 645 crop system ?

    • Sorry, but I don’t have the time to do something like that. And it’s not a meaningful comparison anyway because the sensor resolution is different.

      D810 to 645Z: no idea, I haven’t used the former. The D800 is one generation behind in sensor tech, and the 645Z actually has slightly larger pixels anyway (5.2 vs 4.88 microns).

      No idea on the adaptors.

      • Greetings Ming,

        Kudos for the best article(s) yet on the 645z universe. I’m deciding when/if to make the jump into this system.The only other option I’m likely to have is a Nikon D810. Regardless of which way I jump, it would be my first foray into either realm (I have never done medium-format or used any products from Nikon). As a 100% landscape, art-oriented photographer I am concerned about rendition, resolution, large hi-res prints, etc. My main concern with the 645z isn’t with the camera itself but rather on the lenses. Most of the time I’d be using the Pentax 25mm D-FA 25. However, the chromatic aberrations concern me. How do you remove or mitigate the c/a? That is, what post-processing application do you use and what settings within said application make the best corrections? I’m assuming that software such as DxO or Adobe Camera Raw has a general lens correction profile and that you must use some other way to lessen the c/a. I’d also assume that since I’d be buying a new lens sample variation won’t be as likely. Even so, what is a good check for such a lens to determine if the relevant parameters are sufficiently good to retain the purchase? In any case, It seems that few camera retailers are thrilled about customers returning $5000 lenses.

      • That’s a pity because it will be hard to find another photographer who own both the 55 Otus and the Pentax 645Z system. Anyways, if you find the time one day this would be a very meaningful comparison for other photographers who are on the edge to purchase a digital medium format camera. I watch your website quite a lot and saw that you already compared different systems with similar but slightly different sensors, so I guess this would be an appropriate test. Anyways thanks for your time.

  12. DAMNED, I was really interested in getting the 25mm in expectation of a true 645 camera. Well, 19mm is already plenty wide and the corners aren’t apparently best until stopped down, this would weaken the lens even more if it was covering FF 645…Now the real question is, is the new Pentax worth it in comparison to the D810 and legacy fast glass. The Zeiss 15mm and Otus 55mm are maybe the best SLR 35mm ever created and the sensor technology is quite similar (Sony exmor) – they both are exempt of AA filter, but the smaller mirror and extra speed is in favor of the Nikon. On the other side, I do prefer he ratio of the 44 xx 33 sensor. Ming, you wrote a brief paragraph about the old 645D color output vs the new 645Z, what is your experience and what software are you using ? Thanks !

    • 1. Lenses – the Zeisses have the edge. But not enough to bridge the resolution gap.
      2. Sensor/color – the 645Z has the edge over the D800E, haven’t used the D810. Dynamic range is noticeably better, noise a little better. And colour is much better – little to no correction required. ACR 8 in PS CC.

  13. Great test, great review!! I own a 645z since 2 days and wonder whether you came across the problem, that there seems to be zero display information, while shooting with long exposure times. No time…nothing. So when doing a 25sec shot you need to look at your watch or wait until it clicks again. weird!!!!

  14. First off, thanks a lot for those tests and comparisons, really appreciate the effort and professionalism.
    Now I have some questions regarding the crop factor of the 645 “medium format cameras :

    - what are the true focal equivalencies of the 25, 55 or 90mm lens, knowing that the 645D or S2 are not true 645 sensors ? (in other words, what is the multiplication factor)

    - Is their any chance that the dedicated 645Z and S2 lenses will cover a larger field of view in hopes of an hypothetical true 645 sensor ?

    Thank you.

  15. Paul Lloyd-Roach says:

    Another brilliantly detailed article, Ming. I’m curious to know whether you would be likely to see much difference in say a 40 inch print from the 645 z c/w 25mm lens and the D800E with the Zeiss 21mm. Would there just be a resolution difference or is there a certain indefinable quality to the larger sensor?

    • I’m pretty sure you’d see both a difference in resolution and the way the image renders – wide doesn’t ‘feel’ as wide because of lower geometric distortion on the larger format.

      • You have mentioned the “lower geometric distortion” of larger formats before, but it doesn’t make sense to me. Two cameras with different formats, eg m43 vs P645z, using lenses with same angle of view, shot from the same position, will give the same geometric distortion. In fact, if you can get the entrance pupil of the two lenses to be the same, and make prints the same size, viewed from the same distance, the DOF will appear identical too. Granted, the smaller format will require a much faster aperture to match the entrance pupil of the larger format so that’s unlikely with the current lens lineups. Also the smaller format image will start to show weaknesses in resolution, dynamic range etc sooner than the larger format. But my point is, up to a certain limit the output of the two formats will be essentially identical.

        • It logically doesn’t make sense either, but I have no other reason for why the 19mm-e on the 645 looks less wide than a 21mm on the D800E even if they are used in the same way. The edges of the 21 just appear to be more ‘stretched’. I’m sure it has something to do with the field projection.

          • Barrel distortion will stretch the edges less than a lens with no distortion or pincushion. That’s why fisheyes don’t have the same corner stretching as rectilinear lenses (actually the often go too far and squash the corners) – it’s a tradeoff between corner stretching, or keeping straight lines straight. Could that explain the differences you see? Or maybe differences in print size or apparent DOF make things look different? It would be interesting to see A-B comparisons, but I guess you have enough to do!

  16. I agree with Sebastian regarding the “A” lenses, the build and tactile quality is easily up there with Nikon manual focus AI lenses. One thing about A lenses -,they don’t report the focal length to the camera so the exif data will be somewhat limited.

    The 120/4 macro is a fantastic lens, if you need 1:1 it is the obvious choice, the optics are the same in the A and FA versions but I think the A version is much nicer to handle. The 150/3.5 is also excellent, sharp with smooth backgrounds, a very nice portrait lens in a compact package. The FA 150/2.8 is probably even sharper but it has more of a clinical rendition. The 200s (A and FA) don’t have good reputations, so I skipped this focal length. If you need something longer, the 300/4 is a “star” (premium) lens and has very good reputation but it’s quite a big lens. I got the FA 300/5.6 instead due to the smaller size and closer focusing. Oneof my most used lenses, performance is excellent, although there are occasional shots which are oddly soft (shake or backlash?). Although it is “only” f/5.6 I found the AF performance is quick and positive (at least it was with my Pentax 645 NII), and manual focusing is decent too. I heard good things about the 150-300/5.6 also, which is an interesting zoom option, I kind of regret not buying one, but I had the 300/5.6 already.

  17. The K-3 has a composite average mode. . .which gives long exposure results without the long exposure. It stacks several exposures in one raw file. It cancels noise and doesn’t require a dark frame. Is something similar not implemented on the 645Z?

  18. Interesting read. It again show that lenses are still key to a system and to get the most out of the Pentax, a large investment is required – $5k per lens ain’t cheap. The 25mm though look interesting, especially given it does not give much distortion for how wide it is. Oh one thing you don’t mention is how massive the lenses are!

    I’m feeling more confident that the D800ED810 is way more than enough for amateurs, only if you really know what to do with all that resolution is this worth going for. Any ideas if you can find a commercial application for the 645Z in your line of work?

    • I think the commercial application would be documentary/ studio still life/ product when you know you need the resolution, or perhaps landscape if you can get yourself into the art market. But the system needs some maturity, I think; that said, it isn’t any less incomplete than the Hassy V system (and that misses perspective control too if you don’t buy a Flexbody).

  19. Hans van Driest says:

    Focusing and recomposing gives a focusing error (distance error), which is not caused by field curvature. That is why Hasselblatt uses a very novel method with sensors detecting the rotation after focusing, and correcting the lens focus distance accordingly.
    A lens does not use equidistance projection, but attempts to project a flat image on the flat sensor. As a result, the focusing distance increases the further you get away from the center of the image. For example a subject 20 degrees of center, will have a distance of 1.064 times the distance in the center. at 30 degrees this difference increases to 15.5% and at 40 degrees it is already 30.5%. The result is the focus will be to near, after recomposing. Especially with a fast lens this gives a visible focusing error.

    • There’s distance error, which is what happens if your focal plane is actually flat – the camera swings in an arc – and then there’s field curvature, which might work with you in that you can focus and recompose without penalty, or negative curvature which compounds the error even more – the latter is what I’m seeing with the Pentax lenses. The focus distance is too far – i.e. in the opposite direction to distance error or positive field curvature.

  20. Sebastian says:

    Just to add a few things to your general lens explanations:

    – AeroBright is not new. Those coatings were used only for a few years (roughly between 2009 and 2013, if memory serves). The new coatings are called “HD” (hence the 90/2.8′s name). (The difference seems to be that the new coatings are mechanically tougher. Also, they probably sell better.)
    – “A” lenses have very high build quality and are made of metal. I’ve handled five of them and would say that their tactile quality and precision is nearly equal to modern Zeiss DSLR lenses (excepting the Otus). Also, the FAs are mostly just As with added autofocus but but no (or minor) optical advances, so if manual focus is of great concern, one should look into them instead of the FAs. They’re also very cheap to get these days, some below 100 €/$.
    – “DA” in Pentax speak means “reduced image circle” (since both lines of Pentax DSLRs have crop sensors compared to the original film format). The DA version of the 25 is the newer one and has a slightly reduced image circle, as per the dimensions of the digital 645 sensors. (That is why it can have a longer hood.) Unlike the other lenses, it cannot be used on a film body. I believe there is no optical difference between the two, though.
    – Correspondingly, one can expect the upcoming zooms to be HD and DA. (Not that it matters much.) I’d be surprised if they had image stabilization — an MF zoom is big enough as it is. But who knows.

    • Thanks for the added info.

      The FA lenses seem to be mostly plastic and not great feeling; have not tried the As simply because I don’t think the finder is up to the task of critical manual focus, and live view means using a tripod.

      The 25 DA/ D-FA difference is only in the hood, I believe – the optics are identical and the D-FA will cover full 645.

      Let us hope the upcoming zooms match the 90, or at least the 55…

      • Sebastian says:

        Yes, all D-FAs are full frame.

        I am doubtful about the zooms. They’ll certainly be f/4 or slower, and Pentax – to put it mildly – does not have a history of optimizing for open aperture. I would guess they will prove useful mostly in the f/8 – f/22 range.

        • That appears to be the case even with the SDM primes, with the exception of the 90mm. The 25 needs f8 for optimum performance cross-frame; the 55 is good from about 5.6 cross-frame, but the 90 is excellent already at 2.8. I wonder if this is a conscious design choice or a limitation of their optical abilities…

          • Sebastian says:

            I’ve been wondering the same thing, especially considering that Pentax was highly regarded as a lens maker in the film era. It almost seems like they got stuck there, not caring that today’s digital sensors require a fundamentally different approach to lens design. (It’s the same with the APS-C lineup, really.) I had hoped that the Ricoh acquisition would help turn things around, but no indication of that so far.

            On the other hand, the Pentax user base hardly seems to care anyway…

  21. What about the 150 2.8 pentax lens as stellar wide open as the 120 4 macro is?

    Wonderful shots love the lighting! You could really and easily feel the different ambiance/mood of each situation….thats what one big goal of photography is to transfer the mood/ambiance of the captured situation….

    • Not quite, but the one sample I tried doesn’t appear to be far off. I’ve come to the conclusion in the last couple of days that the 200/4 is a bit of a dog, though. 120 is too close to 90 for me, though it does go to 1:1, which the 90 does not…

      The latest generation of cameras has this ‘transparency’ and clarity that previous ones did not; my objective – at least in Ultraprint form – is to have a feeling of looking into the scene, not a representation of it.

  22. Great reading Ming !
    Thank you.
    Very interested how it performs vs D810 ;)

    • Won’t know until I have access to a D810 – I don’t see how the D810 can out resolve it though, unless you put a really bad lens on the Pentax and the Otus on the Nikon…

Trackbacks

  1. […] This series was shot with a Pentax 645Z, 25, 55 and 90mm lenses. […]

  2. […] series was shot with a Pentax 645Z, 25, 55 and 90mm lenses and a Ricoh GR. You might also find the Monochrome Masterclass workshop video handy for the […]

  3. […] set was shot with a Pentax 645Z, 25/4, 55/2.8 and 90/2.8 lenses as well as a Ricoh […]

  4. […] This series was shot with a Pentax 645Z, the 55/2.8, 200/4 lenses, but mostly the 90/2.8 SR. […]

  5. […] Zeiss 1.4/85 Otus for short tele and cinematic work; the midrange is covered by the Pentax 645Z and 55/2.8 SDM. I leapfrog again with an older manual focus 150/3.5 Pentax lens to provide a ~120mm option. The […]

  6. […] This series was shot with a Pentax 645Z, 25/4 and 55/2.8 lenses. […]

  7. […] also brought a partial Pentax 645 kit – the 645Z body, 55/2.8 and 90/2.8 SR lenses. I was debating on also packing the 25/4, but that’s a very large/heavy lens and not really […]

  8. […] Ming Thein (including comparison to the 645D, Nikon D800E and Hasselblad CFV-39 cameras) […]

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