Review: The Pentax 645Z, part I

After a bit of – drought, it’s review bonanza week: at the opposite ends of the spectrum. First we had the Sony RX100 Mark III, and today will be the first part of the Pentax 645Z review; to be split into an assessment of the camera itself and a relative comparison to its predecessor, a previous generation CCD-equipped Hasselblad CFV-39 digital back, and the Nikon D800E. As far as I can tell, this is the first review of a production 645Z, anywhere. This part alone is going to be a 4500+ word monster, so grab a large coffee and settle in for a bit. Unfortunately the weather at the moment in Kuala Lumpur is extremely hazy – 120+ APIs thanks to various burning vegetation – which is not ideal for camera reviewing. However, as the 645Z is part of my personal equipment, bought at retail from Malaysia, it will be with me for some time and be subject to mid and long term updates – much like the Nikon D800E.

Let us begin. I know my reviews are already long; this is likely to be longer still because there’s a lot to cover. As a starter, you may want to read my early thoughts on the 645Z immediately following it’s announcement. Though the Z’s body design is not new – it shares most of the external and internal layout with the 2010 645D – it is somewhat unusual for modern medium format digital in that the design is completely integrated and the sensor/ processor portion is not removable or replaceable. This also means the body can be weather sealed to the same extent as the best conventional DSLRs, and in fact, the Z handles very much like one of those – albeit a very, very large one. Not all of Pentax’s lenses are weather sealed, however – only the 25, 55 and 90mm lenses enjoy the same level of environmental protection. The seals appear to be fairly robust and I’d be confident of using it in inclement weather.

The reformed tree – available to buy as a 12×15″ Ultraprint in a limited series of 20, here. Please remember to include your phone number in the comment box for the shipper – thanks!

The 645Z shares a 51MP, anti-alias-free 33x44mm Sony CMOS sensor with the Hasselblad H5D-50C and Phase One IQ250; both of which are significantly more expensive cameras. This trip represent the first time CMOS has made an appearance in ‘medium format’* digital – cameras larger than 35mm, at any rate. There have been a lot of concerns over the tonal rendition of CMOS compared to CCD; having a bit of experience with both, I’m inclined to prefer the native tonal look and color of CCD, but the lower noise, latitude and linearity of CMOS. Unfortunately, you cannot have it both ways. My solution thus far has been to shoot the CCD digital back when I know I’m unlikely to require heavy tonal edits and use output that’s fairly close to out of camera, and develop a workflow for the CMOS cameras – the D800E, basically – for everything else, including custom color profiles. I understand from several in the industry that the underlying photosite technology in this trio of cameras is an evolution of that which debuted in the D800 two years ago. This means we can expect live view, video recording, huge dynamic range, a very low noise floor, surprising high ISO capability, and excellent acuity. Color accuracy should be very good but still not quite up to the medium format CCD backs. I’ll return to whether this really is the case or not later on. In short: medium format’s shooting envelope has just greatly expanded.

*I use quotation marks because 33×44 is to 645 much like APS-C is to full frame, and nowhere near the much larger 6×6, 6×7 and 6×9 formats also common in the film world.

Face, I

The 645Z is a really solid lump of metal; a more awkward shape than most DSLRs owing to the longer flange back distance inherited from the film 645 system. It’s ergonomically well-thought out with most major controls falling under the fingers of your right hand or thumb of your left (if you cradle the lens with your left). There have been some minor button moves and reassignments from the 645D to accommodate the tilting screen; I personally think these are an improvement, and I definitely want the waist level finder option in case I miss my Hasselblad. The viewfinder is larger than the 35mm full frame cameras, but not that large; smaller than my Hasselblad and HC-4 prism, for instance. It’s enough to gauge focus accuracy for most lenses, but you’d better use live view for critical applications and wider lenses whose depth of field transition profile is too shallow. No point in throwing away all of that extra resolution; it came at a premium.

Face, II

Camera design is now mature enough that there really shouldn’t be any handling issues on equipment of this price or level; and there aren’t. The button assignment, menus and mode dial memory positions are hugely customizable and flexible. I spent a month with the previous 645Z to familiarize myself with the handling and operation, as well as to test the lenses I’d acquired in advance. Even if I hadn’t, the controls are plenty logical and wouldn’t have required much familiarization time coming from my usual Nikons. If anything, there’s almost too much information presented to you – though the back screen is useful, all of the critical things you need to know are easily gleaned by looking at the position of the knobs or the top panel LCD; the back LCD duplicates much information, is very bright/ conspicuous and I suspect also power hungry. Fortunately, it can easily be turned off, and the camera will remember this setting (or you can append it to one of the custom U1-3 modes on the dial, though I wish there was a way to save and export these settings to a card – both U1-3 and the custom functions). The only thing I don’t like about handling is that it’s too easy to press the buttons on the camera’s left shoulder unintentionally when shooting in portrait orientation. That said, there is a customizable lock button to disable these buttons (and others, if you wish) and provision of two tripod mounts is a very useful touch. It means that a standard 90° L bracket off eBay will do a great job without having to pay even more for a custom unit.

Now is probably also a good time to mention remote control options; like every other manufacturer out there (but few medium format ones) the camera can be operated wirelessly over wifi plus a smartphone/ tablet app – but only with the optional proprietary Pentax FluCard wireless SD. I haven’t had a chance to test this yet, but I could see it coming in useful for longer exposures, light painting, etc. – most of which I do very little (or none) of, but would like to try at some point. Most medium format shooters are used to operating tethered – partially because the monitors on all but a few of the latest generation digital backs are utterly abysmal (really only useful for confirming the camera took a picture, checking the histogram, and perhaps changing a setting or two) and partially because focus confirmation becomes more critical**. The 645Z will operate tethered over USB3 – not Firewire – but I think the larger screen combined with wireless review of JPEGs (forget trying to send the enormous raw files over wifi in a hurry) will prove to be more than sufficient here.

**And there are also clients who simply like to watch.

Magritte attacks

The 645Z inherits the K-3’s 27-point AF system, 25 of which are cross-type. This is useful for off-center subjects and the greater precision required for focusing medium format due to shallower depth of field for a given aperture and angle of view. The only downside is that all of the points are clustered near the center of the frame, as the system was originally designed for APS-C. Still, it’s the only medium format camera to have more than one AF point at all. It will track moving subjects, but not that well – I have a feeling this also has a lot to do with the some of the older lenses’ drive systems having some backlash in the gearing (they’re driven by a motor in the camera body). For static subjects however, it’s accurate and snappy – more so with SDM lenses – and if it isn’t accurate enough, it can be fine tuned easily. This was the first order of business with my camera to obtain optimal performance. Subjectively, I find it feels faster than the Hasselblad H5, a little behind the D800E but light years ahead of its predecessor. Metering also deserves a notable mention here, because matrix just seems to always get the exposure right – you have the option to bias exposure towards the area underneath the AF point or not (partial spot, I suppose) – which is something the new Nikons sorely need but lack. It feels like the Nikon matrix meter in the ‘good old D3 days’ – when it was less likely to surprise you. I do wish we had the option to set lowest shutter speed thresholds with auto ISO though; the ‘slow-medium-fast’ program with respect to lens focal length doesn’t go fast enough to really be assured of sufficient shutter speed to avoid hand shake. That said, there IS the TAV mode which will set ISO based on your aperture/ shutter requirements, but it isn’t quite the same as it doesn’t allow an unbounded upper shutter speed. Useful at night, though.

The Pentax 645 system has quite a number of lenses available – either new or used off the usual second hand sources. However, not all of these lenses are equal performers, and for the most part, only the newer lenses – with built in motors and weather sealing – perform adequately wide open for digital, especially the 645Z. There are also a host of manual focus options which will also work, but you really need the impossible to find and out of production split prism screens to make the most of them – though if you work mainly off a tripod, live view is an option. However, what I do find glaringly missing is a decent normal zoom and tilt shifts. There’s also an enormous difference in price (but not quality) between buying the older screwdriver focus lenses new vs used; no idea why. As with all other new medium format lenses, the newer sealed SDM versions will empty your bank account very quickly. It’s also worth noting that manual focus lenses (or AF lenses in manual focus mode) will beep once the camera thinks the lens is in focus – a very useful touch. I believe the trigger point for this is also affected by the AF fine tune setting, but further testing is needed to confirm this.

Prior to even seriously considering the camera, I spent a significant amount of time determining which lenses were adequate, which were good, and which would serve my purposes – I landed up purchasing the D-FA 25/4 SDM, D-FA 55/2.8 SDM, FA 75/2.8, D-FA 90/2.8 SR Macro SDM and FA 200/4. The 55 and 90 SR lenses are excellent; the 25 needs to be stopped down a bit to reach excellence, and the 200 is not bad if you can nail focus precisely. The 75 is so-so wide open, better stopped down, but has focusing issues – it’s just outside AF microadjustment range. The older screwdriver AF lenses don’t seem to focus very precisely; both of them consistently back focus on both my 645Z and the loan 645D. I suspect there are some differences in the tolerances involved for film vs digital capture. By comparison, the SDM lenses required very little to no adjustment.

The camouflaged predator

With cameras of this resolution come serious considerations of shot discipline, shutter and mirror design: if there’s too much recoil, vibration or it’s difficult to hold the camera steady, then you’re going to find all of that extra resolution you’ve paid for disappearing very quickly indeed. A lot of us – myself included – learned this the hard way with the D800E; not only did 1/focal length become insufficient, 1/2x was marginal under ideal conditions. And nailing focus becomes really very critical indeed. There are of course other factors beyond resolution which dictate the minimum shutter speed one can ‘get away with’ – your threshold of acceptability for acuity, for instance. I personally junk anything that isn’t perfect at 100%; with this as a benchmark, I find that 1/2x is sufficient for a D800E, and was expecting to need 1/3x or higher with the 645Z – however, it seems that the shutter and mirror mechanism combined with the mass of the camera is sufficiently well-damped that 1/2x stands, or 1/1x or slightly lower for the SR-enabled 90 macro (which also happens to be the only medium format lens of any kind with an optical stabiliser).

A false autumn in the tropics

The mirror/ shutter mechanism might be loud, but it’s well-damped. It’s also different from the unit in the 645D, which has different acoustics and a lower 50,000 shot life (the 645Z is 100,000 – and I’ve burned about 1% of that already in the testing/ reviewing process). And mirror lockup is just the twist of a dedicated knob away. Better yet, if you use the self-timer, the mirror locks up by itself when the timer starts. Remarkably, for a sensor of this size, there’s even an ultrasonic sensor shaker built in to remove dust. There is one catch, though: maximum shutter speed is 1/4000s, which is very high for MF, but sync speed is just 1/125s. With a shutter opening roughly twice the size of the D800E’s, it’s not surprising, but it does severely limit your ability to balance flash and ambient.

Momentary indecision

There are also effectively no leaf shutter lenses. I don’t consider this to be a major issue as I don’t plan to use this camera outdoors with speedlights anyway (in fact, I almost never use speedlights outdoors) nor do I do the kind of jumping/ moving/ motion-freezing stuff; but others who do will probably want to think again. In any case, I still have my Hasselblad V lenses which all have their own PC-sync ports; it should be a relatively simple matter to use the 645Z body in bulb mode and sync/trigger the actual exposure to the 1/500s leaf shutter in the V body. Hopefully at some point Pentax will release some leaf shutter lenses – 1/1600s Phase One sync, anybody? It’s worth noting that leaf shutter lenses top out at 1/1600 for the most part, or less (1/500s on my Hasselblad V, which is terrible for tropical light – it means constantly switching NDs or not having much DOF control); they’re also limited in maximum aperture to f2.8 for the ‘normal’ 80mm, but mostly f4 (and more DOF control limitations). Bottom line: if you plan to use your camera mostly in the studio, then the leaf shutter rules; but if you plan to use it for available light work, then the 645Z is probably the better choice. Note: The Phase One bodies will also go to 1/4000s on their focal plane shutters.

Pillars

I’ve got a lot to say about image quality. I received a lot of email traffic expressing concern over the samples; one look at the EXIF data and very strange exposure choices (high ISOs, frequently 1600 and up, and very small apertures) already suggested something not quite right. Who knows what was going through the mind of their photographer at the time. Fortunately, I can report in a nutshell that image quality is really excellent – at all ISOs, and without any major caveats. Firstly, there’s the whole question of 14 vs 16 bit: I’m not going to go into that in any depth beyond what I can empirically (and subjectively) observe through my experience shooting the D800E and CFV-39. Remember also that the Hasselblad H5D-50C and Phase One IQ250 use the same sensor; the Hasselblad claims 16 bit files, but Phase One also outputs at 14 bit – either one of them isn’t really, or the whiners have no reason to complain.  The 645Z’s tonal response and color is not really like either camera. The 645D also only had 14 bit files, and I don’t recall any complaints there. It has the adjustability and latitude of the D800E, but the pleasing natural-ness straight out of camera of the CFV-39; it doesn’t share the same color palette – not better or worse, just different. Your preferences will vary. However, with a color checker chart and a bit of work, it’s not difficult to make a custom profile that will please your personal tastes – I do this for every one of my cameras and set it as a default as part of the ACR conversion process. Does it have that ‘medium format look’? Well, given that such a thing is a property of both the angle of view, real focal length and aperture as much as the technical qualities of the recording medium, I’d say yes and no: it looks different from FF35, but not like full frame 645 (the CFV-39 has a 1.1x crop factor to 645). Remember, the sensor is 33x44mm after all.

Enough detail for you?

And another one

What really impressed me about the 645Z’s sensor is the amount of latitude it has. Dynamic range is definitely a notch above my D800E; situations where the D800E would have clipped do not clip in the 645Z. I would put dynamic range at around 14-14.5 stops under ideal conditions (perfect file, some recovery of shadows and highlights in ACR); this is more than enough for most situations and to produce very pleasing monochrome images – though it doesn’t have the incredible highlight tail of Fuji Acros, I believe it’s possible to come close to that tonal feel by taking advantage of the very low noise floor, underexpose for zero clipping, then use a curve to bring up the shadows – this is something I want to experiment more with. Note that such a process would of course sacrifice image quality somewhat since data is being pushed. Regardless, I think it’s pretty clear to see that the 645Z shares the same special sauce as the GR for B&W conversions.

Low ISO test series; screen capture of 100% crops of DNGs converted via ACR. Click here for size here.

Low ISO test series; screen capture of 100% crops of DNGs converted via ACR. Click here for full size.

For the first time, I’ll be making all of the full size DNGs from the bookshelf test series available – you can download them here, until such time as I need the space in my Dropbox account freed up but at least for two weeks. These were shot with ideal shot discipline – focus with live view magnified, on a heavy tripod with mirror up and self timer; but under deliberately horrible light (mixed tungsten, fluro and LED) to see how the camera’s AWB would handle it. (Answer: quite well.) It should also give you a good idea of just how much detail is in one of these files.

Part of latitude is noise: by the time we hit ISO 51k, usable dynamic range is appears to be somewhere around the 7-7.5 stop mark (the amount will vary with your tolerance to noise); I can’t see any difference between ISO 100-400, there’s 1/2-2/3 stop loss at ISO 800, and roughly 2/3 to a whole stop thereafter. For a full size file, I place the usable limit at 12.8k for color, and 25.6k for monochrome. ISO 6400 will clean up almost completely with some NR. This is unheard of for medium format – and represents an excellent performance for cameras in general. At the pixel level, I’d say this camera is perhaps a stop cleaner than the D800E – not surprising given the newer photosite architecture and 20% (or possibly more) light collecting area – 5.3um pixels play 4.88um pixels. If you don’t need a full size file, oversampling and downsizing to 16MP – comparable to say the E-M1 and D4 – will yield some surprises: ISO 51k is very, very clean. It’s so clean I’d say it looks something like a ISO 2500 file from the E-M1, and an ISO 12.8k file from the D4 – and of course thanks to the downsampling, fine detail is much better, too. Food for thought for the reportage shooters – I certainly intend to make full use of this.

Coils

The slightly larger pixel pitch means that diffraction should theoretically kick in later than the D800E; the 645Z also has no anti-aliasing filter. On the D800E, you can see diffraction softening happening after f8-11, and it’s very noticeable by f16. I’d move that cut point somewhat later with the 645Z – to perhaps f16 with noticeable limits a bit higher – this is partially due to the larger pixel pitch, partially due to the longer focal lengths involved, and some technology by Pentax that supposedly corrects for diffraction. How exactly it does this is unclear – I suspect some sort of unsharp masking or a slightly different interpolation of the raw file – but the difference is visible, and better, even with the DNGs. It’s switchable, though I can’t imagine why anybody would want to turn it off. It’s also worth noting that the camera will record either raw in DNG or proprietary PEF format; both are 14 bit. The latest version of ACR supports the native PEF format – again, more investigation is required into whether there’s any visible difference between the two formats, but my testing up to this point suggests not. There’s also one minor firmware bug in the files – on my camera at least, no matter how I have the rotation tagging set, the images always seem to come out of the camera upside down in ACR despite appearing fine on the LCD. Overall, image quality is superb. I was expecting it to perform as a ‘D800 plus’; so far it’s met all of those expectations, and frankly, surpassed them. The 645Z extends the shooting envelope quite a bit beyond that of the D800E – not only are the files cleaner at the pixel level, but you’ve also got the benefit of being able to downsample. I’d love to see this sensor in something much smaller, with an optical finder, and with a fixed lens perhaps – GR Digital VI, perhaps?

Ripples

I shot several hundred test frames during the course of making this review and familiarising myself with the camera; being cautious made me swap batteries out after every session, but the most I could get the gauge to move was lose one of the three segments after about 150 images shot mostly live view – this is an impressive performance given the size of the sensor, considering my D800E would probably be down 50% or so if shot under similar conditions. A second battery is probably recommended for heavy shooters to get through a day, but you’re probably going to run out of card space first – for the first time, I’m considering moving to 64GB cards. The 645Z also records video, which is another reason to consider larger cards. However: there are some unfortunate gotchas: bit rate appears pretty low – just 21mbps, there’s no way to get a clean HDMI out only from the sensor, and it doesn’t use the full area – you lose about 10% from the left and right, which actually makes the video size…the same as a 36x24mm sensor. So perhaps there isn’t much point after all, especially given there are better full frame options out there for video work. Oh well – you can’t have everything, it seems.

2.4:1 and still more than enough pixels left (28) to Ultraprint.

There’s no denying that with Sony’s entry to the medium format sensor game, the whole market has changed. Available light becomes possible, excellent, and not just a challenge; what’s especially interesting is the enormous difference in pricing between the Hasselblad H5D-50C, the Phase One IQ250 and the 645Z – all of which use the same sensor. Granted, the Hasselblad and Phase One bring leaf shutters, an (arguably) better lens selection in some areas, and interchangeability of the backs with your other (large format perhaps) cameras – but we’re talking a factor of three or more here. For the price of the IQ250 alone, you could get two 645Zs and a decent set of lenses – redundancy and two-body shooting if you want. Or you could buy a 645Z and subsist on second hand manual or early AF lenses and not spend much over US$10,000 – for a medium format camera with state of the art performance. You could even add the 645D if you decide you prefer the CCD ‘look’, or an older Phase One back with a larger sensor and a Hasselblad V system for the best of both worlds. Granted, as relatively ‘cheap’ as the 645Z is, it is still going to be far too expensive – and too much weight – for most photographers to consider; it’s a niche product and overkill for pretty much everybody but a very small group. But those whose pockets are deep or whose business can justify it now have a more interesting option. I’ll be revisiting the comparison in the next article – between the 645Z, 645D, CFV-39 and D800E. No way of getting my hands on the H5D-50C or IQ250, unfortunately – there isn’t even a Phase One dealer in my region; not surprising as the annual medium format market in Malaysia is probably not more than 20-25 cameras. That should give you a pretty good idea of the state of the industry.

Shadow etching

But I digress. Perhaps the most amazing thing about the 645Z is not its pixel count, its high ISO ability, dynamic range, ergonomics, handling, battery life etc. – it’s the fact that it makes it so easy to get such incredibly high image quality; it has a shooting envelope many times larger than any other medium format camera, and in my experience so far, larger than even the D800E. Everybody who’s used medium format digital previously will be extremely cautious with the camera and slowly be surprised that they do not need to be; DSLR upgraders will shoot it without the benefit of context and not understand what the big fuss is about. I personally think this camera represents a significant step forward for medium format; it’s no longer as intimidating and the results can now compete with DSLRs under almost all conditions. Of course, high shot discipline and care will always pay off; those who have it will be rewarded with extraordinary image quality. Paradoxically, whilst most cameras benefit from being shot with the deliberation and care of medium format, this camera benefits from being shot like a DSLR – under such situations is where it’ll extend your image quality envelope enormously and bring previously unimaginable results. This earns it a ‘highly recommended’ rating from me, with one caveat: if you shoot primarily flash/ studio work, this is probably not your camera because of the slow 1/125 flash sync. For everything and everybody else – if you need the resolution, there’s really no better choice at the moment; Pentax deserve credit for not just brining this camera to market, but pricing it at a very sensible level. MT

I’ll be uploading images from this camera continuously to this flickr gallery.

The Pentax 645Z is available to buy here from B&H. Lenses are available here from B&H and Amazon respectively.

__________________

H2 2014 workshops now open for booking – Making Outstanding Images San Francisco, Chicago and Venice; Masterclass San Francisco and Venice – click here to book or for more info

____________

Visit the Teaching Store to up your photographic game – including workshop and Photoshop Workflow videos and the customized Email School of Photography; or go mobile with the Photography Compendium for iPad. You can also get your gear from B&H and Amazon. Prices are the same as normal, however a small portion of your purchase value is referred back to me. Thanks!

Don’t forget to like us on Facebook and join the reader Flickr group!

Images and content copyright Ming Thein | mingthein.com 2012 onwards. All rights reserved