Pentax 645Z Field Test Part II

Pentax 645Z Field Test Part II

Straying outside of the medium-format comfort zone

By Mike Tomkins | Posted: 10/07/2014

When I published part I of my Pentax 645Z Field Test a little before the Photokina tradeshow, I promised that another report was on the way that would look at Ricoh's mighty medium-format camera in more challenging conditions. After a manic stretch of camera announcements and news coverage for the show -- plus a little time to recuperate -- I'm finally back and fulfilling my promise. It's time to take this medium-format DSLR outside of the traditional comfort zone for medium-format cameras!

Downtown, sun down

And boy, did I ever have some fun shooting the 645Z at night in downtown Denver, my extremely patient wife serving as lens caddy while I carried the 645Z and a Feisol Traveler CT-3441S tripod all over town looking for interesting shots. I'd have liked to have had a sturdier tripod with me, but the Feisol was small and light enough to fit in my carry-on, yet rated for a reasonably generous 22 pounds, and actually did a pretty good job.

I started the night off with a quick side-by-side comparison of base ISO and ISO 3200 -- which, bear in mind, is already a full-stop higher than the ISO 1600 limit of the earlier 645D -- and was immediately rather impressed. You can see the overall scene at ISO 100 above, and the ISO 3200 shot in the gallery.

Under a fairly complex mixture of city street lighting, white balance was perhaps just a touch pink, but that's easily corrected in the digital darkroom. And the comparison in terms of detail definitely looks good for the 645Z compared to its predecessor. While the 645D's ISO 1600 was quite usable, there was already a fairly noticeable step downwards in detail from the base ISO when viewed 1:1. With the 645Z in JPEG mode, even by ISO 3200 equivalent that difference is much less noticeable.

And yet more detail is there for the taking if I simply open the raw file and process it myself -- and with in-camera support for DNG raw, even my now rather aged copy of Photoshop CS5.1 happily opens the files straight out of the camera.

In the 1:1 crops above, you'll see ISO 100 at top, ISO 3200 out-of-camera at center, and a very quickly-tweaked ISO 3200 from DNG raw processed in Photoshop at the bottom. To my eye, it actually has just a little more detail than the out-of-camera shot at ISO 100. Just a slight touch of color and luminance noise reduction have been applied in this third crop.

I must admit that I was rather expecting this, as I'd already shot a little around the house while waiting for the rain to go away, and had bumped the ISO sensitivity up to 3,200 equivalent to get a reasonable shutter speed. Just like this city shot, there was more detail to be found in the picture of my son if I looked to the raw file, although the difference was hardly night and day-- even the out-of-camera shot had clearly visible thread detail in the fabric of his T-shirt. (Sadly, I focused a little far forward; the shot would've been better were the focus on his eye.)

So things were looking promising already, but how about some long exposures. That was the next thing I wanted to try, while there was still some traffic around. (It had been raining that day, so we'd gotten downtown quite a bit later than I'd hoped, after most sensible folk had already left for home.)

I wanted to get a shot or two with some light trails in them, for one thing. What little traffic there was remaining just wasn't cooperating, though -- every time I'd started to move my tripod a few cars and buses would show, and then just as quickly disappear before I set back up. And then I hit on a slower target -- a street cleaning vehicle of some kind with a pulsing strobe light on its roof that shows up as a pattern of long, yellow streaks.

Perhaps not the most visually-interesting composition, but I liked the shot nonetheless, and the rough granite walls and carved archway in the background are absolutely packed with detail in this six-second exposure at base ISO.

While I was waiting for vehicles, I looked around for other interesting details. One, you can see in the shot above -- the entrance to a bar called Marlowe's. The tiny pinpoints of light pulsing behind its sign caught my attention, as did the small fairy lights surrounding the arches above. The 645Z rendered the mixture of different light sources quite nicely, although not surprisingly some negative exposure compensation was needed to render this low-light scene as I saw it.

I also rather liked the shot below of a glitter-painted pedal cab, sitting forgotten once the pedestrian district had largely emptied out. This particular image was shot with live view so I could get a lower perspective, and I focused using contrast-detection, which worked just fine. I did find with some lower-light shots, though, that contrast detection failed to get a lock while phase-detection worked just fine, even with fairly contrasty subjects. The phase-detection almost never let me down -- if I could see my subject, the camera could focus on it first time, nine times out of 10.

It wasn't long before I got fed up of setting up and breaking down the tripod, though, or lugging it around with camera still attached. No problem -- I'd gotten a fair few long-exposures already, so it was time to try some handheld shooting at higher sensitivity. My wife, Bethany, become lens and tripod caddy -- have I already mentioned her limitless patience? -- while I roamed in search of more interesting subjects in a near-deserted downtown.

I decided I'd start from the extreme, with an ISO 204,800 shot. I can still remember those heady days when loading a roll of ISO 3200 film into my completely manual film SLR seemed incredible to me, yet these days we take high-sensitivity shooting almost for granted. Still, when you crank the sensitivity of a camera all the way up to ISO 204,800 equivalent, you get a thrill not unlike what I once felt with ISO 3200 film.

You also dial your expectations back. Way back. As I set the sensitivity for the shot above, I did just that -- and I was wise to do so. No two ways about it, the out-of-camera JPEG is both noisy and very mottled / blotchy. Doubly so because this was one of the rare few times the phase-detection autofocus let me down -- a relatively low-contrast subject in the very dimly-lit entrance to a downtown restaurant. My better-exposed shots weren't usable, with focus well off. Hence, I had to live with a shot that was overexposed by two-thirds of a stop.

Once I opened the raw file, though, I got a bit of a surprise. Yes, it's still extremely noisy, especially if you dial the noise reduction sliders all the way back. Given the sensitivity we're talking about here, though, more detail remains than I think I had any right to expect. Text can be made out -- if not quite read -- in the menu in the window. The various credit card and other promotional stickers in the windows are surprisingly legible. Strands of hair can even be seen silhouetted against the menu display.

You can see a 1:1 crop comparison of the out-of-camera JPEG above, alongside a raw conversion where I've intentionally left quite a bit of noise so as to retain as much detail as possible. (Both have been dialed back by two-thirds of a stop to correct for the overexposure.)

Is either crop going to stand much 1:1 scrutiny? No, but the raw conversion is closer to usable than I had expected, and could probably be cleaned up a good bit more in Photoshop if I had some time to spare. I'd love to see what DxO Optics Pro 9's PRIME denoising engine could do with this shot, but sadly it doesn't yet accept raw files from the Pentax 645Z.

The net result is that while I'd only use the extremes of the Pentax 645Z's ISO sensitivity range in a very tight pinch, and I'd make sure to shoot in raw only, I might actually find myself using it were there no other option available. Frankly, I didn't expect to find myself saying that.

And that's at the extreme upper limit of the camera's sensitivity. Dial it back to more reasonable levels, and you can get some very nice results indeed. The shot above at ISO 6400 equivalent, for example, has visible grain when viewed 1:1, but it's film-like, unobtrusive, and cleans up very nicely in Photoshop.

And I felt quite happy to use higher sensitivities, as well. Everything up to ISO 51,200 equivalent was quite usable, although I found myself preferring to work from the raw files once I strayed past ISO 6400. By default, the 645Z's noise processing is a bit heavy-handed past that point, and while I could have dialed it back in-camera, I prefer the added control of shooting raw.

For my money, though, ISO 51,200 did serve as a pretty firm cutoff point. Beyond that, I did feel I was giving away too much detail, and so I only strayed beyond that limit when there was no other choice. Below is an example of an ISO 51,200 shot with 100% detail crops, and as you can see, you can still make out individual strands of hair on the pedal cab driver's head!

High ISO in better lighting

All of the above was in relatively dim lighting out on the city streets of Denver -- but what about under better (albeit still not terribly bright) lighting? For decades now, I've been a fan of author Clive Cussler, and have read most of his books, most of which weave classic cars that he personally owns into the plotlines. I was thrilled to find out, shortly before my trip, that Mr. Cussler has a museum showing a portion of his personal collection in Arvada, Colorado, and doubly so to find that the Cussler Museum allows photography on the premises.

After a first couple of shots near the door, where at least some daylight was filtering in and allowing me to shoot at ISO 3200, I quickly ramped the ISO up to ISO 6400 for a more realistically hand-holdable shutter speed, and there I stayed for the remainder of the museum visit thanks to some very even lighting.

Given its very high 51.4-megapixel sensor resolution, the Pentax 645Z managed to avoid moiré in almost all of my shooting, but in the shot below of a late-'20s Duesenberg, I spotted a little. If you look inside the trumpet of the horn at screen left, there's a small grille that, in my shot, appears somewhat rainbow-colored. Comparing two shots from my bracketed sequence side by side, the positions of the colors change because the camera itself moved between shots -- thereby neatly confirming the colors aren't there on the actual wire mesh.

For this particular shot, it's very easily fixed in Photoshop with the Color Replacement tool, but with some subjects moiré will likely prove more challenging. It's a simple fact of life on cameras that forego an anti-aliasing (or optical low-pass) filter, as most do these days.

You'll forgive me if I let the pictures do the talking at this point. Surrounded by some of my favorite books and over 100 stunning cars dating all the way back to a 1906 Stanley Steamer -- plus some surprises that will only make sense to Cussler fans -- I was just a little bit overcome. Words simply can't do it justice. The pictures tell the story far better than I can. (You'll find a couple more of them in my final thoughts, at the end of this Field Test.)

HDR and raw, combined

Back when I reviewed the Pentax K-3 last April, I was thrilled by its ability to combine in-camera HDR capture with raw file storage. The Pentax 645Z inherits that same capability, and I'm no less happy to see it included here.

There is a downside, in that I've yet to find any third-party software which can accept the HDR raw files created by these recent Pentax models, which essentially contain three separate raw images in a single image. (Every third-party app I've tried simply treats them as if they were a single raw file, rather defeating the purpose.)

The solution to this is to use Pentax's provided, Silkypix-based Digital Camera Utility software. Unfortunately I didn't receive a copy of the software CDs along with the camera, and as it turns out, while the version I received with the K-3 can view the 645Z's raw files, it can't process them.

However, from my experience with the K-3, I know that this setup made it much more likely for me to shoot in-camera raw in the first place, and in the process, sometimes saved me feeling that I needed to do a manual HDR merge. As a raw-only shooter, that's a big deal for me, because usually these kinds of features apply only in JPEG mode.

Note, though, that the 645Z's HDR raw files are truly stupendous in size. We're talking close to 180MB per image here, so if you plan on shooting a lot of HDRs and keeping raw copies, you'll want to invest in lots of storage as well. (You can expect to fit only around 80 HDR raws on a 16GB SD card, and even the largest SD card on the market will only fit 2-3,000 or so.)

Medium-format movie capture

And so we come to the final feature of the Pentax 645Z that I was particularly excited to try out -- movie capture. If you're used to consumer APS-C DSLR or mirrorless cameras, or even professional full-frame models, the ability to shoot Full HD (1,920 x 1,080 pixel) video might not seem that special. Heck, even your smartphone almost certainly can do so these days -- in fact, some will even shoot at 4K resolution.

But in the medium-format world, movie capture is a very rare beast. Even live view was impossible until the switch to CMOS sensors in current-generation medium-format models. Movie capture is nigh on unheard of, and there's a reason for that: the logistics of reading off the sensor data fast enough without overheating becomes progressively more challenging as its surface area increases. What's easy for a small-sensor compact and challenging for a full-frame 35mm sensor becomes exceptionally tough to achieve in a worthwhile manner on a full-frame sensor.

But be that as it may, Pentax and sensor partner Sony have pulled it off in this camera, offering a choice of progressive-scan 30 frames per second or interlaced 60 fields per second capture at Full HD resolution. While the feature set is fairly limited -- there's no full-time autofocus, for example -- it's still potentially a handy feature to have.

After shooting a variety of videos, I quickly came to the realization that the 60i interlaced mode is of relatively little utility, sadly. As you can see above, it's not just the fact that the video is interlaced, but that the image quality is significantly degraded. Moiré is also much stronger in 60i video, and that's bad news, as it stands out much more in moving video than it would in a still image. If the perception of smoother motion is needed, you'd be better off interpolating the halfway points between frames than degrading image quality to this degree.

Image quality at night was much like that in the day: At 30p, quality was fairly acceptable compared to other cameras that lack full-sensor readout, but at 60i resolution was significantly reduced and artifacts more prominent.

Of equally little utility was the Movie Shake Reduction function, which while it did steady motion somewhat, also introduced very unsightly artifacts into the video, both in the form of distortions and a shimmery, "shivering" look that's extremely distracting.

In the clips below, I did my best to walk and carry the camera in the same way. Note that I'd accidentally left spot metering on, so the brightness level changes somewhat, but that shouldn't affect the stabilization algorithms. Unfortunately, I didn't notice immediately, and didn't have time to get back for another go at the comparison before our review camera had to be returned.

Where the 645Z's medium-format sensor pays dividends is for shallow depth-of-field effects. With such a large sensor compared to APS-C or even full-frame cameras, you can really isolate subjects from their background, or throw the entire scene out of focus for artistic effect. Below, you can see a couple of extreme examples of this shot both at day and night, the first shortly before sunset with a very nearby foreground subject, and the second simply ending with the lens as far from focus as possible.

Although you can record audio either from an internal microphone or an external stereo mic, and audio levels can be adjusted manually in 20 steps, the Pentax 645Z sadly lacks headphone connectivity. Sound quality from the onboard mic is fairly good, however, with little hiss and fairly good sensitivity.

Final thoughts

The most painful part of every great review is that where I have to give the camera back. (And since we pick our subjects for review here at Imaging Resource very carefully, it's actually quite rare that I don't feel a small pang of sorrow as I pack a camera up for return.)

With the Pentax 645Z, though, that was magnified a hundred-fold. I've never shot extensively with a medium-format camera before, and it's unlikely I'll get to do so regularly any time soon. This camera is far, far beyond my budget, but if it's within yours -- and if you're willing to take the time to learn to extract the best from it -- then I envy you deeply.

In almost every respect, the Pentax 645Z looks, feels and shoots like a supremely well-considered photographic tool, and its image quality is absolutely top notch, especially around its base sensitivity. This camera doesn't just demand good glass, it simply devours it.

With a relatively short time to become accustomed to it (and surrounded as I was by unfamiliar subjects and a million happy distractions), I will freely admit I've only scratched the surface of what it's truly capable of. With more practice, experience and familiarity, though -- and perhaps in the hands of a photographer with better compositional skills than I -- it's pretty obvious to me that this camera can create truly spectacular artworks, and at a resolution that will allow prints of equally spectacular size.

I'd love the chance to get some more practice in, but sadly, just as I had to bid beautiful Denver, Colorado a fond farewell, I must also do the same for the Pentax 645Z. A tiny part of me is determined, though, that one day we shall meet again. It's time to start saving pennies! ;-)