The Pentax 645Z

There have been rumblings for months about a new Pentax 645 based on the Sony 50MP 33x44mm chip that’s in the Phase One IQ250 and the Hasselblad H5D-50c. The buzz was that it would be cheap (for a medium format camera) and that Ricoh would put some marketing, service, and distribution wood behind the camera in the US, unlike with the 645D.

The announcement came yesterday – actually, most everything was on the web a day or two earlier – and it was everything the rumor mill said it would be and more. The price wasn’t $10K, but $8500. It will take all the Pentax 645 lenses, and Ricoh has already ramped up production of them. It shakes the sensor to clean it, like a 135-style DSLR. There are 27 autofocus points, unfortunately concentrated in the center.

There’s a reflective LCD on the top of the camera, like a 1DX, a D4, a D800, or an H-series ‘blad. That’s great; you won’t have any trouble seeing what you’re doing outdoors, as is the case with cameras whose only display main panel or the EVF (Sony and Leica, I’m talking to you). I wish it would display the histogram after every shot like the Hassy, but you can’t have everything.

You’re going to use mirror lockup a lot on a camera like this. The 645Z has a separate control for it, which I like. It’s a knob, not a button, and I’m not so sure about that. I like mirror lockup to work the way it does on the H-series ‘blads, with a toggle-mode button. The Hassy’s button is hard to reach (but it’s reassignable) and the Pentax knob looks to be easy to get to.

It looks solid mechanically: magnesium body, lots of weather sealing. It’s got two tripod mounts, so you can shoot verticals without the instability of an L-bracket in that orientation.

I’m excited about the articulating LCD panel. Using the similar panel on the a7R has spoiled me, and if a bought a MF camera without one, like the IQ250 or the H5D-50c, I’d have to rig up tethering to a tablet to get the same viewing angle.

Communications with the outside world is via USB3, like the IQ250. I hate it that the only way you can talk to the HxD is with the nearly-obsolete Firewire; it’s one of the big reasons why I haven’t upgraded my H2D-39 in seven years.

A camera like this needs great focusing, and these days that means great live view. Initial reports say that the 645’s implementation is good. The H5D-50c requires tethering for good live view. The IQ250 has respectable live view on its touch screen.

Whether a 33x44mm sensor rates being called medium format is a legitimate question. I leave that to others. I’ll call it that for now, just for convenience. The sensor has 5/3 the area of a 24x36mm sensor. If you’re making a print with a classical 4:5 aspect ratio, you’ve got 90% more area in the 645Z because of its native aspect ratio of 4:3.  For full frame prints, the photon noise would be 23% lower than with a similar-area 50 MP 135 sensor (if one existed); for 8x10s, the photon noise would drop by 27%. The differences are a bit smaller than those between APS-C and full frame 135. A nice improvement, but not dramatic.

What’s not to like about the 645Z? Those of you who followed my struggles with the Sony a7R’s shutter shock know that it doesn’t take much shake to cut into the effective resolution of a high-pixel-count sensor. There are two ways to drive shutter-induced vibration to very low levels. The tried-and-true method is to use leaf shutters. With interchangeable lenses, that means a shutter in each lens, with the associated costs (Yeah, I know that there are ways to put a big leaf shutter behind the lens like an Argus C3, but really…). The cost of the shutters is a big deal with inexpensive lenses for 35mm-sized cameras, but not so much for MF lenses. However, Pentax has always had the shutter in the camera, and it doesn’t look like they’re going to change now.

That leaves me looking at third-party leaf-shutter lenses.

The flange distance of the Pentax 645 lens mount is 70.67mm. The Hasselblad H-system flange distance is 61.63mm, so H-system lenses won’t work on the Pentax. Mamiya 645 lenses won’t work either. Hasselblad V-series lenses, with their 74.9mm flange distance, should work with an adapter, but many, if not most, of them have marginal performance with a five-micron sensor. As far as I know, a convenient way to wind and trigger those shutters on the Pentax doesn’t yet exist. So the leaf shutter option doesn’t look too promising.

The next way to reduce shutter shock is with electronic first-curtain shutter (EFCS). I have seen how effective this can be in my testing of the Sony a7. Unfortunately, the 645Z doesn’t offer that feature.

So, in the new Pentax, our weapons in the war against camera-generated vibration dwindle down to what we’ve had with SLRs for years: mirror lockup. That eliminates a big vibration generator, but leaves the first shutter curtain – for some reason that I’ve never been able to figure out, the launching of the second curtain does not seem to contribute much to blur. Whether that’s enough remains to be seen.

It doesn’t look like Ricoh is offering variable delay between mirror up and shutter trip, like Hasselblad does in the H3D and following cameras. I don’t consider that a big deal, since I don’t envision using the camera handheld, but those who plan to use it that way should think about doing some vibration testing to see if it’s a problem with the lenses and shutter speeds that are important to them.

Personally, I view this camera as a special-purpose device, for use where resolution and clean tonality are paramount. Resolution is not the most important thing in a camera for most purposes. The camera that gets the most exposures from me is the Nikon D4, which is the lowest-resolution big-boy camera I own. Fast AF, reasonable (but admittedly not small) size and weight, rapid exposure ability, a big buffer (60 raw images to the 645Zs 10), and a feeling that you could drive nails with the camera when you’re not taking pictures trump pixel count for most purposes.

If you’re a working commercial photographer, you might come to a different conclusion and use the 645 as your go-to camera. At the price, you could buy a backup body or two and still come in under the price of the Hasselblad H5D-50c, which is the lowest-cost alternative (did I really say that Hasselblad was the lowest-cost anything?).

Then there’s stepping up to buying lenses for the camera. The good news is that the lenses don’t feature Leica or Hasselblad-pricing. But there’s even better news. If, like me, you’ve decided that this is a special-purpose camera, you’ll only buy lenses as needed for particular projects. That means that one or two will probably do you for a while.

The 645Z is not a perfect vehicle for the Sony 50MP chip. It doesn’t have leaf shutter lenses. Its flange distance means you can’t use many third-party lenses. But it’s so good that I found my mouse finger twitching over the pre-order button on the B&H website. In the end I decided to wait in hopes that some camera manufacturer – are you listening, Sony? – will put this sensor in a short-flange distance, mirrorless body. The best being the enemy of the good, by the time that happens, I may be holding out for a full-frame 645 sensor.