Pentax 645Z First Impressions

Impressive medium format image quality at a record-low price

By PF Staff in Hands-On Tests on Jul 16, 2014
Pentax 645Z First Impressions

Nearly two weeks have passed since the first shipments of the Pentax 645Z left retailers worldwide, and we have now had a chance to test the camera and go hands-on in a variety of scenarios.  In this post, we will be presenting our first impressions of the camera.

For those of you unfamiliar with the 645Z, here's a quick overview: it's a 51-megapixel medium-format DSLR camera, which means it uses larger lenses and has a larger image sensor than most other consumer and professional DSLRs out there.  This size increase is accompanied by an increase in image quality, since physically-larger sensors can essentially deliver more resolution with less noise than smaller sensors.  The design and purpose of the 645Z is centered around image quality, and we feel that the camera is most appropriate for studio and especially landscape photography. 

The 645Z is the successor to the Pentax 645D, which was originally launched in 2010 with a $9999 price tag. The 645Z is available for $1500 less: $8499.  While this price may seem astronomically-high at first, it is actually extremely competitive within the medium-format market, where the bill easily ends up in $20,000+ territory for a camera body or kit.  Plus, by launching the 645Z at $8499, Pentax has narrowed the gap between the cost of a complete 645Z system and the cost of competing full-frame DSLR systems, which adds the potential to attract additional customers who crave extra-high resolution.

The bottom line is simple: the 645Z is a camera primarily for professionals who require high-resolution files as well as extremely demanding enthusiast photographers who are willing to fork over the cash. 

Now, let's get back to our first impressions review of the 645Z!

Hardware and Features

Just like the 645D, which used the internal hardware of the then-current Pentax K-7 APS-C flagship, the 645Z uses the Pentax K-3's PRIME III processor, menu system, and SAFOX XI autofocus system. The new and much more modern internal hardware delivers several enhancements which can easily be appreciated in daily use, and when combined with the fact that the 645Z's sensor is a CMOS type, the ball really starts rolling.  Here's what's new or improved in the 645Z:

  • Faster image processing and card writing speeds (UHS-I support)
  • USB3 connectivity
  • HDMI out
  • Live view mode (a much-needed feature)
    • Focus peaking
    • Image magnification
    • Contrast detect autofocus
    • Real-time exposure preview
  • Full-HD video recording
  • 3FPS burst shooting
  • 21-point viewfinder autofocus with -3EV sensitivity
  • Overhauled metering and white balance system
  • FluCard Tethering Support

The 645Z's added processing power is still only barely enough to keep up with its massive 51-megapixel files, but the rest of the items in the list above are quite significant. 

Unlike other Pentax DSLRs, the 645Z's live view screen reflects the actual exposure and can brighten or darken in manual mode.  Finally!

Speaking of tethering: the 645Z can currently only tether via the FluCard Wi-Fi accessory.  This fall, dedicated Pentax Remote Control software will be released allowing you to perform wired tethering.  This software will be available for purchase separately.

Construction and Handling

The Pentax 645Z is weather-sealed and built like a tank, and in your hands, it feels just like its predecessor.  The camera has a very large main grip and its mirror box is so deep that you get two generous surfaces for a tripod mount: one on the right side of the camera, and one on the bottom as usual.  This combined with the fact with the camera's unique symmetry makes it very easy to switch between landscape and portrait orientation while on a tripod. 

Pentax 645Z vs K-5
The Pentax 645Z dwarfs a K-5 IIs APS-C DSLR

With the D-FA 55mm lens (one of the smaller 645 lenses), the 645Z weighs in at 4.5 pounds, or just over 2 kilograms.  As you can see in the photo above, it almost makes a Pentax K-5 IIs look like a Q.  Hand-holding the 645Z is more than realistic if you absolutely need to go mobile, even without stabilization (which is only available in the 90mm macro).  During the day, bumping up the ISO to 200 or 400 will be enough to use a fast shutter speed; when it's darker, you will need to choose a much higher sensitivity, but thankfully the 645Z's sensor is quite capable in this regard.

Still, to really take advantage of the 645Z's resolution, one must marry it to a tripod.  This isn't a camera you want to carry around your neck while sightseeing: that's what smaller formats are for.  Unless you plan to use it as an exercise tool, you will be tempted to set this camera down after a few minutes of hand-holding it, especially with lenses larger than the 55mm, which can make the combo front-heavy.

When looking through the viewfinder, one of the first things you'll notice (apart from the fact that you'll never want to look through an APS-C viewfinder again) is that the LCD data is unusually large and therefore easy to read.  The same applies to the top LCD, but there's one catch: because the screen is slanted, if you look straight down at the top of the camera, you actually won't be able to see the data.  Pentax should have increased the viewing angle as the 645D suffered from a similar problem.

Pentax 645Z ScreenThe Pentax 645Z has a convenient tilting screen

One addition really pushes the 645Z ahead of the 645D when it comes to daily use, and that's the tilting screen (which has also seen a 10% resolution increase).  While it might seem like a gimmick at first, the tilting screen actually makes it much easier to compose and review shots in the studio, especially if you're frequently adjusting the shooting height.  Since the optical viewfinder does not offer 100% coverage, live view is helpful for fine-tuning compositions.  We also can't complain about the fact that it's finally a breeze to adjust the focus thanks to the magnification feature and focus peaking.

Pentax 645Z ButtonsNew button layout on the 645Z

Compared to the 645D, Pentax has modified the 645Z's button layout considerably, although primarily shooting controls (e-dials, ISO, AF, AE-L, green button) remain unchanged.  Again, we'll leave the specifics for our in-depth review, but one thing that we found to be a little bit annoying is the fact that the dedicated custom image, flash, drive mode, and white balance buttons have been removed in favor of a dual-function 4-way controller.  Because of the way that new AF area button (from the K-3) is implemented, sometimes you'll have to press two buttons to get back to where you wanted to be.  Such button duplication should simply not be present on a camera this large.

The SD1 and SD2 buttons on the left side of the mirror box have been replaced by an AF area button and a lock button, as control over the memory card slots has been transferred to the menu system.  Sadly, just like the K-3, the 645Z doesn't allow you to directly choose the primary SD card slot when saving to just one card ("sequential mode").  It will write to whatever card was used last, so the only way to force the camera to write to the other card is to remove the currently-active card, power cycle the camera, then replace the card.  This could trivially be fixed via a firmware update and we are surprised that it hasn't already happened.

To sum things up: the 645Z is still big, heavy, and durable, but its user-friendliness has been greatly improved thanks to the tilting LCD and live view.  The camera has a handful of interface quirks, but these issues are quite insignificant in the grand scheme of things.

Performance and File Size

A detailed analysis of the 645Z's buffer size and file processing speed will follow in our upcoming in-depth review.  What we can say right now is that the files that this camera produces are massive: expect RAW files to be between 60-85Mb and full-size JPEGs between 20-35Mb.  This combined with the fact that 51-megapixel files measure 8256x6192 pixels sets the bar high for PC hardware.  Be sure to have plenty of RAM and disk space!

Since the 645Z can take full advantage of UHS-I writing speed (but not UHS-II), we recommend 64Gb or larger Sandisk Extreme Pro SDXC cards.  Even with these cards, the 645Z spends several seconds saving a RAW file, but fortunately this does not lock up the camera outside of live view.

The 645Z offers two handy JPEG resolutions in addition to full-size: you can choose from either 36Mp or 21Mp.  If you save a smaller JPEG file to one SD card and a RAW file to the other, you'll be able to review your photos faster on your desktop, and perhaps process the smaller JPEGs directly when no significant adjusting or cropping is necessary.  A 36Mp JPEG from the 645Z still contains plenty of detail and only occupies 16-20Mb of space.

36-megapixel 645Z sampleTest photo shot at 36Mp

Here's an example: compare the 36-megapixel unedited JPEG to a 51-megapixel JPEG developed from RAW.  Plenty of detail remains in the smaller file for all but the largest prints.

As a side note, the 645Z doesn't apply much sharpening to its JPEGs by default, so we strongly recommend that you adjust the JPEG Custom Image settings to your liking prior to use.


Like the K-3, the 645Z can focus in very low light: down to -3EV. This level of performance is still best-in-class among DSLRs.  Its SAFOX XI autofocus system has 27 points (19 cross-type), up from 11 on the 645D.  The 645Z has also been fitted with the K-3's more powerful screwdrive motor, which increases the focusing speed of screwdrive lenses.  In practice, the new viewfinder autofocus feels more decisive and accurate than that of the 645D.

This isn't a camera you'd buy for AF speed, however: with SDM lenses, focusing is still somewhat sluggish, and in live view, the camera loves to hunt.  The 21 autofocus points still cover a very small portion of the viewfinder (since SAFOX XI is APS-C-sized), so don't expect to do much tracking.

For landscape and studio photography, we recommend using live view magnification to check and fine-tune the focus setting, since even slight inaccuracies can cost you dearly when it comes to resolution.

Image Quality

Now, let's take a look at the 645Z's most important aspect (by far).  With its 51-megapixel sensor, the 645Z offers the highest resolution currently available in a DSLR under $10,000, much like the 40-megapixel 645D did when it was released.  More important than the resolution bump, however, is the fact that the 645Z's sensitivity and dynamic range has been greatly expanded.  It can shoot up to ISO 204,800 while the 645D could only go up to 1000, or 1600 in "expanded" mode.  While the 645D struggled against the 36-megapixel Nikon D800E at high ISOs, based on what we've seen so far, the 645Z is back in the game and once again ahead.

Before we move forward, let's take a moment to put the 645Z's sensor size in perspective.  It is a "cropped" medium format chip measuring 44x33mm; in other words, its area is some 1.7x larger than that of a 24x36mm "full-frame" sensor but still considerably smaller than 645 film.  If one were to cut the 645Z's sensor down to full-frame size, it would be left with approximately 30.5 megapixels.  Cut it again to APS-C size and you'd be down to 13.5 megapixels.  What this means is that the 645Z has slightly larger pixel pitch than current high-resolution (36Mp) full-frame bodies and much larger pixel pitch compared to 24-megapixel APS-C bodies, and this promises lower noise.  With that said, if low-light photography is your primary goal, you would still be better-off with something like the Sony A7s (12Mp) or Nikon D4s (16Mp).  The 645Z is without question designed to offer the best possible image quality at high resolution, rather than the lowest noise possible overall.

As an aside, last week we posted plenty of full-size/RAW Pentax 645Z sample photos that you might want to play with on your own.

Detail and Noise

The 645Z's files are so detailed that you might be tempted to leave all your telephoto lenses at home.  Even a fraction of this image could be cropped to deliver a nice small print or web-sized photo.

Click to Enlarge | Full-size JPG | RAW ISO 100 | ISO 200 | ISO 400 | ISO 800 | ISO 1600

Below are out-of-camera full-size crops of the area just underneath the peak of the mountain, with no noise reduction applied.
100% Crop

As you can see, between ISO 100 and 800, the 645Z delivers exceptionally-low noise and plenty of detail, so you can comfortably use these sensitivity settings without even thinking twice.  The first significant increase in noise occurs at ISO 1600, where fine details can become hard to spot.  Let's take a look at another example.

645Z Landscape SampleTest Scene | Full-size JPG

Here's a photo of a rather uninteresting valley.  But, if we were to zoom in, we'd discover that there's actually quite a lot going on in the distance:

100% crop

These photos were developed from RAW and processed in Adobe Camera Raw with a little bit of sharpening and noise reduction.  Again, at low ISOs, we observe that the 645Z renders an incredible amount of detail.  Things don't start to get challenging until ISO 6400, where scaling becomes is the only effective way to clean up noise.

ISO 6400 and above should only be used in low-light scenarios, when a fast shutter speed is required, or when you're hand-holding.  In terms of noise, the 645Z's ISO 51,200 setting is similar to the Pentax K-3's 6400 or 12,800: in other words, it's more than adequate in low light and quite good in daylight.  The 645Z's high ISO settings enable you to hand-hold the camera in low light, something that was impossible with the 645D.

Click on either thumbnail below to see how much detail an ISO 51,200 photo retains compared to ISO 100.

ISO 100: F3.5, 30s exposure

ISO 51,200: F3.5, 1/15s exposure

In our in-depth review we will evaluate the 645Z's entire ISO range in various types of lighting.


At low ISOs, it is possible to observe moire in man-made objects such as rooftops or fences.  We also were able to spot some moire in the cactus photo from earlier in this post.  However, the 645Z's immense resolution renders moire a non-issue in all but the tightest of crops.  Moire correction is included in the 645Z's retouch menu.

Colors, Exposure, and Dynamic Range

The 645Z has an impressive dynamic range at low ISOs, something that you can explore in these full-size RAW samples.

The improved white balance system that the 645Z has inherited from the K-3 makes its colors very true-to-life, especially in low light.  The auto white balance is so good that it will often be better than what you can come up with in a RAW editor.  However, when left untouched, the 645Z's files are sometimes lacking in terms of contrast and saturation (something that can easily be corrected in post or applied through a JPEG custom image preset).  Nevertheless, the camera's RAW files always allow you to take things to the next level with the proper edits.

Cropped/Edited Examples

The 645Z's 51-megapixel resolution really gives you a lot to work with when combined with its impressive dynamic range and accurate white balance.  Consider this wide-angle lightning photo: 

645Z LightningOriginal 30s exposure at 55mm, ISO 200, F4.5

Even when left unedited, you can see that the shadows (clouds) contain plenty of detail.  Crop and tinker with the image a bit and you get something of an entirely different nature:

Cropped version of the above photo, with boosted brightness, contrast and vibrance (click to enlarge)

The same goes with this wide-angle landscape photo, which we were able to transform into a printable panorama.

Landscape Photo
Original Photo at 55mm, ISO 400, F6.7, 1/750s

This photo was shot hand-held at the side of a highway at ISO 400.

Cropped and edited panorama (click for 2000px version) | Full-size

Preliminary Verdict

The Pentax 645Z has greatly impressed us with its image quality.  It's a notch above high-resolution full-frame DSLRs when it comes to pixel count and noise, and it's well ahead of Pentax's own APS-C cameras such as the K-3 (in our in-depth review, we will offer comparative examples between the 645Z, the Nikon D810, and the Pentax K-3).  The possibilities with the 645Z's sensor are almost endless for landscape shooters, especially in low light!

It is also impressive that Pentax is offering the 645Z for less than its predecessor at launch ($8499); we can almost certainly thank the Pentax-Ricoh merger for this.  We likewise can't complain about the recent $2000 price drop on the 645D, which is now selling for just $4999.

One must realize, however, that the 645Z isn't a no-compromise camera, and it is not for everyone.  Even though the 645Z has few flaws of its own, its impressive image quality comes at the expense of versatility: the camera is very large physically, slow at times, and its lens selection is limited.  There are no lenses faster than F2.8, no lenses wider than 25mm (21mm full-frame equivalent), and only 3 weather-sealed lenses.  Therefore, it really isn't an optimal choice for many types of users: but we already knew this after reviewing the 645D.  The 645Z feels the most at home for landscape applications, and it also works well in the studio, despite a few small caveats (tethering limitations and slow flash sync speed, for instance). 

We haven't discussed video in this post as the 645Z isn't designed for videographers, but we will cover its video capabilities in our in-depth review.  From a feature standpoint, the 645Z's video mode is very similar to that of the Pentax K-3, though we expect there to be considerably lower noise.

To conclude, we find the 645Z to be a perfected version 645D.  While it shares many of the same traits of its predecessor, the hardware and sensor improvements as well as the addition of a tilting LCD screen and live view have addressed most of the reservations we had about the 645D.  The Pentax 645Z is truly a compelling, powerful camera available at a very reasonable price point within the medium format market segment.  It is without question the most appealing product that Pentax/Ricoh Imaging has released so far in 2014.

Availability & Pre-Ordering

The Pentax 645Z is currently back-ordered at US retailers, including B&H, Adorama, and the Pentax Web Store.  Based on what we know, Adorama will be receiving a substantial shipment of the 645Z next week, so if you pre-order now you may be able to get the camera before the end of July.  Free expedited shipping is included and your credit card will not be charged until the order ships (except for international orders).

Comments PentaxForums @PentaxForums News | Reviews | Forum

Support Pentax Forums Donate to Pentax Forums Support Pentax Forums