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Pentax 645Z Performance


Timing and Performance

Improved AF speeds, cycle times and burst performance compared to its predecessor.

Startup/Play to Record

Power on
to first shot
~1.5 seconds

Time it takes for camera to turn on and take a shot.

Play to Record,
first shot
~0.7 second

Time until first shot is captured.

Startup to first shot was a bit sluggish for a DSLR, and noticeably slower than the 645D's ~0.7s startup time. Switching from Play to Record mode and taking a shot wasn't bad, but also significantly slower than the 645D (which tested at ~0.3s).

 

Shutter Response (Lag Time)

Full Autofocus
Spot AF (center)
0.158 second

Time from fully pressing shutter button to image capture. (All AF timing measurements taken with a Pentax 55mm f/2.8 D FA SDM lens.)

Full Autofocus
Auto Area AF
0.170 second

Time from fully pressing shutter button to image capture.

Manual focus
0.117 second

For most cameras, shutter lag is less in manual focus than autofocus, but usually not as fast as when the camera is "pre-focused."

Pre-focused
0.112 second

Time to capture, after half-pressing and holding shutter button.
Live View

Full Autofocus
Spot AF (center)
1.174 seconds

Time from fully pressing shutter button to image capture.

Pre-focused
0.385 second

Time to capture, after half-pressing and holding shutter button.

The shutter lag numbers above measure time from shutter button press to image capture, with the lens already set to the correct focal distance. This largely removes the issue of differences in lens focusing speed, and measures how fast the camera can measure and act on focus information. In this metric, the Pentax 645Z was quite fast. The 645Z required only 0.158 second for full AF and capture when using Spot (single center point) AF mode (our default full AF lag test). The lag increased only slightly to 0.170 second when using 27-point Auto-area AF mode. Manual focus lag time was faster as expected, at 0.117 second. When pre-focused, shutter lag was just slightly faster than manual focus at 0.112 second, which is slower than most DSLRs but still pretty responsive.

Unlike the 645D, the 645Z supports Live View mode, but as is usually the case, full autofocus lag was quite slow at almost 1.2 seconds with our 55mm f/2.8 SDM lens. This performance is likely to vary a lot, though, depending on the lens used. Pre-focused shutter lag wasn't too bad though, at 0.385 second.

Overall, the Pentax 645Z's autofocus is very fast, with slightly improved lag times compared to the 645D.

 

Cycle Time (shot-to-shot)

Single Shot mode
Large Fine JPEG
0.35 second

Time per shot, averaged over 20 shots with no signs of slowing.

Single Shot mode
DNG RAW
0.33 second

Time per shot, averaged over buffer depth of 10 shots.

Single Shot mode
DNG RAW +
Large Fine JPEG
0.33 second

Time per shot, averaged over buffer depth of 10 shots.

Early shutter
penalty?
Yes

Some cameras refuse to snap another shot if you release and press the shutter too quickly in Single Shot mode, making "No" the preferred answer.

Continuous H mode
Large Fine JPEG
0.33 second
(3.06 fps);
12 frames total;
14 seconds to clear*

Time per shot, averaged over the buffer length of 12 shots, then slows to an average of 0.69 seconds (1.45 fps) for subsequent shots while buffer is full.

Continuous H mode
DNG RAW

0.33 second
(3.06 fps);
10 frames total;
22 seconds to clear*

Time per shot, averaged over the buffer length of 10 shots, then slows to an average of 1.29 seconds (0.77 fps) for subsequent shots while buffer is full.

Continuous H mode
DNG RAW +
Large Fine JPEG
0.33 second
(3.06 fps);
10 frames total;
30 seconds to clear*

Time per shot, averaged over the buffer length of 10 shots, then slows to an average of 2.04 seconds (0.49 fps) for subsequent shots while buffer is full.

Flash recycling
N/A

Flash at maximum output.

* Note: Buffer clearing times measured with a SanDisk Extreme Pro 95MB/s UHS-I SDHC card. Slower cards will produce correspondingly slower clearing times. Slow cards may also limit length of bursts in continuous mode. ISO sensitivity and noise reduction settings can also affect cycle times and burst mode performance.

Shot-to-shot cycle times were excellent at about a third of a second no matter the file type; quite an improvement over the 645D's 1.1 seconds.

Maximum continuous mode speed was also noticeably improved, at just over 3 frames per second for best quality JPEGs or RAW files, which is almost triple the 645D's 1.1 fps burst speed.

Buffer depths are however lower, ranging from 10 to 12 frames depending on the file type (the 645D managed 15 to 19 frames), but not a surprise given the faster burst rate and larger files. Note that you should be able to do better with typical real-world shots when shooting JPEGs, as our target was designed to be difficult to compress. Pentax claims up to about 30 JPEGs.

Buffer clearing was noticeably quicker than the 645D (likely due to to the 645Z's support for UHS-I cards), however it can still be quite lengthy at up to 30 seconds after a max-length burst of RAW+JPEG frames.

 

Bottom line, the Pentax 645Z is generally fast for its class. Compared to its predecessor, it's slightly faster at autofocus, much faster at cycle times and bursts speeds, and faster at buffer clearing as well. However Startup time and mode switching tested slower, and buffer depths weren't as deep. Still, the improvements over its predecessor are significant.

Battery

Battery Life
Fairly good battery life.

Operating Mode Number of Shots
Still Capture,
(Optical Viewfinder, CIPA standard)
650

The Pentax 645Z uses a custom D-LI90 rechargeable lithium-ion battery for power (the same type as the 645D), and ships with a charger. Battery life appears to be decent for such a large, very high-resolution sensor, but is lower than the 645D's 800 shot rating. Also keep in mind the Pentax 645Z does not have a built-in flash, which is normally enabled for 50% of shots when determining battery life to the CIPA standard. Pentax does not seem to publish battery life for Live View mode, but it will most certainly be significantly lower.

The table above shows the number of shots the camera is capable of (on either a fresh set of disposable batteries or a fully-charged rechargeable battery as appropriate), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))

 

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