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Full Review at: http://www.imaging-resource.com/PRODS/645D/645DA.HTM

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Pentax 645D digital camera image
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Pentax 645D

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Pentax 645D Performance


Timing and Performance

Startup/Shutdown

Power on
to first shot

~0.7 second

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

Shutdown

~0.6 second

How long it takes to turn off.

Buffer clearing time

27 seconds*
after 19 Large Fine JPEGs

Worst case buffer clearing time. -- This is the delay after a set of shots before you can remove the card. Some cameras won't shut down until the buffer is cleared.

See Cycle-Time table below for more buffer clearing times.

53 seconds*
after 16 Large RAW frames
71 seconds*
after 15 Large RAW + Large Fine JPEGs

* Note: Buffer clearing times measured with a SanDisk Extreme III 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.

Startup and shutdown times were a tad slow for a DSLR, but not too bad at about 0.7 and 0.6 second respectively. Buffer clearing is very slow, but no surprise given the 40-megapixel files the 645D produces.

 

Mode Switching

Play to Record,
first shot

~0.3 second

Time until first shot is captured.

Record to Play

~6.0 seconds

Time to display a Large/Fine quality JPEG file immediately after capture.

Display
recorded image

~0.2 second

Time to display a Large/Fine quality JPEG file already on the memory card.

Time to switch from play to record mode is fast, as is displaying a previously captured image, but switching from record to play after taking a shot takes about 6 seconds, which is quite slow.

 

Shutter Response (Lag Time)

Full Autofocus
Single Area
(center) AF

0.164 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

0.180 second

Time from fully pressing shutter button to image capture.

Continuous AF
0.138 second
This mode is release priority so subject may be out of focus; we have no way to measure performance with moving subjects.
Manual focus
0.141 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

0.142 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 645D was quite fast. The 645D required only 0.164 second for full AF and capture when using Single-point (center) AF mode (our default full AF lag test). The lag increased slightly to 0.180 second when using 11-point Auto-area AF mode. Continuous AF and Manual focus lag times were faster at 0.138 and 0.141 second respectively. When pre-focused, shutter lag was about the same as manual focus at 0.142 second, which is slower than most DSLRs.

 

Cycle Time (shot-to-shot)
Single Shot mode
Large Fine JPEG
1.09 seconds

Time per shot, averaged over buffer depth of 21 shots.

Single Shot mode
Large DNG RAW

1.10 seconds

Time per shot, averaged over buffer depth of 17 shots.

Single Shot mode
Large DNG RAW +
Large Fine JPEG
1.09 seconds
Time per shot, averaged over buffer depth of 16 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 mode
Large Fine JPEG
0.90 second
(1.11 fps);
19 frames total;
27 seconds to clear*
Time per shot, averaged over the buffer length of 19 shots, then slows to an average of 2.07 seconds (0.48 fps) for subsequent shots while buffer is full.

Continuous mode
Large DNG RAW

0.90 second
(1.11 fps);
16 frames total;
53 seconds to clear*

Time per shot, averaged over the buffer length of 16 shots, then slows to an average of 3.79 seconds (0.26 fps) for subsequent shots while buffer is full.

Continuous mode
Large DNG RAW +
Large Fine JPEG

0.90 second
(1.11 fps);
15 frames total;
71 seconds to clear*

Time per shot, averaged over the buffer length of 15 shots, then slows to an average of 5.27 seconds (0.19 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 III SDHC card. 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 quite sluggish for a DSLR, at about 1.1 seconds for Large/Fine JPEGs or DNG RAW files.

As you'd expect given the class of camera, continuous mode speeds were also quite slow at a very consistent 1.11 frames per second no mater the image type. This matches Pentax's claim of 1.1 fps quite nicely. The Pentax 645D's buffer depths were quite good for its file sizes, though the relatively slow burst speed probably helped a lot here. Buffer clearing is also quite slow, as you'd expect. The camera does not appear to take advantage of faster UHS-I cards.

 

Download speed

Windows Computer, USB 2.0

11,194 KBytes/sec

Typical Values:
Less than 600=USB 1.1;
600-769=USB 2.0 Low;
Above 770=USB 2.0 High

Connected to a computer or printer with USB 2.0, downloads are quite fast. That's a good thing, given the huge file sizes.

 

Bottom line, the Pentax 645D is pretty fast at some things like autofocus and switching to record mode, but cycle times, burst mode, and buffer clearing are quite slow compared to "full frame" (35mm) and APS-C DSLRs. That's probably no surprise to most potential 645D customers given the class of the camera, though. The 645D is not intended for high-speed photography like photo-journalism and sports, afterall.

Battery

Battery Life
Good battery life.

Operating Mode Number of Shots
Still Capture
800

The Pentax 645D uses a custom D-LI90 rechargeable lithium-ion battery for power, and ships with a charger. Battery life appears to be pretty good, though keep in mind the Pentax 645D does not have a built-in flash, which is normally enabled for 50% of shots when determining battery life to the CIPA standard.

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))