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Performance

The new model's most noticeable improvement over the K20D is the continuous shooting speed which has increased from 3 to 5.2 frames per second. From a continuous shooting point of view this puts the K7D firmly above the entry level segment and even enthusiast cameras such as the Nikon D90 but not quite on the same level as semi-pro models such as the Canon EOS 50D or Nikon D300.

Overall the camera's performance is pretty much identical to the K20D and in most respects on par with its direct rivals. An exception is the AF speed which, despite the upgraded AF system, still feels a little sluggish next to the competition.

Timings & File Sizes

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 4672 x 3104 JPEG Fine (approx. 8,300 KB per image).

The media used for these tests was a 8 GB Sandisk Extreme III (30mb/s edition) SD card

Action
Details
Time, secs
(8 GB Sandisk)
Power Off to On *1   3.2
Power Off to Shot   0.6
Shot to shot time (JPEG)   0.3
Shot to shot time (RAW)   0.4
Shot to shot time (JPEG) Live View 0.6
Shot to shot time (RAW) Live View 0.8
Switch from live view *2   0.6
Power On to Off *3   0.3

*1 This is the time from turning the switch to the 'On' position to the status display appearing on the LCD monitor (as soon as you would be able to verify camera settings). The K7 briefly shows a very basic status screen before the standard status display comes on.(As you can see from the 'Off to Shot' time this doesn't actually affect how quickly you can begin using the camera (as good as instant) assuming you knew the camera was in the correct mode.
*2 This is the time from pressing the Live View button to the status display appearing on the LCD monitor (as soon as you would be able to verify camera settings).
*3 This is the time from when the switch is set to off till the status LCD going blank.

Continuous Drive mode

To test continuous mode the camera had the following settings: Manual Focus, Manual Exposure (1/500 sec, F5.6), ISO 100. Measurements were taken from audio recordings of the tests. Media used were the same as above.

The tests carried out below measured the following results for JPEG and RAW:

  • Frame rate - Initial frame rate, this was always 5.2 fps (+/- 0.05 fps) at the higher continuous shooting setting and 3.3 fps at the lower continuous shooting setting.
  • Number of frames - Number of frames in a burst (for JPEG there is no limit with a fast card)
  • Buffer full rate - Frame rate if shutter release held down after burst (buffer full)
  • Write complete - How long after the last shot before the SD lamp goes out

Burst of JPEG Large/Fine images Continuous High

Timing
8 GB Sandisk
Frame rate 5.2 fps
Number of frames 23
Buffer full rate 2.0 fps
Write complete 9.3 sec

Burst of JPEG Large/Fine images Continuous Low

Timing
8 GB Sandisk
Frame rate 3.3 fps
Number of frames 45
Buffer full rate 2.6 fps
Write complete 9.2 sec

Burst of RAW images Continuous High

Timing
8 GB Sandisk
Frame rate 5.2 fps
Number of frames 15
Buffer full rate 1.4 fps
Write complete 9.7 sec

Burst of RAW images Continuous Low

Timing
8 GB Sandisk
Frame rate 3.3 fps
Number of frames 19
Buffer full rate 1.4 fps
Write complete 9.7 sec

The K-7 delivers exactly the specified continuous shooting rate with the High setting shooting at 5.2 frames per second and the low setting at 3.3 respectively. After the buffer has run full (23 frames in High/JPEG or 15 frames in High/RAW) the camera slows down to 2.0 fps in JPEG mode and 1.4 fps in RAW. While this is not quite as fast or the same buffer performance as either the Canon 50D or Nikon D300, it is a big improvement on the 2.9 fps of K20D.

USB transfer speed

To test the Pentax K-7 USB speed we transferred approximately 350 MB of images (mixed RAW and JPEG) from a SanDisk Extreme III (30MB/s edition) SD card. When the K7 is connected to a computer via a USB cable, by default the camera appears on the system as a 'mass storage device' (but you can change this to PTP in the menu). At 11.9 MB/sec the transfer speed in Mass Storage mode cable has improved and is now comparable to using an external USB 2.0 card reader.

Method
Transfer rate
Pentax K7 USB 2.0 - Mass Storage 11.9 MB/sec
Pentax K7 USB 2.0 - PTP 6.9 MB/sec
Sandisk Extreme III (using built in USB connector) 20.2 MB/sec
SanDisk Extreme III in USB 2.0 reader 11.3 MB/sec

Autofocus speed / accuracy

While Pentax managed to quite significantly improve the continuous shooting speed the K-7 still lags very slightly behind the competition in terms of autofocus speed. This is especially true for fast-paced situations where you might want to make full use of the 5.2 fps but the AF can't always keep up. Occasionally the K-7 autofocus also has a tendency to hunt in low light, even with fast primes such as the FA 50 F1.4. Having said that, the AF is accurate when it locks on (in none of our several hundred real-life sample shots that we took while working on this review did we have any issues with focus accuracy) and performs more than sufficiently well in the vast majority of shooting situations. The built-in AF-assist light avoids having to use the rather irritating flash strobe that some other cameras have to work with.

Live view focusing uses the contrast detection AF method by default and can be painfully slow – taking around a second or so to lock focus in bright outdoor light and around 2-3 seconds to lock focus in a well lit room. To be fair, this isn't significantly behind any of the competition's models. If you need quicker focusing in live view you can also switch to 'conventional' phase detection AF (although this requires flipping the mirror before you can shoot the shot).

Battery life

The Pentax K7 is powered by the new D-LI90 battery which offers a higher capacity than the K20D's equivalent. CIPA testing shows that battery life has improved from the K20D's 530 shots to 740 shots on the K7. However, you are likely to get fewer images from a battery charge if you use live view a lot or shoot a lot of videos.

Temperature
No Flash
50% Flash use
At 23°C / 73 °F
740
610*
0°C / 32°F
680
560

*The 50% Flash use at 23°C figure is the most commonly quoted CIPA figure

Image Stabilizer

Pentax is one of the manufacturers that provide image stabilization in the camera body rather than making it a feature of lenses. There are convincing arguments for both approaches, let's see how the Pentax system fares in our test.

The stabilization test

Twenty hand-held shots were taken of a static scene, half of those with stabilization, half without, the shutter speed was decreased by a stop and repeated (from 1/125 sec to 1/2 sec). The lens used was the Pentax 50 mm F1.4 (producing a 75 mm equiv. FOV), the test chart was 2.0 m away from the camera. to exaggerate the effect of camera shake the camera was only supported with one hand.

The resulting 120 images were then inspected and given a blur score from zero to three where zero represented a very blurred image and three a sharp image with no noticeable blur (see crop examples below). Obviously the amount of blur which is acceptable will depend on your personal taste and the final image size (for instance a '2: Soft' will still look fine as a 4x6 print or in a web gallery). Example crops from these four blur scores can be seen below.

0: Very blurred 1: Blurred
2: Soft 3: Sharp

Hand-held, no stabilization (50 mm lens, 75 mm equiv.)

With no stabilization we could not get any sharp shots at all below 1/8th of a second and couldn't be guaranteed to get perfectly sharp shots below 1/60th.

Hand-held, with Shake Reduction (50 mm lens, 75 mm equiv.)

The K-7's IS system certainly works but is not as impressive as some other systems we've seen. It generates an advantage of somewhere between one and two stops. However, it significantly increases your chances of getting a usable shot at the very slowest shutter speeds and therefore certainly provides a real benefit in many shooting situations.

Horizon correction

Apart from the usual ant-shake system the K-7 also offers something called horizon correction. This system detects a tilt of the camera and corrects for it by moving the sensor. We tilted the camera by approximately 1.7 degree to take the image on the left. This was almost but not entirely corrected by the system.

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