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Timings & File Sizes

The K20D is not the fastest camera in the semi-pro class but it's also not too far off the performance of its peers. The off-to-shot time is perfectly respectable and is likely to be a problem only in the very unlikely circumstances that a press photographer decides to use one. The time taken to display the shot just taken are certainly below average and extend still longer if ISO is increased above 1600, at which point you can expect to wait for another second if you apply noise reduction. However, because the K20D is happy to let you continue shooting during this time, it's not something that really gets in your way.

The K20D offers four levels of JPEG compression: Good, Better, Best and (new to the K20D), Premium. The Premium setting offers a minimal 1/2.8 compression ratio. This is higher than quality '12' in Photoshop terms and results in monstrous files that can push on for 12MB. This offers a super-low compression option for those people who don't want to shoot RAW but still need image quality that is even better than 'best.' We've tested the camera using the default 'best' setting because the use of of the top setting is likely to come at a premium and we see little reason for most people to use it.

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 4672 x 3104 JPEG Best (approx. 6,500 KB per image).

The media used for these tests were:

  • 4 GB SanDisk Extreme Ducati Edition SDHC card
  • 4 GB Lexar Professional 133x SDHC card
Action
Details
Time, secs
(4 GB SanDisk)
Time, secs
(2 GB Lexar)
Power Off to On *1   0.7 0.7
Power Off to Shot   0.5 0.5
Sleep to On *1   <0.1 <0.1
Power On to Off   <0.1 <0.1
Record Review *2
RAW
1.3 1.3
Record Review *2
JPEG
1.7 1.7
Play
RAW
0.4 0.4
Play
JPEG
0.4 0.4
Play Image to Image
RAW
<0.2 <0.2
Play Image to Image
JPEG
<0.2 <0.2

*1 Time from the power switch being turned to the On position to status information shown on the LCD monitor (this happens to be the same amount of time as Off to Shot taken).
*2 Time taken from the shutter release being pressed to the review image being displayed on the LCD monitor.

Continuous Drive mode

To test continuous mode the camera had the following settings: Manual Focus, Manual Exposure (1/500 sec, F3.5), ISO 200. Measurements were taken from audio recordings of the tests. Media used were the same as above.

The K20D provides three different continuous shooting options; High (3 fps), Lo (2.3 fps) and the unique Burst (21 fps, 1536 x 1024 JPEGs approx 116 frames). The K20D has corrected its predecessor's erratic continuous shooting rate, though shares the specified 3 frames per second. This rate is almost certainly dictated by the speed of the mirror return mechanism, rather than a lack of, or slowness of buffer memory.

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

  • Frame rate - On average 2.9 fps (Hi mode)
  • Number of frames - Number of frames in a burst
  • Buffer full rate - Frame rate if shutter release held after burst (buffer full)
  • Next burst - How soon after the burst it is fully written to the card (indicator goes out)

Burst of JPEG Large Fine images (Hi mode)

Timing
4 GB SanDisk
Extreme Ducati SDHC
4 GB Lexar
Pro 133x SDHC
Frame rate (average) 2.9 fps 2.9 fps
Number of frames 38 *1 47 *1
Buffer full rate - -
Next burst - -

Burst of RAW images (Hi mode)

Timing
4 GB SanDisk
Extreme Ducati SDHC
4 GB Lexar
Pro 133x SDHC
Frame rate (average) 2.9 fps 2.9 fps
Number of frames 16 14
Buffer full rate 0.8 fps *2 0.9 fps *2
Next burst 15.8 sec 14.3 sec

*1 Continues to shoot approximately as quickly but with occasional very short pauses.
*2 Average, again shooting once the buffer is full becomes somewhat erratic.

Burst mode

In our quick test the ultra-fast burst mode, which uses an electronic shutter instead of the mechanical shutter and shoots at 1.5 megapixels shot 117 frames in 5.8 seconds (approx 20 fps).

A combination of the continuous shooting rate and the speed of autofocus means the K20D isn't likely to appeal to sports photographers. On the whole it behaves predictably, if not spectacularly.

File Flush Timing

Timings shown below are the time taken for the camera to process and "flush" the image out to the storage card. Timing was taken from the instant the shutter release was pressed to the time the storage card activity LED lamp stopped flashing. Media used were the same as above.

Image type
Time, secs *1
(4 GB SanDisk)
Time, secs *1
(4 GB Lexar)
Approx.
size
4672 x 3104 RAW + JPEG Best 3.7 3.6 21,100 KB *2
4672 x 3104 RAW 2.8 2.8 14,800 KB
4672 x 3104 JPEG Best 1.9 1.9 6,400 KB
4672 x 3104 JPEG Better 1.8 1.8 3,700 KB

*1 The 'processing delay' varies depending on the file format, the first number is the total time from pressing the shutter release to the write process completing, the second number (in brackets) is the actual write time.
*2 File size reported here is the size of the RAW and JPEG files added together.

The K20D's write times suggest a writing rate of around 6MB/sec for RAW files using fast cards such as those used here. The slightly longer than average write delay of between 1.9 seconds doesn't ever get in the way of shooting JPEGs in a normal shooting environment thanks to the K20D's good buffering, all image processing and card write occurring in the background.

USB transfer speed

To test the K20D's USB transfer speed we transferred approximately 622 MB of images from a SanDisk Extreme Ducati Edition 4 GB SDHC card. Mass storage device mode produced very good results, almost nine megabytes per second is 'good' USB 2.0 reader territory (the SanDisk Extreme IV reader here is exceptional).

Method
Transfer rate
Pentax K20D (Pictbridge mode) 2.9 MB/sec
Pentax K10D (PC mode) 7.3 MB/sec
SanDisk Extreme USB 2.0 card reader 12.0 MB/sec
SanDisk Extreme Ducati card integral USB connector 13.0 MB/sec

Pictbridge really isn't the way to get images off your camera. Using a card reader is considerably faster than the camera's PC mode and doesn't drain the camera's battery, so makes more sense than trying to connect the K20D via USB.

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