Pentax 645D, Photography, Uncategorized
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64GB SDXC Card Comparison with Pentax 645D – a rudimentary test.

Do different 64GB SDXC cards perform differently when used in my Pentax 645D camera?

Why is this question important? SD cards of the same memory capacity vary in price. Some claim “faster shot-to-shot performance” but does it make any difference with my particular camera.

The cards:

Transcend SDXC Card 64GB

Transcend SDXC Card 64GB

Transcend 64GB SDXC Card Price 4,769 Yen (Amazon Japan) or $46.99 (

SanDisk Extreme 64GB SDXC Card

SanDisk Extreme 64GB SDXC Card

SanDisk Extreme 64GB SDXC Card Price 6390 Yen (Amazon Japan) or $73.69 (

SanDisk Extreme Pro 64GB SDXC Card

SanDisk Extreme Pro 64GB SDXC Card

SanDisk Extreme Pro 64GB SDXC Card   12,819 (Amazon Japan)  or 128.95 (

Whether purchased in Japan or in the U.S. there is a clear difference in pricing between the three cards. Prices shown are the best available prices on the Amazon websites as of writing. (Please feel free to click on the links, and I’ll make a few cents from any purchases you make. This is a bonus, but not the purpose of the post.)

Pentax 645D with dual SD card slots

Pentax 645D with dual SD card slots

The camera:

I’m using my Pentax 645D camera. It has twin SD card slots. I have them set up so that the camera writes the RAW DNG file to both cards simultaneously. If there is a problem with one of the cards I have a backup. Also after filling the pair of cards with images I can then store the two cards separately. This reduces the possibility of all data being lost due to theft or another calamity. The Pentax 645D is a 40 megapixel camera, each RAW file is around 70 MB. On a 64GB card I can fit 712 images.

In the camera’s settings, high ISO noise reduction and slow shutter speed noise reduction are turned off.

The test:

Shooting continually, approximately 1 frame a second. How many frames will the camera take before it won’t let me capture any more images.

After shooting 5 frames in succession how long does it take for the preview image of the last shot to appear on the viewing screen.


The results:

All three discs produced the about the same results.

They camera shot about 17 frames in a row and then wouldn’t take any more images

After shooting 5 shots it took about 13 seconds for the most recent shot to appear on the preview screen.


The conclusion:

For the 645D camera, shot to shot performance was not significantly affected by the choice of SD card.   I presume that limiting factor with regards to speed is the camera’s processor rather than the type of SD card.

Other types of camera may have better performance when using cards with fast write speeds, but in my case it would be better to choose one of the cheaper options.

Speed and price, however, are not the only variables when considering SD cards. Reliability is another issue. I have found more issues with corrupt files with the Transcend cards than with SanDisk cards. I have not done even a rudimentary test on this, but as a personal preference I would stick with the SanDisk brand.

Test winner: SanDisk Extreme 64GB SDXC



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