In order not to miss the "once in a lifetime" sea lions Hunting scene in the Serengeti or the decisive moment during the children's birthday party, because the camera is still blocked by the storing images, are for me the write speed and reliability the key criteria of an SD card. Below I would therefore like to put my relevant test results available to anyone interested.
A.) Write speeds:
With my Nikon D800 I have made a comparison of writing speeds my SD card. Here I have 16 pictures (the size of the internal memory of the D800 is) taken in RAW format and the time until all the pictures (= 1,183 GB) were written on the SD card (exact test setup see below).
1st place: SanDisk Extreme Pro SDHC, 95MB / s (32GB): ....... 25 s = 46 MB / s
2nd place: SanDisk Extreme Pro SDHC, 95BB / s (64GB): ....... 26 s = 45 MB / s
3rd place: Transcend Ultimate SDXC 600x, 90MB / s (64GB): ... 31 s = 38 MB / s
4th Place: SanDisk Extreme SDHC 30MB / s (32GB): ............. 44 s = 27 MB / s
5th Place: Transcend Premium 300x SDXC, 45MB / s (64GB) ... 51 s = 23 MB / s
(Note: All figures have been rounded)
To 300x Transcend Premium according to the manufacturer a write speed of 35MB / s (read: 45MB / s) own. But in my testing it reaches a meager 23 MB / s, making it just half as fast as the SanDisk Extreme Pro. Due to the acceptable price / performance ratio (see below) I'll keep the card, but used only for Still-shots.
The same applies to the SanDisk Extreme 30MB / s: not recommended when it comes to speed.
Transcend Ultimate 600x reaches almost exactly the declared by the manufacturer write performance: 40MB / s (manufacturer) over 38MB / s (measured) and represents the "golden mean" in my comparative test: it is fast enough for almost all situations, this cheap and to now very reliable. Currently (October 2014) it will be offered for almost 40 euros and was therefore my best quality / price deal (see example)
The SanDisk Extreme Pro 95MB / s are my "cream-pieces": very fast and totally reliable. So far I have not found a faster SD card. Even faster write speeds are only with CF card possible (for example SanDisk Extreme Pro CompactFlash 160MB / s).
For all Nikon D800 owners here quickly the camera settings and test conditions:. Image size / quality: RAW, 14-bit, uncompressed. Focus = manually and attached lens cap. Exposure: "M" at 1 / 1000s, open aperture (2.8), ISO = 100th Lens: VR = OFF. By pressing the shutter timer is started. Can trigger depressed, to 16-frame buffer of the D800 is full, then let go and stop stopwatch timer when the memory light on the camera goes off.
B.) Price / performance:
(!) If the write speed of the tested cards in relation to my purchase price to be set, the following picture results:
1st place: Transcend Ultimate 600x, 90MB / s (64GB): .... 1.0 (MB / s) /; 08/2014 buy
2nd place: SanDisk Extreme Pro 95MB / s (32GB): ......... 0.7 (MB / s) /; 07/2012 buy
2nd place: Transcend Premium 300x, 45MB / s (64GB): ... 0.7 (MB / s) /; 10/2014 buy
4th Place: SanDisk Extreme Pro 95MB / s (64GB): ......... 0.4 (MB / s) /; 06/2013 buy
(Note: I have put here my purchase price basis Since I've listed the Part 2-year-old maps here is a completely different picture may arise when one considers for the calculation approach for updates.)
For me make the SanDisk Extreme Pro SD cards the "non plus ultra" of reliability. They had me in the last 2 years on several multi-week or -monatigen Africa Stays under very adverse conditions (dusty, damp, vibration in many off-road trails and rides) accompany and have never let me down.
Transcend Ultimate I have not long enough to make the use of, a serious statement about their reliability. Just this: on my recent trip to Africa has, during hours of nocturnal photo sessions several thousand Milky Way photos stored in the open air in humid dusty environment, very "well-behaved".
Although the SanDisk Extreme Pro cards are faster, I forgive for Transcend Ultimate full 5 stars because it is still quite fast, while the manufacturer's instructions for the writing speed almost exactly achieved, has been shown to date to be very reliable and currently a super Price / performance ratio! By the way, due to their own qualities now already two of these Transcend Ultimate cards and can therefore recommend with a clear conscience.
I hope this information will help in making decisions when buying SD cards.