Lately, I had a lot of mileage with SD cards at work.
1) The speed the manufacturers print is not always the speed of the card!
2) Depending on how you format your card, you may also degrade its speed.
3) The faster cards may be overkill for the work you do with them.

I used a free tool used to benchmark SD cards called iozone (http://www.iozone.org/)
that is well known for "testing performance of hard disks".The SD cards were checked in different platforms. (Embedded Linux, PC with Ubuntu Linux, PC with Windows7).

Usually the write speed is limited by the capabilities of the device, in our case, the D7000. Using cards faster than the camera will not give you any advantage, therefore you can save money by getting slower cards. (The only advantage is that you will be able to download the photos faster using a faster card reader).

The speed of the card depends a lot on how you "Format" the card,

Formatting the card with the camera(D7000 in my case), and also under Linux(Using the default parameters for FAT32) caused some degradation on the card speed. The reason is that data access is not aligned with the hardware requirements on the card.

Formatting the card under Windows7 produce good results, similar to the ones using a card that was formatted by the SD Card manufacturer (the approved ones).

If the card comes already formatted, it will produce the best results for you, you may not need to re-format it, due to the fact that the manufacturers will format the card in such way that will produce the best results for the card.

My purpose was to share my findings, although I can not publish here the real results due to some "Legal reasons".

I have a lexar pro sdhc x133 class 10 perfect no problems got on ebay for $90 brand new and it comes with recovery software i had problems with my phones micro it got erased software restored it

Hence the buy the cheaper cards considering you're automatically getting a backup..

rbid said:
Nice feature, specially if you don't want to miss the event you are photograpying...

Good idea, the problem is $$$ for the spare SD cards.

still cheaper than film

jonnyapple said:
You have one card in each of the SD card slots and then change the camera settings to write all pictures to both cards. If there were problem with the main card on importing the files, the other card has the same files on it.

Nice feature, specially if you don't want to miss the event you are photograpying...

jonnyapple said:

Someone here (username soap) had the idea of mailing yourself SD card backups of your photos while on trips in case your camera bag is lost/stolen. Dual slots make doing that very simple.

Good idea, the problem is $$$ for the spare SD cards.

You have one card in each of the SD card slots and then change the camera settings to write all pictures to both cards. If there were problem with the main card on importing the files, the other card has the same files on it.

Someone here (username soap) had the idea of mailing yourself SD card backups of your photos while on trips in case your camera bag is lost/stolen. Dual slots make doing that very simple.

Paperman said:
There is no card that can stand upto 6 fps RAW ( 100Mb/sec ) or full size JPEG ( 30-40 Mb/sec ) so I don't really see the point in spending fortunes on extra extreme/supreme cards . ( I am shocked to see SD cards arond 200-400 ). If you are not taking videos , the 4 Mb write speed difference between cards makes no difference ( see first sentence ) . Class 6 cards are enough for 720p video on D90 & D5000 - I don't know about HD.

For some pros , getting 20 shots in a row instead of 18 might make a difference and it may be OK to pay $300 for that but for those who can hardly afford a $1000 DSLR ,it is a waste . And if you miss a shot ( or if the card fails ) , believe me the images you lost won't be worth $300 . They go for 25 cents in ShutterStock :-)

The maximum I ever paid for a 8 Gb card is $49 (Just plain Lexar 80 x, 200x or Panasonic Class 6 ... None of them failed and I don't remember a time any card slowed me down. )

You can easily buy a lens or two with that money ...

I agree with you, and many, many thanks. You helped me a lot in this issue related to the D7000 and SD cards.

jonnyapple said:
My point is that unless you need faster than 10 MB/s (and I'm claiming you don't for video), why not buy two less expensive cards instead of one of the more expensive ones? They are less than half the price of some of the top ones and with the D7000's ability to back up using its dual slots there's almost no worry because the chances of both cards going bad simultaneously is vanishingly small.

Question: How the camera deals with this situation? Does the camera switch automatically to the second card when an error occurs or you need to switch manually?
(I guess that the camera does not switch to the second slot, it just tells you that there is a failure and you are urged to do the switch... Is this true?

Welcome to the forum, autopot (automotpot?). Your link makes the point that I was trying to make. Salamander was implying that you needed a fast card for video, but even the D7000's 1080p24 doesn't need more than 24Mbps, which works out to 3 MB/sec. The slowest card he tested was faster than that.

My point is that unless you need faster than 10 MB/s (and I'm claiming you don't for video), why not buy two less expensive cards instead of one of the more expensive ones? They are less than half the price of some of the top ones and with the D7000's ability to back up using its dual slots there's almost no worry because the chances of both cards going bad simultaneously is vanishingly small.

Talking about memory cards like this is like talking about car parts on a car forum and people saying they felt a difference with one verses another... some people are more in tune with what is actually going on than others, so an average seat of the pants feel is virtually meaningless. I had done some research and came across the following actual tests of cards in the D7000:

Sportsphotoguy

Obviously, from the tests, Sandisk comes out on top, but I'm struggling with the question of how much speed one really needs. I'm probably in the same boat as a lot of you with having just pushed the budget to buy the D7000 and thinking about memory as an afterthought. My solution was to borrow a cheap class 4 card from my brother, and I will probably wait to buy the latest Sandisk UHS-1 card when I can more easily afford it or definitely before I might actually need it (like for shooting a big car show coming up in April).

Welcome to the forum, Sgt S. Do you really notice a difference shooting video on a D90 between class 6 and class 10? I don't see a difference on the D7000 video, but I know it's a more efficient codec.

I know this thread is a little old, but I wanted to add my 2 cents. I have been shooting Panasonic Class 10 cards for almost 2 years and have racked up many thousands of images. Recently I took my d90 to the Grt. Smoky Mountains in Tennessee and shot about 1400 pictures on my Panasonic cards. I have not had any problems with them. Like someone else said, you get what you pay for. Lexar and Panasonic seem to be high quality brands. Transcend, Patriot etc. are much cheaper and from my experience have a much higher failure rate. DON'T buy a cheaper card. Also, people keep saying that there is almost no difference in speed between Class X and Class X cards. I have shot Class 6, followed immediately by Class 10, and there is a significant difference in speed when shooting 4.5 fps. It really only matters when you're shooting continuously or if you're shooting video. Otherwise, the speed of the card will likely not hamper you much.

Welcome to the forum to both of you Daniel and Jay!

Daniel,

I've seen a video comparing writing and reading speeds from both transcend cards class 6 and class 10 (class 10 was the 16gb, class 6 was a 4gb tho)

And while the class 10 shows faster read speeds, the write speed was faster for the class 6 card.

I can't wait to see results for these cards.. pretty sure they will do fine for video... might not be the best for 6 frames per sec shoots but still..

Daniel. Yes, those are both flash memory.

I'm ordering 2 of them from B&H to try out for my D7000 that should arrive this week (hopefully)

http://www.bhphotovideo.com/c/product/700169-REG/Transcend_TS16GSDHC10_16GB_SDHC_Card.html

Am I missing something? Here are two Transcend 16 gig SDHC cards for $25 each (see links). The class 6 card is listed as "flash memory", the class 10 card is not. But all these cards are flash memory, aren't they? Why would one consider the class 6? Thanks!

http://www.amazon.com/Transcend-Class-Flash-Memory-TS16GSDHC6E/dp/B001ECQVTM/ref=pd_cp_e_2 (class 6, listed as flash)

http://www.amazon.com/Transcend-16GB-Class-SDHC-TS16GSDHC10/dp/B002WE4HE2/ref=pd_cp_e_1
(class 10, not listed as flash)

I'm from Canada and considering the transcend 16gb sdhc class 6 or class 10 (not a matter of that 2$ difference between both, it's just that apparently the class 6 has better write speed)

Anyone knows how well they perform in the D7k?

Drab said:
D7000 video is peaking around 25Mbps.
A class 4 card is more than fast enough for video when unfragmented, class 6 gives you plenty of margin.

If a class 10 card is slower than a class 6 it is falsely labeled. Period. No reputable class 6 card is faster than a reputable class 10. I have yet to see a disreputable brand mentioned in this thread.

And, Paperman, you've dropped plenty of good facts on here, except for the fact you have consistently used b instead of B. A factor of 8 is important!

No, You could have a class 10 the does the minimum, and then you could have a class 6 that does beyond what it is suppose to and can beat a class 10. Most good name brand class 6 cards can beat the min specs for a class 10.

That Lexar card at costco should be many times faster than you need for 1080p video. Like drab said, the video stream is about 25Mbps (~3MB/s), and the card is rated at 15 MB/s (probably the max read speed, but still...).

I can't buy Sandisk cheaply before my D7000 arrives. Lexar Platinum II 16GB, Class 6 is $50 at Costco so was planning to buy that. From the Manual it is supposedly approved card for D7000 and Class 6 is all that is required for video. Any D7000 owner have contradictory experience for 1080p24?

ithurtswhenipee said:
If you are going to shoot video - definitely go with class 10.

D7000 video is peaking around 25Mbps.
A class 4 card is more than fast enough for video when unfragmented, class 6 gives you plenty of margin.

Seshan said:
It depends, some class 6 can be faster then Class 10, it just depends on the quality of the card.

If a class 10 card is slower than a class 6 it is falsely labeled. Period. No reputable class 6 card is faster than a reputable class 10. I have yet to see a disreputable brand mentioned in this thread.

And, Paperman, you've dropped plenty of good facts on here, except for the fact you have consistently used b instead of B. A factor of 8 is important!

If you are going to shoot video - definitely go with class 10. If not and you don't need sustained 6 fps - class 6 will do you just fine. In fact if all your are going to shoot is portraits/landscapes or other things that stay still - write speed is irrelevant.

As far as brands and reliability. I have only used Sandisk and have had no problems. Experience is your best measuring tool for this. Is Sandisk worth the price? Well compare spending more on your memory and having higher reliability vs. saving a few bucks in the beginning and loosing all your clients images. I guess if you are not shooting professionally this just a matter of your own opinion.

butkusrules1985 said:
Well Wouldn't a $30 class 10 panasonic be faster than a $33 dollar Class 6 SanDisk? I could have 3 class 10 panasonics for the price if 2 San disk cards of the same type.

It depends, some class 6 can be faster then Class 10, it just depends on the quality of the card.

Well Wouldn't a $30 class 10 panasonic be faster than a $33 dollar Class 6 SanDisk? I could have 3 class 10 panasonics for the price if 2 San disk cards of the same type.

Amazon has the class 6 8gb for $33 shipped. Class 10 are $48.

adamz said:
You don't have to pay $300-$400 to get decent speed. Get sandis extreme 8gb for app $40 and be happy with it. Maybe on d7000 You will not see a difference, but on d90 it was pretty visible. I could shoot continous jpg's on my sandisk, although couldn't say the same about kingston card I own.

Where do you get it for $40, The cheapest I see is $75 and over.

You don't have to pay $300-$400 to get decent speed. Get sandis extreme 8gb for app $40 and be happy with it. Maybe on d7000 You will not see a difference, but on d90 it was pretty visible. I could shoot continous jpg's on my sandisk, although couldn't say the same about kingston card I own.