Mr PC Loc: Austin, TX

I currently have 2 64GB cards, with the second one backing up the first. One is a Sandisk rated at up to 60MB/sec, the second is a Sony, rated at 40 MB/sec. Am I correct in assuming that the best speed I can expect when continuous shooting is limited by the slowest card? I'm considering getting 2 newer Sandisk cards rated at 90 MB/sec, so they match. Which brings up a related question. Does anyone know if using a single card is faster than using 2 of the same speed? And yes, I've done the Search function, but don't find any threads that really address these 2 questions. Thanks in advance for any help.

jethro779 Loc: Tucson, AZ

According to the articles I have been reading the camera will write to the slowest card speed. Otherwise once the buffer filled it would never catch up. My D7100 will write to the slowest card speed if I use 2 different speed cards. Since you are writing to only one card I would guess it must be faster.

Mr PC Loc: Austin, TX

Currently I'm writing to both cards simultaneously, using the second card as a mirror image backup in case disaster strikes. I do mission work in Africa twice a year and get the opportunity to go on some great photo safaris. I like the insurance of a second card. I'm a computer guy and my intuition agrees with you, the slower card probably rules.

tusketwedge Loc: Nova Scotia Canada

I just bought 2 32 95 MB/sec cards for my D7100 and they work great.Just make sure that the write is high and not just the read speeds.They make 2 diff. right speeds.

Revet Loc: Fairview Park, Ohio

I would assume that is only true if you are using slot 2 to backup slot one?? I use slot 2 as overflow and it is a slower card than I have in slot 1. The d7100 in this case is always writing to card 1 I believe (its the only one with pictures on it). Since I never fill card one up, slot 2 is kind of storage for me if I need another card (ie. card one fails). If I was a Pro or shooting something really important, I would use the backup scenario.

jethro779 Loc: Tucson, AZ

As I always write raw to card one and .jpg to card two it writes to the speed of card two. Card two is not that much slower with .jpg's being written to it though.

hank6595 Loc: Amesbury, MA

I do the same as jethro.

tHANKs

AZNikon Loc: Mesa, AZ

Do you re-format both cards after downloading your files to your computer?

dscloo

If by "second one backing up the first" you mean the second card is storing an identical copy of the image as in the first card, then I'd agree with the other answers: the best write speed will be limited by the slowest card (as the camera will need to be sure the file is written to both cards before flushing the buffer). So I think to get the best speeds, it's better to have both cards with the same rating.

I usually write just the Raw file to Card 1, and use Card 2 as overflow. The last set of cards I have is Lexar 64GB (I can't remember the speed rating, I think it's 600x), and I rarely fill up Card 1, so Card 2 is usually empty. Having an overflow card did save me once: I took out Card 1 to copy images to my computer, but forgot to put it back in the camera before going out for my next shoot. The D7200 happily wrote to Card 2 without a hiccup.

I don't store the Jpeg files, as the Raw file embeds the Jpeg version, and there are readily available software that will extract the Jpeg from your Raw files.

Using both cards simultaneously (both cards storing identical copies of the Raw files, or one storing Raw and the other Jpeg) is a good backup, but I think it'll slow down the writing somewhat. I can't be sure, but I don't think the D7200 is writing to both cards in parallel, but one after the other; so you're basically doubling the write-time with every shot. I don't shoot much action, so this slight decrease in speed shouldn't be much of a problem. However, if I'm on a critical shoot, I'd probably set the D7200 to write identical copies to both cards; just in case one card suddenly fails.

After every shoot, I'd copy the images from Card 1 to my computer (and also to 2 other backup hard drives) and make sure all the images are readable (I usually just do an import of the images into my software and check that there are no file-errors). If all is good, I'd swap the cards (so what was formerly in Slot 2 is now in Slot 1, etc.), and format both in-camera. This way, both cards get used regularly.

Mr PC Loc: Austin, TX

Yes I do, in the camera.

hank6595 Loc: Amesbury, MA

I format both cards in the camera after the download.

tHANKs

PVR8 Loc: Raleigh, NC

It's the same for me with my D7000.

tomeveritt Loc: Fla. + Ga,NY,Va,Md,SC

Always, In Camera