How many cards?

[Jack56]

At the moment I've got a 60d and an mark5dIII.
I've got two Lexar professional 16GB 400x speed SD cards and with the mark5dIII (bought today) I bought a sandisk 16GB 400x speed. At home I thought, why did I buy a card with the mark 5dIII?
Will two cards be enough?

[Random Orbits]

I'd keep the compact flash.  The camera writes to it much faster and it's also much faster when transferring the files from the card to the computer.  SD cards are slower in practice.  For more critical shots, I'll set the 5DIII to write RAWs to both cards.  Otherwise, I'm leaving the SD card in there but I'm only using the CF.

[Jack56]

Is the compact flash card for shooting in raw only or for jpeg also?

[Random Orbits]

You can choose.  It is up to you.

[Drizzt321]

Depends exactly on how much you shoot and if you are going to shoot so much at one time you'll fill up the card and need another.

For me, I find a 32GB CF to be more than enough for an average random day out and about with my 5d3, but if I know I'm shooting an event or something I'll always have a 2nd just in case. For some events, I make sure I have my 3rd & 4th with me. Sometimes I shoot so many photos it scares me. Usually at concerts/events/performances. Stuff where I always shoot in 2-3 (or more) frame bursts because things can change so much moment to moment.

[JPAZ]

The 5diii files, (especially RAW) are a bit bigger than on the 60d.  Relatively speaking, memory is cheap.  If you think you'll take more than 400 shots before being able to backup or download the files to a computer, I'd get another CF card.  I know I like not to delete anything off my cards when I travel, even if I back them up (that's the belt and suspenders in me) so I always have at least 2 copies of every shot until I get home.

[neuroanatomist]

I always have (at least) one more card than the camera has slots.  That way, you keep the files on the card as a backup, until your HDD is also backed up (in at least two places, preferably).  Now that I have a 1D X, I write RAW to both cards, and I've got two or more copies of each image from the moment of capture.

[ejenner]

I always have (at least) one more card than the camera has slots.  That way, you keep the files on the card as a backup, until your HDD is also backed up (in at least two places, preferably).  Now that I have a 1D X, I write RAW to both cards, and I've got two or more copies of each image from the moment of capture.

x2.  Although I slightly break this rule with the 7D since it's not my primary camera.  I shouldn't though.  Anything serious better be backed up on two HDD before I delete it from the card.  It I'm traveling then I keep a copy on the card and one on the PC, or copy to other external drives before re-using the card.

More than two cards per camera per slot can get confusing, so I like two and get them as large as need be for a days shooting.

[Eldar]

I always have (at least) one more card than the camera has slots.  That way, you keep the files on the card as a backup, until your HDD is also backed up (in at least two places, preferably).  Now that I have a 1D X, I write RAW to both cards, and I've got two or more copies of each image from the moment of capture.

+1
I have two 2x2 64GB 1000x CF card sets for the 1DX and 2x (1 64GB 1000x CF + 1 128GB SD) for the 5DIII. Only once have I filled the 64GB cards before downloading though, but better safe than sorry. I have seen some very good deals on memory cards lately.

[wickidwombat]

I have a dozen or so 32gb cf cards and maybe 8 32gb 45mb/s SD cards
If I only had 2 or 3 cards I'd have a nervous breakdown

[cid]

I always carry 4 or more SDHC cards (Sandisk Extreme), since SDHC are small and light there is no issue having some spare cards with me all the time.

For some time I even carried one backup card in my wallet all the time, even in situations I hadn't my camera with me.

[eli452]

Event (and I'm assuming you are not a pro, just shooting in an event) takes a lot but for you recording of the event 32GB is enough. Also for a casual day trip. As a tourist on a long vacation/trip away from download options - The rule I know from film days is 1 roll every 1.5 days to 1.5 rolls per day (top about 50 per day, every day including flight days) in digital we tend to shot more.

[JohnUSA]

Depends what kind of shooting you do.

Having a dual slot is beneficial for redundant backup of files. Also for myself as a second wedding shooter the main photographer will give me one of his/her cards that will be returned at the end of the day. This way there's no need to download the images at the end of the night or give one of my cards to mailed back in a week or two.

Anyway I have two 64 GB cards that stay in my 5D3. Was considering the 32 GB cards but some weddings go past 32 GB and I don't want to change cards during a wedding.

In a nutshell... you can't have enough cards.

[neuroanatomist]

The rule I know from film days is 1 roll every 1.5 days to 1.5 rolls per day (top about 50 per day, every day including flight days) in digital we tend to shot more.

At $2.50 per 36-exp roll plus $7 developing with 4x6" prints, the number of shots I took on a recent 3-day family vacation would have paid for a new Rebel with kit lens. 

[scottkinfw]

I always have a few.

Look for some deals that are around not (twofers).  In the off chance that one may fail, or get filled up, or dropped, etc.  I write to the CF and keep the SD in as overflow.  Some of the SanDisks at a great deal now, like $85 USD if you look on Amazon, etc.  You won't regret having them.

Scott

At the moment I've got a 60d and an mark5dIII.
I've got two Lexar professional 16GB 400x speed SD cards and with the mark5dIII (bought today) I bought a sandisk 16GB 400x speed. At home I thought, why did I buy a card with the mark 5dIII?
Will two cards be enough?