If you’re shopping for memory lately, you’ll see a dizzying and probably confusing array of performance indicators on the label or in the name of the product.  I guess one way to know which is faster is to just buy the more expensive ones within the same brand, but that isn’t the best way to shop or get the performance you want.

One increasingly common way of denoting card speed is “X” (e.g. 133X, 400X, etc.) – which is a carry-over of the way we used to measure the speed of optical drives.  Ultimately, it isn’t a guaranteed way to measure speed, and even “speed” is a reference to two different things that usually have different performance.  So what do you you want to look at?  Read Speed and Write Speed.  What are the benefits of each one?

Write Speed:  There are a couple of related advantages to a card with a fast write speed.  If you’re shooting at high speed (maximum frames per second), you’ll be able to take more shots before you have to stop due to the camera’s buffer hitting its memory limit.  This is because the camera is able to write the shots from the buffer to the card more quickly.  When you do hit the wall, you’ll wait less time for the buffer to clear so you can shoot more photos.  You’ll notice the little light that means your camera is writing images to the card goes out more quickly.  At the end of the day, if you don’t shoot a lot of continuous shots, you won’t see the benefit of fast write speeds.

Read Speed:  Do you get tired of waiting for your photos to download from your card to your PC?  I definitely do.  I have three spawn and a wife who I constantly compete with for time on the family PC (the one with the big screen).  The longer I wait for my shots to import the more people I’ve had to defend against for the rights to my chair.  The benefit of read speed is easy.  Faster is always better – it helps eliminate the “watched pot” syndrome.  You’ll get the benefit every time you transfer photographs off your card.  A caution:  I’ve heard that 1000X cards (currently the fastest available speed, only available on CompactFlash) require a USB 3.0 port and a USB 3.0-based card reader as well.  It is unclear to me whether that is a true compatibility issue or just getting the full performance of the card.  I’ll try to get some clarification.  I haven’t heard similar issues with speeds under 1000X.  When looking at cards, the premium brands tended to have better performance here.  For example, the 16GB Lexar Professional 1000X CompactFlash card is rated for 95MB/sec. write and 150MB/sec. read where Delkin 1000X cards (the only other 1000X cards currently available at B&H) are rated for 150 MB/sec. read but only 50-80MB/sec. write depending on which capacity you choose.

Even those numbers don’t tell the whole story.  Rob Galbraith has a great collection of speed testing on a huge variety of cards.  See the results here.  What you’ll find is the premium cards like Lexar Professional and SANDisk Extreme are the fastest in their class (pretty much in that order) and then you see the less-expensive guys.  Net: when it comes to speed, you get what you pay for.  Or maybe it is you pay for what you get.  Whatever. 

On the subject of compatibility, you might have questions about whether your camera is compatible with the latest cards.  We’re kind of left on our own here: camera manufacturers don’t spend too much time testing new cards on old cameras, and the information isn’t always complete or easy to find from the guys who make the cards.  So what do you do?

The good news is that for the most part, the cameras use nearly any card that fits the slot.  You might not get the highest in-camera performance possible from the card, but it will probably work.  That said, if you have an older camera – let’s say more than 5 years old – I wouldn’t bother investing money in the latest card technology or the biggest card.  My D300s, the flower of 2009 technology, works fine with the 1000X UDMA 7 CompactFlash cards from Lexar.

Is it worth it?  It really depends.  I don’t typically fill my buffer – I can shoot several seconds of RAW shots at 7 frames per second before filling up my buffer, and in JPEG mode I’ve got even more than that.  I don’t know if I’m getting any benefit while shooting from UDMA 7 (I doubt it).  But I noticed a huge bump in speed pulling my shots off the card when I moved from my 133X SD cards to my current 400X.  I’m waiting for my 1000X CompactFlash cards, and I’m expecting even faster transfers.  That is worth it to me.  If the price is too high for your budget, the good news is there are usually several tiers of performance available with lower prices to match.  Pay attention to the write and read speeds specifications, and buy the best you can afford.  For the same money, I’d buy smaller cards of better quality/speed than bigger cards from the cheapo guys.

As far as brands, I’m personally a fan of Lexar, and all my current cards are from their Lexar Professional series.  I like them because they make their own chips and have direct control of virtualy all aspects of their components and manufacturing.  Even SANDisk can’t say that.  Lexar’s warranty and support are excellent.  I wouldn’t shy away from SANDisk (who also makes some of the fastest cards along with Lexar, in their SANDisk Extreme line).  Kingston and Transcend both seem to have loyal followers.  I buy Lexar cards because I think memory is a poor place to get cheap.  If your card is bad, your photos are likely gone forever (though Lexar does have some software that can sometimes help if you have a corruption issue, formatted the card, etc.).  From my work in the technology industry, I know a little about the world of component sourcing, and the cheap guys are cheap for a reason – they are often buying chips that don’t meet the quality and/or performance specifications of the big guys, among other things.  The price differences between the premium brands isn’t much, and I think it is worth it not to worry about it.

I’d love to hear your comments – what brands do you use?  Any horror stories?  Got a good experience?  Do you prefer several smaller cards or one big one?