Flashonomics: Buying Flash Memory

Quite possibly one of the more confusing counters at the camera store—or sections of a website as the case may be these days—is the area full of Compact Flash and SD memory cards. It’s easy enough to tell the cards apart by capacity, but what about speed? What the heck does 45x or 300x really mean? And are some brands really better than others? It’s all just memory anyway, isn’t it? Can’t one just get the biggest capacity card for the least price and call it a day?

Unfortunately, there isn’t an easy one-size-fits-all answer. Everybody’s needs are somewhat different. For some, things can get really tricky depending on the conditions we find ourselves working in. While I can’t give you a definitive simple answer, I can walk you through my own thought process when I buy memory cards for my camera. As it turns out, I’m currently right in the middle of buying a batch of cards right now, so can give you a timely set of thoughts on the matter.

First, however, if you shoot no more than a few dozen frames a day, I can give you this solid bit of advice and then you can skip outta here at the end of this paragraph. If you shoot in low volume, you don’t need to sweat the details so much. Go ahead and shop on price. Get a name brand 2GB or 4GB card that has an attractive price and you’ll be just fine. Happy shooting!

Still with me? Alright. Let’s dive in. To start with, there are five things that really matter, beyond the obvious difference of Compact Flash verses SD, when it comes down to selecting the flash memory card to buy:

• The reliability of the card
• The speed at which your camera can write to the card
• The speed at which your computer and card reader can pull data from the card
• The price of the card
• The card’s capacity

Let’s address the reliability issue first. Almost every serious photographer I know shoots with either Lexar or SanDisk cards. The reason is that serious amateurs hate to loose a shot, especially when they’re out in the landscape all day waiting for just the right light. A card going south on you can mean a wasted day. For a professional working for a client, a failed card with all the right shots suddenly means that they can find themselves in the contingency portion of their contract.

To complicate things, memory cards aren’t standalone devices. They have to work in concert with your camera and card reader. Sure, the interfaces that these devices all use to talk to each other are well understood, but that doesn’t mean that incompatibilities can’t creep in and ruin your day. For better or worse, this pushes a lot of photographers to stick with widely used and known brands. If it sounds like there’s a bit of FUD (fear, uncertainty, and doubt) going on here, well, there is. But, there’s probably also a bit of wisdom in the crowd. After all, if Joe McNally stands up and says that he’s been shooting with Alphazetratronics cards for years and they’ve been treating him great, then that’s a definite vote of confidence. And if a bunch of other respected photographers chimed in, then it’d be worth looking into Alaphazetratronics cards. The truth of the matter, however, is that according to Joe McNally’s equipment list page, he shoots with Lexar.

Over the last ten years or so, I’ve personally owned dozens of compact flash cards. Currently, I’ve got a wallet full of SanDisk cards. I used to have a mix of Lexar and SanDisk, but for one reason or another have pretty much standardized on SanDisk. They treat me well and haven’t caused any issues. The few times I’ve had a couple of cards look spooky, I later determined that the card readers were to blame. Believe me, those card readers were taken out of service mighty quickly.

Since I’ve had good luck with SanDisk and that’s what I primarily use, that’s what you’ll see most in the discussion below. That’s just my own experience showing and you shouldn’t take that as a sign that you shouldn’t use Lexar cards. Or that you shouldn’t look into something like Kingston or the like. Just, think twice or three times before taking advantage of those Alphazetatronics special deals.

Camera Write Speed

The second factor to consider is the speed at which your own particular camera can write to a particular card. This depends on the card, the camera, and the interaction between the two. Because of the vagaries of how cameras and cards interact, the numbers on the card don’t tell the whole story. Luckily, Rob Galbraith maintains a database of Compact Flash and SD card performance data that compares a wide range of cards and cameras together. Since my primary camera these days is the D700, I’m most interested in the page of Nikon D700 card write speed results. If you’ve got the latest 5D, you’ll want to check out the Canon 5D Mark II card write speed page.

For example, here are the first few rows of the D700 test results table:

Using these tables, you can get really good idea of what cards are the absolute best for your particular camera. For example, the fastest card tested (as of the writing of this post) in the Nikon D700 is the SanDisk Extreme Ducati 4GB card, with a RAW write speed of 29.9MB/s. In the Canon 5D Mark II, the same card turns in a write speed of 32.4MB/s. Looking at less expensive cards, the SanDisk Ultra II 4GB card turns in a speed of 9.5MB/s in the D700 and 10MB/s in the 5D Mark II.

The D700 and 5D Mark II are state of the art camera bodies and can take decent advantage of the latest cards. If you have an older camera, the story is different and you won’t see write speeds that are nearly as high. For example, the first generation Canon 5D writes to the Ultra II card at 6.6MB/s. That’s almost as good as it gets. The best result the 5D can turned in on Rob Galbraith’s tests is 7.7MB/s. When the 5D was my primary body, most of my cards were Ultra IIs. At the time, that’s all I needed and gave the best bang for the buck.

The moral here? If you’ve got a recent digital SLR, you can take advantage of the write speeds of the fastest cards available. The faster the card, the quicker your memory buffers will clear. If you’re shooting fast paced action this will matter to you, especially if you work with long sequences of continuous shots. If you are shooting out in the landscape, then it won’t matter as much. As well, if you’re shooting with a slightly older camera, such as the original 5D, anything faster than a SanDisk Extreme III or Lexar 133x card is wasted potential as far as camera write speed is concerned.

Camera write speed, however, is only one part of the equation. Once your image data has is safely written on your card, you have to get it back off.

Card Reader Speed

The next factor to consider is how fast you can move data from your card to your computer. This matters a whole lot to some folks, especially those of us that are likely to shoot a thousand or more images in a day during an event. When I shot TED2009 earlier this year, the photo editing staff were under such tight time pressures and dealing with so many images that they set a minimum bar on which cards they wanted to see come through. SanDisk Extreme IIIs or equivalent cards were the minimum bar. On the other hand, if you don’t mind hanging out an extra few minutes for your cards to ingest, then maybe this doesn’t matter so much.

To get hard data on this, Rob Galbraith provides information on card-to-computer transfer speed for various card readers. For example, I use a SanDisk Extreme FireWire 800 card reader. In a card reader like this, the latest cards really strut their capabilities. For example, according to Galbraith’s testing, data can be pulled off a SanDisk Extreme IV 45/MBs 16GB card at 43.4MB/s. The Lexar Professional 300x 16GB card turns in a result of 47.1MB/s. These are staggeringly fast results.

On the other hand, that SanDisk Ultra II 4GB card posts a top speed of 12MB/s in the same card reader. With a data transfer speed spread of 4x, it’s easy to see the appeal in faster cards for heavy workload situations. It’s also easy to see that the biggest win with buying a card like the Extreme IV or the top end Lexar 300x series is on the read side of the equation.

The last thing I should say on this point is that if you are using Lightroom or Aperture as your primary workflow tool to ingest data off your cards, the time it takes your images to get to your hard drive is likely overshadowed by the overhead of adding the image to your database and rendering previews. A 30% pickup in card reader speed might not have a huge impact on your overall ingest time. On the other hand, if you are using a more streamlined ingest workflow using Photo Mechanic, then that extra bit of speed will be more noticeable.

Armed with this data, it’s time to bring the budget into play.

Cost of Compact Flash Cards

If it were just a matter of selecting the fastest card for both camera write and computer read speed, we’d be done. SanDisk Extreme IVs or Lexar 300xs please! But, it’s not quite that easy. The price differential between slow and fast cards isn’t just a small one. In fact, the spread can be huge. The MSRP of a SanDisk Ultra II 4GB card is just under $40 while the MSRP of the latest blazingly fast SanDisk Extreme IV 4GB cards is just shy of $100. Same capacity, but you’re paying loads for performance. In other words, you have to really want or need the speed of the fast cards to justify them.

Furthermore, given acceptable performance considerations, you want to be able to get the maximum amount of space for your money. Is it better to get four 4GB cards, two 8GB cards, or one 16GB card? It’s at this point that I break out the spreadsheet and punch in some data. After all, we’re juggling three different factors here.

Before I go any further, however, let me stress very vigorously that these tables reflect pricing as of early April, 2009, the fact that I’m using a D700 and SanDisk cards. Prices change all of the time and the performance numbers with your camera equipment will vary. The primary purpose of these tables is to show you the things you can potentially think about, not to serve as a shopping guide. If it were a complete shopping guide, I’d include data from B&H and the like. Clear? Good. Let’s continue.

First off, here’s the current (as of early April) pricing of the SanDisk Ultra II card series:

To explain this table, the first column is the model number of the card. This is important when comparison shopping as you want to make sure you are comparing apples-to-apples. Card makers will introduce new cards under the same name quietly and you’ll sometimes find older older and slower cards out there. For example, there’s a significant difference in performance between older SanDisk Extreme III and IV cards and their newer variants.

The second column is the capacity in GB. The third column is the RAW write speed of the card in a D700 according to Rob Galbraith’s data. The fourth is the read speed of the card in my SanDisk Extreme FireWire 800 card reader. Then, we’ve got the price of the card from SanDisk along with a $/GB calculation. Finally, I’ve added the price of the card from Adorama. This gives us a better idea of real-world cost. In short, if you’re buying Ultra IIs and want the maximum amount of capacity per dollar, get the 16GB version.

Here’s the same analysis applied to the SanDisk Extreme III 30MB/s Edition cards:

I should note here that the Adorama price includes the the current SanDisk rebate on Extreme III and IV cards valid through June 27th, 2009. I’ve also included one extra set of columns here with this table showing the price for a 3 pack of cards which nets out the maximum savings with the rebates. When you look at final cost here, the winner on price per GB is the 3 pack of 8GB Extreme III cards. In fact, if you’re willing to buy in bulk and send in the rebate forms, the 3 packs of Extreme IIIs come in cheaper than their slower Ultra II counterparts.

Interestingly enough, however, in Rob Galbraith’s tests, the 8GB Extreme III cards run about 15% slower than their 4 and 16GB counterparts with the D700 with the 1.00 firmware. This is one of those areas where the interface between camera and card may come into play. If you dig into Rob Galbraith’s data on the Canon 5D Mark II, you’ll see that this pattern aren’t reflected there. In the 5D Mark II, the 4GB Extreme III turns in 22.5MB/s, the 8GB Extreme III hits 23MB/s, and the 16GB Extreme III runs at 23.2MB/s. Perhaps a future version of the D700 firmware will even things up. Or maybe not.

Finally, here are the results for the SanDisk Extreme IV 45MB/s Edition cards:

The most important thing to note with this data is that the price per GB of capacity goes way up on these top end cards. It’s a lot of money to pay over the Extreme III series to get an additional 15-20% pick up in write speed and around 33% faster read speed. The question you have to ask yourself is whether this last increase in speed is that valuable to you and will it be reflected in your workflow?

Now, should you build out spreadsheets like this to determine what kind of card you want to get? Only if you’re being super anal about things. Usually, when I do this kind of analysis, I just do some rough math on a calculator and scribble figures on a napkin. The main reason I’ve put it into spreadsheet form here is so that you can more easily see the variables at play. But, now that I’ve done it and found that it takes all of about 5 minutes to do, I might keep doing this in the future… Anyway, moving along.

Card Capacity

The last factor to consider is how much capacity you really need and how you want to divide that between cards. Of course, card capacity is directly related to the size of the files that your camera produces. If you are shooting JPG only, then you’ll need much less total capacity than if you are shooting RAW or even RAW+JPG. As well, the resolution of your camera has a big impact on capacity. I could shoot all day on a 1GB microdrive with the Canon EOS D30 I picked up at the turn of the millennium and its 3MB RAW files. These days, the 14-bit RAW files on my D700 weigh in close to 15MB each. The RAW files from a Canon 5D Mark II weigh in at 20MB each and the 14-bit RAW files from a D3x weigh in at 25MB.

For some, especially JPG shooters, a single 4GB card may be more than enough. Others might need 16GB of capacity or more to give them a comfortable buffer in their workflow between ingest cycles. And, if you are going off to Africa on safari and don’t want to assume that you’ll have the ability to download your photos, you might want a lot more total capacity.

If you are working on your own, then it might make sense for you to go for fewer larger cards. This means that you have fewer items in your camera bag or card wallet to keep track of. On the downside, if you loose a card—or one goes bad—then you have more of your eggs in one basket. There are some photographers that prefer to have more smaller capacity cards to avoid just this problem.

Likewise, if you are working with others—say you have the relative luxury of handing off cards during an event to be ingested and worked on by a photo editor—then you really want a set of smaller capacity cards. That way, when you change cards out after shooting only a two or three GB of data, you’re not paying the unused capacity of a 8 or 16GB card.

My Current Decision Point

I haven’t yet finalized my own current purchase decision based on this data, but I’m leaning strongly towards the SanDisk Extreme III 30MB/s Edition cards. The Extreme III price point is certainly more attractive than the Extreme IV right now, especially considering the real world performance differences. In another six months or a year, this evaluation will look quite different I’m sure. It used to be that the Ultra IIs were the sweet spot on the curve.

In general, I don’t see a real reason to pay a huge premium to pick up that last bit of speed to be somewhat more “future proof”. My approach to storage is generally to buy what’s needed now and let the future pricing trends take care of themselves. And boy do they take care of themselves. You don’t want to know how much I paid for my first 1GB Microdrive. The price per GB of camera storage has dropped by something like two orders of magnitude in the last eight years or so.

No, the only real debate I’m having with myself is whether it’s worth an almost 20% more money to buy the 16GB variants rather than the 4 or 8GB cards and whether the slower write speed that Rob Galbraith observed in the 8GB cards matters to me. Most likely, considering my current workflow needs, I’ll pick up a couple of 3 packs of the 4GB Extreme III 30MB/s Edition cards so that I’m set up nicely for fast turnaround event workflows. Amazingly, that will turn out to be 24GB of additional fast card space for less than $100 after the rebates come in. Wow. That’s almost a no-brainer after it’s all spelled out.

Rebate And Product Links

If you’re going to grab some SanDisk cards in the near future, say before June 27th, be sure to snag the SanDisk rebate form. This rebate form is valid for cards purchased from a wide variety of camera stores, including B&H and lots of local stores, including my Portland favorite, Pro Photo Supply. Notably, it isn’t valid for purchases from Amazon. Interesting that.

Also, if you’re going to buy some CF cards in the near future and this article was of use for you, please consider using one of the following links to Adorama to purchase some of the cards I’ve talked about above:

• SanDisk 4 GB Extreme III 30 MB/s Edition Compact Flash Memory Card
• SanDisk 8 GB Extreme III 30 MB/s Edition Compact Flash Memory Card
• SanDisk 16 GB Extreme III 30 MB/s Edition Compact Flash Memory Card

And, if you’re going to take advantage of the rebates, here’s some links to multipacks which really amp up the value proposition:

• SanDisk 4 GB Extreme III 30 MB/s Edition Compact Flash Memory Card - Pack of 3
• SanDisk 8 GB Extreme III 30 MB/s Edition Compact Flash Memory Card - Pack of 3
• SanDisk 16 GB Extreme III 30 MB/s Edition Compact Flash Memory Card - Pack of 3

Most importantly, you should make sure you have a kick ass card reader to get the maximum benefit for ingest speed for years to come. Here’s the one I use:

• SanDisk Extreme FireWire 800/400 Card Reader

Full disclosure: If you use these links, I do git a bit of a kickback. It’s not much, but it’ll go towards buying more gear which I’ll undoubtedly write about on this blog. Thanks!

Update

A few days after I wrote this, Derrick Story recorded a podcast with his thoughts about buying memory cards. His focus was mostly on selecting a card for recording video with his Canon EOS 5D Mark II, but highlights many of the same points I gave here.