Choosing an SD card

[ezimon]

Hi...

This is my first post here and my first week with an SLR camera.

Just bought Canon EOS 450d and I'm using an old 2GB SD card from my pocket camera.

I'd like to buy a new SD card of about 8-16GB. any suggestions for brands, speed issues, etc. ?

Thanks in advance.

 

[Boomn4x4]

There are two primary differnces between SD cards:
1. Read/Write speed.
2. Quality of microchip.

The first thing that needs to be said is that digital photographs are, well, digital. They are stored as a series of 1's and 0's on the disk. A 1 is exactly the same on one disk as it is on any other, and a 0 is exactly the same on one disk as it is on any other. In other words there is absolutly NO difference in image quality on an expensive disk as there is on a cheap one.

Now, to get into the difference. The biggest difference is the Read/Write speed. SD Cards come in 3 (soon to be 4) classes, class 2, 4, and 6. Class 2o cards write at 2MB/second, class 4 @ 4MB/sec, class 6 at 6MB/sec...all of which are minimum speeds. These speeds are defined by the SD Association.... but are not verified by any governing body. This means, its is possible to buy a cheap card maufactured by some generic factor in China labled as a Class 6, but it is only a class 2. It should also be noted that you may find some SD cards advertise a "maximum speed"... but you should ignore this as that speed is pretty much impossible to obtain under normal operation.

What this means to you.... First lets look at the photo's you are taking.
8 megapizel photo in RAW12 = 12MB, JPG100 = 1.9MB
6 megapixel photo in RAW12 = 9MB, JPG100 = 1.6 MB
4 megapixel photo in RAW12 = 6MB, JPG100 = 1.2 MB

If you are shooting an 8MP picture in JPG100 format and have a more expensive class 6 SD card (which you can be sure IS a class 6) you are able to write the 1.9MB image in about 1/3rd a second. If you are using a cheap class 6 (that is actually a class 2) you can only write the image in about 1 second. This may be fine for still photography or portraits, but if you are shooting in burst mode, this can cause some problems.

Fortunatly, most SLR's (all that I know of) have a built in memory buffer that will hold the image until it can be written.... this greatly incrases your burst photography ablity. However, that buffer is limited, and if it can't write fast enough to the card, it will fill up, and the shutter of your camera will be disabled until the buffer has written the data to the card.

Bottom line here... and all technical googlebits and digibytes jargon asside... a cheap SD runs the risk of severly slowing down the burst capture of your camera... An expensive SD card may get you 5 frames per second, and a cheap one may only get you 2.

The second draw back, and this one is more hit or miss that the first, is the quality of the microchip and its ability to store data. Cheaper cards use cheaper chips, and while there are no moving parts to wear out in an SD card, the "disk" surface itself can wear out after repeated use and no longer be able to read or write. This limitation isn't as predominant has it was 10 years ago, even the cheapest cards are realitivly stable... but if you want to reduce the odds of losing data, a cheap card is a poor choice.

To summarize.... You certainly can use a cheap SD card, cheap SD cards will have no difference in image quality over a more expensive one, but you are going to be limited in your ability to do burst photography especially if you are shooting RAW images. This may or may not be a concern to you. And with a cheap SD card, you also run a slightly higher risk of the card itself failing.

Most any card with a name brand on it, Kingston, Kodak, SanDisk, Panasonic, PNY, HP... all of which are reputable cards and will do what they say they do.

 

[usayit]

Hi...
Just bought Canon EOS 450d

I wouldn't be too concerned with spending the cash for the fastest SD cards as the camera itself will most likely be the bottleneck. Just buy something in the middle of the road. I stick to Sandisk, Lexar, and PNY. Be aware of counterfeits being sold online and on ebay.

 

[MDWine]

You should look to the camera manufacture and/or the manual first, I would think.

 

[Jeremy Z]

Good question, and good reply by Boomn4x4. I was curious myself, but rarely shoot in burst. For me, it is frustrating to have to wait 3 seconds for my card to write an image. Any image. Cards are so cheap for their capacity now, I'm probably going to be a Class 4 8 GB card before going to Europe at the end of this month. I already have a 1 GB and a 4 GB, so I'll probably have more than I need. I'm going to shoot more video this time, so I want to err on the side of caution.

To me, the limiting factor usually tends to be batteries, not memory. Make sure you have plenty of spares. I carry two sets of spares for my SLR (which uses AAs) one of which is lithium. Two spares for my S90 also.

 

[Boomn4x4]

I'm going to shoot more video this time, so I want to err on the side of caution.

Video is a whole different demon. Read/write speeds are much more critical. You can get by with cheap cards for still photography, but I wouldn't recommend anything less than what the video manufacturer recommends in their product manual.

 

[pbelarge]

I purchased a Class 10, Sandisk Extreme 16 GB-30mb/s SDHC card about 2 months ago. I have a fairly new high capacity, very fast computer. I definitely noticed a faster download of the photos. It was a difference in speed that made me happy I spent about $90 on the card. "time is money"


Unfortunately, my photos are not any better...:mrgreen:

 

[ezimon]

Thank you all for the reply.
Thank you Boomn4x4 for that very nice explanation :thumbup:
There is no specific detail about the eos 450d writing speed but from what I understand searching around the internet, it should be about 6-8 MB/s.
So I'm thinking of buying at least class 6 of a good brand.
As pbelarge, at least it's going to download the photos faster

 

[ghache]

i have a bunch of class 6 lexar 133x, i tested them and the write speed is about 16mb/sec. this is bellow the rating of 20 mb/sec but its still decently fast.

i wouldnt buy anything below a class 6 66x,

on my d90, i didnt notice any difference shooting with the 133x or 66x,

 

[FemFugler]

i had no idea there was much of a difference in SD cards.... I always just bought the cheapest. When i bought my camera the cheapest happened to be 2x 4GB Kingston SD HC cards.... I just checked my SD card and it appears it's a class 4.....

 

[anm90]

I've been using a class 2, 2gb card from sandisk for the majority of my photos and haven't had any real issues with write speed. I never have to wait for it to load pictures to the card, and burst mode worked fairly well. I did just buy a class 6 8gb card from transcend but haven't had much chance to try it out yet.