Which Memory Card

[alf6]

Hi, I have a Canon EOS 1000D bought 8 months ago which was supplied with a Sandisk Extreme HD Video card. The camera does not shoot video. I am looking for another 8GB card - my questions is which one? I shoot mainly moving objects - cars and people. Nothing I have researched tells me why I should buy HD Video over SDHC, etc - confusing! The Sandisk reccomends Ultra for my camera rather than extreme - Why.

I look forward to some assistance in this matter - many thanks.

[gorillagirl]

I'm also keen to learn a bit more. I'll be picking up a Pentax K7 and am confuzzled over the card speed needed.

[ricktas]

Ultimately the speed of the card comes into play when shooting video, or taking multiple frames per second. The other time it is useful is when downloading the photos from the card to the computer.

There are several links in this chain that limit the usefullness of extremely fast cards.

1. Your camera. Your camera has a speed limit as to how quickly it can copy data from the sensor to the card at capture. A faster card can mean photos are transferred to the card faster, but there is also a hardware speed limit, in your camera. Camera's have a memory buffer to store data as it is being written to the card, so you can take multiple photos per second, and the buffer stores them and then transfers them to the card. The biggest issue here is buffer memory. When your buffer memory runs down, your camera FPS rate will also slow, as it cannot keep up with the data transfer to the card.

2. Transferring your photos to your PC. Again a faster card can be of benefit here, but your PC hardware, can limit this. If you use USB2 then you hit the transfer speeds of USB2. If you use USB3 then you can get much faster transfer rates. More so if you use a USB3 card reader, rather than plug your camera into your computer.

3. Video. If you can take video with your DSLR, then this is where a fast card can be advantageous, both for data transfer to the card at capture and transfer to the computer.

4. Note that often the speed rating of a card is its READ rating, not its WRITE speed.

5. Technology is improving rapidly, what is a fast card today, will be considered slow in 18 months time.

So, buy the fastest card you can afford, with the storage capacity you need. I still use some old cards from about 5 years ago that are very slow, but they work, and when doing landscapes, often speed is not a factor. Shoot sports and you might want faster cards than what a landscaper can get away with.

[alf6]

Thankyou Ricktas, I fully understand the speed side of things now. Correct me if I am wrong - as I understand it now, the difference between a Sandisk 'Ultra' and a 'Extreme' card is just the speed - 15MB/s versus 30MB/s. Is there is difference in image quality? Thanks again.

[ricktas]

Thankyou Ricktas, I fully understand the speed side of things now. Correct me if I am wrong - as I understand it now, the difference between a Sandisk 'Ultra' and a 'Extreme' card is just the speed - 15MB/s versus 30MB/s. Is there is difference in image quality? Thanks again.


Your card just stores 0 and 1's, nothing more. It just takes the data the camera sends to it and stores it as a digital entity. This alone cannot affect image quality. Image quality is affected by photographer skills (choosing right aperture, ISO and shutter speed), quality of lens used, focus point chosen, composition etc. When you press the shutter button, what is sent to the card (any card) is only as good as the photographer makes it. But the card itself just stores a series of digital information, so in its very basic form, just 0 and 1 (on or off) for each bit of information, and what is on the card cannot change depending on card speed.

[JudiN]

Interesting topic - I was wondering this myself and haven't found anyone who could answer the question to thanks Ricktas you have cleared my foggy understanding up:)