T2i & San Disk Ultra 15MBs class 4

I have had my T2i for a couple of weeks. My 8 GB Sandisk Ultra 15 MB's (Class 4). Seems to be doing a perfectly capable job with video as well as continuous shooting.

Am I somehow mistaken?

I haven't had enough time to play with mine yet. Was using just a 1GB card my wife uses for her P&S. It is definaetly two slow for video.

I have a 16gb class 6 card on the way. I am sure that will be fast enough, but if indeed you can get away with a class 4 I certainly would like to know that. Those are much cheaper. The Manual say to get Class 6, but they could just be trying to get us to spend the big bucks.

I've used an 8GB SanDisk Ultra 15MB/s Class 4 card ever since I got the camera and it works flawlessly during 1080p 24fps recording. I ran CrystalDiskmark which showed 19MB/s read speed and 11MB/s write speed. That is enough for up to 75mbit/s video bitrate (550D is capped at around 45-50mbit/s). It seems like the finer cards by SanDisk is a lot faster in reality than what their class rating suggests.

What video settings are you shooting at and for how long. You could just have a really good class 4 card. I picked up the 16GB Class 10 ADATA card this weekend at Fry's for $39.99.

http://www.frys.com/product/6011918?site=sr:SEARCH:MAIN_RSLT_PG

It has been working great for video and pictures.

I've tried out all video resolutions/frame rates and not seen a single stutter, performance drop or skipped frame. Unfortunately there is no Fry's where I live (in Sweden). All the 16GB cards are over 55$ here. The 8GB SanDisk class 4 is just 27$ and gives a better performance than the class 4 Transcend.

According to a review at DigitalVersus ( http://www.digitalversus.com/transcend-sdhc-16-gb-class-6-p388_7493_161.html ) the Transcend 16GB class 6 manages about 7-9 MB/s write speed and about 15-16 MB/s read speed. That is enough for every aspect of 550D, but the SanDisk 8GB class 4 gave me over 19 MB/s read and 11 MB/s write (testing with 500MB files) when testing with CrystalDiskMark sequential.

This makes me question why there is class ratings when they don't seem to say very much at all. A good class 4 card seems to be superior in every aspect to a bad class 6 card.

SanDisk UltraII 8GB class 4
Kingston 8GB class 4
PNY HD 8GB class 4

I've used all of the above cards with the T2i and have no problems with video or stills. The only thing a faster card might show an improvement with is continuous shooting with RAW stills (or RAW+JPEG). I got all of the cards for around $15 each.