hi moira.
i usually stick with scandisk extreme,or recently,i bought a lexar pro 8 gb,on sale by the way at future shop in whitby.it,s a very fast card,which is handy when doing IF,to clear your camera quickly,so you can get back into action.it,s highly recommended,for cameras with a high burst,ie( mark 11,mark 111 8-10 fr/per/sec ). since you,re hooked on IF,get a fast card. you wont regret it,as the shot of a lifetime,flies by,and your camera,s still writing files to your card.