What the num­bers mean

SD cards and Com­pact Flash mem­ory cards carry a be­wil­der­ing ar­ray of names, num­bers and icons. Let us ex­plain what they mean, and why they are im­por­tant

NPhoto - - Over To You… -

1 ‘Ex­treme Pro’ is just one of SanDisk’s brand names. It’s not a de­fined stan­dard for card per­for­mance. Most mak­ers break up their mem­ory cards into ‘fam­i­lies’.

2 This logo tells you whether it’s an SDHC card (which this one is), or­di­nary SD (rare these days) or SDXC. 3 If you see an additional ‘I’ here, it means the card con­forms to the faster UHS-I stan­dard. There’s an even faster UHS-II stan­dard found on the most ex­pen­sive mem­ory cards.

4 This in­di­cates the card ca­pac­ity. Card ca­pac­ity and speed don’t al­ways go to­gether, though the more ex­pen­sive cards gen­er­ally of­fer both.

5 A num­ber in a cir­cle tells you the card’s min­i­mum speed rat­ing. Class 10 cards are de­signed for shoot­ing full HD video. Class 6 and Class 4 cards can do it in the­ory but may stut­ter or drop frames.

6 This ‘1 in a bucket’ sym­bol in­di­cates that this card also con­forms to the UHS-I stan­dard. It’s broadly equiv­a­lent to Class 10 speed, but uses an in­trin­si­cally faster sys­tem. 7 This is the card’s max­i­mum speed, but it will only achieve this un­der ideal con­di­tions. It’s help­ful for choos­ing a card for stills, but not for video, where you need a re­li­able min­i­mum speed.

8 This lock switch is unique to SD/SDHC/SDXC cards – you don’t get it on Com­pact Flash cards. You can use it to pre­vent ac­ci­den­tal dele­tion of the card con­tents. 1 The ‘Pro­fes­sional’ brand­ing iden­ti­fies this mem­ory card within the Lexar range, but it doesn’t re­late to any over­all stan­dard for Com­pact Flash mem­ory cards.

2 The max­i­mum speed of the mem­ory card is some­times quoted as a mul­ti­ple of the old CDROM stan­dard, which was 150KB/s. This card’s ‘1066x’ speed equates to 155MB/s. 3 Com­pact Flash cards don’t use SD card ‘Class’ rat­ings for min­i­mum sus­tained speed, but some have a VGP (Video Per­for­mance Guar­an­tee) logo. VPG 20 is 20MB/s, VPG 65 is 65MB/s. 4 Newer mem­ory cards use the faster UDMA stan­dard, and all re­cent Nikon D-SLRs sup­port UDMA (see the ta­ble over­leaf). UDMA 7 is the new­est and fastest vari­ant. 5 Com­pact Flash cards once came in Type I and thicker Type II vari­ants. Type II is no longer made and not sup­ported by to­day’s Nikon D-SLRs. All Com­pact Flash cards now are Type I.

6 Card ca­pac­ity is quoted in GB, as it is with SD cards. This one has a ca­pac­ity of 128Gb, but Lexar has re­cently an­nounced it is mak­ing a 256GB Com­pact Flash card.

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.