Group review: compact flash memory cards
Most, if not all, of the UK’s top wildlife photographers have now converted to the digital format. With new cameras coming onto the market every few months, it seems that as the megapixel count gets higher the price of entry-level cameras gets lower. The manufacturers of memory cards have mirrored this development, with some companies now offering cards capable of storing 16 GB, while a generic 1 GB card can now be bought for as little as £12. Here too there is confusion for new converts to digital photography – what size card should be used and what are the differences between the cards?
Compact flash memory cards are rated based upon the speed that data is written to the card. This value is typically expressed as a comparison against a CD that writes at 150 KB per second. For example, a card that is rated as 10x write speed should write at (10x150 KB) 1.5 MB per second, while a 100x write speed card writes at 15 MB/s. A single frame from a Canon 20D camera is typically 2.5 MB in size and you can shoot at five frames a second for 23 consecutive frames. This repository of 23 frames is known as the image buffer. Once the image buffer is full the camera becomes inoperable until images are transferred to the memory card. Therefore, the faster the images can be written to the card the better.
With that in mind, I tested some of the faster cards from three of the best-known manufacturers. All cards were tested in my 20D while trying to get flight shots of swifts during the summer.
Sandisk Extreme III 2 GB 133x write speed (£63)
Sandisk was the original creator and manufacturer of the compact flash card, so you would expect the company’s cards to benefit from innovative technology. This card delivers super-fast transfer with a 133x write speed of 20 MB per second – the Michael Schumacher of compact flash cards! Bundled with the purchase of the Extreme III is a CD of Sandisk’s image recovery software, RescuePro. This file recovery software will enable you to recover images accidentally deleted from your card, even after the card has been reformatted. Once loaded onto your PC this software will recover images from any memory card, whether Sandisk or not.
Kingston Technology 4 GB 100x write speed (£152)
I first used this card while attempting to capture images of the Wirral Alpine Swift in flight, and by necessity had to shoot a lot of frames. I found it difficult to fill this 4 GB card using the JPG fine setting, even though I took more than 1,600 images. This large capacity card is ideal for users who like to shoot in the RAW format, as individual files are much larger in RAW. Writing at a fast 15 MB/s was beneficial, and I never filled the image buffer.
Lexar Professional 1 GB 133x write speed (£31)
This card delivers a performance comparable to the Sandisk, with a 133x write speed of 20 MB/s, and again is bundled with Lexar’s version of image recovery software. Herein lies the main difference between the two. Lexar’s software is pre-programmed onto the flash card and this must be installed onto your PC before you format the card ready for use – personally I prefer the CD method.
In conclusion I would say that the Sandisk and Lexar cards have the edge over the Kingston versions in terms of write speed, but Kingston cards are great value for money.