Compact Flash Cards, Size, Lies and Compromise


I have, over the years, used many different types of storage media, initially starting with the 170mb Viper Cards, which were double height PCMCIA cards with a small hard disk inside ; these were very fragile and temperamental, and when the opportunity came to replace them with IBM Microdrives I jumped at the chance. These cards were used in an old (obviously it wasn’t then) Canon/Kodak DCS3, 1.3 mega-pixel SLR.

The IBM Microdrives proved to be much more reliable, but were still vulnerable to knocks and bumps, so a few years ago I swapped to the Solid State CF cards.

I have over the last few years chopped and changed CF cards, depending upon what was flavour of the month or offered the best value for money. When choosing CF cards there are several things that you have to consider:-

Size
All compact flash cards are 36mm x 43mm and come in two types (strangely enough Type I and Type II) Type I CF cards are 3.3mm thick and type II are 5mm thick, the 50 pin connectors however are identical, so if your camera supports Type II it should also accept type I cards.

CF cards range in capacity from 8mb to several Gigabytes, I believe the largest currently available is something like 16gig, but it is not generally available for photographic uses (and a £9,000 ‘a pop’ nor is it likely to be).

The size of the CF card you require will depend on the type of photography and the type of camera that you use, my recommendation is don’t by a single card that will fill your needs because although reliable, if the CF card fails you will lose all of your images (Eggs and Basket spring to mind). It is rather better is to buy several smaller cards and rotate them as they fill.

Solid State CF cards are very reliable, but they can and do go wrong, and you can guarantee that when they do it will be when they are three quarters full.


Lies

Nearly all CF card manufacturers misrepresent several facts about their CF cards, firstly, capacity. 1 megabyte is (and has been for many years) 1,048,576 bytes: however as far as CF card manufacturers are concerned 1 megabyte is 1,000,000 bytes which means very little in percentage terms, however when dealing with small cards it can make a significant difference to the number of images that can be stored. Secondly, speed which we will address later.

Before buying your CF cards check for compatibility with your camera, some cameras support only FAT16 (16 bit File Allocation table) which means that they can only address up to 2 Gigabytes of Data, so using anything larger (whilst reasonably academic at the moment) is a waste of time as the HDD controller cannot read anything of 2 gig. FAT32 compatible means that any car up to 137 gigabytes can be used. There are also some other technologies that are available that, may not be compatible, including Lexar’s Write Ahead Technology.

CF cards are speed rated, however the ratings themselves are open to interpretation and abuse by the manufacturers. Write Speeds are general done as x (times), and even then there are other factors that affect performance including how well the software installed on the camera works. Lexar are quoted as say that the “x” in the speed rating is 150kb/sec in which case a 40x CF card (it could be deduced) would enable the transfer rate of 6,000kb/sec. in reality however, you will not achieve that sort of write rate. Until manufacturers adopt a standard measurement, it will be impossible to gauge just how cards compare, short of buying them all and testing them. Which is not a task that I am prepared to undertake.

The construction of CompactFlash cards is relatively simple (says a man who can barely tie his own laces) consisting principle of two parts the memory space itself which is a grid of cells each with two tiny transistors, each cell starts with a zero value, and through the application of electrical current this can be changed to a value of 1 (in binary you only have these two values) The job of regulating which cell values are changed is the 2nd part of the CompactFlash card the data controller. The controller takes image information from the camera’s buffer and stores it on the CF card as a series of binary switches.

Originally introduced in 1994 CF has become the most popular media card available, despite Sony getting all proprietary, the excessive cost and small capacity has practically killed the memory stick (and the memory stick pro) and initially solid state cards were limited in size and very expensive for high capacity cards, hence the popularity of the IBM Microdrives, although now there is no really need to purchase anything as fragile as a mini hard disk, as solid state cards are available (up to 8 Gigabytes at least) to my knowledge, and even with the advent of the new Canon EOS1Ds MKII with some ridiculous number of pixels (16.7megapixels and creating a near 17Mb Tiff file) there should be very few who will need much more storage space on a single job.

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