The digital camera has changed the way people take pictures. It is now easier to take a picture, decide if we want to keep it, and delete it if we don’t. Some cameras even allow you to apply effects to your pictures, such as colour replacing. How are digital cameras able to do this? Pictures are stored as files on a memory card that you load into your camera.

There are many types of memory cards on the market today, and different digital cameras require different memory cards. Some cameras even allow you to use two types of memory cards. What is the difference between all the types, and which one is better? This post will describe the various popular memory types and discuss their differences.

What is Flash Memory?

Before we look at the various cards, it is important to understand what I mean I say flash memory. You may be familiar with computer memory (RAM) or hard drive space, which have been around for many years. Both of these storage mediums have their advantages and disadvantages. The RAM in your computer has no moving parts so it may not break as easily than a hard drive, but it is volatile, meaning that it won’t keep the data once the power is turned off. Hard drives are non-volatile, can hold enormous amounts of data, but they have many moving parts, that could easily break.

Flash memory is non-volatile memory with no moving parts. They have been known to be durable even on some intense testing. The memory can be electrically erased and written to just like a hard drive, and very small physically. Although they don’t have the storage capacity of a hard drive, they are becoming larger each year.

CompactFlash / MicroDrive

The CompactFlash cards were once the most common flash cards used, however, that crown now belongs to the Secure Digital memory. CompactFlash is rather large at 3.3mm x 36.4mm x 42.8mm (thickness x length x width) for the Type I compared to the other memory cards. Type II cards are thicker at 5.0mm, but the length and width sizes are the same. Cameras that use Type I cannot use Type II, however, cameras that use Type II can use either.

Some older cameras that use CompactFlash may not be able to use any size larger than 2GB. This is because CompactFlash uses FAT for sizes under 2GB, and FAT32 for any sizes above 2GB.

Some cameras that accept CompactFlash Type II may also be able to use a MicroDrive. A MicroDrive is a small hard drive usually in sizes of 340MB and 1GB.

Secure Digital (SD) / MultiMediaCard (MMC)

This is perhaps the most common memory card in use today. They are much smaller (2.1mm x 32mm x 24mm) than the CompactFlash cards but have the same amount of storage space.

Both the SD and MMC cards are almost identical in terms of size and look on the outside, but inside they are technically different. Although your digital camera may accept SD memory cards, it may not accept MMC cards as well.

There are also miniSD cards on the market mostly used in MP3 players and mobile phones; I have yet to see any digital cameras that use this memory card. The miniSD is smaller than the SD card since it is only 1.4mm x 21.5mm x 20mm.

Sony Memory Stick (MS)

This type of memory card, or rather stick, was created by Sony in 1999 and is used in all of their Cybershot digital cameras as well as their digital video Handycams.

The original blue Memory Stick was incredibly slow compared to today’s SD and CompactFlash cards. There have been several versions, or types of memory sticks developed by Sony over the years.

There is the Memory Stick Select which allows you to select between 128MB and 256MB to make it compatible with older digital cameras. Next came the Memory Stick Pro that had a capacity up to 2GB. With the exception of the Cybershot F717, this Memory Stick was not compatible with any of the pre-2003 digital cameras. There is also a high speed Memory Stick Pro that is capable of transfer speeds of 80Mbps.

xD-Picture Card (xD)

The xD card was developed by Olympus and Fujifilm and is about the size of a postage stamp. Most Olympus digital cameras now use the xD card. There are currently two types of xD cards on the market: the M series and the H series.

Not all cameras can accept both types of xD memory cards, so check your manual before purchasing an xD card. The H series cards are reported to be about 2-3 times faster than the M series.

Summary

There are many types of flash memory cards on the market to use with your digital camera. Any digital camera you purchase today will use one of the memory cards mentioned in this post. Always read your instruction manual that came with your camera to determine the exact memory card that you can use. As always, technology progresses, and there may be a time when the above memory cards will be replaced with something else. As long as you can keep taking pictures, you don’t need to worry about that, though.

I mentioned in a previous post, About Digital Cameras, I mentioned that you should always buy two sets of rechargeable batteries. In this post I discuss the two most common rechargeable batteries used by digital cameras, although there are other types of rechargeable batteries on the market.

Nickel-Metal Hydride (NiMH)

Although research into the NiMH system began in the 1970s, these batteries first began being used commercially around 1990 and are currently used in digital cameras in AA form. In the early days of NiMH batteries, the metal hydride alloys were unstable so the desired performance characteristics were not achieved.

In the 1980s, new metal hydride alloys were developed that were stable enough for use in a cell. By the late 1980s, the energy density of the NiMH batteries had gradually improved.

The metals used in NiMH batteries are environmentally friendly and have a high energy density, which have contributed to its success.

The fast charge time of a battery is 2 to 4 hours. The charge-discharge cycle life of a NiMH battery is roughly 300-500 cycles at up to 80% of the initial capacity. If not used, a NiMH battery will lose 30% of its charge every 30 days.

Lithium Ion (Li-ion)

Early work with creating the lithium battery began in 1912 by G.N. Lewis. The first non-rechargeable lithium batteries became available in the early 1970s. The instability of the lithium metal during charging caused safety concerns during attempts to make a rechargeable lithium batter in the 1980s.

Lithium metal is a light-weight metal and has the greatest electrochemical potential and also provides the largest energy density per weight. Since lithium is unstable during charging, non-metallic lithium has since been research. Although lower in energy density than lithium metal, lithium ion is safe, provided that certain precautions are following during charging and discharging.

The first Li-ion battery was first commercialized by Sony in 1991.

It will take 2 to 4 hours to fully charge a Li-ion battery. The number of charge-discharge cycles for a Li-ion batter is 500 to 1000. The Li-ion battery will lose about 10% of its charge every 30 days.

The charge of a Li-ion battery will decrease over time because of oxidation. This occurs naturally and cannot be restored with cycling or any external method. The loss of charge capacity is permanent because the metal used in the cells is only designated to last for a certain period of time.

Which Battery Should I Use?

Many digital cameras include a large battery that can be charged within the camera itself. These batteries are usually the Li-ion type of rechargeable battery. They will usually last quite a long time when not in use, so you won’t need to recharge as frequently. The Li-ion batteries are usually more expensive to purchase, and your digital camera may only accept a specific model.

If your camera only accepts AA batteries, then you should choose the NiMH rechargeable batteries. These batteries may come with their own charge since you won’t be able to charge them right in the camera. Always buy two sets of batteries, so when one set has discharged, you can use your spare while recharging the first set.

Look at the milliamp hours (mAH) value when purchasing rechargeable batteries. This value is a measure of the battery’s total charge capacity. The higher the number means the larger the capacity.