How many photos will my Memory Card hold? – Revised Edition
September 16, 2010 | In: e:volve tech blog
Since we first posted this article back in 2007, then reposted in mid 2010 on our new blog we’ve had some requests to update it. And true, the card sizes and content has changed a lot since 2007 with capacities doubling at least every 18 months if not more often. So here we go…
How many photos will my Memory Card hold? – Revised Edition
Firstly, the digital camera you on or buy will dictate which type of memory card you need. Secure Digital (SD), Memory Stick (MS) and xD-Picture Cards are the most popular among pocket digicams and CompactFlash (CF) and SD cards for Digital SLRs (professional zoom style cameras). A few cameras have two card slots and some models have a single slot that will accept two different types of cards (for example, xD and SD).
Prices of all memory cards have dropped considerably since mid-2007, making high-capacity cards affordable to even the most cash-strapped photographers. Here we’ll outline typical capacities for a range of memory cards and provide guidance on how much memory you require for some typical shooting situations.
How Many Images Can You Store?
The table below shows the approximate number of pictures popular memory cards can store for digicams of different resolution levels. The figures provided are based on JPEG images from compact digicams, taken at the highest resolution and quality settings.
The actual number of pictures that can be stored on a card will depend on the camera model and how much the JPEG files are compressed. Some cameras apply higher compression ratios that others. Card capacities will be significantly higher when lower resolution/quality settings are used.
Photographers who use DSLR cameras will find they need higher storage capacity – especially if they shoot raw files. For this reason, we recommend at least a 4GB card. The table below gives the approximate capacities for high-resolution JPEG files at a compression ratio of 1/4 from typical DSLR cameras.
Compression ratios vary for raw files, although all manufacturers provide lossless compression. For example, 10-megapixel raw files can range in size from 17.66MB to 9.8MB, depending on the file format used and the degree of compression applied. TIFF files, which are usually uncompressed, are roughly three times the resolution of the camera’s sensor in size (e.g. around 30MB for a TIFF file from a 10-megapixel camera).
How Much Video Can You Store?
When memory cards are used for storing video clips, capacities are measured in time, rather than number of image files. The compression ratio applied by the camera will dictate the size of the video files. Most camera manufacturers put a limit of 4GB on video capacity – or up to one hour of video recording. The table below shows typical video recording times for three different video formats with three card capacities.
|MPEG4||2 min 33 sec||4 min 68 sec||9 min 38 sec|
|Motion JPEG/ stereo WAV (VGA@ 30fps)||3 min 49 sec||6 min 59 sec||13 min 58 sec|
|AVI (VGA@ 30fps)||7 min 31 sec||15 min 19 sec||30 min 36 sec|
How Much Memory Do You Need?
Assuming you always shoot with your camera’s highest resolution and quality settings, it’s easy to calculate the size of the memory card you require. Back in the days of film, most amateur photographers would shoot up to two 36-exposure films in any one day; the equivalent of 72-75 shots. With digital, we’re less conservative, so a better estimate for a day’s ‘normal’ shooting would be 100-150 shots. In photographically exciting places, this figure could safely be doubled – and if you plan to shoot video as well as stills, you will need at least four times more memory capacity.
When you’re travelling, we recommend allocating at least 1GB per day . A total of three 1GB or 2GB cards will provide for one ‘emergency’ spare that can be used when you need more capacity. Cards are light and take up very little space in your camera bag. It’s better to have several spares than to be forced to shoot at lower resolution and compromise your ability to make big prints. You should be able to find services that will transfer images from a memory card to a CD or DVD in most population centres. If it’s a trip of a life time we recommend purchasing two copies of each disk: one to keep with you and the other to send home as a back-up (in case the other disk is lost or damaged).
Take at least two 1GB cards when setting out for a day’s photography.
Do You Need a High-Speed Card?
CompactFlash and SD cards are supplied with a range of speed ratings, typically 40x, 80x and 144x (where x represents a transfer speed of 150 kilobytes per second). These speed ratings can be useful for photographers as they can help you to choose a card which matches your camera’s data transfer speed.
Memory card manufacturers charge premium prices for their high-speed cards but, for photographers who shoot with digicams, fast cards will be of little benefit. Even many DSLR photographers will find standard 40x speed cards will be adequate for most shooting situations. However, they will make a difference in how long it takes to download files to a computer, particularly if you have a fast PC. High speed cards are also worthwhile for video recording tho.
Is it worth paying more for a high-speed card? It is if your camera can match the card’s data transfer speed, if you use burst mode frequently or if you shoot a lot of video. If you take shots one at a time, the speed of the card is irrelevant.
Memory Card Tips
Beware of counterfeit cards that appear to be from a leading manufacturer but lack the warranties of the genuine products. Replicated cards with labelling and packaging that resembles cards from leading brands are readily available on the internet. Check card labels very carefully and only buy from reputable re-sellers. If the deal seems too good to be true it probably is.
Treat memory cards with care. Keep them in dust- and water-proof cases while they are not in use. Always carry at least one back-up card in case you run out of memory on a shoot.
Moving the lock on the side of an SD card down protects all the files it contains against erasure. To delete the files or format the card you simply return the lock lever to its up position.
Don’t open the camera’s card compartment while the files are being written; it will almost certainly cause shots to be lost. Shots may also be lost if the battery fails while files are being written. In many cases these ‘lost’ images can be recovered if you stop using the card immediately. Many computer shops like ourselves provide a file recovery service for a small fee.
Always format each card in your camera before you use it, making sure you have transferred the images it contained to an archive folder. Some digital cameras can’t operate with cards that were formatted in a computer or a different camera. Don’t expect a camera to display images captured on a card by a different camera – even if it comes from the same manufacturer. Also, you may corrupt your existing photos if you swap them between cameras.
Secure Digital (SD) cards have a built-in facility that allows you to lock files stored on them so they cannot be deleted. This is useful when you are using several cards over a period of time and don’t have facilities for downloading the shots. A sliding lever on the left side of the card locks in this write protection. When it is pushed down towards the lower edge of the card, all data on the card is protected. Pushing it up towards the top of the card removes the write protection and allows image files to be deleted individually or collectively. The card can also be formatted.