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Digital memory card conversion chart


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Does anyone know of any coversion charts that gives you the amount of images you could take per

memory card size and megapixel setting on your camera. I know the camera will tell me the amount of

images it will hold per setting, but I am looking for a chart with this information before hand too help me

with my present and future memory card purchases.

 

ie.- How many images will fit on a 4gig card, shooting at 2 megapixels, or at 10?

 

Tahnks,

 

John

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Sorry I don't have the requested link, but once you have a value for a given IQ setting and card size, you can multiply or divide to get an estimate. For example, RAW only on my 350D with a 2GB card tends to come in around 200-233, so 4GB would be twice that, 1GB half that.

 

Usually the camera underestimates. For example, I had a hot finger this morning and packed 275 onto a 2GB card -- real pity that because the HD won't take another byte till I do some pruning. But you just can't resist your first Baltimore Oriole sighting of the season :-)

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John,

 

While it sounds simple to compile such a chart, there are many variables. Not the least of which is camera make and model. The firmware alogrithms that manufacturers use are all over map.

 

As you may know, the size of a file is dependent upon not only the megapixel setting, but the file type as well. An uncompressed RAW file can take up as much space as 20 jpegs (for example).

 

To complicate things further, the complexity of the subject matter can also affect file size. In other words, a shot of a blank wall will use fewer pixels than a shot of a detailed landscape.

 

Anyway, I see where you're going with this but there can be no chart that's 100% accurate under all conditions. The best that you can hope for is an approximation based on the chart in the instruction manual for a given camera.

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Suggestion: read your camera's manual. (Many are downloadable as PDFs.) Megapixel don't mean everything. Here I can choose between 3 JPG compressions and at full res also RAW and Tiff. Tiffs are the only files of predictable size. The amont of JPGs is subject dependant, more details mean less frames. RAW sizes vary sometimes even between different models of the same manufacturer. I doubt that your framecounter will give you the desired answer, since my own ones have only 3 digits, which aren't enough for the low res JPGs. I'd guess you might get between 2400 - 6000 2MP JPGs on your card (numbers pessimistic according to a Pentax 1.5MP chart highest and lowest JPG compression)
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The size of a compressed file (raw or JPEG) varies not only with the subject matter, but with the ISO setting. Compression depends on removing redundancy within a file. Noise at high ISO settings is random, so compression can't work well. A noisy file is a large file.

 

It's possible to make a reasonable estimate of images per gigabyte based on average file sizes. But you really can't rely on it.

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