What speed of flash memory do I need?

[mallen]

As I shop for a camera and the required additional memory card, what specific camera specifications affect memory speed?

I am guessing that it is something like resolution and continuous shooting mode speed. For example, a 5 megapixel image (~2 Mb per image) x 2 images per second = 4 Mb per second minimum write speed requirement?

Please post the right guidelines - Thanks!

[cwphoto]

Megapixels first; the more MP the more time it takes to write to the card. Shooting speed obviously also comes into it as you state.

Also consider the camera buffer. A large buffer may allow you to take a fast burst of images without the need for ultra high-speed cards.

[mallen]

For continuous shooting, the buffer will be exceeded. In that case, what are some reasonable guidelines? Thanks!

[cwphoto]

How many continuous frames do you envisage shooting?

[mallen]

Until the card is full theoretically...

Let's say 100, and the buffer fills in 5.

[cwphoto]

That seems like quite an odd example, but so be it - for these needs you'd need the fastest you can get, like Sandisk Extreme IIIs - unless your camera can't exploit it.

[mallen]

OK, I admit that I am looking at a Panasonic Lumix DMC-FZ5 that shoots 2 frames/sec in continuous mode. This would be nice during something like a sporting event where you are hoping to find a special frame and then you toss the rest. My current 2 Mpixel camera saves ~800 Kb files, so I am guessing ~2 Mb for the 5 Mpixel and at 2 fps the card need to write at >4 Mb/s, so ultra-high speed like 20 Mb/s seems unnecessary. But I really don't know, I am just hoping someone can point me to the right amount of high speed

Thanks for the help cwphoto!

[cwphoto]

OK that's better.

Try this - should help explain what you need:

http://www.dpreview.com/reviews/panasonicfz5/page4.asp

[mallen]

In the review for the FZ5 on this site, Jeff Keller recommends a high speed card for continuous shooting, but doesn't clarify what speed. I haven't been able to fing any guidelines on this site regarding how to determine how much memory speed a particular camera can benefit from.

[cwphoto]

I'd guess he means 80x plus (like an Ultra II).

[mallen]

Excellent!

The bottom of page 4 states 4.8 Mb/s write speed for the FZ5 Venus II engine. This matches up nicely with the continuous shooting mode data higher on page 4 using ~2.015 Mb/frame x 2.3 fps.

Final answer: The high speed card requirement for a given camera can be determined by the above formula. A slower card means the continuous shooting rate (past the initial buffer size) will be lower than achievable and a card more than 2x faster may be a waste of money. For the FZ5, a 50x (~7.5 Mb/s write speed) memory card is plenty.

Thanks for the guidance cwphoto!

Make this a Sticky?

[ReF]

a card more than 2x faster may be a waste of money.

keep in mind that megapixels and read/write speeds keep going up so it's likely that extra speed will be utilized in the near future or whenever you upgrade cameras. my first card was a regular speed sandisk CF that i bought with my a80. still using the camera at the time, i bought a larger capacity card but decided to go with an Ultra II (even though the A80 made no use of the extra speed) keeping in mind what i mentioned above. i have since upgraded to a 300d and then a 350d, and now think the regular speed card was a was of $$$! i keep it around as extra storage but the slowdown caused by the card is quite annoying.