Memory card speed

[johna901]

When using my Sony A700 to capture birds in flight, I want the highest possible drive speed. Would the drive speed (frames per second) increase significantly if I used a faster memory card? I am using a SanDisk Extreme lll CF card (30 MB/s) at present. Would a faster card such as SanDisk Extreme Pro (90MB/s) make a big difference? Any advice on this will be much appreciated.
Johna901

[Mark K]

Yes.
I have used Extreme III and IV once, and subsequently got my self Ultra, Extreme 60MB/s and Transcend 400x. All works wonderful. The Transcend is even a bit faster.

[Dusty]

Are you running into long write times and subsequent wait time for the buffer to clear? I don't know how fast the 700 can write to a card, but unless your overfilling the buffer, faster cards will do you no good.

If, however, you shoot lots of frames and keep holding down the shutter after the buffer is full, then you'll have to wait until the buffer has room to take another shot. That means a faster card may help, but as the 700 is several years old now, it may have a transfer rate that's lower than some modern card's write speed. In that case, faster cards will do you no good.

All 3 of my cards are SanDisk, the 8G Extreme III I bought in '08 is 30MB/s, the 4G Ultra II I bought last year is 15MB/s and the Ultra that I bought this Spring is 30MB/s. Seems like the terms Extreme and Ultra change with time!

Dusty

[KevinBarrett]

Extreme Pro might be over-doing it. I use an 8GB Extreme IV card (45 Mbps) and already reach the maximum specified sustained burst duration (or perhaps exceed it by one frame...hard to be sure). I think the buffer fills up at about 21-22 frames, at which time your sustained speed drops.

[johna901]

Thank you for all suggestions. Presumably the camera cannot go faster than its design speed of 5 frames per second, however fast the card. I have now photographed a stopwatch that counts in hundredths of a second. This shows that an eleven frame burst takes two seconds. This is the same for RAW or JPEG shooting. This is a long enough burst for my purposes, so I guess it means that a faster card would make no difference.

[Dr. Harout]

It might for JPEGs.

[Dr. Harout]

Oh, sorry... Welcome to the forum Johna901

[dynax800si]

Before I was found one test about write speeds and buffers of some DSLR's, but now I can't.
There were tested A700, D300, 40D, E-3 and some other cameras and A700 was one of the fastest, if not the fastest camera in writing speed on the CF, with speeds about 40mbps.

[KevinBarrett]

I should have added that with a Sandisk Extreme IV card the 5 fps RAW burst of an a700 lasts 4 seconds, or 21-22 frames. With Jpeg, it'll keep slapping that mirror back and forth until you become uncomfortably conscious of the camera's tested shutter durability of 100,000 cycles, or until your card fills up.

[01af]

As far as I know, the Sony A900 supports the UDMA-5 mode but not UDMA-6 (i. e. the latter will be treated as UDMA-5, as higher UDMA modes always include the lower ones). The SanDisk Extreme is an UDMA-5 card; the SanDisk Extreme Pro is an UDMA-6 card. So the Sony A900 cannot fully exploit the Extreme Pro's superior speed.

I have a SanDisk Extreme IV and a SanDisk Extreme; the latter is faster in the A900 but only by a minuscule margin. You need a stopwatch to notice. Faster means, the camera's buffer will take less time to clear; it won't improve the maximum burst rate of 5 fps (or 3 fps if you're using the A850). If you want a fast CF or SD card these days then get a SanDisk Extreme but stay away from the Extreme Pro as the latter is very expensive and hardly any faster in cameras which don't support the UDMA-6 mode.

If you want to shoot long sequences, or rapid successions of short sequences, at maximum frame rate then consider switching to JPEG only. With a fast card, this will remove any limit from frame buffering, as Kevin already has pointed out above. Of course, this means you'd have to nail white balance and exposure at capture time, as JPEG files have only minor latitude for adjustments at post-processing time.

-- Olaf