Ted and I were experimenting with the Nikon D70 the other day and got to wondering if faster compact flash (CF) cards were worth the extra money. Cameras like the D70 have large internal memory buffers, which allows more shots to be queued before having to wait on the CF card's relatively slower write speed.

I borrowed a Lexar 40x 256MB CF card from the office. I've been using a basic 256MB card from Viking. I thought it would be interesting to see how they compared. I know from other tests that the Lexar is capable of much faster transfer rates, but would the D70 take advantage of this?

The test was to put the D70 into multi-shot mode and then hold down the button and count how many rapid fire shots get taken before the camera starts pausing. In multi-shot the D70 captures sequential images pretty quickly, a little under a second between shots (1.2fps). Once the buffer is full this wait starts getting longer, how much longer depends on card speed.

The Viking card took 7, sometimes 8 shots before slowing down. The waiting time between shots once the buffer was full became 3 seconds or more. The Lexar on the other hand typically managed 15 or 16 shots before the buffer filled up, and even then the delay between shots was less than 3 seconds.

Summarizing this to Ted in an email I didn't think it warranted buying new memory since I've never used multi-shot mode on any of the cameras I've owned. Even if I started using that mode it seems that six or seven sequential shots are sufficient.

That is until I ran across the heron.

Zeke and I walked home from the office this morning (alas, after dropping off the fast memory card). We took the long way home and somewhat south of Poverty Lane ran across a Heron at an old Beaver dam. Zeke spooked it when he jumped in for swim, but the Heron didn't go far, landing in the branches of a tree at the end of the pond.

I had the camera in multi-shot mode, no real plan in mind, and stood still, waiting, hoping to catch it in flight. It took about five minutes and when it finally took off I held the shutter button and let the D70 rip. I'd forgotten about the filled buffer delay or I would have paced the shots.

Reviewing the photos on the computer I realized that it turned into an interesting real world example of why you would want faster memory. The composite shot below shows six of the first eight shots (two were in branches). The ninth shot was much later, when the Heron was almost overhead. The tenth shot is shown below as the heron passed by overhead.

In case you are curious I made the composite by overlaying the photos as layers in photoshop. Turn off all layers but the first two, with the second layer set partially transparent I aligned it with the first shot, then erased everything but the heron. The sequence was repeated for all of the remaining layers.

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