D3200 SD card performance (and fallacies surrounding the D3200’s buffer capacity)

SanDisk Ultra 32 GB vs Lexar Professional 600x 32 GB.  On paper the Lexar is at least twice as fast for writes, thrice as fast for reads.

Test setup:  Nikon 55-300 @ 55/4.5 switched to manual focus (and slightly out of focus), VR on, in Program mode in a dimly lit room, framed roughly the same (closed blinds, if you must know).  The camera thus chose to shoot at ISO 6,400 and ~1/80.

Both cards typically achieve seven shots before “filling the buffer”.  In repeated trials the Lexar was able to get that as high as nine, just once, while both were able to hit eight perhaps a quarter of the time.

The Lexar then shoots at about 0.75 FPS.  All told 21 shots take 32 seconds to capture and completely flush to the card (of which ~19 seconds is pure write time).

The SanDisk shoots at about 0.5 FPS, with 21 shots taking over sixty seconds to capture and completely flush (of which ~35 seconds is pure write time).

Tangentially, and sadly, on a 2011 iMac’s built-in SD card reader they both perform essentially the same – limited by the SD card reader’s pitiful performance of at most 20 MB/s.  The Lexar might have a slight edge in writing, within that 20 MB/s limit, but both cards are far from their limits most of the time.  Stupid iMac.

It’s also a bit of a crappy performance from the camera itself.  Nikon’s own advertising (not to mention the camera’s official manual) state that it can fit eighteen RAWs in its buffer, but with the small-print caveat of being only at ISO 100 with noise reduction and distortion correction turned off.

Switching to Shutter-priority mode (1/500), at ISO 100 (thus producing a completely black image in my room, but representing a reasonable sunny outdoors config), the SanDisk was able to achieve nine, sometimes ten shots before the buffer filled.  Turning off automatic distortion correction gave it maybe one more.  Turning off noise reduction gave it another one, bringing it to at best twelve.  Pretty far from the eighteen Nikon claims.

The Lexar is actually able to get close, achieving seventeen pretty reliably.  Turn noise reduction back on, however, and that goes down by about three.  Bizarrely, turn on automatic distortion correction and it goes down to nine, which is both a dramatic drop for a pure black exposure – hint: there is no distortion! – and actually less than the SanDisk.  It was in fact barely better than at ISO 6,400.

The bottom line is, in realistic use the D3200 is capable of maybe ten shots at its advertised 4 FPS.

And the winner of the two SD cards?  The Lexar does have a clear advantage, even if you’re not filling the buffer immediately.  It flushes faster so you can do more frequent short bursts of four or five, which is much more typical of my use.  And it feels much more dramatic in practice than the numbers suggest.  It was also much more consistent – those 0.75 FPS were very evenly spaced, whereas the SanDisk had gaps of up to several seconds (which I’ve been very frustrated by in practice repeatedly).

Worth the price difference?  ~$30 vs ~$60.  Hard to say when comparing them in a vacuum.  But when you consider that the camera gear is worth way more than $30 to begin with, and capturing the right moments can be highly valuable, then $30 seems a pretty ridiculous corner to cut.  From now on, I’ll be choosing high end cards.  And possibly investing in a real SD card reader, one that doesn’t suck arse.

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