Some guy bought some off-the-shelf parts and attached a Canon SLR lens to an iPhone, and without even releasing sample photos from his “iPhone DSLR prototype”, suckered several major sites into giving him traffic. The “tech bloggers” and most of the commenters are excited about the “potential” of this “cool idea”, going so far as to say that even if the initial results are low-quality, surely someone can refine it.

Optically speaking, this is precisely as cool as taping a 50-cent magnifying glass to your camera, just a lot more expensive and clumsy. It’s like putting on a pair of reading glasses: put a prime lens in front of another prime lens, and you get something that can only focus on nearby objects, with some amount of magnification.

Here, watch me turn my Blackberry into a large format view camera, with full movements!

Yes, I too can hold an expensive lens in front of a crappy one, and take a crummy picture! Send money so I can develop my prototype into a real product!

Now, it’s true that a $500 SLR lens will make a higher-quality close-up lens than a 50-cent magnifying glass, but for best results you should actually mount it backwards, so that the rear element is sticking out. And you should never, ever leave your rear element sticking out (this advice applies to more than cameras…). A tiny scratch on the rear element is much worse than on the front one, and there’s all those nice electrical contacts, etc. And, of course, no place to mount a lens hood.

(and why do I have a Walmart gift card handy? Because they opened a new superstore about a mile away, and sent us all grand-opening ads; some last-minute delays meant that the cards actually expired before the store opened, but I hadn’t planned to go there anyway)