It's hardly rocket science. Your smartphone doubles as your day-to-day compact camera but occasionally, just occasionally, you have a photo in mind that needs a serious zoom lens. You can't justify the expense of a dedicated lens, but you do have a pair of half-decent binoculars in the cupboard for occasional walking holidays and rare fits of ornithology. If only there was some way to fit the binoculars to your smartphone.
Regular readers may we call that, in the Snapzoom, just such a product is on the way in the shape of a US$69.99 adaptor (if you preorder, it'll cost more than that after the September launch) designed to fit any smartphone to any pair of binoculars. The effect (in the case of 10x-magnification pair of bins) is that of strapping a 330-mm lens to your phone.
But at $17.99, Carson Optical's adaptor significantly undercuts the Snapzoom. It's limited to iPhones – in fact it's designed specifically for the iPhone 5 and requires an adaptor case to work with the 4 or 4S (older iPhones need not apply). It also looks like a much simpler and more lightweight piece of kit, so dedicated snappers anticipating heavy use might do well to consider the Snapzoom. But for casual snappers, Carson Optical's adapter may be worth a look.
Neither product makes sense unless you already own the binoculars, mind.