Perché 56mm

L’iPhone 7 Plus ha due fotocamere, a differente lunghezza focale: 28mm e 56mm. 56mm, come nota astramael, è molto simile al campo visivo di un umano — per questa ragione la lunghezza focale più comune su una DSLR è di 50mm:

35mm is an established standard for general photography. It was natural for Apple to target roughly that focal length in 2007, but since then the iPhone camera has mostly featured even wider lenses. Phone thickness limited focal length, and perhaps wide lenses are favored by customers as well. Then came iPhone 7 Plus. The dual camera system has significant implications for the iPhone as a photographic tool. I was not sampled an iPhone 7 Plus for this article. Comparison photos were taken using a camera set to 28mm and 56mm equivalent focal lengths.

Previously the iPhone had a significant limitation as a camera. It was wide angle only. Some marvelous photos are taken with a wide lens; many are not. According to ExploreCams the most common focal length used to take photos with DSLRs is 50mm. The most commonly used prime lens in DSLR systems is a fast 50mm. This is not an accident. 50mm is a well-placed compromise between wide and narrow focal lengths. It’s a very “human size” lens in terms of field of view, and it lets you isolate subjects effectively. Just as with 35mm in the first iPhone, it’s no surprise that Apple picked something around 50mm for their longer lens.

La nuova fotocamera funziona peggio in scenari a bassa luminosità, e in generale risulta meno stabile. Però funziona meglio nei ritratti e, assieme alla fotocamera da 28mm, permette all’iPhone di generare una mappa di profondità di una foto: essendo le due lenti a pochi millimetri di distanza fra loro, vedono una scena da una prospettiva leggermente diversa. L”iPhone può quindi sapere cosa si trova davanti e cosa dietro.

Apple usa per il momento questa capacità solo per l’effetto bokeh, ma secondo Ben Thompson è il primo tassello per una fotocamera più avanzata, che apra scenari più interessanti nella realtà virtuale e aumentata:

Bokeh, though, is only the tip of the iceberg: what Apple didn’t say was that they may be releasing the first mass-market virtual reality camera. The same principles that make artificial bokeh possible also go into making imagery for virtual reality headsets. Of course you probably won’t be able to use the iPhone 7 Plus camera in this way — Apple hasn’t released a headset, for one — but when and if they do, the ecosystem will already have been primed, and you can bet FaceTime VR would be an iPhone seller.