[vosper]

Is low light something that a lens attachment over the iPhone camera could help with? There's a few lenses out there that are supposed to be quite good (like the Moment ones) but I don't know if they help out with that. It would be interesting if they kept the FOV the same and just provided more light.

[overcast]

No, you still need a LARGE sensor to capture all that light. You're just not fitting that in a cell phone.

[sho]

Well, you could collect a huge amount of light and send it through to the phone sensor; that would have the same effect. But you're talking a very big lens. The pro DSLRs have a 35mm sensor - that's ~865mm². The iphone's is what, 60mm²? Thereabouts?

No matter how you cut it, that's generously 1/10th the sensing area/capacity (same thing). And it's not like the sensor tech in the iPhone will be 10x more efficient than contemporary DSLRs - iPhone sensors are made by sony, who will use the same tech in their own cameras. To get comparable light cell for cell into that you'll need a lens with 10x more light ingress, and sophisticated optics to focus it precisely down to a tiny half-square-centimetre. This lens would be larger, heavier and more expensive than the phone itself. Think "large can of tomatoes" size.

Not saying it's impossible. Mobile phone companies have pulled off some amazing advances and I have no idea what tricks might be up their sleeves. But for now, no mobile even touches full frame DSLRs in low light, and it doesn't seem like an easy hill to climb.