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>The lens is f/3.9, which gives a resolution of about 400 lp/mm in visible light Assuming that you've got a perfect lens. As you say yourself "You must not ope

>The lens is f/3.9, which gives a resolution of about 400 lp/mm in visible light Assuming that you've got a perfect lens. As you say yourself "You must not open the lens fully", in which case the f/3.9 is irrelevant. And even stopped-down, the glass (of which there's several elements in the average compact's zoom) is rarely of the highest quality. All of this makes for an effective resolution some way short of the figures you're quoting. The quality of the lens can make a huge difference. On my main DSLR, the difference in quality between, say, the 50mm f1.2L and and an identical shot taken with a bog standard 17-85 f/4, even at the same f-stop is vast. If the cheaper lenses on DLSRs aren't able to really give enough quality to fully take advantage of higher MP, I'm not quite sure why you'd think that the ones on a compact would be.

klodolph 14y ago
> If the cheaper lenses on DLSRs aren't able to really give enough quality to fully take advantage of higher MP, I'm not quite sure why you'd think that the ones on a compact would be. You might be surprised at the quality of some of the P&S lenses. There have been excellent lenses on cheap fixed-lens P&S cameras for decades: a modern example is the Sony Cyber-shot DSC-RX100, an older example is the Yahsica Electro series from the 1960s. From resolution tests you can find modern P&S cameras with soft lenses and you can also find ones with real, honest 10+ MP resolutions. You don't need to trust my math, you can go check out test shots online. > As you say yourself "You must not open the lens fully", in which case the f/3.9 is irrelevant. I also wasn't really explaining things fully with the maxim. Opening the lens reduces diffraction and increases aberrations. A few good lenses will open all the way to, say, f/2 and still get sharper as you open them up. Some terrible lenses aren't sharp at f/8. However, the trade-off is different at different system sizes. For a P&S, wide open might be the best way to go. For MF and LF, you'll probably want f/11 or f/22 to start with, as ridiculous as that sounds. Of course, this assumes you want maximum resolution.
- prof_hobart 14y ago
  >You might be surprised at the quality of some of the P&S lenses. As I have owned several P&S cameras, and done plenty of test shots with them (including in controlled conditions, on tripods in good light etc - despite this not being how the average user is taking the vast majority of their photos), I would not be surprised by the quality of most of them at all. They simply aren't good enough to take a great deal of advantage of much about about 5MP. Yes, you can get ones with pretty good lenses on. But that's far from the norm - and the norm has for years been to fit high megapixel sensors on cameras than can simply not do them justice. Which was the point of my comment.
- Gravityloss 14y ago
  The RX100 ain't a point and shoot camera though, it costs more than entry level system cameras, 600 €.

klodolph 14y ago

> If the cheaper lenses on DLSRs aren't able to really give enough quality to fully take advantage of higher MP, I'm not quite sure why you'd think that the ones on a compact would be. You might be surprised at the quality of some of the P&S lenses. There have been excellent lenses on cheap fixed-lens P&S cameras for decades: a modern example is the Sony Cyber-shot DSC-RX100, an older example is the Yahsica Electro series from the 1960s. From resolution tests you can find modern P&S cameras with soft lenses and you can also find ones with real, honest 10+ MP resolutions. You don't need to trust my math, you can go check out test shots online. > As you say yourself "You must not open the lens fully", in which case the f/3.9 is irrelevant. I also wasn't really explaining things fully with the maxim. Opening the lens reduces diffraction and increases aberrations. A few good lenses will open all the way to, say, f/2 and still get sharper as you open them up. Some terrible lenses aren't sharp at f/8. However, the trade-off is different at different system sizes. For a P&S, wide open might be the best way to go. For MF and LF, you'll probably want f/11 or f/22 to start with, as ridiculous as that sounds. Of course, this assumes you want maximum resolution.

prof_hobart 14y ago
>You might be surprised at the quality of some of the P&S lenses. As I have owned several P&S cameras, and done plenty of test shots with them (including in controlled conditions, on tripods in good light etc - despite this not being how the average user is taking the vast majority of their photos), I would not be surprised by the quality of most of them at all. They simply aren't good enough to take a great deal of advantage of much about about 5MP. Yes, you can get ones with pretty good lenses on. But that's far from the norm - and the norm has for years been to fit high megapixel sensors on cameras than can simply not do them justice. Which was the point of my comment.
Gravityloss 14y ago
The RX100 ain't a point and shoot camera though, it costs more than entry level system cameras, 600 €.