Neuroanatomist, thanks so much for that explanation. I was totally unaware of the sensor being a different size between those models.
Sorry for all the questions, but I’m just trying to understand the sensor size to picture quality relationship:
I already knew that DSLRs achieved better IQ due to the larger sensors, but I also assumed it was related to the lens being bigger in diameter therefore capturing more light.
The main thing that results in very large lens elements is the absolute aperture size. The aperture width increases in inverse proportion to the f number and in direct proportion with the lens focal length. Lens focal length increases linearly with sensor size.
So for example, the aperture on an 840mm f/5.8 full frame lens (same fov as the SX30IS) would be about 14cm wide. The front element would need to be somewhat larger than that.
So larger sensors require larger lens elements as do low f numbers, but the larger lens elements don't in themselves result in better image quality. So for example, the 35mm f/1.4L produces excellent images, and it's not a very large lens.
But in the case of (I’ll use current models so it’s not as speculative) S95 vs. SX30, the S95 has a larger sensor with a smaller lens, and vice versa. Does the larger piece of glass in the SX30 have any IQ advantages at all, or is it all about getting that "super " zoom?
You need a larger piece of glass to get the longer effective focal length. The reason they use such small sensors is that a full frame sensor would require a larger lens than Canon's 800mm f/5.6 lens.
I don’t want to be that consumer enamored by a gimmick, but on the other hand, 35x zoom is pretty useful assuming it’s not destroying IQ.
It's a trade off. Larger sensors result in better image quality, especially low light performance. Prime lenses and zoom lenses with a relatively short zoom range (about 3x or so) usually perform much better than super zooms. If we all cared about quality at all costs, we'd all use medium format cameras with primes.
But there are tradeoffs. Having said that, the fact that zoom range is very visible to the naive consumer whereas sensor size and maximum aperture are not, means that the typical user tends to give up a lot in terms of low light performance to get more zoom.
I know this is the Canon forum, but does anyone happen to know if the Sony DSC-HX9V and DSC-HX100V use the same sensor?
They both use small 1/2.3" sensors. All super zooms use small sensors. The 30X zoom camera weighs more than twice as much.
Another question: Assuming the S95 (and its successor) does have a larger sensor and better IQ than either of the Sony cameras above or Canon SX series, what other point-and-shoot cameras (Canon or otherwise) have a large sensor? Sensor size has not been on my radar until now.
You won't find any super zooms. Off the top of my head, the Canon S95, Canon G12, Olympus XZ1 and Panasonic LX5 are some of the leaders among compacts. You won't get a wide zoom range in any of these -- they're in the 5x ballpark. You can find more by searching snapsort.com, here's a starting point:
http://snapsort.com/explore/best-digital-cameras/1.7-sensor-size If you want good image quality in a compact, these are the ones to look at.
The mirrorless cameras (e.g. micro 4/3 like Panasonic GF3, Olympus EP3, Fuji X100) are small and have almost SLR sized sensors, but even a 3x zoom is quite large on one of these -- because you need more glass to cover the big sensor.
