Why are there no digital cameras with ultra-bright integrated lenses, like f1.0, f1.2 or even f1.4?
One would think that with smaller sensors vs. film, it would be much cheaper to build an ultra bright lens. It's easy to find superzooms, 20X or 35X, but I have not been able to find a camera with a decent sized sensor and an f1.0 or f1.2 lens. There are also no EF-S lenses brighter than f2.8 I think. On the other hand, camcorders routinely have f0.95-f1.2 lenses. Does anyone know if there is a technical reason for this?
I believe F1.4 is the best you can do on a compact so far:
You know from 35mm format lenses that it is hard to find those that are sharp wide open. it is hard to get all those rays of light to hit a single small dot. On a compact sensor, those dots are even smaller and you need a lot of glass to correct those rays to fit into a tight spot, making the lens design pretty expensive. Now, expensive components and compact cameras don't go hand in hand, because people who buy compacts, are usually not the type who wants an expensive camera - they go for DSLRs. So the F1.4 is pretty impressive for a 500-600E price point, but the lens does take up quite some space for a compact.
The larger the maximum aperture, the larger the lens. Therefore fitting an ultra-bright lens works against making the camera small. The size also increases in proportion to the focal-length, so the more zoom you fit in, the harder it becomes to make an ultra-bright lens can keep it compact.
There are a number of F/1.8 lenses in compact cameras but you will notice that most dim down quite a bit as they zoom in and rarely reach more than 4X optical zoom. A Fuji XF1 for example closes down to F/4.9. Notable exceptions are the Olympus XZ-1 / XZ-2, Pentax MX-1 and Panasonic LX7 which has the brightest lens on the market, an F/1.4 - 2.3, equivalent to 24-90mm.
On "On the other hand, camcorders routinely have f0.95-f1.2 lenses", I simply dispute this finding. Take a skim at PL lenses available, there aren't any lens close to f1 that's economically reachable, which brings me to point 2.
I refer to Erwin Puts, lens expert. In his Leica Lens Compendium, he mentioned many technical difficulties in achieving fast apertures beyond f1.4 e.g. Noctilus. The details are beyond the scope of this discussion; it suffices to say that making "ultra bright integrated lenses for digital cameras, like f1.0 f1.2" isn't feasible for consumer class small cameras (think phones). Stuffing and miniaturizing those glasses in a small package, while trying to make an acceptable image on a small sensor proves to be difficult for this price segment.