One for camera buffs

[John Rumm]

With DSLRs it still would not help since you will still get different results on a full frame model than you will with an APS one.

[John Rumm]

Most of them...

If you buy into one lens system (say canon, or nikon etc) they both have models of camera with a number of different sensor sizes - and they will all take the same lenses (mostly).

The angle of view will change with the sensor size in the same way the effective focal length will.

[Richard]

Found this page with a variety of interesting calculators:

[Martin Brown]

Unless it is an extremely top end DLSR with a full frame sensor the right answer would be about 0.7x the 35mm film equivalent. So 17-1400mm.

But nowhere near the required resolution to use it. A lot of that huge zoom range must be empty blurry magnification disguised by camera shake. Handheld it is hard to go beyond 500mm even with shake reduction unless the exposure is very fast and the lens eyewateringly expensive.

Even with the degrees of freedom that are available to lens designers on compact cameras a 10x zoom range is really pushing it. Unlike for a classic film lens it doesn't have to create RGB images with exactly the same magnification only flat and in the same focal plane the software sorts out the final image during the demosaic process. Before these constraints were lifted a decent zoom range of around 3x was the norm.

To put it into context a 2000mm f10 mirror lens would be more usually considered to be an 8" SCT astronomical telescope and sit on a rigid tripod with 2" legs similar to that used by professional camera crews.

[Dave Plowman (News)]

With the same focal length lens, yes. The whole idea of stating angle of view for the combination.

[dennis]

A 16Mpixel sensor will have the same angular resolution in all the sizes for the same effective focal length. The larger sensors will usually have bigger cells so a higher dynamic range which can translate to better noise performance. There aren't many lenses out there that will out resolve a 24Mpixel camera let alone those 45Mpixel sensors that are about. I doubt if there are any old film lenses out there that are worth having a sensor with more than 16Mpixels, especially APS sized ones which put higher demands on the lens quality due to the smaller pixels.

2 inch legs are a bit thin for such a large scope IMO. Scopes are diffraction limited very few camera lenses are anywhere near that quality as they don't need to be. Its quite common for a scope to have lenses accurate to 1/10 wavelength or better but camera lenses don't have that accuracy.

[John Rumm]

The key there is "for the combination". I.e. the angle of view is not independent of the sensor size, and so is no more useful that the focal length.

The 35mm equivalent focal length of the lens / sensor combination however does tell you something more useful.