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p.2 #8 · APS-C compact digicam? | |
Rob Riley wrote:
apparently my answer wasn't lucid enough for you
You are confusing short registers with focals close to the film plane.
the fact as you state it, that the Zeiss lens sits 2.1mm from the sensor in its operating state gives zip room to collapse the lens into the camera. That is the issue with the type of lens you prescribe.
I think you are missing the fact that when a lens collapses, it doesn't necessarily all collapse together. The elements move relative to each other, eliminating space between the elements (groups). That's how the space is saved. The whole lens doesn't have to move en masse. Take a look at some of the compact cameras out there. When the camera is turned on and the lens is extended, the lens becomes longer as each of the elements or groups of elements move into their position for use. It doesn't need space behind the rear element if it close, as that element (or group) doesn't have to move for storage when the camera is turned off. Further whether it is a "short register" or elements close to the film plane, it doesn't matter (but the 2 are, in many cases, related). It's all how the maker decides to move the lens and its elements between storage and use.
Finally, I didn't bring up the lens register issues. You did by saying, "such a concept is greatly dependent on the short register of the lens". That is only the case, if the lens is design NOT to collapse. Further, existing short register lenses for film and cine that you cited, are not a constraint on the design of such a camera, as the camera/lens maker can design a lens to meet the application -- such as they did with the R1 (short register and rear element close to the sensor plane).
In short, just so it is clear and to sum up, for a fixed-lens, compact digital camera there are basically 2 lens approaches possible:
1) A collapse-able lens design can be used to save space, or
2) a non-collapse-able lens can be designed so that the can be lens situated as far back in to the body of the camera as possible to save space and make the camera as compact as possible.
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