The 5% Solution

Started Aug 5, 2014 | Discussions thread
OP Stephen Barrett Contributing Member • Posts: 683
Re: The 5% Solution

MarioV wrote:

Maybe the 5% is the total amount of optical correction in the system.

Hello Mario,
When you say optical correction, do you mean that the original RAW image is distorted? I realize that there is a lot of distortion at the wide-angle end of the zoom, but thought that it should be negligible at the telephoto end where the full horizontal view angle is only 2.4 degrees.

So is this perhaps what is going on?: At and near maximum zoom, the focal length near the lens axis (centre of the frame) is as specified but, near the edges, the focal length and magnification are, say, 10% smaller. Once the corrections are applied to the RAW image by in-camera software, an undistorted jpeg image is produced, but with an over-all magnification that is about 5% smaller than the original at the centre.

Is that sort of what you have in mind? It sounds like a good explanation but I am surprised that there could be so much distortion at the telephoto end of the zoom. Perhaps the design at the telephoto end has been compromised in order to get a large zoom range, meaning that the distortion has been deliberately made worse at the long end in order to lessen it at shorter focal lengths.

It would be interesting to compare RAW and jpeg shots at full zoom of something with straight lines, like a faraway building. Thanks for your input.

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