Patents related to photo lenses

Started 6 months ago | Discussions thread
AiryDiscus Senior Member • Posts: 2,138
Re: Leica Summicron Mandler 1976

bclaff wrote:

AiryDiscus wrote:

bclaff wrote:

AiryDiscus wrote:

bclaff wrote:

AiryDiscus wrote:

bclaff wrote:

Dibyendu Majumdar wrote:

https://patents.google.com/patent/US4123144A/en

Officially the Leica Summicron R 50mm f/2

Like many "50mm" lenses it's actually 52mm

With how much distortion? Odds are pretty good that with the barrel distortion it has the field of view of a 50mm lens, or 50mm +/- some closer tolerance than 2mm.

For more information you'll need to try a more sophisticated program.

I said distortion not field curvature.

Sure. With a simple geometric ray tracer I'm not sure I can fully answer that question but the 45 degree angle of view in the patent matches up with a 52mm focal length scaling of the 100mm optical prescription.
Wouldn't distortion affect the angle of view? I'm pretty sure I've seen that with some extreme wide angle lenses.

Distortion is the difference between the paraxial and real image heights, if you tie FoV to a specific image height, then they are coupled that way. Otherwise, no.

OK. So with Image Height of 43.2mm and (measured) focal length of 52.02mm trigonometry predicts a 45.10 degree Angle of View. So the (measured) 45.59 degree measurement indicates a bit of distortion.

Real or paraxial image height?

All "normal" (in the sense of EFL/FoV) double gauss lenses have on the scale of 1-2% distortion.

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