Why do many Z lenses have concave front elements?

Started 3 months ago | Discussions thread
Boudewijn van der Drift
Boudewijn van der Drift Senior Member • Posts: 1,229
Re: Why do many Z lenses have concave front elements?

capanikon wrote:

And why do many Z have very small front elements, like the 28mm f/2.8?

(Compare that to the 28mm f/2.8 F mount).

Because of the imaging process, the overall of all elements must be + (= concave). Otherise you would get no image on your sensor.

Then for most lenses it is desirable to keep them short, which asks for a + (group of lenses) and a - rear (gol). This was the original definition of telefocus design.

The reverse is necessary for (extreme) short focal lengths (especially for SLR's which have a flapping mirror to miss), a retrofocus design.

The sweet spot seems to be 55-58 mm (FF) where the designer can concentrate on correcting the front lens(group) alone. S0 there they splurge with Noctiluxes and the like.

 Boudewijn van der Drift's gear list:Boudewijn van der Drift's gear list
Panasonic Lumix DMC-LX3 Nikon Z7 Nikon Z6 Nikon Z 70-200 F2.8 VR +2 more
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