New Zeiss M-lenses

[doubice]

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what is the another factor that make these large aperture WA big lenses?

 

Matthew

 

Hi Matthew,

 

Just read my post no. 17. The explanation for the size of retrofocus wideangle lenses is quite clear.

 

All the best,

 

Jan

[MP3]

Dear Jan

 

As some members here said, "Thanks for bringing down the hay for we sheep to eat =) " on the relationship between retrofocus and lens size. That said, the ZM Distagon must be a prime example of rf WA lens.

 

Best

Matthew

[rosuna]

Retrofocus designs helps in getting some degree of "telecentricity" to the lens.

[wizard]

what is the another factor that make these large aperture WA big lenses?

 

By using larger (larger than necessary by the pure mathematical calculation for a given f-stop that is) front elements, lens designers try to counter artificial vignetting (light falloff in the corners) as much as possible. A case in point are the comparatively small CV wideangle lenses (4/21, 4/25 etc.) that do produce much more noticeable corner vignetting (due to their smaller front element) than e.g. their Leica counterparts (2.8/21asph. and 2.8/24asph.). Only part of the much bigger front element diameter of the Leica lenses seems to be needed for the additional f-stop, the rest is most likely used to reduce the extent of corner vignetting.

 

Andy

[albertwang]

How can we measure the amount of light fallout? I would be interested!