CV21 short term

[sean_reid]

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OK, 9 cm Leitz adapter and code as Elm 21/2.8

 

Cheers,

 

Sean

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[scott kirkpatrick]

Hi Bill,

 

Thanks. Do you want to code the 50 and 90? It will give you EXIF data but I doubt there will be much to correct in the way of vignetting or drift.

 

I think there may still be some surprises in store as we find out what Leica has quietly done in their firmware. For example, the longer lenses may actually get some vignetting because the microlenses at the edges of the Kodak chip are drawn in towards the center to catch the low angle rays of light from wide angle lenses. It will probably not be a big effect, and the coded Leica lenses will never show it... Cyan should not be a problem, as you say.

 

The lenses wider than 28 mm and faster than the Leica 2.8 and CV3.5 seem to be bigger than their focal lengths. In fact the Leica ultra wides get longer and vignette less as the focal length decreases. This suggests that they are getting more telecentric (and the pictures on the Cameraquest site support the same picture) as they get wider in angle. Which means that the vignetting problems, both overall and the extra red vignetting, may not get any worse as focal length decreases, until we add IR-cut filters in front. In front the AngleOfView does increase as focal length decreases. But Leica is adding those corrections to their promised 1.10 firmware next year...

 

scott

[waterlenz]

 

The lenses wider than 28 mm and faster than the Leica 2.8 and CV3.5 seem to be bigger than their focal lengths. In fact the Leica ultra wides get longer and vignette less as the focal length decreases. This suggests that they are getting more telecentric (and the pictures on the Cameraquest site support the same picture) as they get wider in angle. Which means that the vignetting problems, both overall and the extra red vignetting, may not get any worse as focal length decreases, until we add IR-cut filters in front. In front the AngleOfView does increase as focal length decreases. But Leica is adding those corrections to their promised 1.10 firmware next year...

 

scott

 

 

The Leica WA's are retrofocus designs (compare the current 21's to the non-retrofocus Leica Super-Angulons). The ratio between FL and BF of the longer WA's is less than that of the shorter FL WA's, hence the degree of 'retrofocusness' of the WA's is inversely proportional to FL. Probably also their tele-centricity as you surmise. It would be nice if Leica published the position of the exit pupil in the lens data sheets.

Tom