IQ250 Alpa FPS and Zeiss 25mm f/2 or Zeiss 14mm Image Circle

[Murray Fredericks]

Hi All,

Further to an earlier post,

has anyone tried the Zeiss  25mm  f/2 on the IQ250 using and Alps FPS? Does it cover the sensor (completely, almost, not at all)?

Also, has anyone tried the 14mm Zeiss after removing the lens hood?

Cheers

Murray

[chrismuc]

I can test and tell 2 weeks later when I have the Zeiss 25f2 and the FPS in one location.
But from using the ZE 25 on 24x36 I know that already there the corners are not perfectly sharp at f 8 or 11, so I would not expect anything convincing outside a 43mm image circle.

[Murray Fredericks]

Thanks Chris,

that softness in the corners on 35mm is quiet surprising...I thought the lens was some sort of 'super-lens'...

Thanks

Murray

[ErikKaffehr]

Hi,

Many Zeiss designs drop of in the corner. They design with a large 'sweet spot', but compromise on the corners.

See the MTF curves below.

From this document: http://www.zeiss.com/content/dam/Photography/new/pdf/en/downloadcenter/datasheets_slr/distagont2815.pdf

Canon T&S lenses 17 and 24 mm may be the best option for your FPS if you are looking for 135 lenses usable with MF.

Stefan Steib of hartblei.de used to have a table of usable image circles, but I cannot find it.

Best regards
Erik

Thanks Chris,

that softness in the corners on 35mm is quiet surprising...I thought the lens was some sort of 'super-lens'...

Thanks

Murray

[chrismuc]

The ZE 25f2 is a "super lens": sharp from f2, but only within 90% of 135 image circle ;-)
Same issue with ZE 21f2.8 and ZE 50f2.
But the old CY 21f2.8 is a "super-duper lens": sharp within 100% of 135 image circle :-))
Btw, I tried the CY 21f2.8 on my FPS: Unfortunately no extended image circle.
Hmm, as far as I remember, the image circle of the Leica R 28f2.8 (last version) was slightly larger, so maybe a wide angle option for the FPS with 44x33mm sensor.
And: The (affordable) Schneider 28f2.8 PC and Zeiss CY 35f2.8 shift lenses both have 62mm image circle, so should work well with a 33x44mm sensor.

[ErikKaffehr]

Hi,

AFAIK the ZE 2.8/21 doesn't have the same problem and it is identical to the CY 2.8/21, but the CY lens was made by Yashica/Kyocera using Hoya glass.

Best regards
Erik

The ZE 25f2 is a "super lens": sharp from f2, but only within 90% of 135 image circle ;-)
Same issue with ZE 21f2.8 and ZE 50f2.
But the old CY 21f2.8 is a "super-duper lens": sharp within 100% of 135 image circle :-))
Btw, I tried the CY 21f2.8 on my FPS: Unfortunately no extended image circle.
Hmm, as far as I remember, the image circle of the Leica R 28f2.8 (last version) was slightly larger, so maybe a wide angle option for the FPS with 44x33mm sensor.
And: The (affordable) Schneider 28f2.8 PC and Zeiss CY 35f2.8 shift lenses both have 62mm image circle, so should work well with a 33x44mm sensor.

[chrismuc]

Sorry Erik, they are a bit different. The CY 21 is a 15 lens design using glass with abnormal partial dispersion and high refractive glasses, the ZE/ZF 21 is a 16 lens design described by Zeiss: "This full-frame lens is the direct successor to the legendary Distagon 2,8/21. It has been recalculated on the basis of the proven design and equipped with modern, environmentally friendly types of glass."
The 40 l/mm mtf of the ZE 21 is slightly higher over 90% of the frame than of the CY 21, but the fall-off towards the corners is steeper.
Unfortunately only f5.6, no f8 of f11 mtf curves available.
Sample pic by CY 21 @ f11 on 5DII:
https://dl.dropboxusercontent.com/u/18437364/dpi/CY21f2.8atf11_5D2-02.jpg
Sorry, I can't provide a sample pic of the ZE 21 but the slight lack of corner sharpness is described by many users online.