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Mid to late 1890’s. Zeiss patent lenses made by Ross had own their serial number progression.
This is a series IV wide angle design (Protar) covering just 12x15cm. Front lens has a diameter of 12mm. 80 to 100 degrees.
I guess this lens covers much more than 12x15cm.
I have a f/9 75mm Protar and Zeiss listed it with 90° angle of view and it really covers 4x5 inch.
The f/12.5 protar lenses have a larger angle of view. I mean 110° when I remember right.
So it should cover 8x10 inch.
Don't await an extreme sharpness but it is usable.
No it is the Series V (F1:18) which is the 110degree WA. The 112mm focal length covers 5x7”. The series IIIa (F1:9) has a 97 deg coverage so the no.3 ( focal length 172mm) is OK for 5x7”.
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