View Full Version : Image circle Zeiss 120 macro?
Does anybody know what the image circle is of the Zeiss S-Planar 120 mm f/5.6 macro? I understand it is a single coated (not T*) lens issued both as a large format lens (barrel/Copal 0) as well as for Hasselblad. The latter would suggest limited LF application (maybe 6x9, but possibly not 4x5).
Given that it was also used for MF, I guess it is most likely optimized for around 1:5-1:2, with decent performance at 1:1, maybe 2:1. So image circle at 1:5 - 1:2 would be most meaningful.
Anybody has any opinion on performance for colorwork in 4x5?
Some guideline for experimentations !
Regarding the possible image cirle of a 120 S-planar 120-5,6, my feeling is that the effective image circle is probably mechanically limited by the Hasselblad mount and not by the optical design itself.
The S-planar being a quasi-symmetrical 6-element lens I would expect at infinity a usable angle bigger than for a tessar, i.e. bigger than 60°. We know that the Schneider G-claron, another symmetrical 6-element design is given for 64° and this figure is well-known among LF aficionados to be conservative.
But if we assume 60°we should expect and image circle at infinity bigger at least than 120 mm (at 53° : diagonal = focal length). If we double this diameter at 1:1 ratio, we eventually expect something usable for 6x9 at infinity ; for 4x5", my guess would be : optically, yes it could cover at the nominal reproduction ratio of 1:5, if stopped down properly, but check with the lens mount.
Daniel, if you're going to try the lens above 1:1, reverse it. It is designed to have the large subject in front, the small negative behind. Above 1:1, it will have the small subject in front, the large negative behind, and this isn't what it was designed for.
Emmanuel, the lens covers 80 mm at infinity. So at 1:1 it will cover 160 mm. Possibly more, as you suggest. I have no experience with f/5.6 6/4 double Gauss types, but my faster ones (f/2.8, f/2.0) don't cover much more than their focal lengths.
Thanks to both of your informative replies. The bottom line is that it may be marginally suitable for 4x5 (diagonal 160 mm) at 1:1 with not a lot of movements. Re limitation by Hasselblad mount, I don't think that is it. The lens in the LF variation has the typical double cone arrangement.
Daniel, the one I had would produce a 4x5 image up close, but suffered from chromatic aberration in the corners. It looked like it was intended for a much smaller format.
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