10 mm f/5,6 OP-Fisheye

[Kim Pilegaard]

Probably, but available scale factors are limited by the focal ratio of the lenses of the relay module. Around 0.7X (or 1.4X if the module is reversed) is easy.

Combining two images taken with the 10.5mm and camera rotated 90 degrees between them will suffice, and is far easier to implement.

Here is a 10.5 mm capture on Nikon D750 (FX).

Thanks Bjørn,

I am aware of this technique which is of course great for completely still targets. For targets with some motion a relay lens could be a benefit. Could you give an example of what lens and extension combination could achieve the 0.7X needed. How about a reversed 20/3.5 ? I haven't yet completely understood the merits and metrics of using relay lenses.

 

[Bjørn Rørslett]

A single lens usually is insufficient as a relay option, unless there is a need for massive increase in image magnification. In this case the secondary lens simply magnifies the *real* image projected by the primary lens thus it ends up rotated 180 degrees on the recording camera. An example of this might be upscaling small-format cine optics to match an FX camera. Thus, I do have a set up for a Canon 6.5 mm f/1.8 cine lens ('D' mount made for the tiny double-8 cine format) that projects nicely onto FX, using a 19 mm f/2.8 Macro-Nikkor as a scaling agent.

The relay acts in principle to alter the conjugate distances for the primary lens. Thus it "transports" the image over some additional distance to a (more convenient)  location in which the image can be recorded. The relay module may alter scale of the final image, a feature usually desirable when working with fisheye lenses on different format cameras. Using two lenses in tandem (facing each other frontally) facilitates more advanced matching of the primary lens to a given format than available for the single-lens option.