Daisies in Black & White -- NEX-5N & Leitz Hektor 120mm f2.5 Projection Lens. Click for larger.
I now have a helicoid with aperture control, which adds a lot of flexibility. Sometimes a little bit of depth of field can make the picture look quite different from wide open. Often, I like pictures taken wide open. This seems to bring out the optical qualities of the lens in use. This is the case with the Hektor 120mm f2.5. When stopped down, the bokeh looks a bit strange. Maybe it's due to the aperture blades of the helicoid. Both the Hektor 120mm f2.5 and Colorplan 90mm f2.5 share similar optical qualities.
Young Iris - NEX-5N & Leitz Hektor 120mm f2.5 Projection Lens.
I think this type of circular formation bokeh is the result of placing the aperture iris way behind the lens and close(r) to the image sensor. The only supporting evidence I have for this hypothesis is that damaged rear lens elements affect images much more than damaged front elements. Also almost all lenses place the aperture iris somewhere in the middle of the lens group, allowing the rear elements to correct any issues.
ReplyDeleteYou are probably right. Having the aperture behind the lens is a bit weird and unusual. Oh well, it's either front, or rear, I guess.
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