Jerome Marot
Well-known member
(As Dave Barry would say, this title would make a good name for a rock band).
I shall say it up front: I have a weak spot for optics. I don't necessarily make better pictures for it, but I find it difficult to resist the call of the weird -optical engineer on acid- lens. I also have a weak point for bokeh and love the perspective given by a 100-135mm lens (on 35mm film). So the stars were aligned for the following test.
"Bokeh" a Japanese word (ぼけ) meaning "unsharp" is used to describe the appearance of the parts of a photographic image outside the plane of focus. I am sure you all know about it and how fuzzy elements can be nicely fuzzy or horribly fuzzy. Believe me, there is a whole theory behind it.
Camera lens manufacturers being what they are (that is: Japanese), there have been lenses designed especially for bokeh. For 35mm film or equivalent digital formats, two manufacturers shall be presented here: Nikon with their DC series lenses (that means "Defocus control") and Minolta (today: sold under the Sony brand) with the 135mm STF (that means "smooth trans focus", I swear I am not making this up).
Nikon has two "DC" lenses, a 105mm f/2.0 and a 135mm f/2.0. They are AF-D lenses, meaning screw-drive autofocus with a real aperture ring. They should work on most Nikon cameras. They are very well built, mostly metal, but have a real manual focus ring like in the old times. They are supposed to autofocus, but my experience has been that the DC feature fools the AF system wide open, even if you try to refocus. They are very sharp lenses, don't let yourself be fooled by the "defocus" in "DC". The bokeh part: they have a ring to adjust whether you want what is in front or to the rear part of the focal plane to look nicer. Optical engineers will understand that this command fiddles with the spherical aberration of the lens. You will find a review here or here.
Minolta issued a special bokeh lens in 1999, the 135mm STF. It is one weird piece of engineering: it won't AF (but has a manual focus ring better than the ones we had in the old times), has two diaphragms (only one is used at a time), one with a wealth of blades for the bokeh thing and confuses you with two set of apertures: T and F stops. It has the transmission of a f/4.5 lens with the depth of field of a f/2.8 lens (in plain English it is dark). It does not fiddle with aberrations as Nikon does, but uses an apodization element (which is a fancy word to describe a lens dark on the outside). There is a whole site devoted to it here. It is also a very sharp lens in its plane of focus, of course.
That was a very long introduction, but I suppose you understood where I was heading to: I had the occasion to compare the two lenses today. Here are the pictures:
I shall say it up front: I have a weak spot for optics. I don't necessarily make better pictures for it, but I find it difficult to resist the call of the weird -optical engineer on acid- lens. I also have a weak point for bokeh and love the perspective given by a 100-135mm lens (on 35mm film). So the stars were aligned for the following test.
"Bokeh" a Japanese word (ぼけ) meaning "unsharp" is used to describe the appearance of the parts of a photographic image outside the plane of focus. I am sure you all know about it and how fuzzy elements can be nicely fuzzy or horribly fuzzy. Believe me, there is a whole theory behind it.
Camera lens manufacturers being what they are (that is: Japanese), there have been lenses designed especially for bokeh. For 35mm film or equivalent digital formats, two manufacturers shall be presented here: Nikon with their DC series lenses (that means "Defocus control") and Minolta (today: sold under the Sony brand) with the 135mm STF (that means "smooth trans focus", I swear I am not making this up).
Nikon has two "DC" lenses, a 105mm f/2.0 and a 135mm f/2.0. They are AF-D lenses, meaning screw-drive autofocus with a real aperture ring. They should work on most Nikon cameras. They are very well built, mostly metal, but have a real manual focus ring like in the old times. They are supposed to autofocus, but my experience has been that the DC feature fools the AF system wide open, even if you try to refocus. They are very sharp lenses, don't let yourself be fooled by the "defocus" in "DC". The bokeh part: they have a ring to adjust whether you want what is in front or to the rear part of the focal plane to look nicer. Optical engineers will understand that this command fiddles with the spherical aberration of the lens. You will find a review here or here.
Minolta issued a special bokeh lens in 1999, the 135mm STF. It is one weird piece of engineering: it won't AF (but has a manual focus ring better than the ones we had in the old times), has two diaphragms (only one is used at a time), one with a wealth of blades for the bokeh thing and confuses you with two set of apertures: T and F stops. It has the transmission of a f/4.5 lens with the depth of field of a f/2.8 lens (in plain English it is dark). It does not fiddle with aberrations as Nikon does, but uses an apodization element (which is a fancy word to describe a lens dark on the outside). There is a whole site devoted to it here. It is also a very sharp lens in its plane of focus, of course.
That was a very long introduction, but I suppose you understood where I was heading to: I had the occasion to compare the two lenses today. Here are the pictures: