 Posted: Wed Apr 22, 2009 4:34 am Post subject: Aetna Auto Coligon 135/2.8 T-mount - wait, how can that be ? |
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luisalegria wrote:
This is a very weird lens.
Its a T-mount lens, regular old T/T2 mount with no auto linkages.
It is in fact a pre-set, of a sort. The vendor called it "Auto" because of this -
That button on the focus ring stops down the lens when pressed; let go of it and the aperture springs back to open. It can also be locked, and then lens is pure manual aperture.
The button is on the focus ring because the apparent way one is supposed to use this is to use the focusing hand to close the aperture prior to pressing the shutter. Very good idea! Great ergonomic solution ! Well, not quite.
The cost of this is a complicated diaphragm mechanism and linkage system from the rotating barrel. Its ingenious, but it has problems.
It is an interesting solution to a very practical problem of its time - probably 1963 based on the JC sticker. Back then the T-mount was just becoming extremely popular with Japanese third-party lensmakers as it let them make a single lens good for all SLR mounts. They would otherwise have to supply 6-10 different versions of each lens, a terrible problem for a small manufacturer. However, Auto lenses with camera body linkages were also just then becoming popular, and this could not be handled with a T-mount. Some makers eventually developed interchangable auto-lens mount systems, like Tamron, Tokina, Sigma, etc. Whoever made this lens tried a different approach !
The downside is that it is complex, probably more so than an interchangable Auto-mount system, and also probably unreliable - mine sticks, for one thing. The second problem is that the focus rotation has to be short - this one turns just about 100 degrees to go from 6ft/2m->infinity vs the more usual 200+ degrees on a tele lens. This makes focusing challenging.
I don't know who made this. The Aetna brand, a successor to Taika, was used by a US photo importer for lenses by several makers, originally Tamron and Kyoei, and later Sun, among others. If I have to name a suspect here I would have to start with Sun, which did a lot of odd things like this, such as their pistol-grip zoom, which does something similar in a less complicated way.
As a lens, its not very good. It is rather poor at f/2.8 and it is difficult to focus accurately particularly at short ranges. Its quite sharp (what isn't?) by f/8. It doesn't suffer much from flare. I missed a lot of excellent shots with this. For collectors only !
The bird -
crop -
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I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work. |
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