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Kowa 55mm f1 lens?
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PostPosted: Wed Dec 29, 2010 9:20 am    Post subject: Kowa 55mm f1 lens? Reply with quote
Any idea about this lens?
Click here to see on Ebay

The same as this?
http://forums.dpreview.com/forums/read.asp?forum=1020&message=15838322


PostPosted: Wed Dec 29, 2010 10:35 am    Post subject: Reply with quote
The eBay lens seems to have aperture and focus control whereas the other one has none, so it is probably not the same lens. Could still be the same optical construction, though.


PostPosted: Wed Dec 29, 2010 1:35 pm    Post subject: Reply with quote
8310 wrote:
The eBay lens seems to have aperture and focus control whereas the other one has none, so it is probably not the same lens. Could still be the same optical construction, though.


The aperture and focus control seem to be from another parts lens.

The lens is a blue ray and worth 100$?


PostPosted: Wed Dec 29, 2010 4:08 pm    Post subject: Reply with quote
I guess another lens was butchered to be used as mount and focusing helicoid.
As the Kowa has no iris, I doubt that there is aperture control


PostPosted: Thu Dec 30, 2010 9:38 pm    Post subject: Reply with quote
Hm, I am not convinced.

The aperture rings shows a stop at f/1, how many lenses that one could butcher do have that?


PostPosted: Thu Dec 30, 2010 10:43 pm    Post subject: Reply with quote
8310 wrote:
Hm, I am not convinced.

The aperture rings shows a stop at f/1, how many lenses that one could butcher do have that?

There are some but mostly they are not very good wide open but rangerfinder glass I suppose (or some cine lenses?).


PostPosted: Thu Dec 30, 2010 11:17 pm    Post subject: Reply with quote
8310 wrote:
The eBay lens seems to have aperture and focus control whereas the other one has none, so it is probably not the same lens. Could still be the same optical construction, though.


+1
I was about to say that the seller is crazy by putting that price tag - but i saw it has focus/diafragm rings. I think it may be the same construction but one was x-ray lens and this one 35mm lens, maybe an updated version?
Anyway, i know nothing of kowa's glass, but sounds pretty interesting.


PostPosted: Thu Dec 30, 2010 11:51 pm    Post subject: Reply with quote
Guy in USA makes these conversions. Sadly i cannot find a link but he was mentioned here before and also on m4/3 rumors. His prices are even higher so this seller probably bought a sample from USA and now wants to get rid of it.

As i see USA tinkerer get a hold of many cheap lens parts and combine them with industrial surplus X-ray lenses. It looks great but sadly such Frankenstein lenses makes crappy photos. It seems at least one additional glass element is present in the back which strongly changes optical design. This isn't F1.0 (or faster) lens anymore and sharpness is greatly reduced. To work properly such lens would have to be less then 5mm from sensor.


PostPosted: Sun Jan 02, 2011 4:25 pm    Post subject: Reply with quote
Here is da man: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220717954339&ssPageName=ADME:B:SS:US:1123


PostPosted: Sun Jan 02, 2011 7:16 pm    Post subject: Reply with quote
Yep, that was discussed before somewhere. He must add a rear negative lens element to achieve a larger image diameter and longer register length. That of courses changes the focal length (longer) and decreases the lens speed - which he of course does not mention.
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