Yoshizen's Blog

Helicoid Lens (B)

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Helicoid Lens (B) is a sister of (A).  Both came from the same Sony Zoom lens and I’m using the same size helicoid which I got from China.

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So, this 18~200 Zoom lens became the SZ lens and the Helicoid A and B.  Well done.

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Lens was tested while temporally fixed on the camera using plastic pate, such as whether the lens should be used reversed or not, and with smaller Iris etc. (Photo middle) In order to adjust the infinity, lens was fixed on a M42 to M39 adaptor ring on the M42 to AI (Nikon) mount adaptor. —– after the infinity point was found, the position was fixed with super-glue. (Photo right)

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It seems this lens was an aspherical as the funny shaped reflection on the surface suggests. (Photo left)  This helicoid extends from 17mm to 32mm and the Lens which got about 35mm focal length can focus from infinity to 15cm close-up.  And the calculation from the exposure reading, the brightness seemed to be F2.2.

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Though, this lens is having very strong aberration. ( Astigmatism ?) —– same as the Lens (A), the center wasn’t too bad but image quality was one of the worst = which I appreciate a lots.  😀     (It’s so rare to find this kind of image in the photography because, nobody design the lens like this for sale.)

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(Photo here above, Left was the (B) lens in its finished looks — looks cool isn’t it ?   😀  And the right showed the Lens’ closest view, which showed its softness for comparison.)

For impressionistic fuzzy image, the poorer the lens quality, the image looks more interesting. (I think / and that was where Pinhole Photography stands) —– strangely, the close up image was rather sharp. (I mean its center was) (Photo right)  —– Whatsoever, I’m quite happy with its outcome.   😀

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Catkins on Alder Tree

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Few days ago, I gave a peek to a broken Sony DSLR lens through Canon 5D

and saw it still works as a  200 mm optics.  —– then, I realized, what I saw

was not just a shape of a winter tree.  —– It’s Catkins there already !

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With a serious attempt, I took picture of it with 500 mm lens on a tripod.

Yes, in deed it was the Catkins. = Without having any serious cold spell,

London started to have a Spring. —– I wouldn’t say I like cold but,

I believe the nature needs it as a cycle. 

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The lens I was playing was the one I bought for £10 as a broken junk =

Sony-Minolta’s 18-200 mm Zoom lens, which has been seemingly dropped

and the barrel was broken into pieces. —– Still, amazingly, the main optics

kept its integrity and maintained its function = it can Zoom, and focus,

F-aperture is still working (though, setting only from the body side).

Since the Sony DSLR lens has Flange-back 44.5mm, to focus a bit forward

(in fact, 0.5mm exact) can give an infinity focus on Canon EOS body.

With some test shot, I was pretty impressed with its clever design and the

resilience = It’s a broken lens though, it is still usable as 18 mm to

200 mm lens. (with certain manual improvisation ! )

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Lens Tool-590-001

(Photo Left / Edge of the Lens was welded.   Center / Screw mounted Lens.  

Photo Right / Pincer Tool for the Lens mount ring.  This tool

called “Kanime” in Japan was given by the Pentax (Asahi-Kogaku)

—– Code of the tool = AK-1-1-LA means Asahi-Kogaku-1-1-Lens Assembly

when I had an exhibition in their Gallery in Tokyo )

But because it was made using  “Hot stamp” (drop a lens into plastic barrel

then heat seal) it was not expected to be disassembled and it was very hard

to modify and re-use.  —– I’m thinking what to use or making out of it ?

(Use for projection kind may be interesting, as the lens got

more than x11 times Zooming ratio.) 

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