Frankenlens: Nikkor 105/2.5 AI hacked to Pentax K mount

wlewisiii

wlewisiii

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Since I recently bought a Pentax K5, I've been spending a bit of time hanging at the Pentax Forum as well. Over there in their marketplace I noticed something I couldn't resist - a Nikkor 105/2.5 that had been hacked (no other word for it) to the Pentax K mount. Given the differences in the two mount register differences this is a no return conversion but though it's not the prettiest job it the world it works and for the low price paid I am very happy with it. Still not sure why the ring has no Nikkor PC on it but it's otherwise very much an AI lens as far as I can tell of the later Gauss variety.

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First just a fairly close image in the office to make sure that everything was set correctly...even if it's set at 100 rather than 105 😉

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Channel 13's tower is far enough away from me to count as an infinity test as far as I'm concerned on a 7 degree morning...

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But one quick real image does make me think that, yeah, I'm going to get my money's worth from it...

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Not to take anything away from the Nikkor 105mm or from @wlewisiii's very cool converted lens, but if you're looking for a Pentax mount lens in that focal length, the 105mm f/2.8 Super Takumar is also a fantastic lens, with a very similar 5 elements in four groups optical design and superb Takumar build quality. I have this lens and think it would be very hard to improve upon it. I believe the later K-mount SMC Pentax 105mm f/2.8 and SMC Pentax M 100mm f/2.8 have similar optical designs. There's no shortage of excellent 100–105mm lenses in native Pentax mount!
 
Oh, to be sure, it was just more the fun factor and that it was available cheap and already done. I'd have not done it myself for that reason - lots of good glass native to the mount - but I couldn't resist the temptation to play 🙂
 
wlewisiii said:
Oh, to be sure, it was just more the fun factor and that it was available cheap and already done. I'd have not done it myself for that reason - lots of good glass native to the mount - but I couldn't resist the temptation to play 🙂
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Sounds fun! Looking forward to seeing more of your results.
 
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