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Ghetto P67 to Emount turbo with p67 165 2.8
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PostPosted: Fri Apr 21, 2017 11:16 pm    Post subject: Ghetto P67 to Emount turbo with p67 165 2.8 Reply with quote
Cobbled together this "speedbooster" with foam, black tape and an AP67 2x converter reversed between camera A7ii, and lens P67 165mm 2.8. Obviously due to the mount being male to male at one end could not get proper distances. Somewhere I read that a speedbooster could be thought of as a teleconverter in reverse so that is where the concept came from. Results? well lets just say aberrations abound but the images turned out interesting at least.

the contrivance:












PostPosted: Fri Apr 21, 2017 11:23 pm    Post subject: Reply with quote
I like 'interesting', there's nothing wrong with it at all. Wink


PostPosted: Fri Apr 21, 2017 11:46 pm    Post subject: Reply with quote
The 165 2.8 is REALLY a sharp lens. The AP67 is a "decent" aftermarket converter but not up to Pentax standards. I was kind of hoping for a bit sharper image but sure is a lot of fun to play with these things. I LOVE my A7ii, it makes me look like I know photography. LOL The setup is HUGE, the P165 is a big lens and the adapter is large then a 1/2 inch of foam. Positively dwarfs the camera. I keep hoping Kipon or someone makes a speedbooster adapter from P67 to EOS (or E-mount!).


PostPosted: Sat Apr 22, 2017 8:07 am    Post subject: Reply with quote
There is a medium format speedbooster already on the market...


PostPosted: Sat Apr 22, 2017 3:07 pm    Post subject: Reply with quote
Thanks Klaus, I was unaware they had come out with the p67 to e-mount adapter. I knew they had a Hassy version.... I had heard rumor so I checked a few months ago. Must be pretty new. Anyone out there tried the thing? Five hundred seems pricey.


PostPosted: Mon Apr 24, 2017 10:28 am    Post subject: Reply with quote
A reversed teleconverter is still a teleconverter, sorry about this.
A teleconverter has a negative focal length, a speed booster a positive focal length (like a normal lens).
And this does not change when they are reversed.

You can use a normal lens as speed-booster / lens-turbo - especially those with long flange back distance.
I have done some DIY speedboosting, most times with factors like 0.5 or even more extreme:
http://www.4photos.de/camera-diy/Super-Fast-Tele-Lens.html

At the moment I work a lot with the Kipon medium format 0.7x speedbooster with a bit of modification.
I do not use it on the lenses it was intended for, but for example on the Canon FD 400mm/2.8L super telephoto lens.
https://www.flickr.com/photos/time-4-photos/33271642956/
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