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How to diy a focal reducer from apsc sensor.
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PostPosted: Wed Jul 25, 2018 1:36 pm    Post subject: How to diy a focal reducer from apsc sensor. Reply with quote

I've a fujifilm camera with apsc sensor and I want to convert it in a full frame with speedbooster system.
I've a lot of broken old lenses -
can I diy a focal reducer with vintage spares lens ?
I've seen on internet a dude that construct a focal reducer from Russian binoculars and use it for astronomy photography . He says the Lenses are the same of focal reducer adapters.
If I put this lens on my adapter ring can I obtain a reducer of angle of wiew ?

PostPosted: Wed Jul 25, 2018 4:43 pm    Post subject: Reply with quote

ok! i 've put a lens of a old zoom in the m42 ring and it's ok . There's a large reduce of angle of view. How possible?+
I don't' see a reduction of sharpness .

PostPosted: Thu Jul 26, 2018 6:46 am    Post subject: Reply with quote

I use such homemade speedboosters since years:
DIY speedbooster / focal reducer

From my point of view simple achromats could work as speedbooster, but the image quality and usabel field is not so good when a small factor is wanted. I rather use more complex speed booster systems with at least three lenses, sometimes even 6 lenses Double Gauss systems.
I mainly want factor 0.7x, 0.5x or beyond.

At the moment I often use comercial speedboosters, like the Kipon 0.7 medium format speedbooster for fullframe camera. But for example with the Canon FD 400 mm lens where I often use it, one of my DIY speedboosters showed in a short test nearly the same quality.

PostPosted: Tue Jul 31, 2018 3:05 pm    Post subject: Reply with quote

it's complicated. I've made test but quality of pics is poor .No sharp .
Now , i'll buy mitakon lens turbo II.