|Posted: Thu Jul 26, 2018 6:46 am Post subject:
|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.
Camera modification, repair and DIY - some links to look through: http://www.4photos.de/camera-diy/index-en.html
I AM A LENS NERD!
Epis, Elmaron, Emerald, Ernostar, Helioplan and Heidosmat.
Epiotar, Kameraobjektiv, Anastigmat, Epis, Meganast, Magnagon, Quinar, Culmigon, Novotrinast, Novflexar, Colorplan, Sekor, Kinon, Talon, Telemegor, Xenon, Xenar, Ultra, Ultra Star. Tessar, Janar, Visionar, Kiptar, Kipronar and Rotelar.