How autofocus often works.

Brian

Top Veteran
Jul 7, 2010
103
I have some of the 1970s Photography magazines that explained autofocus. Nikon had a contrast-detection lens for the Nikon F, "almost released". I have a 1983 Nikon F3AF that uses phase-detection.

I still think the Polaroid SONAR system is the best.
 

Luckypenguin

Hall of Famer
Dec 24, 2010
123
Brisbane, Australia
Nic
The great thing about CDAF is that when it gets it wrong, it usually gets it totally wrong. When PDAF gets it wrong, it gets it a tiny bit wrong and unless you review immediately you may not realise until it's too late. I'd relate the story of trying to get the in-camera focus micro-adjustment sorted on a Sigma 30/1.4, a Canon 50/1.4, and a Canon 100/2, or knowing that the same lenses may be virtually unusable at larger apertures on a camera body without micro-adjustment, but I don't think that swearing is allowed on this board.
 

Brian

Top Veteran
Jul 7, 2010
103
The Nikon F3AF in autofocus mode reminds me of Second City TV's "Dr. Tongue's House of 3D cats". With the host bobbing back and forth from the camera to give the 3D effect.
 
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tattee

Regular
Sep 14, 2011
18
Oh that's why my GXR has a hard time focusing. The shallow DOF of the GXR works against the CD-AF. Maybe adjusting the aperture to f4-f8 will improve AF performance? Or am I not making any sense? :biggrin:
 

Luckypenguin

Hall of Famer
Dec 24, 2010
123
Brisbane, Australia
Nic
Funny thing about this article (dated 5 July 2010),
"The major drawback to contrast assessment autofocus is that it is slow"

Today, only 18 months later, look at Panasonic m4/3, Olympus m4/3, Nikon 1...

It could even be argued that in mid 2010 the Panasonic G1, GH1, and GF1 (with the right lens) were no slouches for AF either.
 

Naveed Akhtar

Regular
Dec 8, 2011
28
London, UK
It could even be argued that in mid 2010 the Panasonic G1, GH1, and GF1 (with the right lens) were no slouches for AF either.
Well don't wanna argue =] but is true. AF on my GF3 is noticeably faster than GH1 specially with the new lenses, but still GH1 got a speed that never actually make me feel its an issue of any kind. Its not fastest according to the current standards, but is always fast enough.

Still a good article for getting some insight know how.
 

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