Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: wolfnowl on November 02, 2013, 02:28:54 pm

Title: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: wolfnowl on November 02, 2013, 02:28:54 pm

Interesting read...

http://www.digitalcameraworld.com/2013/11/01/phase-detection-autofocus-how-your-dslrs-af-system-actually-works/

Mike.

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: Ellis Vener on November 02, 2013, 03:57:35 pm

This is a better read: http://graphics.stanford.edu/courses/cs178-13/applets/autofocusPD.html

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: wolfnowl on November 03, 2013, 01:27:33 am

It's certainly more detailed!  That means it's not as simplified and doesn't have a cool infographic.  ;)

Thanks for sharing it.

Mike.

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: NancyP on November 05, 2013, 10:11:04 am

thanks for both.

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: NancyP on November 05, 2013, 10:48:50 am

The Stanford PDAF applet and a linked Stanford CDAF applet
http://graphics.stanford.edu/courses/cs178-13/applets/autofocusCD.html
are helpful in explaining why Canon is making a big deal of its new dual-pixel on-sensor focusing system used on the 70D midlevel APS-C camera.
http://learn.usa.canon.com/app/pdfs/articles/Canon_Developers_Interview_nonfacing_pressquality.pdf
The marketing emphasis had been on the utility of the new Canon AF technology for video, but it strikes me that this Dual Pixel AF would be "a killer app" in a mirrorless camera, allowing phase detection speed with compatible AF lenses. The only non-SLR cameras I have are the Sigma DP2M and DP3M, which I tend to use in manual focus mode almost exclusively, but I have noticed that mirrorless camera users complain about slow focus speed. Canon should move quickly to insert this technology into its fixed-lens and interchangeable lens compact cameras.

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: Isaac on November 05, 2013, 01:34:48 pm

Quote from: NancyP on November 05, 2013, 10:48:50 am

The marketing emphasis had been on the utility of the new Canon AF technology for video, but it strikes me that this Dual Pixel AF would be "a killer app" in a mirrorless camera, allowing phase detection speed with compatible AF lenses.

That sounds good but this this doesn't -- "Worse still, the screen blacks out completely during continuous shooting (http://www.dpreview.com/reviews/canon-eos-70d/12), making the whole thing something of a guessing game, particularly when panning to follow a moving subject. This means that Dual Pixel AF is effectively limited to being a 'one shot' mode when shooting stills."

Title: Re: Phase detection autofocus: how your DSLR’s AF system actually works
Post by: NancyP on November 05, 2013, 07:09:02 pm

Yes, that needs to be fixed. I find it odd that they can manage the video mode without blackout but not high-speed continuous stills.