While looking at the recently published spec comparison at our website many of our users are sending few common questions to us, it includes; How Panasonic is able to do AF in just 0.07 sec with the help of contrast based technology? Does DFD technology is actually a firmware or hardware thing ? Where does the Panasonic DFD Actually placed, inside the sensor or somewhere else ?
I want to keep this post as short as possible
What is DFD?
Panasonic DFD is hardware and exclusively designed & developed by Panasonic and it’s not a software. DFD autofocus relies on special hardware in the camera’s processor, so can’t be brought to older models via firmware updates.
How it Work?
Before we explain that we have to understand how the traditional contrast based system work, the traditional contrast detect system based camera actually. Camera having a normal contrast based Sensor determines the best focus point by moving the AF ring and scanning the entire subject, once the scan is done the lens AF reverse back to peak focus point. However when a Panasonic camera uses DFD technology, it quickly predict aka calculate the AF point and move AF point quickly there, finally it uses contrast based system to fine-tune the AF point.
So don’t get confused that Panasonic newly announced camera is using contrast based system only, the Camera AF based on DFD tech and later it fine-tuned by contrast AF. The biggest advantage of this technology that sensor doesn’t have any single dead pixel like other Hybrid AF sensors have for phase AF.
You are wrong. The CAF will first focus in one way, if thats the wrong way, it will focus in the otherway till it matches the focuspoint. So your wavepath is absolutly r**isch….
DFD ONLY saves this first possible step in the wrong direction, not more.
Regards
Jörg
The article is absolutely correct, in very short they have managed to explain how the DFD work. The DFD doesn’t scan subjects like traditional contrast detect system.. that results focus hunting issue in other cameras.
No, it correct isn’t for CAF, sorry.
It even isn’t correct for Video CAF, because it would “wobble” around the Focusplane, but not on it’s way to the Focuspane
regards
It is correct for DVD, but it isn’t correct for CAF, sorry.
It even isn’t correct for Video CAF, because it would “wobble” around the Focusplane, but not on it’s way to the Focuspane
regards
Best explanation I have found, please have a look at:
http://www.blogarithms.com/2013/10/21/how-does-autofocus-work/
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The only way the camera can determine whether the the image is in focus in the desired region is to send a signal to the autofocus motor, telling it to shift the focus of the lens and then see if the contrast increases or decreases. If it increases, the camera tells the motor to continue changing the focus in the same direction. If the contrast decreases, it shifts the focus in the other direction. The camera and motor keep going in that direction until the contrast starts to decrease, meaning they’ve gone too far. At that point the camera tells the motor to focus in the opposite direction. This hunting can go on for some time until (hopefully) the camera settles down and decides the image is in focus and ready for exposure.
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So the lens moves first in one direction, then check if the contrast is better. reverts the direction if not. (the “not”-part is the “only” part where DFD ist better! DFD moves 100% in the right direction from beginning on). Then it moves in that direction until the contrast stops to increase (on the other side of the focusplane). So it may toggel *around* the focusplane, but only once (not that often like in your diagram) on its way *to* the focusplane.
got it?
regards
Jörg
And here