Faster autofocus! - General Chat - CHDK Forum

Faster autofocus!

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Faster autofocus!
« on: 01 / May / 2008, 05:05:01 »
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Hi folks!

I noticed something interesting on my A630. Well, when I use the scenic mode "kids & pets'', I noticed that the autofocus is quite a lot faster, and I also noticed that the camera did not search focus from the normal distance, say 20cm, but needs at least to be 60 or 70 cm from the subject. That means that the "focusing range" is smaller, and that allows the camera to focus, I would say, twice as fast. That's for the good news. Now the bad one: I never use scenic modes on my camera, I prefer P,A,S or M mode... but this "focus boost" only works when this particular scenic mode is activated.
So, would it be possible to implement this "function" into the CHDK-menu so that it could be used in wathever mode?
Thanks!

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Offline ISO64

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Re: Faster autofocus!
« Reply #1 on: 01 / May / 2008, 22:15:56 »
Noticed similar action on my PS A550. Bu, I think that focus is faster because camera switches to AutoISO, boosting sensitivity and requiring shorter exposures or smaller apertures. Also, it defaults to slightly wider angle. There is the benefit, depth of focus increases and camera does not have to go through many fine steps in order to achieve acceptable focus. As you mentioned, default minimum distance is already shifted further away where same number of focusing steps covers a wider range of obeect distances. You can have simillar effect to Kids&Pets by iso set to highest number that you can live with noise it produces and zooming out. Zoom out also helps by decreasing image smudging (kids run fast  ::))

Re: Faster autofocus!
« Reply #2 on: 02 / May / 2008, 13:57:24 »
Shutter speed and hi-iso has nothing do to with focusing speed. The only common place may be that when there is little light, the camera focuses slower, but that's another problem. The only reason why the camera focuses faster is that the "focusing range" is limited.

Re: Faster autofocus!
« Reply #3 on: 24 / May / 2008, 10:03:44 »
So? nobody wants to care about the question? If you have any information about that faster focus, please let me know.

Re: Faster autofocus!
« Reply #4 on: 25 / May / 2008, 04:49:44 »
I've had some of the same thoughts about my A720. I don't use scene mode either because you never know what settings it is changing.
I've thought of some kind of function where you can specify the focusing range and thereby improving focus speed. That would be a great advantage in many situations. Indoor activities, a ball game ect. It would also reduce focus hunting in low light situations. Maybe this should be a feature request...   

Re: Faster autofocus!
« Reply #5 on: 25 / May / 2008, 07:14:38 »
Thanks! Finally someone who thinks like me! There are lots of interesting feature requests on this forum, but there are also totally useless ones... and I was suprised to see that nobody cared for such an important thing as autofocus speed. I am not a programmer, so I don't know if it is possible. However, I think it is worth a closer look, maybe more than some other functions. As I saw that there are only (very) few reactions here, I will post a new thread in feature request.

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Offline fe50

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Re: Faster autofocus!
« Reply #6 on: 25 / May / 2008, 07:56:48 »
A630Lover, i played a bit with my SD870, i cannot discover this here - in kids&pets scene mode the autofocus seems to be as fast as in manual / auto mode (for SD870), perhaps there could be some ms difference...

On which AF frame setting (Center/AiAF/Face Detect) you'll see this ?

I don't know whether the autofocus can be controlled by CHDK - i think rather not...

Re: Faster autofocus!
« Reply #7 on: 25 / May / 2008, 08:30:00 »
The center frame is enabled, and it is impossible to change that when this mode is used.

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Offline fe50

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Re: Faster autofocus!
« Reply #8 on: 25 / May / 2008, 08:47:53 »
The center frame is enabled, and it is impossible to change that when this mode is used.
On SD870 you can change it, AiAF mode definitly works in the k&p mode, it's also listed in the manual...

Is it only a feature (as Face Detect) on newer models ?

 

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