Universal Manual Focus - page 3 - Feature Requests - CHDK Forum
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Universal Manual Focus

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Offline nirschi

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Re: Universal Manual Focus
« Reply #20 on: 11 / July / 2008, 09:49:33 »
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@jbourgui:
Focus distance override, bracketing and pseudo MF-mode via ALT-mode+KEY_UP are available on ixus/sd cameras since AllBest 34. They are based on calls to Canon's MoveFocusLensToDistance() routine. As far as I remember, ewavr did the ixus700/sd500 port and noted that this call always crashed - so it has been disabled.

About magnified focusing:
LjL said it (nearly) all. My tip: use focus bracketing and select the best shot at home.

Cheers
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Offline LjL

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Re: Universal Manual Focus
« Reply #21 on: 11 / July / 2008, 10:16:05 »
Or use focus bracketing while using my best shot selector function to delete all shots but the one in focus ;)

But, while that works in general, it's no real good for very close-up macros (which my A720, and probably most other Canons, are very good at), because the focus step is 1mm, and the depth of field can be less than or very near to 1mm...

So you would have to physically move the camera to obtain perfect focus, but you can't do that if you can't look at the magnified image :(
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Offline fudgey

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Re: Universal Manual Focus
« Reply #22 on: 11 / July / 2008, 10:59:09 »
Couldn't this improved focus thing be somewhat achieved by temporarily overriding the camera to use its digital zoom? The greater the level, the better. This would actually be highly helpful even when using automatic focus (because these cameras don't have point focus and autofocus can't read people's minds...this is probably among the top 3 most annoying things in my a570is).
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Offline LjL

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Re: Universal Manual Focus
« Reply #23 on: 11 / July / 2008, 11:36:05 »
Well, but you can use the "digital teleconverter" setting to invoke digital zoom on demand (on my camera, it can be assigned to the Alt key, except a little bug makes it interact badly with CHDK).

The problem is that it's just 2x, just like the standard magnifying window that you get with manual focus...

Actual digital zoom - not the digital teleconverter - seems to do 4x on my camera (since the optical zoom is 6x, and it claims 24x total), but I have no idea how to invoke it without invoking optical zoom, too.

If that's possible, though, it would indeed be handy!
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Offline fudgey

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Re: Universal Manual Focus
« Reply #24 on: 11 / July / 2008, 12:13:24 »
Quote from: LjL on 11 / July / 2008, 11:36:05
Well, but you can use the "digital teleconverter" setting to invoke digital zoom on demand (on my camera, it can be assigned to the Alt key, except a little bug makes it interact badly with CHDK).

The problem is that it's just 2x, just like the standard magnifying window that you get with manual focus...

Actual digital zoom - not the digital teleconverter - seems to do 4x on my camera (since the optical zoom is 6x, and it claims 24x total), but I have no idea how to invoke it without invoking optical zoom, too.

Hmm.. I had actually forgotten about that one, I've never used that Canon built-in shortcut feature for anything because it interferes with the alt key (always does the selected command after exiting alt mode, even though I guess it shouldn't...). Indeed 2x (1.9x for my a570is) is not that much, but it could be useful sometimes if alt key was fixed.

Digital zoom is 4x max for a570is as well (goes to 16x total). Obviously there shouldn't be a reason why it couldn't be enabled for any optical zoom position, after all that's exactly what the digital teleconverter does. Finding a way is the problem. But you knew that.  :D  Maybe the digital teleconverter could be modified... it has two zoom steps, maybe one of them could be juiced up to 4x somehow?

(this is starting to get a tiny bit off topic...)
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Offline LjL

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Re: Universal Manual Focus
« Reply #25 on: 11 / July / 2008, 17:00:18 »
Well, offtopic or not (indeed, let's move to this topic)... the good news is that it can be done. At least on an A720.

The bad news is that if you look carefully at the maximum digital zoom during live view, I think you'll agree with me that it's just the 2x zoom upscaled (with an ugly interpolation algorithm, at that).

Just look at the quality and pixelation in the live view at maximum + optical, then take an actual picture, and notice the difference.

I think I can implement this anyway if wanted, it actually looks pretty easy.
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Offline fudgey

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Re: Universal Manual Focus
« Reply #26 on: 12 / July / 2008, 02:22:07 »
Hmm.. you may be correct about that interpolation.

And btw I feel pretty stupid now, I just figured that Canon's AiAF "OFF" takes point focus from the middle of the screen from an area I believe is small enough for most of my purposes.
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Offline LjL

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Re: Universal Manual Focus
« Reply #27 on: 12 / July / 2008, 07:42:55 »
It can be made pretty small, especially if you select the "small" size ;-) Although that's not available in Auto mode (but it is in P), I believe.

The nice thing is that the autofocus setting that you select for P will carry over to Av, Tv and M, but not Auto, so you can have a setup where Auto does its face detection and AiAF, while you can still switch to something saner by just changing to P.
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Offline fudgey

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Re: Universal Manual Focus
« Reply #28 on: 12 / July / 2008, 10:11:57 »
Quote from: LjL on 12 / July / 2008, 07:42:55
It can be made pretty small, especially if you select the "small" size ;-) Although that's not available in Auto mode (but it is in P), I believe.

The "small" size? The only size definitions I can find on my a570is are jpeg related...? Or do you mean combining the digital tele feature with smaller jpeg size, which doesn't seem to cause an increase in the focus square size (at least on display, don't know about reality)?


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Offline LjL

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Re: Universal Manual Focus
« Reply #29 on: 12 / July / 2008, 10:30:10 »
No, I mean, set P mode, go to the main menu, select "AF Frame: Center", then an option "AF Frame Size" should appear underneath, select "Small".

It might not be available in your camera, though, I don't know.
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