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04-28-2011, 06:34 AM   #1
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K-x would not focus on clouds

I was heading home from work yesterday and noticed some storm clouds forming into what looked like a funnel. I got out my K-x and kit 18-55 lens, and with a setting of ISO 200, autofocus, and aperture priority at f8, pointed the camera at the clouds and pressed the shutter button. Nothing happened! I kept trying and then noticed at the bottom of the viewfinder a green flashing octagon. I understand that this means the lens is not focussed on anything.

I could not photograph the clouds but could photograph the ground - not what I wanted.

1. Why wouldn't my camera find focus on clouds? It seems a bit of a limitation. I went to manual focussing but have always been unable to focus correctly with this DSLR. I am OK focussing with my film SLR!

2. As the camera is giving an indication that it cannot focus on something, why would it prevent the shutter from being fired? After all, it has told me that nothing is in focus, and it is up to me whether to continue and waste a frame. Can this annoying hand-holding be turned off? Does this happen on pro-cameras?

Rant over...

04-28-2011, 06:41 AM   #2
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If I remember correctly this can be changed in one of the custom settings, so that regardless of focus when in auto it will fire a shot off, even if it hasn't caught a focus yet.
04-28-2011, 06:55 AM   #3
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Turn on manual and set lens on infinity.
04-28-2011, 06:56 AM   #4
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Why not just manually focus in this instance?

04-28-2011, 07:08 AM   #5
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QuoteOriginally posted by Ahab Quote
Turn on manual and set lens on infinity.
The kit lens does not have a distance scale marked on it. Cranking the focussing ring to the end does not seem to be infinity.
04-28-2011, 07:09 AM   #6
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QuoteOriginally posted by DaveHolmes Quote
Why not just manually focus in this instance?
From my original post '...I went to manual focussing but have always been unable to focus correctly with this DSLR. I am OK focussing with my film SLR!...'
04-28-2011, 08:30 AM   #7
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QuoteQuote:
If I remember correctly this can be changed in one of the custom settings, so that regardless of focus when in auto it will fire a shot off, even if it hasn't caught a focus yet.
I was just in the k-x menu yesterday, I believe the option that you're looking for is in the custom menu, page 2 or 3, Catch In Focus.
04-28-2011, 08:44 AM   #8
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QuoteOriginally posted by icywindow Quote
I was just in the k-x menu yesterday, I believe the option that you're looking for is in the custom menu, page 2 or 3, Catch In Focus.
I don't believe this is exactly what the OP is looking for. Catch-in-focus actually prevents the body from releasing the shutter in AF mode with a MF lens until there is focus confirmation.


Last edited by dgaies; 04-28-2011 at 10:36 AM.
04-28-2011, 09:22 AM   #9
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The fastest way to handle this is the AF-MF mode switch on the front of the camera, opposite corner to the shutter button. Page 18 of the manual shows it as #7. My *ist DS had a similar switch and I used it all the time. In that mode, you should be able to shoot no matter what the camera thinks of your focus. Then focus manually, or just focus to the distant end and back off a bit.

Another option is AF.C mode, page 115 in the manual. The camera tries to refine focus continuously when the shutter is half-pressed. When you press the shutter button fully, it takes a shot no matter where the focus is. Sometimes it's exactly what you need, sometimes it is terrible.

With lenses that offer Quick-Shift Focusing, you can manually focus after the camera locks on something, but in the default AF.S mode, the lock has to happen first. So you might notice the camera is having trouble getting focus, point to a random high-contrast thing, let the camera lock on it, keep half-pressing, then recompose, manually focus with Quick Shift, then shoot. Unfortunately your kit lens does not have Quick Shift.

The autofocus sensors detect contrast, and clouds don't always offer enough contrast at a specific distance away.

Autofocus lenses focus "past" infinity for a few reasons, so you can't always just turn the focus ring to its stop and use that. With a small aperture like f11, the difference might not matter.
04-28-2011, 10:06 AM   #10
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QuoteOriginally posted by dgaies Quote
I don't believe this is exactly what the OP is looking for. Catch-in-focus actually prevents the body from releasing the shutter in MF mode with a MF lens until there is focus confirmation.
Really? I was playing around with a manual lens in manual mode yesterday and I took plenty of non-focused shots without the focus confirmation hexagon with this option turned on.
04-28-2011, 10:35 AM - 1 Like   #11
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QuoteOriginally posted by icywindow Quote
Really? I was playing around with a manual lens in manual mode yesterday and I took plenty of non-focused shots without the focus confirmation hexagon with this option turned on.
Yes, you're right. In MF mode with a MF lens (or a lens set to MF with a switch) you can take a shot regardless or whether it's in focus. I meant to say that with if your camera body is set to AF, and you have a MF lens, it won't release the shutter until there is focus confirmation. As far as I know CIF has no effect on anything when the body is set to MF. I'll edit the original post to correct that, thanks
04-28-2011, 10:48 AM   #12
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No matter how tricked-out, current dSLRs are not P&S's, and won't behave as such in trying circumstances. Automation only goes just so far. Sometimes (often?) we need to outsmart the camera. That requires knowing the camera, and thinking about the problem, and controlling it manually. Knowing the camera requires multiple RTFM sessions -- at least for me! Knowing the problems and the solutions... well, we have all the answers here! It all boils down to study and practice, repeat forever. We gain good judgment from experience. We gain experience from making bad judgments. It's an infinite cycle.

So yes, memorize those parts of the manual dealing with focus and exposure. Memorize some guides to focus and exposure. Maybe think of the camera not just as a tool, but as a careless adversary, like other drivers on busy roads. They aren't ALL trying to kill you, but you'll live longer if you drive as though they are. And your camera isn't REALLY trying to screw-up your pictures -- but you'll get better shots if you treat the camera as an idiot-savant doing its own thang despite your intentions. A dSLR is just a dumb lens-bearing robot. Don't let it take control.

[/me brutally puts down an uprising by Sony P&S's]
04-28-2011, 11:53 AM   #13
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Seconded RioRico!
Read the F***ing Manual.
04-28-2011, 08:33 PM   #14
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QuoteOriginally posted by kitkat Quote
I could not photograph the clouds but could photograph the ground - not what I wanted.
Hi, Kitkat. I have a K-x as well and have this happen to me. What I do is point the camera at the furthest distant object while holding down the shutter button halfway so it locks on to infinity and then recompose on the clouds still holding the shutter button halfway.The focus is now locked. It works for me and I only seem to have to do it once if I'm taking a few shots in a row. Obviously this has other applications as well. I also have mine set to spot focus. Have fun!
bruce
04-29-2011, 06:17 AM - 1 Like   #15
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If you were on spot focus, sometimes switching to the "multi-focus points" setting will work.
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