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05-31-2017, 03:14 PM   #1
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Back button Focus

Just setup back button focus. Question is when using continuous focus while taking muntiple shots does one hold the back button focus button and press the shutter release button simultaneously or press the back button focus obtain focus let go of the the back focus button and than press the shutter button. Thanks folks.

05-31-2017, 04:47 PM   #2
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Hi Adsouza ,
I use the back button on my K3II like this . Moving subjects : hold the back focus button on continuously while tracking the subject and either pressing the shutter release selectively or hold on while capturing the subject . If it is something like a bird moving in a tree , i hold the back focus button continuously on and fire shots with the shutter selectively while the subject is moving but if the bird stops moving i release the back focus button momentarily while using the shutter button to get the shot . A bit trickey to get used to but it will become easier with practice . The theory here is the camera is not trying to find contusion focus on the bird when the bird stops moving and therefore less moving actions which could soften the image via motion blur . I have done this sort of focusing for many years and believe it is the only way to go with moving wildlife photography . You must be set in continuous focus mode with rear focus button activated and have the shutter set up release only [ no focus ]on the shutter button .
Regards Anthony .
05-31-2017, 04:55 PM   #3
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If the K3 is like the K-1 this will depend upon whether you've disabled the AF on the shutter release button. If you haven't or can't disable AF on a half press of the shutter button, when you release the back AF button the camera will refocus (if it's an AF lens) prior to releasing the shutter. If the shutter release is set to AF priority (instead of release priority) as well this will slow things down as it refocuses. The camera might 'hang up' if using a manual focus lens with this type of set up unless it still reads your subject as in focus.

When I use the back AF button I tend to press and hold the button as I release the shutter. I do this as I haven't disabled the AF on the shutter button. This way I can work with both options and I prefer to hold the back AF button to reduce camera movement and focus on tracking my subject.

So your options are to press and hold the back AF button or disable the AF on the shutter button then it won't matter if you release the back AF button when you squeeze the shutter.

Tas
05-31-2017, 05:01 PM   #4
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The operations are now completely independent of each other, Adsouza.

That's the advantage.

With the 'old way', after you take a picture, you release your finger and it might stop focusing in the meantime.

05-31-2017, 05:16 PM   #5
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QuoteOriginally posted by adsouza Quote
Just setup back button focus. Question is when using continuous focus while taking muntiple shots does one hold the back button focus button and press the shutter release button simultaneously or press the back button focus obtain focus let go of the the back focus button and than press the shutter button. Thanks folks.
Yes. Hold the back button down as long as the subject is moving and keep your finger on the shutter release for as long as you need to keep shooting. If I'm panning across something or something is moving between me an the subject I will take my finger off the back button until it has cleared the AF points.

There are times you will want to hold one and release the other for a few seconds. I will often hold the back button to keep the focus tracking but only release the shutter in bursts as I try to anticipate the subject. I also don't want my buffer to fill up which is often a problem.
05-31-2017, 06:18 PM   #6
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QuoteOriginally posted by Winder Quote
Yes. Hold the back button down as long as the subject is moving and keep your finger on the shutter release for as long as you need to keep shooting. If I'm panning across something or something is moving between me an the subject I will take my finger off the back button until it has cleared the AF points.

There are times you will want to hold one and release the other for a few seconds. I will often hold the back button to keep the focus tracking but only release the shutter in bursts as I try to anticipate the subject. I also don't want my buffer to fill up which is often a problem.
Do you have the AF/shutter disabled when you shoot that way?
05-31-2017, 06:55 PM   #7
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QuoteOriginally posted by jpzk Quote
Do you have the AF/shutter disabled when you shoot that way?
Yes. The shutter release doesn't control AF at all.

05-31-2017, 09:07 PM   #8
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For moving subjects, use AF.C and and keep the rear AF button held down continuously. That keeps the moving object in focus. Press the shutter button whenever you want a photo. You can keep the shutter held in a half-press then press the button the rest of the way to fire the shutter; that might cause less camera shake than completely releasing the shutter button.

In other words, when using back button AF, the shutter half-press has no influence on AF. AF activation gets 100% reassigned to the rear button. Note that the shutter half-press might still do some secondary stuff; on my K-1 half-press turns off the rear LCD

06-01-2017, 12:16 AM   #9
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For the dancers, are you using AF-C or AF-S?
06-01-2017, 08:01 AM   #10
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When using back button focusing and AF.S, what settings are required to prevent exposure if the subject is not in focus? Or is this out-of-focus exposure prevention possible only if using the shutter button to focus?
06-02-2017, 04:29 AM   #11
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Thanks kind folks for your advice
06-02-2017, 08:37 AM   #12
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QuoteOriginally posted by cpk Quote
When using back button focusing and AF.S, what settings are required to prevent exposure if the subject is not in focus? Or is this out-of-focus exposure prevention possible only if using the shutter button to focus?

On a K3 go to AF Setting Menu and select Focus-priority. I've never tested it to confirm that it works with back button focus. I always wait for focus confirmation, whether you are focused on your subject is dependent on you. I just tested it and Focus-priority doesn't work for back button focus, I removed the lens cap and pushed the shutter button and it took the photo out of focus. So you will get exposure and lots of them depending on your drive mode settings.....LOL.


I guess the focus priority setting is for those folks with a "happy" shutter button finger to prevent the finger from going past half press. Logically thinking using the back button and getting focus confirmation should prevent the photographer from missing focus, unless you are old and shaky like me
06-02-2017, 09:00 AM   #13
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QuoteOriginally posted by Larrymc Quote
...I just tested it and Focus-priority doesn't work for back button focus, I removed the lens cap and pushed the shutter button and it took the photo out of focus...
Focus-priority is only supposed to act while you are telling the camera to focus. By not pressing the rear AF button you were telling the camera that you wanted to keep the current focus distance when you pressed the shutter. The camera did the correct thing taking a photo when you pressed the shutter. That's how focus-and-recompose works when the desired subject is at the edge of the desired composition.

Catch-in-focus might be what you want if you never want the shutter to fire when the center is out of focus. It doesn't work with all lenses, though, and there are threads devoted to tricks to get it to work better.
06-03-2017, 06:57 AM   #14
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QuoteOriginally posted by DeadJohn Quote
Focus-priority is only supposed to act while you are telling the camera to focus. By not pressing the rear AF button you were telling the camera that you wanted to keep the current focus distance when you pressed the shutter. The camera did the correct thing taking a photo when you pressed the shutter. That's how focus-and-recompose works when the desired subject is at the edge of the desired composition.

Catch-in-focus might be what you want if you never want the shutter to fire when the center is out of focus. It doesn't work with all lenses, though, and there are threads devoted to tricks to get it to work better.

Thanks for the reply DJ, but here is how its supposed to work and it only works with the shutter release button not with the back button (AF button). When the camera is set to focus priority and you are using the shutter button to also focus the camera the camera will wait to focus then trip the shutter when the shutter button is pushed fully and not half pressed. What you said made no sense at all to me, you were basically telling me that the camera always "though" it was in focus so therefore it would trip the shutter no matter what. So in essence if you are using the back button to focus (Camera Menu-menu 4-button customization-AF Button-AF2) you control when to release the shutter not the camera if you are not using back button focus AF2 the camera will decide when to trip the shutter. You can test this by pointing the camera toward a completely black object with no detail and pushing the shutter release button fully and the camera will NOT trip the shutter no matter how long you wait.


Thanks again
06-03-2017, 11:48 AM   #15
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QuoteOriginally posted by adsouza Quote
Just setup back button focus. Question is when using continuous focus while taking muntiple shots does one hold the back button focus button and press the shutter release button simultaneously or press the back button focus obtain focus let go of the the back focus button and than press the shutter button. Thanks folks.
All you folks have been excellent in helping me and for that I thank you all. But now I am a little more perplexed. I shot a pole dancing event no flash permitted. I used my K3 in manual mode, my ISO was set at 800 and or 1000. My shutter varied between 1/200 to 1/250 which gave me an aperture of F3.5 to F4 to work with which did affect some photos DOF. I used back button focus held continuously. I set my Auto Focus mode to AFC and shot in burst mode medium. Focus point used was spot. Attached is one of 1500 shots taken at this event. The lens I used was a DA70 Limited.

The combination of all the advanced features are all new to me, but I reckoned this event called for using these features primarily at the speed that these dancers performed. In my opinion the images are soft. Can you kind folks please help set me up or guide me to improve my technique and obtain tack sharp images using these features
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