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03-05-2014, 09:45 AM   #1
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Back button AF

OK, first noob question about the K5IIs:

When is it better to use the back button for AF over the shutter half-press?

What situations and what are the pros and cons?

Thank you.

03-05-2014, 10:01 AM   #2
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It is a matter of personal preference to some extent. In situations where you don't want to the focus to change - i.e. you focus on a spot waiting for the action to arrive - disconnecting the shutter press from the focus makes sense. See here for a discussion on the topic from one particular perspective.
https://www.pentaxforums.com/forums/38-photographic-technique/236970-perfect-...everytime.html
03-05-2014, 10:04 AM   #3
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It's a matter of personal preference. I changed to the back button AF approx 3 months ago and, after an adjustment period relearning, I like it a lot.

I can now keep the camera in AF.C all the time. If I hold the AF button I get continuous focus. A single AF press gives AF.S. No button press equals MF. It is incredibly versatile and much easier to mix focus modes.

Only 2 con's so far. I sometimes fall back to old habits, expecting a shutter press to focus. This will fade as I use the rear AF button more.

Cold weather shooting in heavy gloves is the other con. My thumb sometimes hits other buttons. I'm talking about extremely cold days like 10F where thin gloves aren't adequate. Spring will eventually end this con.
03-05-2014, 10:21 AM   #4
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I definitely prefer back button focus. Doesn't force the camera to AF for every shot.

QuoteOriginally posted by DeadJohn Quote
Only 2 con's so far. I sometimes fall back to old habits, expecting a shutter press to focus. This will fade as I use the rear AF button more.

Cold weather shooting in heavy gloves is the other con. My thumb sometimes hits other buttons. I'm talking about extremely cold days like 10F where thin gloves aren't adequate. Spring will eventually end this con.
Third con..... Extremely confusing when someone else is using the camera. Makes it difficult for family members to take a shot.

davek

03-05-2014, 10:25 AM - 1 Like   #5
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QuoteOriginally posted by davek Quote
Third con..... Extremely confusing when someone else is using the camera. Makes it difficult for family members to take a shot.
A solution to that con for some camera bodies is to set USER modes that use the shutter for focusing.
03-05-2014, 10:43 AM   #6
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Personal preference of course. But I use back AF only, took a few weeks to completely retrain my hands but no going back. It's the first setting I change on a new camera. My wife still uses the shutter button focus so we do get confused if we end up with the other's camera for some reason.

Why:
You can leave the camera in AF.C and with back button it can act as AF.S or AF.C depending on your preference.
On the tripod you can focus once and then shoot as much as you want without refocusing.
You can manual focus at will without having to worry about the AF messing things up when you shoot (assuming QS lenses)
03-05-2014, 11:16 AM   #7
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QuoteOriginally posted by davek Quote
I definitely prefer back button focus. Doesn't force the camera to AF for every shot.
This is really helpful with a lens like the DA-L or DA 55-300 which has really slow focusing and a really slow aperture, resulting in really wild hunting. Focus once and you can still let go of the shutter release without the lens going back and forth.
QuoteQuote:
Third con..... Extremely confusing when someone else is using the camera. Makes it difficult for family members to take a shot.

davek
I consider that a pro, not a con.
03-05-2014, 11:26 AM   #8
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I can't think of any reason why you *wouldn't* want to set the button for AF. Unless you always make pictures that have the main subject exactly in the centre. Or you are happy to have the camera always decide what to focus on.

03-05-2014, 12:51 PM   #9
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This thread is fascinating, I would never have thought to use the back AF button this way. I don't think I've ever used it since I started shooting with my K10D in 2007.
03-05-2014, 01:20 PM   #10
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I set my K-7 to BBF a long time ago, wouldn't have it any other way.
03-05-2014, 01:20 PM   #11
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It's great too for catch in focus with manual lenses. Hold down the AF button, depress shutter release and rotate lens barrel. The shutter fires when you're in focus.
03-05-2014, 01:33 PM   #12
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My keeper rate has increased since I started using the back AF button in AF-C mode dial. I also use it on both camera and grip.
03-05-2014, 01:49 PM   #13
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QuoteOriginally posted by davek Quote
I definitely prefer back button focus. Doesn't force the camera to AF for every shot.



Third con..... Extremely confusing when someone else is using the camera. Makes it difficult for family members to take a shot.

davek
I just turn it to green mode in such situations, among other things it enables the shutter half press focus.

---------- Post added 03-05-14 at 09:53 PM ----------

I always wanted to have back button focusing but the K-3 is the first camera that makes it practical.

While both my two previous cameras, K-30 and K-r, have back button focusing the location of the button is not at all suited for frequent use - I would use it only when shooting with a tripod.

When I got the K-3 I immediately and permanently switched to back button focusing but now I'm having difficulty using the other two cameras.
03-05-2014, 03:12 PM   #14
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I was very frustrated until I discovered BBAF. I switched the K-3, but found the K-50 button to be hard to find without looking.
Having two cameras set differently AND one of them doesn't do BBAF is 66% more frustrating (this would only be 44% more frustrating in full frame).
I will live with the awkward button position. Its better than having the AF jumping around when I'm using the shutter button.
03-05-2014, 03:27 PM   #15
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I like to use it in conjunction with disabling the front shutter half-pressed focusing (Menu->Button Customization->Shutter Button Half Press-> Off) , for Landscapes/Cityscapes , long exposures, Bracketing, since it allows me to focus and change the composition without continuous re-focusing when the shutter is half pressed. Also it is a good Idea for still portraits
I have saved the setting in User 1 along with Av my most used setting. In such way I can lend the camera to someone without confusion.

Last edited by yygomez; 03-05-2014 at 03:36 PM.
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