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SB focuses with Back Button focus on--Help please!
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Feb 12, 2019 00:30:48   #
Greer Loc: SOUTH GEORGIA
 
I'm a newbie and having problem with back button focus. Everything seems to be working properly but when I change viewfinder position of subject and press shutter button, D750 refocuses. What have I done wrong? Last shoot of baby shower pictures were barely salvageable. Thanks!

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Feb 12, 2019 00:47:01   #
rgrenaderphoto Loc: Hollywood, CA
 
I found this YouTUbe video which goes over back button focus AND exposure lock on the D750. Quality is not the greatest, but he is attempting to address your problem. When you "change viewfinder position," are you changing exposure?

https://www.youtube.com/watch?v=k5UJhSHbj4I

Also, do you have continuous focus turned ON?

https://www.youtube.com/watch?v=FzqQskGoURE

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Feb 12, 2019 00:55:48   #
CHG_CANON Loc: the Windy City
 
Do you also change the function of the shutter button so that it only is the shutter release and no longer includes focus activation? Pages 361-362 makes it seem like you only need to reassign AF-ON to the AE-L button.

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Feb 12, 2019 03:39:22   #
User ID
 
`

Tho it doesn't make sense, enabling an alternative
AF activation button usually does not automatically
disable AF activation by the shutter button. You'll
find a menu choice to remove AF from the shutter
release, but in some cameras it's not a straight out
"enable/disable Shutter AF". One of my cameras [I
don't recall brand] offer combinations of multiple
functions for the shutter button: AE on, AF on, AE
lock, AF lock, etc in several fixed combinations ...
and ONLY ONE combination does NOT include the
"AE on", so that is the only choice for BBAF users.

So scour your menus for all choices regarding AF
and regarding customizing button assignments.
The solution is in there, reasonably well hidden :-)

.

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Feb 12, 2019 08:09:23   #
LittleRed
 
Greer wrote:
I'm a newbie and having problem with back button focus. Everything seems to be working properly but when I change viewfinder position of subject and press shutter button, D750 refocuses. What have I done wrong? Last shoot of baby shower pictures were barely salvageable. Thanks!


I don't know if this is any help to you as it refers to my Canon camera's (Rebel Series) and not a Nikon. Also not quite sure if you have at the same time both the back-button and the shutter button working the focusing or in what mode you are using. On my Canon T6i (750D) when I set it up for back-button focus it is activated only for those settings on the mode dial that are in what is called the "Creative Zone" which includes P (program AE where the camera automatically sets aperture and speed), Tv (shutter priority), Av (aperture priority) and M (manual exposure). These are the only modes where back-button works. If I select any other mode such as those in the Basic zone i.e. A (fully automatic), any Scene options such as Sport or Portrait then my focusing is automatically put back on the Shutter Button and the back-button is disabled. Since I seldom use the settings in the basic modes it does not bother me. However the one excellent thing about this is that if I want anybody else to use my camera to take a pic of me and my wife I don't have to bother instructing them on the use of a back button, I just set the mode to A which basically changes my dSLR into a expensive P&S. Makes life much simpler.
But like I said at the start this holds true on a Canon (Rebel Series at least) but may not on your Nikon.

LittleRed (Ron)

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Feb 12, 2019 08:24:03   #
boberic Loc: Quiet Corner, Connecticut. Ex long Islander
 
Ask You Tube the following question--How do I turn off the 1/2 shutter press on camera (model name and number) there will probably be a tutorial

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Feb 12, 2019 09:28:50   #
pesfls Loc: Oregon, USA
 
The Nikon menu will have an option called “release” in the autofocus tab you’re looking at. Turn that off. Your issue is you have given the body two ways to initiate autofocus. Then you can select your focus point with the back button, let go of the bb and recompse and fire off your shot. I faced the same dilema in the past so understand your frustration. Good luck.

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Feb 12, 2019 16:38:11   #
Greer Loc: SOUTH GEORGIA
 
Thanks. Fixed the problem. Not sure about other D750 users, but mine is a bit finicky. I can be shooting indoors under constant ambient light and with speedlight, but without changing exposure settings have one image bright and the next dark without moving subject or camera. Do you think it's time to replace my speedlight or is this more common than I think?

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Feb 12, 2019 17:12:15   #
speters Loc: Grangeville/Idaho
 
Greer wrote:
I'm a newbie and having problem with back button focus. Everything seems to be working properly but when I change viewfinder position of subject and press shutter button, D750 refocuses. What have I done wrong? Last shoot of baby shower pictures were barely salvageable. Thanks!

You have to disable the shutter release (for focus), if you want to avoid this!

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Feb 12, 2019 19:38:23   #
User ID
 
boberic wrote:

Ask You Tube the following question--How do I turn
off the 1/2 shutter press on camera (model name and
number) there will probably be a tutorial


Nooooo. Do NOT cancel 1/2 press if you like 1/2 press.
It is toadally unrelated to canceling AF activation at the
shutter button. I use 1/2 press and BBAF on ALL my
cameras. Various brands. No problem.

.

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Feb 12, 2019 19:50:09   #
User ID
 
User ID wrote:
`

..................................... One of my cameras [I
don't recall brand] offer combinations of multiple
functions for the shutter button: AE on, AF on, AE
lock, AF lock, etc in several fixed combinations ...
and ONLY ONE combination does NOT include the
"AE on", so that is the only choice for BBAF users.


CORRECTION.
I posted a typo. The highlighted "AE on"
above should have referred to "AF on",
and NOT to "AE on". "E" shoulda been "F".

.

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Feb 13, 2019 06:08:40   #
tcthome Loc: NJ
 
You need to set it for bfn only. Sounds like you have it set for bfn & shutter button. Go back into your menu.

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Feb 13, 2019 08:52:41   #
billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont
 
Greer wrote:
I'm a newbie and having problem with back button focus. Everything seems to be working properly but when I change viewfinder position of subject and press shutter button, D750 refocuses. What have I done wrong? Last shoot of baby shower pictures were barely salvageable. Thanks!


Once you depress the back button focus you cannot let go of it or the camera will refocus. You must continue to hold that button and then click your shutter button while continuing to hold the rear focus button down.

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Feb 13, 2019 08:56:24   #
jerryc41 Loc: Catskill Mts of NY
 
My D750 works okay with BBF. Take a look at some text and video explanations.

https://www.google.com/search?q=back+button+focus+d750&rlz=1C1CHBF_enUS716US717&oq=back+button+focus+d750&aqs=chrome..69i57j0l4j69i64.5704j0j4&sourceid=chrome&ie=UTF-8

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Feb 13, 2019 09:58:43   #
Rab-Eye Loc: Indiana
 
CHG_CANON wrote:
Do you also change the function of the shutter button so that it only is the shutter release and no longer includes focus activation? Pages 361-362 makes it seem like you only need to reassign AF-ON to the AE-L button.


Spot on.

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