#1. "RE: Autofocus - questions" In response to Reply # 0
Yes you are right that it should not take a picture unless the green light is lit in the viewfinder. Now that I have said that, is your camera in Manual mode for the lens as it will take pictures anytime in Manual Mode. Check the front of your camera to see what position it is in, and let us know.
#3. "RE: Autofocus - questions" In response to Reply # 0
The camera is not designed to prevent you from intentionally creating out of focus images. If everything is out of focus, it should hunt trying to find focus and it may give up. It may or may not fire based on a glimpse of something it thinks is in focus.
If you are using any of the Dynamic focus modes, it is going to use a focus point and make a best effort for focus. Try using single point AF.
#4. "RE: Autofocus - questions" In response to Reply # 3
I have it set on single point AF. In AF-C or AF-S it still takes totally out of focus shots when it should be refusing to fire. I have followed Daryl's recommended settings posted here and in his book, which is why I was wondering about the issue.
It seems to me that it should not take a shot if it is totally out of focus.
#5. "RE: Autofocus - questions" In response to Reply # 4
My D800 has the same behaviour. Even if set to focus priority, it is possible to make it take pictures when it's completely out of focus. For instance, if I aim it at my jeans below the minimum focus distance of the lens attached, it is possible to trick it to take pictures by varying the location at which it aims (still below the minimum focus distance).
As Eric wrote, at some point it thinks it is in focus (and in fact the green dot pops up in the viewfinder). Although it is possible to trick it this way, I have found that in real life the autofocus is very reliable and fast. So what appears to be a bug doesn't seem to have any consequence for normal use as far as I am concerned.
#8. "RE: Autofocus - questions" In response to Reply # 7
I also have af-on only. Aiming at a textured cloth below the min focus distance, I sometimes see the green dot appearing and disappearing when I keep the af-on pressed in af-c mode. This only happens on some textures but not others.
I have never observed the camera triggering without first seeing the green dot appearing, even briefly (in focus priority).
#10. "RE: Autofocus - questions" In response to Reply # 9
If the af-on button is release, then it will always fire as in the video.
However, if I keep the button pressed it will only fire once the green dot has been shown (in af-s) or is showing (in af-c). Except in the circumstances I described above.
I interpret it as follows: as long as I keep the af-on pressed, I tell the camera "keep trying to acquire focus and fire only when this is achieved". Once I release the af-on button, I am telling the camera that I don't require autofocus anymore.
#11. "RE: Autofocus - questions" In response to Reply # 10
>If the af-on button is release, then it will always fire as >in the video. > >However, if I keep the button pressed it will only fire once >the green dot has been shown (in af-s) or is showing (in >af-c). Except in the circumstances I described above. > >I interpret it as follows: as long as I keep the af-on >pressed, I tell the camera "keep trying to acquire focus >and fire only when this is achieved". Once I release the >af-on button, I am telling the camera that I don't require >autofocus anymore.
That is definitely one interpretation, but this is not how it has worked in the past, and it makes trap auto focus impossible. Hence, the OPs complaint (among many others). I believe Nikon will probably remedy this to work as it did in the D700 in the next firmware update.
#14. "RE: Autofocus - questions" In response to Reply # 10 Sat 08-Dec-12 10:39 PM by walk43
With AF Activation (a4) set to OFF it means AF will work with the AF-ON button only hence 'AF-ON only' selected in the menu. In this case the 800 only focuses with the AF-ON button on the back of the camera. If you take your thumb off of the AF-ON button ....still with a4 set to OFF....and move your focus point, then the camera will not focus with the shutter button half-way down but will release the shutter on a full press and record the image.
This is confusing for me because a4 is titled 'AF activation' and 'ON' means the AF-ON button is the only button that will focus and only when it is depressed. If you turn AF Activation to 'OFF' then either the shutter or the AF-ON button will focus the camera.
If I have a4 set to OFF (AF-ON only), then the only focus ability I have is with the AF-ON button.... and I must keep it pressed while I push the shutter button....unless I or my subject do not move at all. (real problem for me doing outdoor macro work with wind, body sway and shallow DOF).
And yes to the one post ....that even if the AF-ON is pressed and focus is not achieved my shutter will release and an out of focus image will be recorded. Personally, when I am taking a picture, I don't always remember or have time to look for the green light as I am frequently looking for the bugs to move or for some other composition issue.
Trap Focus (I know what that is) does not seem to work for me either functionally on the camera or in my preferred shooting process.. so I just forget about it. Maybe, as others have said, it does not work correctly on the 800 or 'AF Lock' fits somewhere in the shooting process ...but I just don't mess with it.
If there is more to this and I am missing something let me know. I still resist using a4 set to 'OFF' and using the AF-ON button because I miss shots due to lost focus. I use AF-S and AF-C set to 'focus' so that I always am assured of a focused image (that's Darrell's useage also I think). I know others use the AF-ON button and it works for them... and wedding shooters have a good use for trap focus, but I have not learned to change my ways and just like the way it works for me. For now...
"My most rewarding photos are those that capture something I didn't 'see' in the frame....so just SHOOT."
Thom Hogan's D800 book, pg 431 says 'trap focus' no longer works on this camera.
So ... Russ may have a point.
You can also, with AF-C and AF-On, prefocus at a point all day long, pick up a target that moves under the focus point and fire - you have to push the shutter release now. But this works rather well. The new AF system is so fast, I prefer AF-C, Release priority unless I'm really doing subjects that are not (supposed) to move - then I may use AF-S.
I'm not doing macro yet, Dan so don't know about your challenges.
#16. "RE: Autofocus - questions" In response to Reply # 15
>This Nikon post takes care of how the D800 and D4 (same AF >system) work with AF-On button. > >http://nikonasia-en.custhelp.com/app/answers/detail/a_id/7497/~/shutter-is-released-even-if-focus-has-not-been-acquired-while-pressing-the > >Thom Hogan's D800 book, pg 431 says 'trap focus' no longer >works on this camera. > >So ... Russ may have a point. > >You can also, with AF-C and AF-On, prefocus at a point all day >long, pick up a target that moves under the focus point and >fire - you have to push the shutter release now. But this >works rather well. The new AF system is so fast, I prefer >AF-C, Release priority unless I'm really doing subjects that >are not (supposed) to move - then I may use AF-S. > >I'm not doing macro yet, Dan so don't know about your >challenges.
Wow, So with Nikon's explaination, they are basically admitting that focus priority may not always work right using the AF-on button to achieve focus, lock focus, and only be in focus before allowing the shutter to fire because of "changes in specifications" in the design of the newer cameras. Isn't that nice...
#17. "RE: Autofocus - questions" In response to Reply # 16
Welcome to Nikonians, Diane!
I don’t know what’s going to happen to trap focus on the D800. I was not a Trap Focus user previously, so I don’t miss it. It’s an emotional topic though. Thom Hogan called the change 'egregious' and felt so strongly about it he contacted Nikon directly. This was back in July when he reviewed the D800/E
There are postings in the broader community that discount the Nikon Asia post I cited above. They cite a variety of conversations and letters with regional Nikon Technical Support. For example, NTS USA saying in a Dear John letter five months ago, the focus trap issue had already been raised to Nikon Japan.
That seems to be a common disposition - the issue was raised to Nikon Japan. Some expect the issue may be addressed in a firmware update. At this point, I wouldn’t bet on that.
This doesn't mean that focus priority is not helpful. When we stop demonstrating that taking OOF shots are possible and try to focus, focus priority may still perform well for us. There are photographers/authors who recommend focus priority, an indication they still prefer the results achieved in that mode.
#18. "RE: Autofocus - questions" In response to Reply # 17
I raised this issue several months ago...taking out-of-focus shots with my D800E.
I wish a feature was available as an option on the D800/E that did not allow the camera to fire unless the subject was in focus. It is a very sensitive camera, especially with top quality lenses, and would help in taking more in-focus images. At least Nikon should offer us this option.
To solve this issue where there can be subject movement (while camera not on tripod) my camera is set as follows: AF-C a1 = AF-C priority selection a2 = AF-S priority selection a4 = AF activation