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  1. #11
    Senior Member

    Re: How to lock focus on D3500?

    Short answer, either hold it or release it. The beauty of the technique is you hold the button for continuous focus or you release it for a simulated af-s mode. The long answer, I have to talk about a few things. There are two focus servo modes, af-s and af-c (nobody uses af-a). Af-c is continuous mode. Holding the shutter half way keeps on trying to focus. Its good for action. Its not good for focusing and recomposing. Won't work for that. Af-s is single focus. The camera grabs focus and does not try again as long as you hold the shutter half way. Its good for stationary shots especially if you need to recompose. Its not good for action. So that is the 'problem'. BBF is a solution. It in effect makes both modes available. The text book way of using the bbf technique is to set the back button to af-on. The camera is also placed in af-c mode, continuous auto focus. Most of our models (not d3000 series) have a menu setting that further defines af-c. It can be focus priority or release priority. Focus priority means the camera must see focus before the shutter will fire. Release priority means the shutter will fire regardless of focus. BBF is used with af-c, release priority. The shutter will fire no matter what.

    So with the back button set to af-on and af-c mode-release priority you are ready to go. When you press the button, you get continuous focus. So you can track moving subjects or a stationary subject too. At any time you can release the button and focusing stops. You can then point the camera somewhere else (recompose) and take the shot. Usually its used with a single focus point for more precision. So you could hold the button down and track something. Or you can point at your friend's eye, hit the back button once to focus, then release it. You can now recompose. Or you can focus on the bird feeder, then release the button. You are now pre-focused on the bird feeder for when the bird comes back. Or you can focus on a very distant tree line. Release the button and you are now prefocused at infinity and ready for a completely different infinity shot. I am not sure the d3500 can do this. The test would be set it up the back button along with af-c mode and single point focus. Focus on something and release the back button. Recompose without pushing the back button again and see if the shutter will fire. Even with your hand in front of the lens it should still fire. I think it may not fire the shutter on the d3500 because the focus point no longer sees focus.

    Now all this doesn't really solve your original question. But being able to quickly pre-focus on a particular point might help you out some if it works on your model.


    › See More: How to lock focus on D3500?
    Thanks/Like blackstar Thanks/liked this post
    Best Answers Needa voted best answer for this post
     
    I must have a really good camera.



  2. #12
    Senior Member

    Re: How to lock focus on D3500?

    Thanks, Nick for your detailed explanation and description on all about focus.

    Following your direction, I did a small experiment: shooting mode=P (handheld), BB=AF-on, Focus mode=AF-C, Focus area=single point, etc. Then press BB to focus an object (use viewfinder); while still holding BB, press shutter to make (catch) a shot; release BB while still on focus, press shutter for a second shot; move camera around and back to the same position, without pressing BB again and look like still on focus, press shutter for a third shot. The outcome: 1st shot is the worst (everything in the photo moving probably due to hand's vibration caused by holding one button and pressing another plus VR is off), 2nd is the best (sharpest), 3rd is a little off focus compare to the 2nd -- though I think it's on focus when taking the shot, but apparently moving camera after releasing BB will (slightly) move the focus ring too! And the range of off-focus could depend on how much and how vigorously the camera moved. I have thought and expected the 1st would be the best IF I CAN KEEP MY HAND STEADY WHILE HAVING TWO FINGERS HOLDING AND PRESSING TWO BUTTONS. Let me know if my interpretation of the test result goes out of line.

    I may later take another real experiment to use BBF on hyperfocal distance for a night star shot in M mode and specific exposure. Is this realistic? The key is that I'll use BB to focus hyperfocal distance and then release BB and turn to sky to take shots (turning to the sky will be many big motions on a tripod... )

    Thank you all for the help and inputs.

  3. #13
    Senior Member

    Re: How to lock focus on D3500?

    Ok, Let me correct myself after re-pondering the experiment outcome. I think Nick hit the point that BBF is one pretty good thing to use. In my experiment, I see the 3rd shot look a little off focus (not as sharp as 2nd), but in reality, the BBF was still on even after released and the camera moved because I could never return my camera to the original spot exactly, only approximately to the best. So the 3rd looked a little off-focus and it's not because BBF's off but camera position's off. If now this is true (BBF effective either be held, released, or camera position changed), it is very good news (at least for me) that BBF can be conveniently and efficiently used for many types of photography.
    Thank you.
    Thanks/Like nickt Thanks/liked this post
     

  4. #14
    Senior Member

    Re: How to lock focus on D3500?

    I typed this before I saw you last update, but it still applies...
    bbf is not a better focus, its just a different method to get there and gives you control over exactly what you want in focus. I think in your tests, any poor results were camera/hand shake/slow shutter speed. Another way that I describe bbf is to call it 'manual focus at the touch of a button' or 'power assisted manual focus'. Just point your camera around the room. Press the bb as that single point passes over various objects. Press it when something is under the focus point and watch how your camera instantly focuses on that object. Whatever you want, you can focus on. Just play with that for awhile and don't worry about taking a picture. Get a feel for it. The objects in your room are stationary, but if they were moving, you would simply hold the bb down to keep tracking them. Just do that for a few minutes and I think you will have a 'wow' moment of the focus power you have.
    As for the night shooting in manual, I do that all the time. There is a distant street light that I point to and tap the bb. Then I am good to shoot the sky. But the question still remains if your d3500 will let you do this. My old d3100 will not. It simply will not allow the shutter to release if that focus point is no longer seeing focus. To test, activate BBF on something close. Then point the camera at something far away or an empty wall. Everything will be out of focus. Don't press the bb again, just try the shutter. If the camera lets you take an out of focus shot, you are good to go. If the shutter will not fire, then this technique is not going to work on your camera, you will not be able to focus-recompose. I hope that makes sense.
    Thanks/Like blackstar Thanks/liked this post
     
    I must have a really good camera.

  5. #15
    Senior Member

    Re: How to lock focus on D3500?

    Thanks, Nick. From what I tried using BBF with D3500, my conclusion is a little off from yours: After pressing and releasing BB, shutter will fire when subject either in focus or out (e.g., the 3rd shot is out of focus). Only when there is nothing in view (e.g., empty wall), shutter won't fire (which certainly make sense for good). So I kind of assume D3500's good to go with BBF. I hope it is and will continue to play BBF for different shootings and report back.

  6. #16
    Senior Member

    Re: How to lock focus on D3500?

    See how it goes. It really should trip the shutter even on a blank wall. I know that seems wrong but the situation will come where it may give a problem recomposing. When you recompose indoors, the focus point may be by luck landing on something reasonably in focus, allowing you to shoot. It might not work if you point to the sky or out in wide open areas. It sounds like you understand the technique so you know what to look for. Good luck.
    I must have a really good camera.

  7. #17
    Senior Member

    Re: How to lock focus on D3500?

    Practically, I am still in a gap to reach the value or beauty of this BBF. Understanding in theory only demands me for more practice and pushes me forward. Thanks, Nick.

  8. #18
    Senior Member
    Needa's Avatar

    Re: How to lock focus on D3500?

    Quote Originally Posted by blackstar View Post
    Practically, I am still in a gap to reach the value or beauty of this BBF. Understanding in theory only demands me for more practice and pushes me forward. Thanks, Nick.
    It will take some time for it to become natural to you, give it a couple weeks. Some find it is not for the them, what counts is does it work for you.
    Thanks/Like blackstar Thanks/liked this post
     

  9. #19
    Senior Member

    Re: How to lock focus on D3500?

    Thanks, Needa.

    I find your hint and advice encouraging and unbiased. It set me back and rewind, rethinking my goal and learning path... There are more tweaks in this BBF thing than I thought (only a little info found in D3500 manual). Need more time to uncover, so wish me luck

  10. #20
    Senior Member

    Re: How to lock focus on D3500?

    It took me a whole season of trying it and hating it and going back and forth. Then I started seeing practical applications for it. Things like picking out a bird or other wildlife in the crowd and then recomposing or tracking on the individual. I also find it helpful for macro. I am the oddball that uses autofocus for macro. I can't go back and forth with regular focus though, I'm all in now. Muscle memory, I can't stop myself from hitting that button.
    I must have a really good camera.





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