Double Back Button Focus (Dual Back Button Focus)

[runyanp]

Hi Steve, I just watched a video that talked about double back button focusing to be used when the camera focus gets stuck on a tree limb instead of the bird. Could you discuss it's merits and how to set it up on a Sony A9ii please?

 

[arbitrage]

I'm not Steve but I can tell you a couple ways to set it up on the A9II...

I'm going to assume you don't want any AF on the shutter. So then you will be making use of the AF-ON and AEL buttons.
AF-On can just be left as "AF-ON" and will be whatever your primary AF mode is set to. Usually I'd have this as Wide or Zone.
Then there are two ways you can go to get the alternative AF mode on the AEL. Usually I'd have that set to switch to Small Flex Spot or Expand Flex Spot but you can choose whatever one works for you.

Method 1: Using the Registered AF mode feature. Switch your main AF mode into the alternative one you want to recall on the AEL. Then long press the Fn button until a message pops up saying that it has Registered that mode. Then in the Custom Button assignments you want to set the AEL to "Registered Area + AF ON" or "Registered AF Area Toggle". Using the "+AFON" option will make that AEL button act just like an AF-ON button but use the alternative registered mode. Using the Toggle option will switch your mode into the alternative and then you'd use AF-ON to actually AF. You'd hit the toggle again to go back to your primary AF mode.

ILCE-9M2 | Help Guide | Registering the current focus area (AF Area Registration) (still image)

helpguide.sony.net

Method 2: Using Reg Custom Shoot Set. You'd assign the custom button for AEL to be "Recall Custom Hold (1, 2 or 3)". You'd setup your Custom Shoot Set (1, 2 or 3) and just tick off the AF-ON and the alternative AF mode. Leaving everything else unticked. Save that and then when you hold down AEL it will perform AF and use the alternative mode. Clearer instructions in the help guide link below:

ILCE-9M2 | Help Guide | Registering shooting settings to a custom key (Reg. Custom Shoot Set)

helpguide.sony.net

Basically the method relies on switching to a more confined AF mode that can narrow down the "watch area". This allows you to target in on the desired subject if one of the wider AF areas like Zone or Wide is getting confused. It also helps if the AF system is not "seeing" a near, out of focus subject and continues to AF on the background. The smaller AF mode like Small or Expand Flex Spot will often "see" the near object and drive focus where the larger Zone or Wide wants to stay with the background.

 

[bleirer]

I'm not Steve but I can tell you a couple ways to set it up on the A9II...

I'm going to assume you don't want any AF on the shutter. So then you will be making use of the AF-ON and AEL buttons.
AF-On can just be left as "AF-ON" and will be whatever your primary AF mode is set to. Usually I'd have this as Wide or Zone.
Then there are two ways you can go to get the alternative AF mode on the AEL. Usually I'd have that set to switch to Small Flex Spot or Expand Flex Spot but you can choose whatever one works for you.

Method 1: Using the Registered AF mode feature. Switch your main AF mode into the alternative one you want to recall on the AEL. Then long press the Fn button until a message pops up saying that it has Registered that mode. Then in the Custom Button assignments you want to set the AEL to "Registered Area + AF ON" or "Registered AF Area Toggle". Using the "+AFON" option will make that AEL button act just like an AF-ON button but use the alternative registered mode. Using the Toggle option will switch your mode into the alternative and then you'd use AF-ON to actually AF. You'd hit the toggle again to go back to your primary AF mode.

ILCE-9M2 | Help Guide | Registering the current focus area (AF Area Registration) (still image)

helpguide.sony.net

Method 2: Using Reg Custom Shoot Set. You'd assign the custom button for AEL to be "Recall Custom Hold (1, 2 or 3)". You'd setup your Custom Shoot Set (1, 2 or 3) and just tick off the AF-ON and the alternative AF mode. Leaving everything else unticked. Save that and then when you hold down AEL it will perform AF and use the alternative mode. Clearer instructions in the help guide link below:

ILCE-9M2 | Help Guide | Registering shooting settings to a custom key (Reg. Custom Shoot Set)

helpguide.sony.net

Basically the method relies on switching to a more confined AF mode that can narrow down the "watch area". This allows you to target in on the desired subject if one of the wider AF areas like Zone or Wide is getting confused. It also helps if the AF system is not "seeing" a near, out of focus subject and continues to AF on the background. The smaller AF mode like Small or Expand Flex Spot will often "see" the near object and drive focus where the larger Zone or Wide wants to stay with the background.

Good answer!

 

[runyanp]

Hi Arbitrage,
I don't post on forums much so I thought I should address my concern to the host. Thank you so much for the detailed info, I will give it a try. I'm thinking this will be faster than going into MF to get the focus off the branch. Greatly appreciate your willingness to help me out!

 

[MikeJ]

Greatly appreciate your willingness to help me out!

You're going to find that a lot on this forum! Steve is, I'm sure, a very busy guy, so you may not hear directly from him. But there is a ton of wealth on this forum and some very helpful people that are very willing to share their knowledge. I don't post a lot here, my skills are somewhat subpar to most of what I've seen here, but even so I've learn a LOT. And the few times I've posted either a photo or a question, I've gotten so much positive and helpful feedback and information.

So welcome to easily one of the best forums on the internet!

 

[Steve]

What Geoff (Arbitrage) said

To add, one way to make manual focus easier is to assign a button, like AEL, for manual focus. Set it to AF/MF control hold. Then, when you hold the button down, it's switch to manual focus as long as you press. Makes using MF to pull focus really fast.

 

[runyanp]

What Geoff (Arbitrage) said

To add, one way to make manual focus easier is to assign a button, like AEL, for manual focus. Set it to AF/MF control hold. Then, when you hold the button down, it's switch to manual focus as long as you press. Makes using MF to pull focus really fast.

I have a button set to AF/MF, but when I saw the video with double back button focus I thought that might be much faster and smoother for an amateur to handle. Thanks for taking time to respond.

 

[Steve]

I have a button set to AF/MF, but when I saw the video with double back button focus I thought that might be much faster and smoother for an amateur to handle. Thanks for taking time to respond.

I use the MF method because sometimes even switching to a smaller AF area doesn't do the trick. Once you get a bit of practice, it's pretty quick.

 

[arbitrage]

One of the reasons I mostly only shoot 600GM now (and have 400GM) on order is for the DMF switch. Actually that has me thinking that maybe I should replace my 100-400 with 70-200II because it has the DMF switch now. hmmmmm.....