Using the AF ON button

I have started to use the AF ON button rather than using the "half press" focus.

Pros for me is the fact that when released, the camera maintains its focus, which allows me to recompose scenes without using AF lock. In faster moving scenes, I can pretty much just hold it in, and it focuses continuously, It is great to use with tracking autofocus modes like this.

Cons are that I still have to retrain my brain to use it-I have missed shots because I'm waiting for the camera to focus when I depress the shutter release.

I guess that housing ergonomics are important too. My housing has a large lever that means that I can keep my hands on all the controls and still focus using it.

I would be interested to hear other's thoughts on this.

Adam

Hey Adam,

For Canon users I found this excelent series of videos put on by B and H Photos that I happened to stumble upon the other day. I think you might find the series informative on the auto focus systems:

http://www.youtube.com/watch?v=iAx86nblZ2g&list=WLCD390E4CC84B5698&feature=mh_lolz

I really respect the presenter in this series. I really like the back button auto focus and the ability to switch the buttons with regards to functions on the back of the 5D MII camera that I have. Depending on the housing you are using it may come in handy with regards to ergonomics for people with various hand sizes.

Stephen

PS you will want to go to the 3rd video in the series (4 minutes in) if you want to want to see the use of the focus back button operation.

Great topic, Adam.

I use it for super macro (physically rocking in and out for final focus) - with a good viewfinder!

in the dark for wreck and cave internals, especially where there is some available light and you have to use a long exposure to get some blue (and therefore cannot use a focus light):

and for big animal shooting at the surface (snorkelling with basking sharks/whale sharks), this is mainly to stop the lens hunting because of particle (plankton) in the water or bubbles on the dome etc

I do not use it for everything, because I believe it is easier to just press one button than two with say small moving fish, especially as you and the subject will be moving:

And it is a unnecessary complication with shooting normal reef wide angle, where multi-area AF will give you great results every time:

I should also note that this mode is activated from different places in the Custom Settings on pro and consumer Nikons. On pro bodies it is in the Focus Menu (AF-Activation) and non-pro bodies it is in the Controls Menu (reassign AE/AF lock).

Alex

I use it all the time, since years, with the thumb lever for AF-ON and the middle finger for shutter release. The hand does not have to be moved for reaching both levers, depending on the housing layout (Subal work great for that). And leaving the Nikon's CSM-switch / AF-switch always on C (continuous servo drive).

Good point on housing differences. Not all housings provide access to the button. From memory from running workshops, I think some Sea and Sea housings don't provide access. Apologies to Sea and Sea users if I am wrong.

Alex

Works great with Nauticam housings. I use back button focus all the time, topside and underwater. Switching back and forth is too confusing for my little brain.

Alex do you set it up as a custom setting in the custom settings menu bank for quicker changes underwater, or just change AF each time.

I'm with Eric on this one. I set it as soon as I get a new camera and there it stays. It seems awfully complicated to change and remember to use different options. I use a Nauticam 7D and have no issues with reach.

I fell in love with the AF on button with my first 7D and the relatively the crude shutter release of the Mk1 NA-7D. With my second Mk 2 NA-7D and my new NA-5D3 the shutter release is far more tactile but my preference remains...

@ Jeff - I just do it for the menus. Since I only use it for specific types of photography it is not a problem to set if the slow way - as it tends to be something I would decide on before going in the water.

Alex

I am finding that I am having to remap my brain to cope with the change. I did find myself pondering long and hard as to why the camera wouldn't focus when I pressed the shutter release on several occasions

As Alex has said above I am also not convinced that using the button is better for fast moving subjects. Quite simply, it does involve two button activations (AF and shutter release) as opposed to one...

Adam

Mr Tattersall recommended this to me when I picked up my housing, not used it any different way

Thanks Alex, great to see such nice examples and how different focus modes/settings can be used so effectively; very enlightening!

Good point on housing differences. Not all housings provide access to the button. From memory from running workshops, I think some Sea and Sea housings don't provide access. Apologies to Sea and Sea users if I am wrong.

 

Alex

Hi Alex,

the Sea&SeaMDX d800 has a nice large lever within easy reach. As I was too lazy to take a picture myself, I just cropped an image from the backscatter page (I hope that is allowed :-) )

oeps...the cropping created a mess.. the link is:

http://www.backscatter.com/hostedstore/templates/backscatter_wideload/product_detail_zoomimage.lasso?img=ss-06162_4

 

in the dark for wreck and cave internals, especially where there is some available light and you have to use a long exposure to get some blue (and therefore cannot use a focus light):

 

When using this technique in a wreck or cave, just be sure not to forget to set the focus ahead of time when you have light - outside of the wreck or cave. I took a dives worth of shots inside the Thistlegorm using this technique and had forgotten to set the focus before I went inside the hold. All of those shots ended up being out of focus although they looked great in the viewfinder. Fortunately, we had several more dives on the wreck for me to get it right.

I use the normal shutter release for auto-focus, not the AF-ON. I found that trying to track a moving subject was easier using the shutter release for auto-focus. It also left my thumb free to make AF point changes which I sometimes want to do, particularly when the moving subject changes direction. When I have a subject where I want to recompose. If the subject isn't moving around too much or if I can predict where it will be, I usually AF and then lock that focus by turning S-C-M switch to M which is pretty easy on my Seacam D700 housings. Ditto for many reef scenes. I've recently seen the new Seacam D800 housing and working this way will be even easier on that housing as the AF-M switch is on the left side of the housing, not the front, and is easier to reach with your left hand still firmly on the handgrip.

Fred

Great topic, Adam.

 

I use it for super macro (physically rocking in and out for final focus) - with a good viewfinder!

 

in the dark for wreck and cave internals, especially where there is some available light and you have to use a long exposure to get some blue (and therefore cannot use a focus light):

 

and for big animal shooting at the surface (snorkelling with basking sharks/whale sharks), this is mainly to stop the lens hunting because of particle (plankton) in the water or bubbles on the dome etc

 

I do not use it for everything, because I believe it is easier to just press one button than two with say small moving fish, especially as you and the subject will be moving:

 

And it is a unnecessary complication with shooting normal reef wide angle, where multi-area AF will give you great results every time:

 

I should also note that this mode is activated from different places in the Custom Settings on pro and consumer Nikons. On pro bodies it is in the Focus Menu (AF-Activation) and non-pro bodies it is in the Controls Menu (reassign AE/AF lock).

 

Alex

Love this reply. Very educational. Sets me thinking about the sea whip-goby scenario - would this have worked better?

.

I use mine all the time for caves now, where the autofocus struggles with the light. With the depth of field of the 14mm lens, I only have to reset it a few times during the dive. One of these is right at the start - I've forgotten this a couple of times and had half a dive of fuzzy pictures before I remembered!

It's also a really useful setting for split shots, to prevent the camera trying to focus on the water line against the dome port, and letting you choose whether you want above or underwater as a primary focus point. And it's good for shooting into the sun in the shallows if you have scratches on the dome or dirt on the inside that the camera tries to grab.

For most ocean dives, when the light is good, I find it easier to let the camera autofocus...it helps me catch high speed fish.