Dissociating Focus from Shutter Nikon D200?

This week's "Image Doctors" on www.nikonians.org described a technique to dissociate the focus from the shutter firing that to my amateur mind mind work well under water.

One uses AF-C (autofocus continuous), and sets the shutter to Shutter Priority (fires when pushed, not waiting for focus). This gives one the advantage of AF-C, but once the camera is focused appropriately using the auto focus button on the back, pushing the shutter button will not cause it to try to refocus.

This gives one the advantage of AF-C with much less battery use. It is also quasi-manual that when in proper focus one can move the camera back and forth a bit to bring the subject into focus then hit the shutter without causing refocusing action.

This seems particularly attractive for my 105VR (which is also not engaged until you hit the shutter button, saving battery power as well).

Has anyone tried this, or am I missing something conceptually on using this technique underwater.

Steve Dingeldein

I understand the AF-C, but what is the reason it needs to be on shutter priority? Shutter priority is exposure related so what's the connection to the focusing mechanism?

I understand the AF-C, but what is the reason it needs to be on shutter priority? Shutter priority is exposure related so what's the connection to the focusing mechanism?

AF-C has two menu options that control shutter release

Focus Priority fires when focus in achieved

Shutter Priority fires anytime the shutter is pushed...not necessarily in focus

Not all housings have access to all the controls...

... my new Nexus housing certainly doesn't have access to the AF/AE button.

There is a third menu option for AF-C that "optimises" the function between release and focus. I use this setting and half-pull the shutter release, and move the focus area around the frame so that it is close to where I want.

The half-pull technique is easier with my housing than half-pressing is out of the housing, so I'm happy.

Tim

B)

Hi Steve,

I think you are spot on with your suggestion of taking focus away from half shutter and using the AF-ON button for autofocus. I think this is a huge advantage as you no longer have switch between manual and autofocus on the CSM switch, thus eliminating an extra step. You also no longer need the use the AF lock because you are technically "locked" whenever the AF-ON button is not being pressed.

The only problem is that many housings either do not have a button for the AF-ON button or it is not ergonomically placed if it is available. The Light and Motion Titan D200 housing has the ability to let you choose whether the lever that you activate with your right thumb will press on the AF lock (the default setting) or can be switched to operate the AF-ON button by moving a rubber bumper on the inside of the back plate of the housing. The Subal housing also has a lever that you activate with your right thumb and will press on the AF lock, but with some custom modification, can be used to activate the AF-ON button. Some other housings that have a dedicated AF-ON button in addition to the AF lock button usually have a long reach that may require you to take your finger off of the shutter release in order to reach the AF-ON button.

It is very important to remember that this technique works only with certain lenses if you want to do manual focus. For example, the 60mm and old 105mm lenses will still need to have the ring on the lens swtiched if you want to manually focus the lens.

The technique works like a dream on the new 105 VR because this lens now features a Manual/ManualAuto switch on the lens. If you have the switch in the MA position, this means you can manually focus and also auto focus the lens without moving the switch on the lens or the CSM switch. If you have the 105VR give this technique a try on some flowers on land to get a feel for it--once you try it underwater you'll be addicted to it like crack.

I never use focus gears on wide angle setups, so everything I do for wide angle works fine.

By now the Canon users reading this have a smirk on their faces because they have been able to do this technique for years now with the star * button on the camera. They can disable 1/2 shutter from autofocus and reassign autofocus to the star * button. Most of the Canon housings activate the * button with the right thumb.

Good luck with trying this underwater!

Best regards,

Jim

Jim,

I have the 105mm VR. I will have to try this technique.

Thanks

Hi Steve,

 

I think you are spot on with your suggestion of taking focus away from half shutter and using the AF-ON button for autofocus. I think this is a huge advantage as you no longer have switch between manual and autofocus on the CSM switch, thus eliminating an extra step. You also no longer need the use the AF lock because you are technically "locked" whenever the AF-ON button is not being pressed.

 

The only problem is that many housings either do not have a button for the AF-ON button or it is not ergonomically placed if it is available. The Light and Motion Titan D200 housing has the ability to let you choose whether the lever that you activate with your right thumb will press on the AF lock (the default setting) or can be switched to operate the AF-ON button by moving a rubber bumper on the inside of the back plate of the housing. The Subal housing also has a lever that you activate with your right thumb and will press on the AF lock, but with some custom modification, can be used to activate the AF-ON button. Some other housings that have a dedicated AF-ON button in addition to the AF lock button usually have a long reach that may require you to take your finger off of the shutter release in order to reach the AF-ON button.

 

It is very important to remember that this technique works only with certain lenses if you want to do manual focus. For example, the 60mm and old 105mm lenses will still need to have the ring on the lens swtiched if you want to manually focus the lens.

 

The technique works like a dream on the new 105 VR because this lens now features a Manual/ManualAuto switch on the lens. If you have the switch in the MA position, this means you can manually focus and also auto focus the lens without moving the switch on the lens or the CSM switch. If you have the 105VR give this technique a try on some flowers on land to get a feel for it--once you try it underwater you'll be addicted to it like crack.

 

I never use focus gears on wide angle setups, so everything I do for wide angle works fine.

 

By now the Canon users reading this have a smirk on their faces because they have been able to do this technique for years now with the star * button on the camera. They can disable 1/2 shutter from autofocus and reassign autofocus to the star * button. Most of the Canon housings activate the * button with the right thumb.

 

Good luck with trying this underwater!

 

Best regards,

 

Jim

Hi Jim!

The 105VR is exactly the lens I had in mind as I listened to The Image Doctors describe this technique. I have one and use it extensively. I get a bit frustrated in shallow water even with mild surge trying to get photos of small things as the lens refocuses and hunts a bit. The technique of dissociating the focus from the shutter seemed to be made for such situations: get it close and then move the camera a bit for the focus. Thank you for all your comments as they are very helpful. I shall try it on some flowers.

Steve D