Standard lens, Nikon lenses and back focus adjustment at DVinfo.net

Cees van Kempen · February 28th, 2010, 01:21 PM

Does the back focus procedure with the standard lens lead to adjustmnets in the camera or in the (standard) lens? Should the back focus procedure also be done when using for example a Nikon 80-200/2.8? And finally, after using a Nikon lens, must the procedure with the standard lens be repeated every time?

I am receiving my EX3 this week and everything will be completely new to me. Hope my question is clear and not too stupid.

Roddy Jamieson · February 28th, 2010, 03:58 PM

Back focus is done electrically on the EX3, with its own lens in effect doing its own back focus. Nikon lenses (Still) there is no back focus adjustment so you can't do zooms, just fixed focal lengths. Other TV Zoom lenses have the normal back focus procedure (manual).

Alastair Traill · February 28th, 2010, 04:07 PM

I am not sure whether the back focus adjustment takes place in the lens or the camera but it would make more sense if it was in the positioning of the rear lens group.
When the back focus adjustment is being carried out the camera automatically changes the focal length of the standard lens during the process. As the camera cannot change the focal length of your Nikon zoom I would say that it cannot adjust the back focus for you in this case. Fortunately it is easy enough to use the finder for critical focusing in the focal length range you mention.

The shorter the focal length the harder it is to be sure of the finder image for focus. At shorter focal lengths it takes only a very small change in back focus distance to cause problems. These could be caused by a bit of grit or a burr on the mount. Personally I try to keep the mount clean and try to avoid rough handling and only use the back focus adjustment occasionally. Other users of this forum suggest using the adjustment after every lens change.

February 28th, 2010, 01:21 PM	#1
Cees van Kempen Major Player Join Date: Jan 2010 Location: Nieuw-Vossemeer, The Netherlands Posts: 455	Standard lens, Nikon lenses and back focus adjustment Does the back focus procedure with the standard lens lead to adjustmnets in the camera or in the (standard) lens? Should the back focus procedure also be done when using for example a Nikon 80-200/2.8? And finally, after using a Nikon lens, must the procedure with the standard lens be repeated every time? I am receiving my EX3 this week and everything will be completely new to me. Hope my question is clear and not too stupid.

February 28th, 2010, 03:58 PM	#2
Roddy Jamieson Regular Crew Join Date: Nov 2006 Location: Aberdeen, UK Posts: 33	Back focus is done electrically on the EX3, with its own lens in effect doing its own back focus. Nikon lenses (Still) there is no back focus adjustment so you can't do zooms, just fixed focal lengths. Other TV Zoom lenses have the normal back focus procedure (manual). __________________ Roddy Jamieson

February 28th, 2010, 04:07 PM	#3
Alastair Traill Major Player Join Date: Nov 2008 Location: Melbourne Australia Posts: 626	I am not sure whether the back focus adjustment takes place in the lens or the camera but it would make more sense if it was in the positioning of the rear lens group. When the back focus adjustment is being carried out the camera automatically changes the focal length of the standard lens during the process. As the camera cannot change the focal length of your Nikon zoom I would say that it cannot adjust the back focus for you in this case. Fortunately it is easy enough to use the finder for critical focusing in the focal length range you mention. The shorter the focal length the harder it is to be sure of the finder image for focus. At shorter focal lengths it takes only a very small change in back focus distance to cause problems. These could be caused by a bit of grit or a burr on the mount. Personally I try to keep the mount clean and try to avoid rough handling and only use the back focus adjustment occasionally. Other users of this forum suggest using the adjustment after every lens change.