When changing between manual and auto focus, should I change the setting on both the body and the lens?

Question

I use my DSLR (Nikon D500) for both photography and video, and I prefer autofocus for photography and manual focus for video (to get rid of autofocus noise).

There is an option for changing between the two on both the body and the lens, and obviously it is very annoying to have to keep flicking 2 switches to do the same thing all of the time.

Do you only have to change one of them, and would doing this cause any damage to the camera and/or the lens?

(I am aware that a similar question has already been asked before, however the answers said more what is "best practice" and not so much if there are any consequences to only changing one of them)

Thanks!

Answer 1

Not sure about Nikon's lenses, but some Canon EF lenses are certainly not designed to be manually focused while the lens is in AF mode. If you try, you can feel your hand actuates the AF motor in the lens, and whenever you focus too fast the gears start skipping. That ain't no good for them. It may result in increased wear or even internal mechanics failure.

However, lenses with an ultrasonic motor are designed to be focused in AF mode, and it is absolutely safe to do so.

Regarding Nikon lenses, it will also probably depend on what kind of lens it is. For example, whether it has a screw actuator (hence, no internal motor) or something else.

In any case, please refer to the manual for the lens and your camera body. Some of the instructions may be precautions, but the manual for sure does contain information on how whatever piece of technology was designed to be used.

You are free to use it whichever way you want, and using your lens or your body in a way it was not specifically designed to be used may be safe, but that safety was not intentional. Those pieces are probably not gonna break from these slight mis-uses, they are made qualitative, but no one is going to guarantee that to you, so it is probably better to stick with the best practices, which are coincidentally described in the manual, unless you know what you're doing.

Answer 2

In my experience, with some Nikon lenses, the focus ring won't move or it won't actually engage the focus, unless the switch on the lens is set to manual. So I personally find it easier to just leave the camera body set to AF and toggle the focus on my lenses. I've been doing this for years with no ill effects on either the lenses' or cameras' auto-focus systems.

Answer 3

If you have the option to switch focus modes on either the body or the lens, and either function produces the desired result - there is no consequence to only switching one or switching both in regards to the equipment.

Answer 4

FujiFilm X-Series cameras and lenses use a focus-by-wire manual-focus systems. To me, they feel as responsive as focusing old fully-manual lenses. Some bodies have an AF/MF switch on them. They also have an option to enable AF with MF override.

Lenses may have various switches, but I have not seen an AF/MF switch on a lens. When a switch is present, whether on the body or lens, it usually overrides the menu settings. If there is no switch, the setting can be changed only from within camera menus.

Whether the switch exists reflects the designers' mental model of use cases. For instance, the XC 50-230/4.5-6.7 OIS-II lens does not have a switch to turn OIS off. The designer most likely doesn't expect anyone to want to turn OIS off on such a slow lens. However, the XF 18-55/2.8-4 R LM OIS does have an OIS switch. The use cases may be to disable OIS at wide angles or on tripods.