Manual Focusing

[OZAmateur]

I've been playing around with manual focusing and i couldnt answer a simple question.
My D90 has a auto focus and manual focus switch, so i know that if i want to manually focus i switch to little selector to "M".
But......my 18-200 lens has a auto focus and manual focus switch also!

So, what is the most correct way to select manual focus. Do i need to switch both to "M", or do i just do one over the other...in that case do i switch the camera or lens over to "M".....or does it simply not matter just so long as one is on manual.

[ricktas]

Which 18-200 lens do you own?

[OZAmateur]

the VR2 Nikon

[ricktas]

Your lens should have three switches : MA/M (focus mode) : VR (on-off) : Normal - Active

The one related to the focusing is the MA/M one, turn that to M and also turn the camera body switch to M as well. Then start shooting in Manual. You can leave the lens in MA mode, which means you can over-ride the AF by turning the focus ring on the lens. It is all on page 15 (English section) of your lens manual.

[OZAmateur]

Yeah the lens does have the 3 switches.
i was more just curious to know what was the most correct way to do manual focusing...i couldnt tell what differences there were when i used just the lens switch, switched to manual and the camera switch switched to manual.
so switching the camera to 'M' and leaving the lens in 'MA' is fine? This is what i have been doing...just wanted to know if it was a habit i should get out of now

[ricktas]

yeah, that is fine, cause in MA mode, you can over-ride the AF by turning the focus ring, which automatically disables the AF.

[kiwi]

Amazing nikons, straight to the pool room

[arthurking83]

Yeah the lens does have the 3 switches.
i was more just curious to know what was the most correct way to do manual focusing.......

You have an AF-S(silent wave brushless motor) focusing lens here, so there is no 'most correct way' to do manual focusing. In other words, all methods of manual focusing are correct.

Some of the Nikon AF-S lenses have M-A focus switches and others have M/A-M focus switches.. eg, if your 18-200VR lens has an M/A-M switch, but the much cheaper(build as well as price) 18-105VR has an M-A switch.
The difference(as can be ascertained so far) is that with the lenses that have an M-A switch, it's best to switch to the M position for manually focusing with these lenses, as it may wear out the focusing parts inside the lens.
You can still manually focus, and the lens will focus (relatively) smoothly, but I read somewhere that Nikon recommends manually focusing when the switch is set to the M position.
The reason is that these M-A lenses, as opposed to the M/A-M lenses use a micro motor with a gearbox and clutch system, where the M/A-M lenses use a ring type motor for focusing. With the ring type focusing lenses, which are more expensive to produce, there is no strain on any peripheral parts, like gears clutches, and whatever else Nikon sees fit to use in their focusing systems. It's therefore a little bit more obvious that with the micro motor lenses, there are shafts and gears and so forth that may wear out with heavy use of manual focusing with those types of lenses.

You original question asked about the manual-auto switch on the D90 itself. This really only for AF/AF-D type lenses that are screw driven by the camera, as opposed to lenses that are AF-S(self driven).
The MF/AF switch on the D90 retracts the small screw driver that just pokes out of the mounting flange on the camera.
If you take your lens off the camera and flick this switch, you can see the small slotted driver retract back into the body by a few millimeters.
This switch may also marked C, S, M(but I can't remember. The D300 type cameras have a three position CSM switch where you can also choose between Continuous, Single shot AF modes or Manual(hence the CSM)
Even tho I said this particular body switch is intended for use with older screw driven lenses, it still disables auto focus on your AF-S type lenses too, so it's a hybrid electro-mechanical switch, whereas the AF-S type M-A and M/A-M switches are purely electronic controls. Some of the older screw driven lenses have M-A switches too, in the form of a slim ring that you rotate to disable-enable focusing without taking your hand off the lens, and these types of lenses are usually restricted to long-ish type lenses... that is most lenses over 50mm long
So even though the body focusing switch has an impact on focusing with all AF lenses, in reality, you wouldn't use the body mounted switch at all(unless it's simply a force of habit).
With AF-S type lenses: for overriding focus by the camera, you simply forget all switches, and just manually focus with the focus ring on the lens(beauty! :th3:) and if you don't want the camera to continually re focus every time you either half press the release, or (if you're using this method) focus with the AE/AF-L button, you would simply set the lens switch to the M position and thus not allow the camera to focus for you.

[OZAmateur]

arthur you have answered my question with just the answer i was looking for. Im not surprised to find out that by manually adjusting lens while it is set to auto will strip or wear out the adjusting gears inside.

Cheers

[fillum]

As per AK's post, if there is a switch on the lens I use that, and if not then I use the body switch.

Some lenses (e.g. Nikkor micro 105 f/2.8 AF-D) disable the focus ring when the lens is in autofocus mode. So setting the body switch to "M" will stop it focusing but still won't allow you to focus manually till you have set the lens to "M".


Cheers.

[kiwi]

All af-s lenses I thought were designed to allow you to just overide af when you manually turn tr focussing ring....I dont believe you're going to damage it, tis a design feature