manual focusing without setting manual focus

[alastair_anderson]

Can someone tell me how much damage I'm likely to have done to my d3 by

manually focusing a lens while in Single-servo AF mode?

 

I've done this inadvertently. AF still works and there's no apparent

malfunction.

[SCL]

If everything still works, no sweat. Just pay closer attention next time and you won't place additional strain on the system.

[trevor_newman1]

This has happened to me on several ocasions with all my AF cameras; especially when placing my camera in a tight fitting bag that grips the focsuing ring. My best suggestion is to just get in the habit of setting it to manual mode before placing it in a bag, screwing on a filter or hood, and especially when handing it to a novice or non-nikon user who is pretty much bound to twist any grippy ring with reckless abandon! The motors in these cameras are extremely robust, as are the gears in the lenses. I have heard of people who did not realize you cannot manually focus non AF-S lenses in AF mode for a year with no problems other than near heart attacks upon realization. Hope this helps put your mind at ease! Happy Shooting!

[alastair_anderson]

I'm new to all this electronic stuff - normally use Leica rangefinders.

 

Perhaps there has been some damage, although it's apparently unrelated to focusing, but I note that the programme exposure mode will not allow me to access the full range of f stops available on the lens. Manual mode gives me f2.8 to f32, but P* truncates this for some reason. Close up it allows a maximum of f3.2 and at 10 feet or so, depending on the light, I can't select a minimum much below f25. Initially I thought this was just because the camera is really sophisticated; maybe f3.2 is the true max. aperture when the lens is wound all the way out. But I don't have a logical explanation for the limit to minimum aperture. Unless I'm being warned about diffraction.

 

This is all academic because in practice one wouldn't use these positions. Perhaps the programme is aware of that.

 

I find it a little frustrating, however, as it seems a somewhat quirky.

[michael_darnton1]

Speaking as someone who makes and fixes things for a living, there are so many ways Nikon could have bypassed this problem if it had presented a real danger, I'm not going to believe it until I read it from Nikon themselves, that thou shalt not turn the focus ring when autofocus is engaged. In these times you do not build a machine with a handy self-destruct ring prominently presented on the front. Any actual Nikon company references regarding this practice, anyone?

[alastair_anderson]

Thanks for your reassuring words, folks.

 

I've created a new thread about the exposure mode issue.

[Matt Laur]

Which lens are we talking about? Some AFS lenses are built <i>expressly</i> so that you can let the camera establish focus, and then grab the focus ring yourself to fine tune (say, to get the focus on the eyes, not the nose). As they say in the IT world, "it's not a bug, it's a feature." Only, in this case, there's no irony involved. It really IS a feature.

[alastair_anderson]

Matt, it's the Micro-Nikkor 60mm f/2.8D

[Matt Laur]

Was the lens's own onboard switch set to A (rather than M)? If the camera is in AF, but the lens itself is set to M, then it's disengaged from the camera's drive anyway. Further, if you have the camera in A, AND the lens in A, then the focus ring is actually disconnected from the focusing mechanism, and again no harm done. You should be just fine, Alastair.

<br><br>

However, if you're worried about that D3, just send it to me for my patented One-Year-Evaluation. I guarantee that I will take at least 10,000 photos with it, the better to see if it's working correctly for you. :-)

[seismiccwave]

Depending on the lens some lenses will let you manually over ride the auto focus when you

turn the focus ring. You need to look at the instruction sheets provided with your 60 mm

micro.

[alex_lofquist]

If you do it regularly, all that will probably happen is running your battery down faster. The motor is drawing more current to try to refocus against your manual focus. You might cause faster wear of the mechanics if done excessively. Otherwise, I wouldn't sweat it.

[alastair_anderson]

Matt, the lens was set to M. If it disengages from the camera's drive anyway, what is the point of the M setting on the camera? One has to ask.

[briany]

Alastair - some (many?) lenses don't have an A/M toggle on the lens - e.g., 50mm f/1.8, so you have to have it on the camera.

 

The question might be then why on any lens - I guess so you can quickly change with your lens holding hand, not to mention not having to dig into menus if that's where the A/M setting is on the camera (D40 perhaps?).

[bernie moore]

Looking at my 105 AF-S VR I see two adjustments "M/A" and "M". I have been assuming the M/A means manual and automatic, and M means manual only. That's how I use them. I usually will screw (literately) with the ring to check if I can improve on the auto setting, usually I can't, but it's nice to know the "M/A" is right on. If I have done any harm to anything I am blissfully unaware. I think Matt is right in saying it's for fine tuning.

[joseph_wisniewski]

Alastair - there are several reasons for having a focus disengage on the camera and a second one on some lenses.

 

On lenses without a disengage, the focusing ring turns when you auto-focus. This isn't much of a problem on a 50mm f1.4, when the focus ring is a 1/4 inch wide thing 2 inches in diameter, but on a big telephoto where the ring itself is a 4 inch diameter, 3 inch wide thing, that happens to be on the part of the lens you want to hold to support it, you can't have the ring turning while the camera auto-focuses. Lenses with a disengage ring actually lock the focus ring, so you can even better support the lens.

 

Since the ring is so big, there's a lot of friction involved in moving it, especially on lenses where they've added dust and water traps. Turning against that friction would divert motor power from the more critical task of focusing, slowing focusing down.

 

And, since Nikon knows that they don't have to account for focusing ring friction on lenses with the AF disengage, they can build a focusing ring that feels a lot better in manual focus mode. I frequently go back and fourth between four lenses that make this perfectly clear. My 105mm f2.5 is an old manual focus lens, with a recently cleaned and lubricated manual focus system. Manual focusing on that lens feels like silk, just the right amount of resistance. The autofocus 50mm f1.4 doesn't have a disengage, and when you disengage it from via the camera's lever, the manual focus ring is very loose and unpleasant. The 85mm f1.4 and 135mm f2.0 DC are nicely damped in their manual focus modes, much more like the manual 105 than the AF 50 in their feel.

 

Another reason is to protect the camera. Many lenses, such as macros, have huge, low geared AF mechanisms. Turning the ring on a little 20mm f2.8 that only turns 1/4 turn can't harm the camera much, but turning it on a big 200mm macro, geared down for two full focusing turns, with a bigger ring, is like taking a long handled "breaking" wrench to the camera's focus gears. This was much more of a problem back in the early days of AF.

 

On a more serious note, the big D cameras like D2X and D3 have a high torque, low RPM focus motor, and nowhere near the gear ratio that low torque, high speed motor cameras have. Try to turn a D80 against the motor, and you're trying to force a 100:1 gear train to wind that little motor up to 10,000 RPM, making it relatively easy to strip the gears. Do it to a D3, and you're going through a much lower gear ratio (and, I hope, better gears). I wouldn't make a habit of it, but I wouldn't worry too much about it, if you do it ocasionally, by accident. (Even the smaller "modern" AF cameras like D80 have improved relative to the early days of AF. Turn an old N8008 against the motor, and there's a very high resistance to turning, and the camera really winds up to a motor scream).

 

I confess, I have a very bad habit of gently turning the 50mm f1.4 back to infinity, against the (powered off) motor, before putting the D3 back in the bag.

[alastair_anderson]

Thanks everyone, especially Joseph for the essay!

Alastair

[joseph_wisniewski]

You're welcome. Sometimes, I just get in an "essay mood".