Camera or Lens issue?

runnah · Dec 4, 2013

So I am having an issue with my 10-24mm 3.5/5.6 lens. When I am at 10mm it won't auto focus. It does fine at all the other FDs even at maybe 12mm it works. I have a D300 and it doesn't seem to be affecting my other lenses so I am leaning towards a lens issue. When I focus manually it comes out nice and sharp. Does it with both spot focus and full field.

The_Traveler · Dec 4, 2013

When does it start focusing?

runnah · Dec 4, 2013

The_Traveler said:
When does it start focusing?

When back down from full 10mm, say 12-13mm.

Derrel · Dec 4, 2013

Sounds like a lens issue. I wonder if maybe the deep inherent depth of field at 10mm does not provide the phase detection AF system enough "in-focus" and "out of focus" data to get the system to activate? That's kind of one of the foibles of phase detection AF...like for example, the Nikon 70-300 AF-S VR-G lens is sort of well-known for sometimes just NOT focusing once it's fairly far off the mark and well out of focus...the users needs to actually grab the focusing ring and turn it, and sort of wake the danged lens up. This happens to me, it happens to SM4Him, and other owners of that specific lens. The Canon 50/1.4 USM also does this at times...just sort of...sits there, doing nothing, until the user initiates focusing, then it wakes up. Not sure how to characterize this type of non-responsive focusing behavior? Operational quirk? AF lens air-speed stalling? lol Lens brain fart?

runnah · Dec 4, 2013

Derrel said:
Sounds like a lens issue. I wonder if maybe the deep inherent depth of field at 10mm does not provide the phase detection AF system enough "in-focus" and "out of focus" data to get the system to activate? That's kind of one of the foibles of phase detection AF...like for example, the Nikon 70-300 AF-S VR-G lens is sort of well-known for sometimes just NOT focusing once it's fairly far off the mark and well out of focus...the users needs to actually grab the focusing ring and turn it, and sort of wake the danged lens up. This happens to me, it happens to SM4Him, and other owners of that specific lens. The Canon 50/1.4 USM also does this at times...just sort of...sits there, doing nothing, until the user initiates focusing, then it wakes up. Not sure how to characterize this type of non-responsive focusing behavior? Operational quirk? AF lens air-speed stalling? lol Lens brain fart?

Kinda sounds like the issue I am having. What is weird is it just started happening.

amolitor · Dec 4, 2013

Does it still focus in "live view" assuming you have such a thing? That would narrow things down a bit.

runnah · Dec 4, 2013

amolitor said:
Does it still focus in "live view" assuming you have such a thing? That would narrow things down a bit.

It does.

amolitor · Dec 4, 2013

Sounds like Derrel might be on to it, then, since the live view focus should be based on contrast detection off the sensor, rather than phase detection?

In any case, it rules out something mechanical like 'focus motor gets unplugged when you zoom in to 10mm' or something and suggests that the camera may be at fault.

Could this be as simple as some dust in the optical path to the AF module? Or perhaps the AF module itself is slightly bodged? Check to see if you're still getting accurate focus, perhaps?