So, I'm uploading a video to Vimeo right now. Not sure how long it will take to upload, but thought I'd start a quick thread.
My D800 is acting weird. When tracking Birds in Flight, as soon as one of the AF points misses a target, the lens starts shuttering back and forth working it's way towards min focus. At that point, while still holding the AF button, it just sits there and does nothing. It takes multiple AF presses to get the lens to start heading back towards infinity to see if it will pick up focus.
Very frustrating and my D600 does not exhibit this behavior at all. It works as it should.
AF-C Release set.
Things I have tried with no success:
1. Changing number of AF points from single, 9, 21, 29, 51. All have the same issue.
2. Change the tracking from slow to fast to off. Usually set to off. No effect.
3. Reset all camera settings
4. Changed firmware to original, then back to latest.
5. Uncoupling all lenses/teleconverters
6. Removing battery
7. A/M - M/A switch - no change
7. Trying a new charged battery - no change
8. Trying a different lens. (longer lenses are worse)
9. Shorter lenses seem to work better.
Another way of looking at it. On my D800 now, as I move from an area where enough contrast exists to achieve focus to one where there is little to no contrast, like going from trees/land to the sky, the camera looses focus and chatters
back to min focus and stays... only with multiple AF-on presses does the focus attempt to come back
Contrary to my D600 where perform the same movement is made from trees/land to sky, the focus usually stays and locks onto the clouds, but if it does loose focus, it makes a quick sweep to min focus, then back to infinity where it usually grabs focus again. As long as I'm holding the AF button on the D600, the af is either searching quickly for a target or locked on and maintaining focus. My D800 used to be like that....
So any hints. Where do I aim a blower to get the af module clean if there is dust on it?
Very poor job on the video. Gonna have to hire a new videographer
Basically, the first video is the d800 showing the stutter to min focus. The second half shows the d600 cleanly focusing throughout the range when it cannot acheive focus. Same settings on both cameras.
You may or may not know.. the AF module is based at the bottom of the mirror box, at the front of the body under the mirror. It takes a fleck or whatever to block a portion of that AF prism/openings to deter finding home correctly.
On a whim, try blowing out the mirror box paying attention to the lower front.
Thanks John. I was wondering about blowing out the AF module but forgot where it was. That might do it. I know my camera is very dirty at the moment. The 70-200mm VRII does the same thing. 58mm and 35mm are fine, same with the 14-24mm.
Should a guy lock the mirror up or keep it down to blow out the af? I'm thinking down.... I'll try both
Well, thanks for the help my fellow Canadian!!!! I blew the **** out of the inside and low and behold it is back to normal. (for the time being anyways... ) I paid particular attention to the bottom of the mirror box. Must have been a bit of dust on something causing it to act all crazy.
I've had this rear it's ugly head over the last 10 years and it's a bugger when it takes place.. One seems to forget the reason, and then POW. I remember! A few pifs and it's all cool by the pool.
Where are yo guys blowing at? through the lens mount? I thought that it wasnt safe to do that with risk of getting dust and dirt on either the mirror or sensor? Do you do it with mirror up or down?
Glad that solved the problem, Corey. It's been SOP for me since the D300 days,
to blast the AF sensor slits on a regular basis...why wait 'til the focus goes wonky.
You KNOW it'll eventually occur at the most inopportune time. Good call, John.
Just for future reference in case people don't know where a Nikon AF module is located, here is a cut-a-way of a typical Nikon body showing the lower AF module location and the sensor windows located just behind the mirror itself.
One should lift the mirror when attempting this fix to blow free anything on the sensor. I have, on occasion needed to take a camel hair brush to this array and then followed up by a 3rd & 4th blowing out. Making sure that NO HAIRS get left behind.
Check that cut-a-way of this 14-24 here... Doesn't that make ya feel funny looking at the cross cut of those elements?
Thanks John for the advice and Corey for bring this issue up. I was going to send the lens to Nikon LA for fix, was quite worried
nextelbuddy wrote:
Where are yo guys blowing at? through the lens mount? I thought that it wasnt safe to do that with risk of getting dust and dirt on either the mirror or sensor? Do you do it with mirror up or down?
Blowing with Rocket Blower, mirror up, holding camera body face down (in case there's something falls, it'll fall outside). Be careful not to touch anything with the blower. I have done this numerous times, didn't seem to hurt anything.
Also, you know you can simply turn the camera off, and gently lift the mirror from the leading edge with your finger....this also reveals the secondary mirror which directs light to the AF module, which can also get a little dust on it...that's how I've blown mine in the past...
NathanHamler wrote:
Also, you know you can simply turn the camera off, and gently lift the mirror from the leading edge with your finger....this also reveals the secondary mirror which directs light to the AF module, which can also get a little dust on it...that's how I've blown mine in the past...
Good to know.
For the moment, AF is working properly. next time it happens, I'll blow there as well. Thanks, I love this forum!
