Nikon D4 strange fault - cannot A/F

trackdemon

trackdemon

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Steve Hall
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Afternoon all, hope this is the right place for this!

On a shoot last night, halfway through one of my D4's started hunting for focus, and the exposures were hit and miss (tbf something I find the D4 does anyway!). This degenerates and I ditch it for my other D4. Back home, the viewfinder is unclear and looks the same as it does when the battery is removed in a functioning camera; exposure is normal if I manually focus, so the camera is 'semi' usable but clearly something is amiss. I'm using aftermarket batteries in both my D4's, have been for two years without issue, and swapping batteries makes no difference. Final note - it's only on 69k shutters so well within lifecycle for a D4 (and it's not a shutter issue anyway).

Would be very interested to hear thoughts, or even better if someone has had a similar experience (and resolved easily). I guess it's going to go to NPS ultimately, but if there's some simple thing which can be sorted at home that would be fantastic.

Further info: the camera focuses fine in liveview (which I use quite often in my line of work). Strange behaviour!
 
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Sounds like an issue with the main mirror... it's not entirely unheard of for them to come loose from the carrier frame.
If it has come loose from the frame you might be able to just put it back in place; but it probably won't hold for long. You can use small drops of gel super glue on the frame for a DIY... if you send it in they will probably want to replace the entire mirror assembly ($$). Before you glue it make certain of the orientation and that PDAF works with normal viewfinder appearance. There is a small pellicle window in the main mirror that allows some of the light to pass to the AF module; I'm not sure if it's dead center or has a specific offset.
 
Presumably tried cleaning contacts on body & lens ... AF sensors?
 
Afternoon folks; just had a look inside and a tiny piece of metal fell out. So fair to assume something has gone technical :/ Contacts cleaned, no difference. Same no matter which lens. Still works fine in LV.... I'm not touching it with glue, I'll only make it worse :D
 
I probably would not keep using the camera... if the "tiny piece of metal" is the AF mirror (small, rectangular, shiny) and it just fell out of its' carrier I might. Or if I absolutely had to use it as is I would consider taping up the mirror assembly. But if the mechanicals are failing and coming apart there's a significant risk of damaging the sensor IMO.
 
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It literally is a tiny piece of metal, maybe 1mm x 3mm x 0.5mm. Disappointed at 61k failure, but hopeful Nikon might offer some goodwill. The camera hasn't been dropped or abused..... just used, hard, as you'd expect of a pro level body
 
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