Nikon N8008s / F801s will not autofocus

alexfilm · Jun 30, 2020

A friend gave me a Nikon N8008s. All functions seem to work, except for autofocus – the drive screw doesn't move. Are there any known repairs for this – is the drive toast, or is there a way to check if it is jammed? Moving the focus select to M does retract the drive screw.

At this point, it's a manual focus camera with a matte screen. If that's the case, are there any suggestions on what focusing screen to use instead of the stock one?

ic-racer · Jun 30, 2020

According to the service manual, the additional features of the "s" model draw more current from the focus mechanism. So check that the battery is good and make sure the battery contacts are clean. Otherwise consider getting a functioning one for about $40 and keeping that one as a spare.

neilt3 · Jun 30, 2020

Check the electrical contacts on the lens and body .
If their dirty / tarnished , the camera can't "see " the lens and won't attempt to focus it .
Presumably the lens works fine on your other Nikon autofocus bodies , film or digital ?

Wallendo · Jul 1, 2020

I know you have probably already done this, but for completeness I would suggest checking to make sure your lens is screw-drive compatible.

Autonerd · Jul 2, 2020

Oops, message withdrawn -- you *did* check the M/S/C switch.

I imagine a screen will cost more than another N8008 or N8008s. They are very advanced cameras that no one seems to want. Definitely one of the great used-SLR bargains.

Aaron

alexfilm · Jul 3, 2020

neilt3 said:
Presumably the lens works fine on your other Nikon autofocus bodies , film or digital ?

The lenses I've tried on the N8008s focus on other film and digital bodies. I can check the contacts on the body, but they seem clean.

alexfilm · Jul 3, 2020

Autonerd said:
I imagine a screen will cost more than another N8008 or N8008s. They are very advanced cameras that no one seems to want. Definitely one of the great used-SLR bargains.

Screens seem to run in the $15-30 range. But then a listing for a body will be $40 in some of the FB film gear groups I'm in.

alexfilm · Jul 3, 2020

Wallendo said:
I know you have probably already done this, but for completeness I would suggest checking to make sure your lens is screw-drive compatible.

Thanks – I'm trying AFD lenses, which should be compatible. They focus fine on an N80 and F6.

Bikerider · Jul 3, 2020

No one has mentioned that the motor for the focusing drive may have failed. On the bottom strip underneath the screen on the focus confirmation, does this still work?. If so it will be down to the motor having given up the struggle. You could still use it in manual focus mode. I have had several F801 and 801s bodies and they were completely reliable but that was over 20 years ago. It may be just plain old age.

alexfilm · Jul 3, 2020

Bikerider said:
On the bottom strip underneath the screen on the focus confirmation, does this still work?. If so it will be down to the motor having given up the struggle. You could still use it in manual focus mode.

Focus confirmation works, but can be a little fussy. It feels like it's more of a concern focusing on something in the midground if it's not quite at infinity.

Bikerider · Jul 4, 2020

alexfilm said:
Focus confirmation works, but can be a little fussy. It feels like it's more of a concern focusing on something in the midground if it's not quite at infinity.

I don't think the manual focussing is fussy, as much as it needs something definite to focus on. The autofocussing is quite primitive compared to the likes of the F100 or the F5 and does not like plain areas. They also do not like lenses of F5.6 or less or dull light which reduces the contrast further. If the rest of the body works keep it as a MF backup.

I have just thought, when you remove a lens, does the AF drive shaft pop out of the hole. It is spring loaded and should protrude by about 3-4mm. If it stays in the recess it could be that a small bit of grit is stopping it from popping out. Try a bit of gentle persuasion with a watchmakers screw driver to see if you can get it to move. Or move the AF/MF lever on the bottom left of the body and see if that does anything
.

alexfilm · Jul 5, 2020

Bikerider said:
I have just thought, when you remove a lens, does the AF drive shaft pop out of the hole. It is spring loaded and should protrude by about 3-4mm. If it stays in the recess it could be that a small bit of grit is stopping it from popping out. Try a bit of gentle persuasion with a watchmakers screw driver to see if you can get it to move. Or move the AF/MF lever on the bottom left of the body and see if that does anything
.

The drive sticks out with no lens attached, and does retract in MF mode.

shutterfinger · Jul 5, 2020

There is a factory service manual for the 8008s at https://learncamerarepair.com/index.php and http://arcticwolfs.net/
Any chance the AF Lock button is stuck in the Lock position even though the actuating button is not? (contacts stuck)

alexfilm · Jul 5, 2020

shutterfinger said:
There is a factory service manual for the 8008s at https://learncamerarepair.com/index.php and http://arcticwolfs.net/
Any chance the AF Lock button is stuck in the Lock position even though the actuating button is not? (contacts stuck)

I assume I'd have to remove the top cover to check.

shutterfinger · Jul 5, 2020

Being the AF-L button is on the lower left of the front/mirror box it may be time to review https://www.cameramanuals.org/nikon_pdf/nikon_n8008_af.pdf
No wiring diagram is provided in the service manual. The mirror box cover will need to be removed and likely the base plate and top plate. The problem can be a bad focus motor or a failure of the flexible circuit strips. If the switch is like most carbon to metal contact switches its likely the carbon on the switch button bad. The shutter button contacts are another likely culprit as switches fair far more frequently than IC chips or other electrical components.
Check the AF-L switch action by pressing it gently and listening for any mechanical parts working. Ensure the switch returns to fully extended by prying out on the button. Also make sure the AF drive fully extends by pulling out on it.

shutterfinger · Jul 6, 2020

I powered up my F4s (bought new while the 8008s was current) and the focus drive motor does not turn without a lens attached and S or C selected.
I found this in the F4 service manual, lens contacts:

See post 20. Ground contact should read 0 ohms from a bare metal point on the body to the contact.
Near to far and far to near will be pulses from the lens focusing. I do not know what RW1 and RW2 are. I will only research it when and if I have a malfunctioning body.

alexfilm · Jul 6, 2020

shutterfinger said:
Check the AF-L switch action by pressing it gently and listening for any mechanical parts working. Ensure the switch returns to fully extended by prying out on the button. Also make sure the AF drive fully extends by pulling out on it.

If I press AF-L, the shutter will fire on S or C mode, but the focus drive itself does not engage, and I don't hear anything engage when I press that button. The AF drive sticks out in S or C, but does seem to be able to extend a little further with a tug. At rest, it seems to stick out as much as any other Nikon AF body that I have.

alexfilm · Jul 6, 2020

At this point my question is whether the microprism or split focus screens interfere with spot metering if I install either one. I thought I'd seen something about the split focus (I think J) causing problems, but I haven't found anything definitive.

shutterfinger · Jul 6, 2020

Focus screen chart for the F4 https://drive.google.com/file/d/1JPI70PBJrP9Uchi4G4_DcndlOO3SCt3a/view?usp=sharing
It may be of help for the 8008.

shutterfinger · Jul 6, 2020

F4s body lens contacts labeled according to the diagram in the service manual.
No power, Digital VoM on Ohms, black lead on a lens mount screw, red lead to each lens contact
A-Inf; B-Inf; C-55.2K; D-10.69K; E- 10.43K; F-Inf; G-0
Red lead to a lens mount screw, black lead on each lens contact
A-Inf; B-1644; C-55.4K; D-10.55K; E-10.29K; F-1547K; G-0
Fresh batteries installed, meter on DC V, AF not activated
A-F 1.2mv; G-0
Auto Focus activated, shutter release pushed half way and released, AF S selected; red lead on each contact, black lead on a lens mount screw.
A-.6V to .8V; B-5.3V; C-5.47V; D-5.44V; E-5.44V; F-4.44V; G-0

Your results may vary but should be similar.

Nikon N8008s / F801s will not autofocus

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