Nikon F4S shutter priority trouble

[Maestrozen39]

Hi there, my just buyed F4S has a strange problem: it works well well in all modes, apart from S mode. I use it with an AF-D nikkor, so fully compatible with the camera.
The camera shows the correct mode on the viewfinder, and meters correctly, calculating the right lens aperture. But when I press the shutter, also the shutter speed varies depending on the light metered! For example if i set 1/4 of a second, the camera shoots at that speed for large lens apertures, shoots at faster speed (like 1/10, 1/15) for calculated aperture near f8 and shoots a lot faster for very small calculated apertures. However, the effective shutter speed is choosed in a certain range from the selected one, and keeps a connection with it, for example if I select 4 second, then it shoot at 4 second on f2, maybe 2 second on f8 and 1 second at f19. In M mode the speed selected is perfectly respected.
There is something i can do?

 

[jimjm]

Are you setting the lens aperture ring to the smallest setting (f16, f22, etc.) when using shutter priority mode?

 

[Maestrozen39]

Yes of course. Otherwise it would not be possible to talk about which diaphragm it has calculated

 

[Maestrozen39]

here's a video of the issue: 1/2 of a second, diaphgram fixed on f22, first on S mode with wrong speed (too fast), then in manual mode with the correct speed of half second.

 

[Robin Guymer]

Maybe try cleaning the CPU contacts on the lens as it sounds like the camera is not recognising the lens as having a CPU so is defaulting to A mode which it would do with a non CPU lens like a manual AI-S.

 

[Maestrozen39]

No: in the VF the camera show "S" mode correctly. With an incompatible lens or dirty contacts it would show "A" even if setted in "S" mode

 

[MattKing]

No: in the VF the camera show "S" mode correctly. With an incompatible lens or dirty contacts it would show "A" even if setted in "S" mode

It is still worth cleaning those contacts - the lens may be communicating an incorrect maximum aperture to the camera.

 

[Maestrozen39]

I will try, but both the contact on the lens and on the camera are clean and shiny. It's a very strange behavior, i can't find anything like that on the web

 

[Maestrozen39]

Ok, new test, new infos:
1- S mode, speed of 4 second, metered "HI" on diaphgram, AE locked, and watched direct through the lens to observe the diaphgram actuation: the effective shutter speed is more fast, and the effective aperture is a bit larger than the one i achieve manually stopping down the lens at f22!!
2- S mode, speed of 4 second, metering "LOW" on diaphgram, AE locked, and watched direct through the lens to observe the diaphgram actuation: the effective shutter speed is correct, the diaphgram is fully open
3- S mode, speed of 4 second, metering "1.8" on diaphgram, AE locked, and watched direct through the lens to observe the diaphgram actuation: the effective shutter speed is mostly correct, but in some cases the diaphgram get partially closed, like a manual stopdown on the fist click of the ring (beetween 1.8 and 2.8 there is a small click)!!

i must test further, but seems like the actuation of lens aperture in AE exposure is not precise (it's a common nikon problem due to stopping down mechanical system), and maybe the camera instead of simply actuating what had metered before the pressure of shutter button, takes another metering with the lens stopped down, just before opening the shutter, but finds that the light is more than what expected, and so compensate reducing the shutter speed!
i must test with an another lens!
any thought?

 

[BSP]

Just a wild guess: are you maybe using rechargable batteries in de F4S?

 

[Maestrozen39]

No

 

[Maestrozen39]

I can say that the effective speed on HI metering is around 1,5 stop faster than the selected speed.

 

[Kino]

Is the lens diaphragm lever sticky or hard to actuate?

Is there any oil on the blades of the iris of the lens?

As you suggest, it might be the metering system compensating for not being at the actual aperture.

 

[Ariston]

If there is a way to do a factory reset to reset all the custom functions, that is worth trying. It cleared up some weird behavior on a newly purchased F90X for me.

 

[Maestrozen39]

Is the lens diaphragm lever sticky or hard to actuate?

Is there any oil on the blades of the iris of the lens?

As you suggest, it might be the metering system compensating for not being at the actual aperture.

no, the lens is like new. maybe the only weird thing is a sort of half click between 1.8 position and 2.8. it is not a full click like all others, and the lens stop down only a little bit. all my others 50mm lens (canon, pentax) have an half stop between 1.8/1.7 and 2.8 which closes the diaphgram so much more than this half stop on nikon...

If there is a way to do a factory reset to reset all the custom functions, that is worth trying. It cleared up some weird behavior on a newly purchased F90X for me.

this camera doesn't have any lcd or custom function, all you can do is move lever and knobs...does exist any factory reset for F4?

 

[BSP]

No

Good. When I had a F4 and was using rechargeables I encountered all sorts of funny behaviour, but nothing like this. I just thought I'd check.

Bill

 

[Kino]

Just tried it with my F4 and the shutter speeds sound equal.

Mystifying...

Does the shutter speed sound identical when in A and S? Maybe there is contamination in the switch, causing it to go into automatic mode rather than shutter priority.

 

[Vilk]

maybe it shows HI, but still tries to keep good exposure by speeding up the shutter

 

[Kino]

What focusing screen do you have in your camera?

Some require exposure compensation in the prism.

I only ask because I just got my F4 recently too and I decided to check it, only to be shocked that it was the "E" version rather than the typical "B" type. Now I am trying to find the exposure compensation value for this screen...

EDIT: OK, it's the same as the standard "B" compensation...

 

[shutterfinger]

If you need a copy of the F4s instruction manual download it here: https://drive.google.com/file/d/1Zccpg3z3UsI5H7mKxliicZOCblbAxMr4/view?usp=sharing
If you need a copy of the F4 view screen chart download it here: https://drive.google.com/file/d/1JPI70PBJrP9Uchi4G4_DcndlOO3SCt3a/view?usp=sharing

 

[Robin Guymer]

According to the manual the S mode only works between 4 sec and 1/8000th sec. so maybe try testing a bit faster than 4 sec could give more consistent results.

 

[labcoat]

I have experienced the exact same issue with my F4 and I believe it is fairly common. It is correct that the camera compensates for the aperture not fully stopping down to the value determined by the meter. The compensating is normal, so the problem is the aperture actuating mechanism in the camera. It is caused by some lubricant gumming up.

F4user posted a nice set of instructions, including photos, a while back:
https://www.photrio.com/forum/resources/nikon-f4-aperture-lever-repair.69/

I was able to repair my camera, but it's definitely not an easy job. I would not recommend you attempt this unless you have some experience doing this sort of thing and the right tools.

 

[Maestrozen39]

First, thanks to all the people who tried to help me, you were very kind, in the italian forums no one gives a s**t about a old beauty like the F4!

I have experienced the exact same issue with my F4 and I believe it is fairly common. It is correct that the camera compensates for the aperture not fully stopping down to the value determined by the meter. The compensating is normal, so the problem is the aperture actuating mechanism in the camera. It is caused by some lubricant gumming up.

F4user posted a nice set of instructions, including photos, a while back:
https://www.photrio.com/forum/resources/nikon-f4-aperture-lever-repair.69/

I was able to repair my camera, but it's definitely not an easy job. I would not recommend you attempt this unless you have some experience doing this sort of thing and the right tools.

Thank you so much!! The reply i was waiting for, finally someone with the same problem! The reparation is very hard, i don't have skill enough, but now at least i know why the camera has this behaviour and that the final exposure on film is correct...better than nothing!!