DOF Preview Nikon F4

[Luckypete]

I've recently acquired a Nikon F4. All seems to be Ok after 3 rolls of film; however. The DOF preview button does not function, its very hard to press in. The Mirror lockup does work ok. Looking at the aperture lever and pressing the button (without an attached lens) the lever does not move. the 3 lenses I have Ai-s, AF-S and G all work in their respective Aperture and Shutter priority modes respectively, its just the DOF preview ??

 

[reddesert]

Take the lens off and fire the camera while looking at the lens mount. You should see the aperture lever go down and back up. This allows the lens to stop down.

It is possible for something to be bent in the DOF preview lever mechanism that jams it, but it is also possible that will prevent the aperture lever from functioning, which is significantly more serious than just losing DOF preview.

 

[Luckypete]

The aperture lever does not go up and down when pressing the DOF button. So this lever should be in a position to open the lens to the maximum aperture when the lens is mounted. I presume then, this lever operates the correct distance/movement according to what aperture is set on the aperture ring when the shutter is fired?

 

[brian steinberger]

My F4 currently has this issue where it will not stop the lens down to correct aperture fast enough. I was getting overexposed shots and couldn’t quite figure out what was going on. With no film in the camera I set it to f/22 and bulb setting. Looking through the front of the lens I watched it take about 1 second for the aperture blades to get to the proper aperture. My DOF preview button does press down ok, and I can still use the camera on the tripod with mirror lock up. Fortunately I have other Nikon cameras to use. I can’t imagine how much this would cost to have repaired. I would imagine as much or more than the camera is worth. I’ve had this camera since 2003 so I’ve gotten my moneys worth out of it.

 

[Luckypete]

I did a test this morning with two lenses and aperture priority. I developed the film and I can see clearly that its not stopping down at all. Every shot is wide open with the shutter speed changing as per usual. I am sending the camera back for a refund. I hope I can somehow get a decent copy of the F4 as I realy like using it.

 

[reddesert]

The aperture lever does not go up and down when pressing the DOF button. So this lever should be in a position to open the lens to the maximum aperture when the lens is mounted. I presume then, this lever operates the correct distance/movement according to what aperture is set on the aperture ring when the shutter is fired?

Not quite. You didn't do the test that I asked for, which is firing the shutter (not pressing the DOF button) and seeing if the aperture lever moves. That's a way to find out if it's functioning without burning film.

The body's aperture lever holds the aperture full-open while you are viewing. When you fire the shutter, the lever moves down/out of the way and (in A and M modes) lets the lens stop down to the working aperture set on the lens. You can see how this works with the lens off-camera, where the lens stops itself down and the lever on the back holds the aperture full-open.

On later Nikons such as the F4, in S and P modes, the lever should move by a prescribed amount to stop down the lens to the aperture that the body wants. Technically, you need a later lens (AI-S or AF) to have the aperture lever movement calibrated to the lens setting to work properly in S or P.

If the aperture lever is not moving when the camera fires, that is a critical failure and the camera needs to be repaired or returned.

 

[AnselMortensen]

My F4 currently has this issue where it will not stop the lens down to correct aperture fast enough. I was getting overexposed shots and couldn’t quite figure out what was going on. With no film in the camera I set it to f/22 and bulb setting. Looking through the front of the lens I watched it take about 1 second for the aperture blades to get to the proper aperture. My DOF preview button does press down ok, and I can still use the camera on the tripod with mirror lock up. Fortunately I have other Nikon cameras to use. I can’t imagine how much this would cost to have repaired. I would imagine as much or more than the camera is worth. I’ve had this camera since 2003 so I’ve gotten my moneys worth out of it.

This sounds like the aperture blades of your lens might be oily/ stuck together.

 

[Luckypete]

Sorry, yes I did perform your test. The lever moves very slightly, more like a tiny bounce. This indicates to me that it is mechanically stuck somewhere in the linkage.

 

[rulnacco]

My F4 currently has this issue where it will not stop the lens down to correct aperture fast enough. I was getting overexposed shots and couldn’t quite figure out what was going on. With no film in the camera I set it to f/22 and bulb setting. Looking through the front of the lens I watched it take about 1 second for the aperture blades to get to the proper aperture. My DOF preview button does press down ok, and I can still use the camera on the tripod with mirror lock up. Fortunately I have other Nikon cameras to use. I can’t imagine how much this would cost to have repaired. I would imagine as much or more than the camera is worth. I’ve had this camera since 2003 so I’ve gotten my moneys worth out of it.

As AnselMortensen also said, this very likely is not a problem with your camera, it's probably oily/sticky aperture blades.

Here's how to test:

Take that lens off your camera. Find the lever on the lens mount that stops down the aperture blades, and set the aperture to something below wide open, say F16. The blades should promptly close down to the aperture you've set it at as you turn the aperture ring. Push the aperture lever over to open up the aperture blades completely, then let go. The blades, if working properly, should immediately snap down into the preset position. If they are slow to do that when you perform this procedure, the problem is with the lens, not the camera. And the blades don't have to be visibly oily to be a bit sticky.

If the lens is performing normally, check the camera. Set the shutter speed on some longer speed, 1-4 seconds, and fire it with no lens while looking at the stop down lever in the camera body, and see if it is traveling the way it should at the proper speed.

More than likely, though, it's going to be the lens--I had to take apart a 200mm/f4 AI lens and give the aperture blades a good cleaning in 98% isopropyl alcohol because they were doing that, and the lens works perfectly now.

 

[Luckypete]

It's not the lens its the Camera.

 

[MattKing]

It's not the lens its the Camera.

Others who are more into the Nikon system may correct me here, but sometimes DOF preview levers only work properly when a lens is attached.
Generally speaking, when things like this go wrong, it is something to do with how the camera body and the lens interact with each other.
And sometimes, damaged bodies can damage the lenses mounted on them, and damaged lenses can damage the bodies that they are mounted to.

All of which is to say, don't jump to that conclusion yet....

 

[brian steinberger]

This sounds like the aperture blades of your lens might be oily/ stuck together.

No. I tried it with multiple lenses that I use on other cameras with no issues. It’s a weak DOF lever. Like I said, I could still use the camera if I pushed the DOF lever before each shot or on tripod with MLU.

 

[reddesert]

Others who are more into the Nikon system may correct me here, but sometimes DOF preview levers only work properly when a lens is attached.
Generally speaking, when things like this go wrong, it is something to do with how the camera body and the lens interact with each other.
And sometimes, damaged bodies can damage the lenses mounted on them, and damaged lenses can damage the bodies that they are mounted to.

All of which is to say, don't jump to that conclusion yet....

There are now two people with slightly different problems in this thread: the OP and Brian, so some of the replies are getting crossed. But both of them have an F4 that doesn't actuate the stop-down lever properly. The DOF button and the aperture stop-down linkage should work with no lens on the body.

This body-lens connection hasn't really changed from the original Nikon F to whatever is the latest DSLR that they still make. The only material change is the way that a few bodies like the FA use the stop down lever incrementally to make S/P modes work. I was wrong above, the F4 doesn't do that; I think you only get A and M modes with a manual focus lens on an F4.

People are sometimes surprised that an all-electronic entry-level DSLR (like a D3400) that doesn't meter with manual focus lenses, is designed for lenses without an aperture ring, and so on, still has this mechanical stop-down lever, so you can mount a manual lens from 1960 on it and still get correct stop-down when firing the shutter (but no metering).

 

[Andreas Thaler]

Here is some information about the common aperture control issue with the Nikon F4, including a test (which has essentially already been discussed here):

Nikon F4: Information about the common issue with the aperture control

This is what the smallest aperture on a Nikkor AF 35/2.0 D should look like. If the Nikon F4 has the common aperture control problem, the aperture closes with a delay or not completely. This can result in exposure issues. The Nikon F4, Nikon's fourth generation of top-of-the-line SLRs...

www.photrio.com

This allows you to check whether a mounted lens stops down correctly—that is, whether the aperture closes completely and without delay.



If this is not the case, the mechanism may be missing a drop of oil (see picture, aperture control mechanism, the flywheel's axle is where the oil goes).

If the aperture button makes a screeching noise when pressed, that is another indication of the problem.

If the aperture button is difficult to press and the described problem is present, the complex aperture control mechanism may have a friction issue. Cleaning and spot oiling should help. For all cases, the F4 must be disassembled for this.

There may also be a mechanical issue. To determine this, you would need to inspect the mechanical components after disassembly.

I'm very interested in this issue. If you're thinking of parting with your F4, I'd be happy to buy it from you and write a report here about my attempt to repair it. That might yield further insights.

A paper on in-depth servicing of the aperture control was also published recently. We could take a look at that:

Nikon F4: Aperture Base Plate Overhaul Tutorial by Vladislav Stanimirović

A tutorial on the aperture control problem with the Nikon F4 has been published on Learn Camera Repair. In this case the aperture on the F4 no longer works properly. Author Vladislav Stanimirović goes much further in troubleshooting the problem, servicing the removed aperture control and also...

www.photrio.com