Nikon F4: Mission Aperture Lever - two ways to fix the aperture problem

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Andreas Thaler

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Bearman said:
As an owner of 2 F4's with currently working aperture controls, I would welcome such a guide. Thank you for all your tutorial contributions.
Click to expand...

Great, thanks for the feedback!

As soon as the tutorial is useful to at least one F4 owner, it makes sense to create it.

I won't write "live" this time, but will finish and evaluate the result first so that only valid information is available.

It should be online here before end of this year.
 
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Andreas Thaler

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All the information you need is already available in the forum, I'll bring it together and try to make it comprehensive but simple.

Technically there aren't too many challenges, the F4 is cleanly constructed.



The destination of the journey. A gear on the mirror box that works as a photointerrupter.


It's all about separating the front part with the mirror box from the rear part, then the gear in question is accessible and can be cleaned and lubricated with a drop of oil.

Some cable connections have to be soldered, but that doesn't pose any major difficulties either.
 
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Andreas Thaler

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The biggest problems were stuck, partially glued screws that I couldn't unscrew.

This is an opportunity to use the knowledge I have acquired in the meantime to remove such unruly guys.

I'm looking forward to an interesting journey that this time won't lead into the unknown
 
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Andreas Thaler

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The complete procedure for removing and reinstalling the mirror box is described by - who else? - Larry Lyells in this edition of the SPT Journal:

SPT Journal: January-February 1993

Society of Photo-Technologists Journal
learncamerarepair.com


Additional information can be found in the Nikon F4 service manual:

Nikon F4 Repair Manual

Nikon F4 factory repair manual
learncamerarepair.com
 
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Andreas Thaler

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You don't need any special tools for this project, i.e. you should have JIS crosshead screwdrivers 0 and 00.

You should also have a soldering iron.

Tweezers, pliers, probes etc. are part of the basic equipment, I will go into this in the tutorial.

I use Nyoil to lubricate the gears and I'm very happy with it. But everyone will have their own preferences

Lubricant, Oil, Shutter 100gram

Lubricant, Oil, Shutter 100gram. NYOILIs a clear, odorless oil for lubricating, polishing, cleaning, and preventing rust. Formulated nearly 100 years ago, it remains the most highly refined oil ever produced. Applications: NyOil works great on cameras, roller blades, fitness equipment, locks...
www.micro-tools.com


For the previous cleaning I use Zippo lighter fuel:

4 oz. Lighter Fuel

Zippo lighter fuel will keep your Zippo windproof lighter and Zippo refillable hand warmer working at its best. Zippo lighter fuel comes in a 4 oz. can. Shop the Official Zippo Store!
www.zippo.com


As always:

All information provided without guarantee and use at your own risk.

 
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PS:

The F4E, which I worked on in March of this year and which I use as a work camera, has worked perfectly since then. I check the aperture function regularly.
 
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Andreas Thaler

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I'll start after Christmas and will re-photograph all the steps and make sure that it stays simple and clear.

The source for everything is the Nikon Service Manual, Larry Lyell's explanations and instructions for repairing the Nikon F4 in an issue of the SPT Journal and the tutorial by @F4user on removing the mirror box as well as my own additions (see thread).

If you should have any special requests or questions about this project, please let me know.
 

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There are very thin endoscopes for specialized work, but they would likely be awfully expensive. I still like your syringe idea. I can see where that fast spinning ratchet gear would cause oil to fly in all directions if oil is applied too liberally. An intriguing idea is to 3D print a frame that could locate a preformed syringe needle in the spot over the ratchet axle.
 
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I envision a simple mechanical frame that could hold a syringe, or something similar, locating itself on features of the camera (say the F mount) and then by virtue of its mechanical location relative to the frame would position the tip of the syringe precisely over the ratchet axle. It would require some experimentation but shouldn't be too difficult for someone who has 3D printed something (not me, unfortunately)...
 

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Andreas Thaler

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Very interesting!
 

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Did you try dribbling the solvent with gravity like this (with the shutter open and mirror up)?

 

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Also, is there a friction clutch to spin the gray metal ratchet gear. For example, when the lever comes down to stop the gray metal gear from spinning, what happens to all the other gears? Do they keep spinning?
 

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Andreas Thaler said:
Is your question directed at me?
Click to expand...

Yes, but I think I answered my question. The 'thing' behind the ratchet gear is not a friction clutch, it is the optical disk with little holes.

I am also still curious if there is a little hole visible with the camera mirror up and shutter open as in picture #134 .
 
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I'll get the mirror box from my spare parts storage so we can examine it more closely.
 
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Andreas Thaler

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ic-racer said:
Did you try dribbling the solvent with gravity like this (with the shutter open and mirror up)?

View attachment 387492
Click to expand...




The cannula must be inserted at an angle from above, with the camera standing upright. Then the benzine is distributed over the area from top to bottom:
Click to expand...

I tried the syringe with the camera in this position, so „upright" isn't accurate.

Post in thread 'Nikon F4S: Mission Aperture Lever'
https://www.photrio.com/forum/threads/nikon-f4s-mission-aperture-lever.205433/post-2777885
 
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Andreas Thaler

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Update on long-term observation:

The aperture control of this F4E (repaired at the end of March 2024 by cleaning with Zippo lighter fluid and lubricating with Nyoil) continues to work perfectly.

This F4E is my work camera for taking photos.
 
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Andreas Thaler

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I have tought through this topic and decided to give up this project as it would only be a repetition that could confuse.

I think we have already a complete repair tutorial for the aperture control problem of the F4, consisting of @F4user's part and my addition, plus the technical documentation in the Nikon service manual for the F4 and the SPT Journal, see above


It looks worse than it is

but the F4 is very clearly constructed and there are no pitfalls on the way to the aperture control and back.

Only the four screws for the tripod plate are secured with adhesive and can resist.

We have discussed techniques for loosening such screws several times in the forum, e.g. heat, solvents.

There is also information on the subject from Richard Haw:

Fundamentals: Screws and Drivers (1/3)

In the previous article we’ve outlined most of the essential tools for repair and maintenance of classic Nikons and Nikkors. Now, we’ll be discussing the best application for these tool…
richardhaw.com

Repair: Nikon Bayonet Screws (Video)

Hello, Everybody! Spring is here! It is definitely getting warmer and while that is definitely good news, the bad news is hay fever is also rampant! I suffer from it just like many people living he…
richardhaw.com

When assembling the two housing parts, it is important to correctly couple the mechanism of the shutter, aperture and mirror. I described this in my article; sources are the Nikon Service Manual for the F4 and the SPT Journal.

If I can help with any questions, I'd be happy to




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All information provided without guarantee and use at your own risk.
 
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Andreas Thaler

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Safety notes and considerations

One thing you should always be aware of when handling bezine/lighter fluid and other solvents is the potential fire hazard.

The F4 contains motors through which high current flows, as well as electronic components such as a power transistor in the area under the mirror box. As far as I understand, there is also a DC/DC voltage converter that increases the input voltage from 9 volts (6 x AA). It is conceivable that contact and sufficient quantity of benzine/lighter fluid could cause ignition.

Everyone should please form their own opinion on this.

The safest method - also in terms of results - is to remove the mirror box and specifically clean/lubricate the mechanical parts in the aperture mechanism, particularly the ratchet gear. Here it is sufficient to oil only specific areas, so benzine/lighter fluid should not necessarily be required unless the parts are visibly gummed up.

With shortcuts, applied without visibility, such as using a syringe, there is always a risk of getting solvent and oil into parts of the camera where they do not belong.
 
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Andreas Thaler

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Of course, you shouldn't inhale the vapors from solvents either.

So, as always, my disclaimer:

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All information provided without guarantee and use at your own risk.
 
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