Vivitar 24/2.8 Auto Wide-Angle (MD): Aperture blades and bayonet ring deoiled

From the collection of defective lenses that I purchased some time ago, the Vivitar 24/2.8 Auto Wide-Angle is a candidate for improvement.




The beautiful and heavy all-metal lens could no longer close its aperture and the aperture blades remained in the barrel. In addition, the aperture lever in the lens bayonet only moved with a delay.

A clear case of oil contamination.

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The bayonet screws offer little resistance.




The bayonet - for Minolta MD in a solid version - is gone.

The oil is already here.




This is followed by the aperture ring and ...






... the rear optical unit, which can be unscrewed.




Details of the aperture mechanism




The aperture can now also be adjusted using the lever that moves the aperture blades.




After unscrewing the engraving ring, I gave up the idea of also removing the front lenses in order to completely clean the tube with Zippo lighter fluid.

The front lens can probably only be removed after loosening the three sealed screws. And these screws are most likely also responsible for the infinity adjustment.

Since I basically don't want to touch any of the adjusted parts, the engraving ring goes back into place.




The ring with control cam to form the apertures, which are adjusted with the aperture ring (GREEN), is fixed by a brass retaining ring (RED).






The thin retaining ring can be carefully removed with the probe.




The control cam ring is off.

To do this, two screws that connect to the aperture ring via a double eyelet must be loosened.

Further details of the aperture mechanism become visible, which helps to understand the mechanism.






To make it easier for me to move the aperture blades, I unhook one of the two springs.

For the oily aperture register, there is Zippo lighter fluid from the syringe.

I move the aperture using the lever for the aperture register and repeat the whole thing. Every now and then I dab off the Zippo-oil emulsion. It is then dried with a hot air blower at 80 degrees Celsius (= 176 F) while moving the aperture blades.

Now the aperture opens and closes again jaggedly

The aperture blades are now clean, but the lens underneath has gotten some Zippo and oil sauce.

This is quickly remedied with isopropyl alcohol and then Aqua Purificata for wiping.

The protective cap on my disposable syringe blocks the aperture under spring tension, so the aperture stays open for cleaning the lens.




Everything ready for assembly






As always, I clean the aperture ring and the aperture catch from oil and grease residue.

There is then a slight lubrication for the detent over which the detent ball for the aperture values runs.










The oily mechanics in the bayonet ring also receive a spray of fuel and cleaning.

Now it runs as it should and the bayonet is screwed on.




And once again a lens that was bought as defective is ready for action

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Conclusion

• Helicoids lubrication that has become oily is almost a routine problem with manual lenses that are several decades old.
• It is pleasing that in many cases the oiliness of the aperture register can be remedied without major dismantling. Doing this the function of the aperture mechanism must be carefully explored during assembly, as the aperture is also adjusted here. Fortunately, with experimentation and patience, the mechanism can almost always be figured out.
• However, this cure is only a temporary fix for the aperture problem. Only when the lens is - more or less completely - dismantled, cleaned and re-lubricated should there be peace in the tube for a few decades.
• This brings us to the topics of assembling helicoids correctly and adjusting the focus. Only for experienced and courageous repairers

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