A little technology
Repair is a profession...
It's also a passion
The purpose of this article is to show that...
Nikkor 500mm f/4 P
Drowning rescue
P = Manual focus with camera link chip.
Should a half victory be considered more like a half failure???
You know that I particularly appreciate challenges, lost causes, impossible missions and other catastrophic states in terms of photographic equipment…
Well, on this one, I’m at the top, although…
I also like deals, which was the case for this Nikkor 500mm f/4 P.
I had been warned of its condition, a dive and stay in relatively fresh water, but probably cloudy.
The focusing mechanism is so simple that it still worked, but the inside was full of brown silt, and in particular the lenses were in pitiful condition.
There are, at the front, two huge lenses that were easily dismantled.
A third, the most degraded, is held by the front part of the barrel.
This one blocked by three point screws, impossible to unscrew.
Optimistic, remove these screws, drill bits and Dremel…
Until then, I was confident, but, IMPOSSIBLE to unscrew this front part…
I tried everything, alcohol, solvent, heating, and even WD40, IMPOSSIBLE!!!
I put this part aside and moved on to the rear part, bayonet and diaphragm.
The rear lens, too, can be easily disassembled and you can reach the diaphragm.
“Misery of misery”!!!
Full of silt, particularly rough, and a small guide partially loosened.
Complete disassembly, very big cleaning, repair of the guide, reassembly,
The diaphragm is stained by its stay in immersion, but works.
Deep cleaning of the rear part, reassembly. Test, the chip still works, the diaphragm is very responsive.
That’s done!
Okay, so what about these internal lenses???
Life is not a long quiet river, this objective remained stored for two years, in the waiting room! When we have no immediate solutions, we must leave things alone, it is not the right time… Then, one day, everything becomes clearer!
By removing the rubber ring from the focuser, we find two Teflon slides. Unscrewing these slides allows the lens block to be removed from the focuser.
Once the main barrel is free, we must try to clean the front lens, which is particularly stained by silt.
At this stage, whatever the method, we must completely clean this lens of all traces of pollution.
Desperate times call for desperate measures…
It was filled with water several times, rinsed and rinsed again. A final bath with a little mild household product and a final rinse with demineralized water. The outside was thoroughly dried, and the inside was gently dried with low-pressure dry air.
“Crazy?” Not at all !!
The minimal mechanism is the focuser ramp that allows the Teflon guides to move the previously dismantled mobile group. There is therefore no risk of degradation, no metal can rust. This ramp is greased at least as originally, it will be again.
It is now necessary to clean the front lens that cannot be removed… It is very seriously stained by silt. I have tried everything, using various products with progressive corrosion!
Nothing worked, it is the glass that is, certainly by porosity, stained indelibly.
As the impossible is not impossible, I continued the restoration.
The condition of this lens at the start can only suggest an improvement. Of course, I do not imagine that it is with its original qualities.
The optical parts, the diaphragm being much cleaner, this 500 mm was temporarily reassembled to test it.
The optical parts, the diaphragm being clearly cleaner, this 500 mm was temporarily reassembled to test it.
First series of test photos in slightly dim light, Nikon D3s at 1250 iso (f/22 was at 1/40), allow to see the influence of the diaphragm closures.
The native images in RAW show an obvious lack of contrast, which is not surprising at all, but the definition is still there.
A minimal post-processing (contrast +50% in Nikon NX) improves the final rendering and gives usable images.
A second series of test photos with a slightly brighter light, although the sky is still gray, gave even more surprising results, since there is
no software post-processing.
The dark side on the right of the images is actually a door jamb, we can notice the increase in its presence as the diaphragm is closed.
Even if this 500 mm is far from perfect, this rescue allows me to have a very long focal length with an interesting aperture.
The greatest satisfaction is to have succeeded in restoring a lens whose destiny was certainly to be forgotten or worse, destroyed…
After these few very quick tests, knowing its main weakness, it will be used as it is, with pleasure.
It only lacks a good lens hood, certainly feasible with a piece of PVC tube…
Its size and weight do not allow frequent use, it is still a baseball bat of more than 3 kg!!