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Kern Switar 10mm AR F1.6 - Any ideas on how to access the helicoil to re-lube?


Al Debruin

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On the Switar 10mm AR F1.6, how do you access the helicoil to re-lube it?
I have a pretty clean copy but the focus is pretty much seized, I tried removing the rear most element but that got me nowhere near the helicoil.

Any advice would be appreciated.

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  • Al Debruin changed the title to Kern Switar 10mm AR F1.6 - Any ideas on how to access the helicoil to re-lube?
12 minutes ago, Maxim Lequeux said:

Take care to mark your lens so that you can put the helicoid back together and keep everything in focus!

Thanks, I have watched that video but unfortunately he doesn't open up the helicoil.
I have removed the lens mount and rear element on mine but it appears the helicoil can only be access from the in front of the focus ring. I can't even see anywhere that I could even try putting a few drops of lube into the helicoil thread.

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8 minutes ago, Simon Wyss said:

My advice is to hand the lens over to a serviceperson who dismantles, cleans, and lubricates correctly. Pouring in some oil will not remove the sticky grease resin from the threads.

I would consider myself fairly experienced with working on lenses, well lets say sufficient enough that I am always happy with the results, so I would only send to a tech as a last resort or on something very special. I have a micro dropper for lube to very precisely apply the lube where required in very measured quantities. Sometimes it works to apply a few drops and work it in to the helicoil, sometimes the helicoil needs to be opened to clean it out properly, you take it as it comes.

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39 minutes ago, Al Debruin said:

Thanks, I have watched that video but unfortunately he doesn't open up the helicoil.
I have removed the lens mount and rear element on mine but it appears the helicoil can only be access from the in front of the focus ring. I can't even see anywhere that I could even try putting a few drops of lube into the helicoil thread.

Sorry, I didn't watch through the whole video before I posted it, but when I relubed my Switar rx10  I watched some of Mikeno62's other Switar videos, maybe they will show the helicoid being opened? 

 

 

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1 hour ago, Al Debruin said:

I can't even see anywhere that I could even try putting a few drops of lube into the helicoil thread.

If your situation is anything like mine I can imagine that you'll have to completely clean out and put in a lubricant - not oil, the old switar grease that I had in mine was very hard and green.

Previous discussion for reference too:

 

Edited by Maxim Lequeux
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10 hours ago, Al Debruin said:

I would consider myself fairly experienced with working on lenses, well lets say sufficient enough that I am always happy with the results, so I would only send to a tech as a last resort or on something very special. I have a micro dropper for lube to very precisely apply the lube where required in very measured quantities. Sometimes it works to apply a few drops and work it in to the helicoil, sometimes the helicoil needs to be opened to clean it out properly, you take it as it comes.

If you think you can apply lubricant to a lens with a dropper you are not experienced enough, I’m sorry. Lenses are never lubricated with oil or otherwise liquid lubricants, only ever grease. And the right sort of grease. Oil, or grease that separates and releases oil, will eventually leach onto optics and iris blades. And you need to thoroughly remove the hardened grease first, otherwise the focus will never feel smooth.

You shouldn’t have to remove any optics to clean and relubricate the focus helical in this lens. The helical is in the rear part that is removed at the very beginning of the video. But you also need to remove the focus ring and clean and lubricate that part. There is a different way to remove that ring for each Kern prime focal length. 

It’s easy to lose the focus calibration so make sure to mark and measure everything before taking things apart. You also need to be aware of the rotational position of the C mount for the right index mark position when fitted to the camera. 

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On 2/13/2023 at 10:25 AM, Dom Jaeger said:

If you think you can apply lubricant to a lens with a dropper you are not experienced enough, I’m sorry. Lenses are never lubricated with oil or otherwise liquid lubricants, only ever grease. And the right sort of grease. Oil, or grease that separates and releases oil, will eventually leach onto optics and iris blades. And you need to thoroughly remove the hardened grease first, otherwise the focus will never feel smooth.

You shouldn’t have to remove any optics to clean and relubricate the focus helical in this lens. The helical is in the rear part that is removed at the very beginning of the video. But you also need to remove the focus ring and clean and lubricate that part. There is a different way to remove that ring for each Kern prime focal length. 

It’s easy to lose the focus calibration so make sure to mark and measure everything before taking things apart. You also need to be aware of the rotational position of the C mount for the right index mark position when fitted to the camera. 

I have used a few drops of liquid lube to resurrect stiff helicoils without disassembly successfully a few times in the past and most of those lenses are still working great to this day. It either works or it doesn't and granted it may not be buttery smooth afterwards but often it's close enough not to matter. You don't do that on mission critical lenses but when you pick up a lens for near nothing and just want to give it a try, if a few drops of liquid lube work to get the focus free again then great. Obviously best is a full strip, clean and re-grease of the helicoil but that is quite an undertaking on some lenses and perhaps not worth the time until it's ascertained that the lens is worth the effort or cost to have it sent in.

But I digress.

Edited by Al Debruin
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On 2/12/2023 at 11:30 PM, Maxim Lequeux said:

Sorry, I didn't watch through the whole video before I posted it, but when I relubed my Switar rx10  I watched some of Mikeno62's other Switar videos, maybe they will show the helicoid being opened? 

 

 

Thanks for your patience and advice Maxim, my helicoil seized with the one lip virtually parallel to the lip of the mating coil so it looked like a solid cylinder instead of 2 halves. I was baffled as to where the helicoil could be but that video gave me a better idea of where to look and I found it. I've only worked on 35mm lenses in the past, Kern lenses are very new to me.
Now to try loosen the helicoil, it's very much frozen, I'll try some lighter fluid as a first stop.

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That was relatively painless once I had a better idea what I was working with. The helicoil has been loosened, cleaned, greased and the lens is back together, the focus feels great. I just need to check infinity and that the focus scale is accurate tomorrow when there's light.

 

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It's a non RX lens so I calibrated/set the focus scale at 1m using a laser measure and a mirror-less camera with a C-mount adaptor. It seems to have translated near perfectly along the focus scale when measuring with the laser while moving the focus through it's throw, including infinity.

Assuming the C-mount adaptor I'm using is set at the correct flange distance how well should the focus scale set on a mirrorless camera translate to a 16mm film body, are there other things to consider?

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15 hours ago, Al Debruin said:

It's a non RX lens so I calibrated/set the focus scale at 1m using a laser measure and a mirror-less camera with a C-mount adaptor. It seems to have translated near perfectly along the focus scale when measuring with the laser while moving the focus through it's throw, including infinity.

Assuming the C-mount adaptor I'm using is set at the correct flange distance how well should the focus scale set on a mirrorless camera translate to a 16mm film body, are there other things to consider?

Does anyone have any ideas on the above?

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Well you sort of answered your own question - “assuming the adapter is set at the correct flange distance”. If that’s correct, and your 16mm camera is also correctly set, then it should work fine. 

If you have a non-reflex Bolex you can use the top viewfinder to check focus and see if it matches your focus marks. Or find a compatible prismatic focusser to check focus at the gate. Or just shoot a test and see how it looks. Or have a technician double check everything with a collimator. 

 

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Thanks Dom, I'll give it a test on a Bolex, granted it's not terribly easy checking for sharp focus in the tiny viewfinder on a H16. Mirrorless cameras are great with their ability to zoom in to focus check and take test shots to preview on the computer.

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