Author Topic: Missing Backfocus screw  (Read 170 times)

ExplosionsAndFire

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Missing Backfocus screw
« on: September 22, 2021, 06:51:21 AM »
Hi all!

I bought a second-hand Chronos 1.4 last year. It was in pretty great condition at a reasonable price (not quite a bargain, but cheaper than new). Looked like it had barely been used actually, with some very outdated software version on it. I've been spending a bit of time getting around it and it's been really enjoyable.

Anyway- to the point: I had tremendous trouble focusing with it, and eventually worked out that's because it has no back focus screw! It's just an empty hole, so the lens easily spins within the C-lens mount while focusing/zooming/aperture adjustment. Whoever packed it up and sent it obviously didn't include it, but that's the magic of selling something 'as is' with 1 or 2 photos attached.

From the manual, I can see that it's described as some sort of brass rod that screws down and locks in the lens at your set distance. Does anyone have the dimensions of this rod?? I suppose I could butcher something together but I don't want to damage anything if it's got a specialist way of locking into the lens thread. Or is there another clever way around this? Thanks!!

Nikon1

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Re: Missing Backfocus screw
« Reply #1 on: September 22, 2021, 07:02:09 AM »
Took me some Time to find mine, because i havent used it in ages, but here is a Picture from mine with some Measurements.
 The Wormscrew a standard M4x6mm Flat end Wormscrew, the Brass rod is 23,5mm long and 3mm Diameter, just Straight untouched Stock, ends seem to be Roughly ground. You should be able to make that Part easily on your own with basic measuring tools and Files / a Metal saw / sandpaper.
 Mine is from an 2.1, but should be identical, from what i know. Length should not be too critical (maybe down to a Millimeter or something).

clkdiv

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Re: Missing Backfocus screw
« Reply #2 on: September 23, 2021, 01:49:13 PM »
Nikon1, you probably will soon get an invitation to canada, to join krontec. did you ever consider to offer them to establish sort of krontec europe support office?

Nikon1

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Re: Missing Backfocus screw
« Reply #3 on: September 23, 2021, 01:51:30 PM »
Wouldnt move to Canada, even if i got an good offer, will stay in Germany ;)
 Also just Trying to help people out, where ever i am able to.

ExplosionsAndFire

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Re: Missing Backfocus screw
« Reply #4 on: September 30, 2021, 04:58:23 AM »
Thanks so much Nikon1 for this!! I should be able to mock up something pretty easily. Will report back with the fix once I get it done!!

Nikon1

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Re: Missing Backfocus screw
« Reply #5 on: September 30, 2021, 10:49:12 AM »
Glad to be able to help you out!
 For a quick fix i assume Aluminum of the Same Size should also work, but shouldnt be used long term. Brass is the correct and appropriate Material to use there.
 Wish you the best luck with that "repair" /replacement!