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Old 15-10-2017, 04:21 PM
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AstroJunk (Jonathan)
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Samyang 24mm focus issue :(

My beloved lens took a tumble and whilst it seems on the outside perfectly OK, it no longer comes to focus at infinity. Rather inconvenient for nightscapes!!!!

Anyone had an issue like this or know of anyone who can fix it? There seems to be plenty of stuff on youtube about fixing the position of the dial itself, but that has no effect on the focus mechanism itself.

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Old 17-10-2017, 04:40 PM
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AstroJunk (Jonathan)
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I contacted Samyang Australia and they suggested sending it back to Korea for fixing at $200. To be honest, the money wasn't that big a deal, but being on the road, the loss of the lens was!

So I have spent a few hours stripping the lens down, only to find that the fix was incredibly easy

Nothing more than removing the rubber grip, loosening three grub screws and rotating a silver collar until the correct focus is achieved. Job done...

(An almost identical method is used on the 14mm I noticed on google)
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Old 19-10-2017, 03:50 PM
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Congrats on the cheap non $200 fix
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Old 19-10-2017, 07:41 PM
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Thanks Colin,

I'm a double winner - My 14mm which I bought 2nd hand on this forum was not so brilliant. A little blotchy and some edge issues too. Well given the same treatment, it's turned out to be a real gem. I need a good sky and a bahtinov mask to finish the job properly, but right now, I'm a happy camper!
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Old 24-10-2017, 06:54 AM
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Quote:
Originally Posted by AstroJunk View Post
Thanks Colin,

I'm a double winner - My 14mm which I bought 2nd hand on this forum was not so brilliant. A little blotchy and some edge issues too. Well given the same treatment, it's turned out to be a real gem. I need a good sky and a bahtinov mask to finish the job properly, but right now, I'm a happy camper!
Interesting, so the distance the elements are moved may be quite critical to its performance. UWA lenses do seem sensitive to spacing.

Greg.
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Old 24-10-2017, 09:09 AM
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The 24mm has three groups of lenses. The front two groups can be adjusted for spacing but only the rear group moves when focussing. I'm not sure if the 28mm has a movable front element though - I didn't need to take it apart.

There is certainly plenty of room for tinkering with these lenses and would be interesting to see how much improvement in performance can be gained. Still waiting for a clear night to play!
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