#1  
Old 15-10-2017, 05:21 PM
AstroJunk's Avatar
AstroJunk (Jonathan)
Shadow Chaser

AstroJunk is offline
 
Join Date: Jan 2006
Location: Brisbane
Posts: 1,669
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.

Reply With Quote
  #2  
Old 17-10-2017, 05:40 PM
AstroJunk's Avatar
AstroJunk (Jonathan)
Shadow Chaser

AstroJunk is offline
 
Join Date: Jan 2006
Location: Brisbane
Posts: 1,669
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)
Attached Thumbnails
Click for full-size image (20171017_162605_1508221519529_resized (Large).jpg)
159.9 KB31 views
Click for full-size image (20171017_152247_1508221520721_resized (Large).jpg)
149.5 KB30 views
Reply With Quote
  #3  
Old 19-10-2017, 04:50 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 5,995
Congrats on the cheap non $200 fix
Reply With Quote
  #4  
Old 19-10-2017, 08:41 PM
AstroJunk's Avatar
AstroJunk (Jonathan)
Shadow Chaser

AstroJunk is offline
 
Join Date: Jan 2006
Location: Brisbane
Posts: 1,669
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!
Reply With Quote
  #5  
Old 24-10-2017, 07:54 AM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,116
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.
Reply With Quote
  #6  
Old 24-10-2017, 10:09 AM
AstroJunk's Avatar
AstroJunk (Jonathan)
Shadow Chaser

AstroJunk is offline
 
Join Date: Jan 2006
Location: Brisbane
Posts: 1,669
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!
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 08:09 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Celestron Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Meade Australia
Advertisement
SkyWatcher Australia
Advertisement
Bintel
Advertisement
Lunatico Astronomical
Advertisement
NexDome Observatories
Advertisement
Astronomy and Electronics Centre
Advertisement