[krp]

The Samyang (Bower, Pro Optic, Rokinon, Bell+Howell, etc) 14mm f2.8 lens is one of the best value lenses you can buy. It's extremely sharp and great for astrophotography (See here)
But many copies have a problem with the focus ring being set incorrectly. The distance markings aren't accurate and sometimes it goes past infinity focus. Mine has been like that ever since I bought it last year. But I didn't want to send it back so I just lived with it. But I just found a video that explains how to fix it yourself in about 15 minutes.
Como calibrar el enfoque del Samyang 14mm. How to fix focus of Samyang 14mm | | VideofyMe
It's in spanish with english subtitles. I found it useful so I thought I'd share.
Kevin

[carrrlangas]

Good tutorial. But, wouldn´t using the TC introduce some focus shift? what warranties that infinit is still infinit?

[dms]

I don't have this lens but I saw the following--which discusses an "optimum" setting.
intothenightphoto.blogspot.com/2013/06/night-focusing-rokinon-14mm-lens.html

[krp]

Good tutorial. But, wouldn´t using the TC introduce some focus shift? what warranties that infinit is still infinit?

I'm not sure. Since TC's are meant for telephoto lenses it doesn't seem like it would be sharp with a wide angle lens. But I don't have one so I didn't try.

I don't have this lens but I saw the following--which discusses an "optimum" setting.
intothenightphoto.blogspot.com/2013/06/night-focusing-rokinon-14mm-lens.html

Royce Bair is one of my favorite photographers. But I'm not sure there is an exact optimum setting due to the sample variation of lenses. But I know my lens is going to be a lot easier to focus now that infinity is where it's supposed to be.

[dms]

I believe the TC should not change the focus--after all it's only enlarging the center of the image form the lens--however I know mention is made of some curvature of the image.

[demp10]

I have this lens and it is amazingly sharp corner to corner even wide open. Mine had the infinity issue also. My simple solution was to shot a series of flames at f2.8 of a distant mountain top and compare the results. I took photos at past infinity, infinity mark, 3m, 2m, 1.5m and 1m. The sharpest was at the 2m mark on the distance scale which became my new infinity marker.

Since I shoot exclusively landscapes with that lens, I set focus to 2m, aperture at f8 and never touched the settings again. Everything from about 1m to infinity is in sharp focus.