Sonntag, 4. Mai 2014

How to fix the focus of the Samyang (Walimex) 8mm F2.8 UMC Fish-eye II

I recently got my new Samyang 8mm F2.8 UMC Fish-eye II with E-mount and was really excited about to shoot some great fisheye photos. The first test shots have been shot under daylight conditions and I used F8-11 but not below to simplify the manual focussing.

Later on I tried to shoot with aperture wide open F2.8. The focus magnification in the Sony ILC 6000 is a great help when it comes to manually focussing but I realized that I couldn't focus to infinity. The focus ring couldn't be turned further to obtain a sharp image.

I changed the lense back to the kit lense E PZ 16-50mm F3.5-5.6 OSS to check the manual focus. A quick comparison of two images of the same subject with the same magnification and the same shooting parameters is show in the following image:

It reveals that my Samyang @F2.8 is blurry or out of focus in comparison to the kit lense. This is a real disappointment since I bought the lense to shoot photos of stars and the milky way with open aperture and I will not accept this kind of blur.

I was already looking for the original packing of the Samyang to box it and send it back to Amazon when I discovered three little screws below the mount of the lense. I couldn't resist to open the screws to see what is beyond the metal ring.

After opening the screws I carefully lifted the first ring with my fingernails revealing the inner organs of the lense.

Below the ring which contains the E-mount, I found two very thin distance rings. I removed the bronze colored ring (with a thickness of 0.2 mm), reassembled the lense and took some test shots:

The results are impressive, the sharpness is back as can be seen in right two images above. However, when focussing now an object which is at infinity I have to turn the focus ring inbetween 1 and infinity.

Also I am not sure if I changed other optical properties of the lense but I will see in the next weeks.

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