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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 14 May 2013 (Tuesday) 22:25
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Sigma 85 F/1.4, Uneven Focus Plane?

 
Chenger
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61 posts
Joined Sep 2010
     
May 14, 2013 22:25 |  #1

Hey all. I just got a used sigma 85mm F/1.4 from ebay. After some Microadjust, the center focus became spot on most of the times However, the outer focus points are having problems.

Specifically, both far left and far right spot consistently back focuses by significant amount. Since they both miss the focus in the same way, I'm inclined to think it's not because my camera focus plane is tilted. This can be only explained by the lens having a convex/semi-circule-ish focus plane.

Is it just me or is this the same across all copies?


Nikon D600 | Sigma 50 F/1.4 | Sigma 85 F/1.4 | Nikon 24-85 F/3.5-4.5 | Tamron 70-300 F/4-5.6 VC | Nikon SB600

  
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oklaiss
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May 14, 2013 23:39 |  #2

Are the outer points all cross type? Inaccurate outer point AF could be an issue


5D Mark II Gripped, 60D Gripped, 450D, 24-105 f/4L, 85 1.8, 70-200 f/4L IS, Nifty Fifty, 28 1.8, B+W/Lee/Cokin/Hitech filters, 430ex II x2
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Chenger
THREAD ­ STARTER
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May 14, 2013 23:57 |  #3

oklaiss wrote in post #15933354 (external link)
Are the outer points all cross type? Inaccurate outer point AF could be an issue

Yes. i disabled all non cross type FPs


Nikon D600 | Sigma 50 F/1.4 | Sigma 85 F/1.4 | Nikon 24-85 F/3.5-4.5 | Tamron 70-300 F/4-5.6 VC | Nikon SB600

  
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smooth3000
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May 16, 2013 11:31 |  #4

http://www.reikan.co.u​k/focalweb/ (external link)


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joysmahal
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May 16, 2013 17:07 |  #5

Hey Chenger, I believe you are encountering a lens that is decentered. I have a Sigma 85mm f1.4 on my 5D3 and it focuses fine on inner and outer focus points - no need for micro-adjustment.

I did however run into a similar situation as you with my 1st copy of the 24-70mm f2.8L II lens. When I first got the lens I had to micro adjust the lens to get the center AF right, but then the outer focus points were "soft". I sent it to Canon right away and when they sent it back the center focus was good, but now the entire right side of the images were soft and the spot that I focused on were not sharp. However, the entire left side of the frame was good. I then contacted Canon and they told me to send in my 5D3 with the Lens. They tested it with my 5D3 and lens and said that the lens was performing within their accepted levels of variation.

This was very disheartening for me because I had the version 1 of this lens and that old copy that I had awhile ago performed better than the II that I just bought. I even sent them photos of what I was experiencing, but they said that I edited the photos and that they needed the RAW images. After I did that, they just said there was nothing else that they could do.

I thought I was out of luck because I was way outside of my 30 day return policy. I contacted Helen at Adorama and let her know the problems I was experiencing with Canon and she was able to get me a refund on the lens and they defected the old one out. My new 24-70mm f2.8L II is sharp throughout the frame at f2.8. I like it so much that I am contemplating selling my 35L which rarely gets used nowadays.

Anyway, here's a link to the photos for those interested in seeing the issue that I was running into. You probably need to download the originals to clearly see the issue. The photos where the luggage is on the left side, you can notice the "American Tourister" logo is somewhat sharp. And the photos where the luggage is on the right, the logo is not sharp at all. http://sdrv.ms/148StR1 (external link)


5D IV | 35 f1.4L | 50 f1.8 STM | 85 f1.4L IS | 135 f2L | 16-35 f4L IS | 24-70 f2.8L II | 70-200 f2.8L IS II | 600EX RT | Gear List | Semper Fi

  
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Sigma 85 F/1.4, Uneven Focus Plane?
FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
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