Calibrate focus – 7artisans 35mm F1.2 lens

Number of 7artisans 35mm F1.2 owners reported that infinity focus at F1.2 is not correct. During my recent review I’ve assumed that three tiny Allen (or Torx) bolts on the focus ring may serve to calibrate the infinity point.

Today I decided to check that. I’ve also realized that my sample can’t perfectly focus at infinity on the very far distance (more than 200ft). And the good news is that it can be relatively easily calibrated without disassembly or sending the lens back to the factory : )

I’m using Torx T3 screwdriver, probably T2 should better fit (update: T2 size confirmed by one of 7artisans 35mm F1.2 owner).

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Calibration steps:

  1. Mount the lens on camera and rotate focus ring to infinity until it stops (focus ring rotation blocker inside doesn’t allow to pass the infinity mark).
  2. Gently unscrew all three tiny Torx bolts on the focus ring, make about 2 full turns on each. It’s important to make sure focus ring is not rotating during that procedure so keep it located at infinity point firm.
  3. When focus ring is loose, rotate it to “5m” mark. Front lens barrel should not move during that wich indicated you are only rotating focus ring without actually focusing.
  4. Gently screw back all three Torx bolts. Congratulations, now your lens can focus more far, and will pass the real infinity distance. Now make sure you set aperture to F1.2 and focus lens to perfect infinity point, it’s preferred to use very distant light source like the street lamp or star.
  5. The final set of steps is to gently unscrew all 3 Torx bolts to loose focus ring, then rotate the ring to “infinity” mark, and tighten 3 Torx bolts. Now my 7artisans 35mm F1.2 sample focuses perfectly at F1.2

UPDATE: here is more detailed guide with each step pictures: calibrating focus – adjustable focus ring

I love the mechanical design, 7artisans did great job making the infinity calibration so easy. The focus ring has stopper at infinity mark, so you just simply align the helicoid to proper position.

BTW, similar approach works for Mitakon 35mm F0.95 Mark II, and 7artisans 12mm F2.8 (performed on my lens samples), the only difference in steps is to use flat screwdriver.

 

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11 thoughts on “Calibrate focus – 7artisans 35mm F1.2 lens

  1. I just read through your guide on calibrating infinity focus again. There might be a small error in there. In the instructions, you say to set the lens to the 5m distance mark, loosen the set screws, then move the loose focus ring to infinity and re-tighten. I think it should be the other way around. Set to infinity, loosen the ring, set to 5m, then tighten. This will give the focus ring some extra range of motion to focus further away.

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    1. Good catch, thank you!
      I’ll correct it now and add pictures later for better visibility of the adjustment.
      I’ve wrote the guide after making adjustment and missed to test steps one more time – classic mistake.

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  2. Yes, please add photos as to what you are doing in each step. ‘A picture says a 1,000 words’. Hard to visual just reading text and comprehending in the mind. Doing this process, does it really add to the sharpness of focus across all distances? F1.2 to infinity?

    I am thinking to purchase the ‘just announced’ Neewer equivalent for only $119. It’s even cheaper but unavailable. https://goo.gl/1uwti9

    This 7Artisans could be an alternate consideration.

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    1. Ok, will do images today, thanks for the interest.
      Yes, that Neewer looks very interesting, I’d love to try it once as well. It says similar optical design and also 9 aperture blades.

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      1. I will enjoy your review! I have 2 of the 25/1,8. First was rubbish at infinity, second 100%.
        Both have a paper shim.
        Taking the shim off the first lens – it works correct now!

        But – the progress of helicoid is not my favorite. It is darn slow at closes and almost a fraction of a degree between 5 meters – Infinity.
        Older lenses, like Canon FD, M42, Minolta are more clever here..

        -J!

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