Calibrate Sigma 18-35mm (Nikon)

Started 3 months ago | Questions thread
SushiEater Veteran Member • Posts: 9,615
Re: Calibrate Sigma 18-35mm (Nikon)

mohxinn wrote:

Kazmarov wrote:

It is difficult to understand your issue if you are using the Sigma Dock. Perhaps you could rephrase?

For the 18-35, the dock has four distances along the columns and four zoom levels. You have to calibrate for the minimum one first and move down the focal lengths, then select the next distance & adjust until you get to & complete the infinity column. If your lens is anything like mine it should show infinity at around 35-40 metres at 35mm focal & f/1.8.

Re your final query, Sigma UK tech recommend starting from the minimum distance - I cannot comment on the statement you quote from other forums.

Sorry for not being clear. I meant that even after calibration focus is still inaccurate when the subject is greater than 0.7m (not 0.5m I checked again). I check the lens scale after taking a picture to get the subject distance.

Is it consistently inaccurate? Are you running the test outside or inside in the low light?

The four distances to calibrate on the dock are 0.28m, 0.35m, 0.5m & Infinity. I have no values in the last column (infinity distance) as I don't plan on shooting at infinity.

Could it be that I need to put values in the last column for accurate focus for subject distance > 0.7m?

The infinity is not just infinity. It has a range. You need to look at the software screen to see where red line is sitting at infinity. Then go outside and focus on something so the white line in your focus distance window matches the software screen. The you have to find your target like a building with a bunch of windows  or a very long brick wall or a fence and make sure you focus at the point at 45 degrees and the be at the distance that the white line is the same as before sitting on the part of infinity range. But it will only work if you have consistent focusing.

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