Autofocus calibration on Tamron 150-600mm G2

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PapaG

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I use a Tamron 150-600 G2 on a D500 for most of my bird photography. After reading Steve's book on autofocus and the section on calibration, I purchased the Tamron TAP-in Console, thinking that any improvement in autofocus performance would be a good thing. Tamron provides a table to input changes for three focal lengths: 7 ft, 65 ft, and infinity. I set up a focus target with a scale at 45 degrees on one side, and set up to do the tests. At 65 feet and the shorter focal lengths, it gets difficult to see the target. At infinity (I used 85 feet, it is near impossible. I'm not sure why those distances were chosen by Tamron. Much of the time I am shooting between 20 and 50 ft. from the subject, so it seems weird to be shooting tests so far away. I looked on Tamron's website and don't find any clues on this issue. I am not certain the lens needs calibration - but I WOULD like to check it in a way that proves it is not front or back-focusing. Has anyone calibrated this lens at multiple focal lengths, and if so, how did you proceed? Did you use the TAP-in console?
 
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I have used the tap in on a 100-4oo Tamron ..same procedure . If the target is too small then get a bigger one ! Mine is about 2 ft square .. You need it square on to the lens not at 45 degrees. Zoom in with the ++ button if you have to .Check you have AF-s on the rear lcd as it will often go to AF-f and it wont work. Fill all your findings on a sheet of paper and transfer to the tap in later. Set camera at 0 fine tune .I found I only did the fine tune once and once again to confirm not the 10 times steve says.
 
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I have the lens and tap in console and have calibrated it to my D500 and I am getting good results. I built a target with an aluminum yardstick with 1/16" markings at 30 degrees. Not knowing your setup, I don't know why you are having difficulty seeing your target as I am not having the same problem looking 1:1 on my computer monitor. Things I have learned: 1) Use a DOF calculator to determine what both the front focus and back focus distances should be from your focus point at the various distances and zoom factors; 2) AF through the viewfinder uses phase detection AF where AF in Live View uses contrast detection AF. Live view AF is more accurate and will show you what the camera and lens are capable of. I always take both viewfinder AF and Live View AF calibration shots for comparison. When they match, I know I am calibrated. 3) Viewfinder AF is a random variable so take roughly five shots moving the focus ring before every shot; 4) For infinity, I focus on tree branches a couple of hundred yards out from my house taking Live View and Viewfinder shots. I make adjustments until the viewfinder image matches the Live View image. 5) Putting a negative value in the table moves the focus forward towards the lens. Putting a positive value in the table moves the focus away from the lens. 6) Watch for camera shake! Use a sturdy tripod and remote release. Make sure the camera and taget have settled before taking the shot.

I have compared the G2 to both the Nikon 200-500mm f/5.6 and 600mm f/4G. The G2 is sharp in the center and gets softer in the corners. IQ is pretty good across the frame with a DX camera as you are not using the FF corners of the lens. If you are not getting good results after tuning, it's probably not the lens.

I have tuned the Tamron 24-70mm f/2.8 G2, 70-200mm f/2.8 G2, and Tamron 18-400mm f/3.5-6.3 in addition to Tamron 35mm f/1.8, Tamron 45mm f/1.8 and Tamron 85mm f/1.8 and they have all walked in just fine and are producting very good to stellar results. Good luck!
 
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