This a continuation from 2 other threads:
https://www.uglyhedgehog.com/t-602554-1.html#10396422https://www.uglyhedgehog.com/t-494368-1.htmlI did not have good results with a 70-210 F/4 lens and Tap-In Console, but Hunt's took it back in exchange for a 18-400 lens. This post documents how that worked out...in short, not perfect, but very well and, with 24 unique focus corrections, it is far superior to the Nikon Auto-AF Fine Tuning, which only handles one per lens. But Nikon Auto-AF Fine Tuning provided a repeatable mechanism for measuring the focus front/back corrections, as described in the other threads. I used the same procedure with the 18-400.
First, I connected the Tap-In to the lens and did a firmware update to Version2. Before Tap-In, that would have meant sending the lens to Tamron in NY. Then, I brought up the Tap-In screen for focus adjustment, which has places to enter values for 3 different zooms at 3 different ranges.. see picture.
Next, i set aside the Tap-In and did a series of measurements using Nikon D7500 Auto-AF Fine Tuning as detailed in the other thread on the 70-210. This process involved about 100 different measurements and took hours. I set up my tripod at 1.5', 8' and 52' (for infinity) and did all 8 zoom measurements at each range before moving it. That gave me 24 values to enter. Next, i attached the Tap-In to the lens and applied them as shown in the picture.
To check how well the corrections worked, i repeated a few measurements for each of the 24 cases, resulting in the "A" values hand-written on the picture with various doodles. The result was overall very good, mostly ranging from -2 to +2, but there were two (of 24) outliers at -6 and +4 (circled in black) that stubbornly did not change at all.
I also computed a Delta to quantify the change, handwritten in the picture. Adding up all of the deltas, the net improvement was +35. It is also shown by rows and by zoom. Circled in green are the best improvements, between +5 and +10. Only one result - the worst - had a Delta of -3. Most were between -2 and +2. Of the 24 cases, 10 improved (some dramatically!), 7 didn't change, and 7 were degraded, but not by much.
Overall, a great improvement! I plan to use it in Antarctica in December, with the D7500 Auto AF Fine tune either off or set to zero. It will work equally well in my back-up D5300. Any comments, like your experience with the 18-400 and Tap-In, or questions will be appreciated.