Traveller_Jeff wrote:
Hi, Barry,
Thank you for your quick reply. There was a fine film of haze last night. Definitely a factor.
Have not yet performed the fine-tune. I've seen setups for the procedure, and I haven't had the time to devote to the meticulousness required. I'm sure you're right, and that after I've finally gotten around to performing it, the focus will improve. Thank you for your insight and helpful comment.
Hi Jeff,
FWIW, in talking with the helpful tech at Tamron, she told me the importance of getting the setting for infinity set correctly. Also, the folks at Reikan told me that the relationship between the Nikon AF fine tune numbers and those used by Tamron are NOT 1:1. However, they are close to 1:1. Other G2 150-600 owners have reported a modest variation in the ratio relationship. Also, he told me that the Sigma equivalent lens ratio is around 2:1 (Sigma to Nikon). Also, the Nikon AF tune values vary from camera to camera.
For our lens, the Tamron tech told me the "correct" way to find the values for the Tamron lens is to input a tune value into the lens using the TAP-IN Console, take a photo of the target, change the value, take photo, repeat until you have the value you desire. And yes, she stated that this means dismounting the lens, mounting the TAP-IN, change the value, take off the TAP-IN, remount the lens, take photo, over and over! We have 18 distance and focal length combinations to measure. ARG!
Oh yes, the AF fine tune in the camera should be set to zero.
What I did was to mount my camera on my solid tripod and use the Reikan FoCal program for the close and intermediate distances. The AF tune values that FoCal finds are close I found to being about 1:1, maybe 1.1:1. Once I got these numbers, I loaded them into the G2 and spot checked the focus using FoCal again. It looked okay. Remember that in Nikon units, having the value good to +/-1 or so is acceptable. I have used FoCal to compensate the back focus error of all of my Nikon lenses and am pleased with the results. Happily only one measurement is needed per lens.
Okay, what about the tricky infinity values? My approach was to wait until there was a very, very clear night to photograph the Moon. With the camera mounted on the sturdy tripod and using a remote trigger, I photographed the Moon. First, I used live view to manually focus the G2 using the magnifier feature to aid in focusing. I used this as a benchmark for knowing what best focus looks like. I then took a series of photos changing the camera's AF tune values and allowed the lens-camera to autofocus. This is not very time consuming except that you may need to reaim you camera during the test since the Moon doesn't hold it position. I did this for all 6 focal lengths and the results were fine. I did tweak a couple of values, e.g., one compensation value for Nikon was +6 and I input to the G2 +7. My approach reduced the number of lens mounts and dismounts to just a few.
Does my description have adequate clarity Jeff?
Barry