Since Tamron announce they were coming out with this lens several people have asked me what I thought about this lens. This lens is real attractive to photographers because of its light weight and reach for the price. However, I had no real infinitive information I could give them other than a guess based on my own experience with other zoom lenses since I had not had the opportunity to test this one.
I had the pleasure of checking out this lens with a student in my photography class in October 2014. We made arrangement to meet another day and check it out using my LensAlign Calibration System to see exactly how the lens would do with such a long range of zoom. My initial thought would be this lens would not be able to hold good focus with such a large zoom.
So on Sunday October 26, 2014 he came over with this Tamron lens and his cameras and we began tested it. We started out with his Nikon D 800 camera at 600mm and found that it was back focusing a lot so we AF fine-tuned the lens to the camera and found we needed to go to minus 10 to have the calibration to be relatively equally focused on both side of zero on the LensAlign scale. We then put his Nikon D 700 camera on the lens and found that camera to be calibrated evenly on both side of zero it would be minus 7. I wasn’t surprised that there was a difference in the two cameras.
Next we moved in closer to evaluate the lens and the D 700 camera at 150 mm and found that the lens was front focusing and we needed to make an adjustment at plus 10 to maintain an equal amount of focus on both sides of the zero on the scale. This was not really surprising to me either since I own a Cannon 100-400 and I have some focus issues with that lens and the Tamron lens has an even larger distance of zoom.
The only real way to possibly resolve this is if you have a camera that will let you auto focus fine tune for a zoom lens and be able to fine tune at 150 and then again at 600mm. I know Canon has a camera you can do that with but not sure about Nikon.
At that point we ran out of time and for now he decided to have each camera fine-tuned differently and so he could try them out in different situations and see how they do.
As far as sharpness of the lens I found that the pictures to be relatively sharp especially when they were calibrated and the glass itself seemed to be good quality. I did find that the auto focus seemed to be a little sluggish but that could only mean he needs to clean the contacts.
I myself would like to spend more time shooting some birds and other subjects with this lens and see how it does before I give a complete thumbs up or Thumbs down. This test was also done without using a 1.4 extender so that might shake things up even further so stay tuned as soon as I can get more time for further testing I will, but for now I would be cautious of spending any money on a lens without doing your homework.