Today’s shot has pushed it, to say the least. I was (according to my camera’s built in distance monitor) 59.6 metres from this heron (about 180 feet). I’ve cropped as far as is possible before the pixels become obvious, and clicking on the image will take you to the 1000-pixel-wide version. You can see the full frame below. I actually like the final image, as it’s a contextual shot of the bird in its environment. It’s been scaled down by about twenty percent to prevent stepping artefacts in the grasses. However, it’s important to point out that the heron’s body makes up just three percent of the original photograph. I used live view to nail the focus, mirror lock up and a remote release, and turned off the VC function. It’s stopped down a bit as well, so this is about as sharp an image as you can expect to see from the long end of the Tamron 18-270mm PZD. However, this is also the softest focal length in the range, so I think it’s fair to say that you get your money’s worth. All I could see was a little bit of white in the undergrowth that could have been anything. For web display, I think this is fine, and I might just about squeeze a satisfactory A4 print out of it.
If your subject is smaller in the frame than this, or near the edges, then you can expect results to drop quite quickly after this. However, I’ve not corrected for chromatic abberation, and have applied only minimal sharpening for web display. You can make your own mind up whether it’s sharp enough, considering how much of the shot has been discarded.
The original frame:
Nikon D300; Tamron 18-270mm PZD @ 270mm; ISO 200; F/9; 1/500s. VC off.