Tried a little experiment tonight.
Two photos taken at the top end of the Sigma 150-500 zoom lens. No optical stabilisation used, tripod mounted, live view, manual focus, remote release, used on both images.
The first is at 500mm, the second at 500mm plus Sigma's 1.4x EX extender.
Both these were taken at night, at ISO 500 in AV mode, giving a 4 second and a 6 second exposure, at f/6.3 and f/9 (I should have done the extender shot first and matched apertures really, but I didn't think of it).
Interesting to see the sharpness using the live view and my eyes on each, and also the difference in sharpness at different apertures (i.e. caused by the 1.4x) on the brickwork of the gate post.
The focal point I used was the number 18 on the door of the house.
On each image, no noise reduction and no sharpening has been used, the only adjustments were to try and get the whites similar, because they were different, though I failed! (I assume due to the glass in the extender having an effect in some way).
Effective focal length - 800mm:
Effective focal length with extender - 1120mm (I think):
I did it because I wanted to try something - no science involved, just curiosity...
Paul.
