Nethawk said:Lee Jay said:lycan said:Soft at 600mm? I don't think so
I've seen plenty of full-sized shots at 600mm to know that it is soft at 600mm wide-open, even on full-frame.
I'm not a sharpness nut, except on telephoto lenses, where it's common to crop like crazy. When I can properly frame, I find my 17-40L and 24-105L to be quite excellent. But on telephoto, it's not uncommon for me to crop 2x into a shot that was shot with a 2xTC on a 1.6-crop camera. That's only 15% of the size of the image circle, enlarged to a full-frame. That requires critical resolving power.
Have a look. This is the Tamron against itself (400mm versus 600mm). There's a substantial difference.
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=929&Camera=453&Sample=0&FLI=3&API=0&LensComp=929&CameraComp=453&SampleComp=0&FLIComp=5&APIComp=0
You continue to repeat this mantra "soft wide open at 600mm" as a deterrent against the Tamron, yet your own 70-200/2.8L IS II and 2x TC III is no different. Citing the same source
"Images are sharp wide open at 280mm (f/4).
The 1.4x reverses the 200mm pincushion distortion (resulting in very low distortion) and adds some CA and slight full frame corner softness. The 2x causes a noticeably softer image at 400mm."
http://www.the-digital-picture.com/Reviews/Canon-EF-70-200mm-f-2.8-L-IS-II-USM-Lens-Review.aspx
No mention of aperture, although I suspect that "noticeably softer" applies only to wider apertures.
The fact is that this characteristic is shared by most long telephoto zooms. Let's move on, please.
My combo is slightly soft wide open at f/5.6 and sharp at f/6.3. The Tamron is soft wide open at f/6.3 and sharp at f/8. Do you see the difference?
Regardless, what I want is something SUBSTANTIALLY better than what I have, in both optics and focusing, in a similar size and weight. The Tamron isn't that. It's too long, and too soft/slow (f6.3/f8). If Canon makes a 100-400L replacement, it's likely to be far better optically even with a 1.4x TC attached, and also likely to focus faster and more reliably than the Tamron. Of course, that's several "if's" that we'll have to wait and see to evaluate (if it's real, if it's good optically, if it's fast-focusing).
For now, I'm keeping my current combo, which is equal to or better than the current 100-400L in several ways.
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