sigma 120-300 review at petapixel

[Rudeofus]

During my searching for that information, I read a lot of articles about lens design, including some very illuminating ones about Nikon 80-400 zooms, showing how different designs give different changes in focal length on focussing. But, I could not find the information about the 70-200mm, perhaps because of my ineptitude. As the tone of your comment implies that you have that data, please put me out of my misery and post the right link.

The data can be found on photozone, see the table at the bottom of that page (The content of that page is written in English language despite the .de domain of that site). According to this table the 70-200 L IS II has a focal length of 172mm at minimum focus distance, the older 70-200 L IS ends at a focal length of 161mm.

Please note that this is a design characteristic of internally focusing lenses and in no way an optical deficiency or a flaw of these lenses. If we add a 1.4x teleconverter to the 70-200 L IS II as suggested by GMC, we end up with 241mm and F/4 which is similar to the 120-300 at minimum focus distance but a full aperture stop dimmer (with the respective effect on shutter speed, DOF and bokeh).

 

[candc]

got a chance to use the lens with extenders today a bit. i have not tried the sigma 2x because i have seen some images taken with it and they don't look very good. i have tried it with the canon 2xiii and the promaster 2x and 1.4. the promaster 2x can give good results but its quirky and inconsistent. the promaster 1.4x is good but the one that i have gets soft on the left side wide open. the canon 2xiii works really well on this lens and would recommend it. the rusty ball and the squirrel are at 600, the cat is 240, all taken with a 70d

 

[AlanF]

They are much, much better at 600mm than you would have expected from the TDP iso tests.

 

[candc]

They are much, much better at 600mm than you would have expected from the TDP iso tests.

that's what i thought too. you would think it would be better with their own brand of tc but with this combo it looks like the canon 2xiii is the way to go.

 

[GMCPhotographics]

They are much, much better at 600mm than you would have expected from the TDP iso tests.

Stop down 2/3 of a stop to f6.3 and it sharpens up nicely. Its certainly a sharp lens, it's nearly as sharp as a Canon prime no question. I'm not sure I'd want to use a 2x TC on a 1.6x crop camera...that's pushing it a bit too far for critical sharpness. But on a full frame, a 2 x TC and a stop drop works very well. I used a Canon 2x mkII and a Canon 1.4x mkII & III. The 1.4x hardly drops any quality and can easily be used wide open. The 2X, not quite so well.