03-22-2012, 11:27 AM
[quote name='mst' timestamp='1332342314' post='16902']
Instead of calling each other silly or brand bashers, can we maybe simply accept that focus breathing exists, is very obvious on both the Nikon 70-200 VR II and the Sigma 70-200 OS (and many other lenses) and almost non-existent on the Canon EF 70-200/2.8 IS II?
Whether it's an "issue" depends on the user. It's an issue for BC, but usually not for me (I owned and used the mentioned Nikons and the Sigma OS as well as non-OS).
-- Markus
[/quote]
Indeed, that is what I wrote in my post. It very much depends on your usage of the lens.
My 70-200mm f4 L USM has no focus breathing either, depending on how one calculates it. Just like the 70-200mm f2.8 L IS USM II or others.
Interestingly, when one calculates it with the correct node whatsitcalled, you get a shorter focal length. When you calculate it without, just ignoring it, you get a longer focal length.
That on its own is not interesting. But what is interesting is that in field of view, you see it getting narrower when focussing closer.
So... that makes me wonder about the relationship of focal length and field of view... they do not seem to be fixed together. The relationship seems to change with focus distance.
To make it more clear: Correctly calculating the focal length shows the focal length going down slightly towards MFD with the Canons. But you see the field of view actually getting more narrow.
The Nikon VR II and the Sigma OS show a strong widening of the field of view towards MFD.
Instead of calling each other silly or brand bashers, can we maybe simply accept that focus breathing exists, is very obvious on both the Nikon 70-200 VR II and the Sigma 70-200 OS (and many other lenses) and almost non-existent on the Canon EF 70-200/2.8 IS II?
Whether it's an "issue" depends on the user. It's an issue for BC, but usually not for me (I owned and used the mentioned Nikons and the Sigma OS as well as non-OS).
-- Markus
[/quote]
Indeed, that is what I wrote in my post. It very much depends on your usage of the lens.
My 70-200mm f4 L USM has no focus breathing either, depending on how one calculates it. Just like the 70-200mm f2.8 L IS USM II or others.
Interestingly, when one calculates it with the correct node whatsitcalled, you get a shorter focal length. When you calculate it without, just ignoring it, you get a longer focal length.
That on its own is not interesting. But what is interesting is that in field of view, you see it getting narrower when focussing closer.
So... that makes me wonder about the relationship of focal length and field of view... they do not seem to be fixed together. The relationship seems to change with focus distance.
To make it more clear: Correctly calculating the focal length shows the focal length going down slightly towards MFD with the Canons. But you see the field of view actually getting more narrow.
The Nikon VR II and the Sigma OS show a strong widening of the field of view towards MFD.