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70-300L change of mind

Started Oct 5, 2014 | User reviews thread
brightcolours Forum Pro • Posts: 15,885
Re: 70-300L change of mind

totleytom wrote:

"extreme focus breathing at the long end and close focus – in fact it gives roughly the same magnification as the 4.0/70-200 at 1.2m means same focal length"

Can I just check that I understand what you mean by this? That when set to 300mm and focused on something very close, it seems to give the same image as a 70-200 at 200mm?

What about at longer focusing distances? Do you have any feel for what distance you need to be at before it starts acting like a 300mm lens?

All lenses change focal length over the focus range, it is normal. The 70-200mm f4 gets a bit shorter in focal length at MFD, which results in a more narrow FOV . The 70-300mm L gets a LOT shorter at MFD, which results in a wider FOV. The FOV at MFD for both lenses, one at 200mm and the other at 300mm, is similar.

The change in FOV over the focus range of a lens is called focus breathing.

The change happens gradually over the focus range. At medium distance to infinity, the lens "acts" like a 300mm lens, for all intends and purposes.

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