11-15-2011, 09:13 AM
[quote name='mousefire' timestamp='1321338467' post='12932']
It's said that a lens is designed best at specific focus distance, is that true? Then will a normal lens suffer from image quality decrease when focusing at very near distance? Or a micro lens perform worse at infinite focus distance?
[/quote]
Not an issue to worry about at all. With OLD lenses you may see a real impact though. My Nikkor 55mm f3.5 Micro, the first version, is said to be (one of) the sharpest Nikon SLR lens(es). But only when used as close up lens. For photography at infinity, it is not so sharp anymore at all. The 2nd version of this lens already has a different focus group that makes it better usable for "infinity" focus.
Most lenses even perform well when used outside their designed envelope (non macro/close up lenses used with extension tubes for instance). Obviously there are some exceptions... for instance my Tokina 12-24mm f4 is not a stellar performer with a 12mm extension tube attached.
It's said that a lens is designed best at specific focus distance, is that true? Then will a normal lens suffer from image quality decrease when focusing at very near distance? Or a micro lens perform worse at infinite focus distance?
[/quote]
Not an issue to worry about at all. With OLD lenses you may see a real impact though. My Nikkor 55mm f3.5 Micro, the first version, is said to be (one of) the sharpest Nikon SLR lens(es). But only when used as close up lens. For photography at infinity, it is not so sharp anymore at all. The 2nd version of this lens already has a different focus group that makes it better usable for "infinity" focus.
Most lenses even perform well when used outside their designed envelope (non macro/close up lenses used with extension tubes for instance). Obviously there are some exceptions... for instance my Tokina 12-24mm f4 is not a stellar performer with a 12mm extension tube attached.