05-05-2011, 08:25 AM
[quote name='borisbg' timestamp='1304525375' post='8066']
For such a fast lens this is an impressive performance. Unfortunately there is one issue that spoils the party a little bit: the lens showed a slight amount focus shift when stopping down (residual spherical aberration).
[/quote]
Hmm, what I don't quite understand is why focus shift would matter much in practical use, especially once you know it's an issue to have in mind <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' /> What I mean is that normally you keep acquiring focus on your subject, almost every second, while the aperture change is far less frequent, and then it's like a natural thing to focus, change parameters, refocus, then shoot.. Or am I wrong here ?
For such a fast lens this is an impressive performance. Unfortunately there is one issue that spoils the party a little bit: the lens showed a slight amount focus shift when stopping down (residual spherical aberration).
[/quote]
Hmm, what I don't quite understand is why focus shift would matter much in practical use, especially once you know it's an issue to have in mind <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' /> What I mean is that normally you keep acquiring focus on your subject, almost every second, while the aperture change is far less frequent, and then it's like a natural thing to focus, change parameters, refocus, then shoot.. Or am I wrong here ?