09-24-2011, 09:01 AM
[quote name='Brightcolours' timestamp='1316808770' post='11798']
Not a 400mm f2.8 lens ....[/quote]
It really depends, on what detail you're looking at:
- Regarding exposure times at a given ISO-setting, the lens is clearly f/2.8.
- Regarding Depth of field, it behaves like a 400/8 on FF.
- Regarding exposuretimes needed (according to the rule of thumb) you'll find
that the lens behaves like a 400mm on FF ... so, you should use 1/400 for
clear results ... but (see first point) the lens will give you short exposuretimes,
as it is f/2.8 ... a 400/2.8 regarding this point.
Just a thought ... Rainer
Not a 400mm f2.8 lens ....[/quote]
It really depends, on what detail you're looking at:
- Regarding exposure times at a given ISO-setting, the lens is clearly f/2.8.
- Regarding Depth of field, it behaves like a 400/8 on FF.
- Regarding exposuretimes needed (according to the rule of thumb) you'll find
that the lens behaves like a 400mm on FF ... so, you should use 1/400 for
clear results ... but (see first point) the lens will give you short exposuretimes,
as it is f/2.8 ... a 400/2.8 regarding this point.
Just a thought ... Rainer