Posted: Tue Jul 22, 2008 5:45 pm Post subject: CAn someone explain?
I have just read the following on someone's flickr site and can't make head nor tail of it.
"So i chose to use a rather wide focal length, quite open to difuse the busy background, but not wide open because the optical resolution of any lens is best one f/stop over maximum aperture."
Isn't saying "one f/stop over maximum aperture" a completely meaningless statement? I'm checking this out just in case it isn't, in which case what does it mean? _________________
basically if you knock a lens in 1 or 2 stops, it's at optimum sharpness - no lens is ever at its best wide open although how far you have the lens zoomed in can also make a difference.
e.g. my 70-200mm f/2.8 is rather nice at f/2.8 but f/4 gives a sharper image, and the lens is sharpest irrespective of aperture in the middle of its range; it's not quite as sharp fully zoomed in to 200mm as it is at 100mm. This happens with all zoom lenses and the cheaper the lens, typically the softer it is at the extremes. _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
Last edited by jonH on Tue Jul 22, 2008 9:43 pm; edited 1 time in total
Thanks Jon, plain English I understand. Are we talking edge distortion in a wide open lens, or does that include the central part of the lens, which I would have thought was unaffected no matter the f/stop> _________________
the aperture will affect all areas mainly because a narrower aperture will provide greater depth of field _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
So, is my reasoning correct here? I tend to shoot landscapes at around f9 to give me good DofF and crisper pictures, whilst giving me an exposure time that is manageable hand held. If I tripod mount would I be better off at f/20 or even higher? _________________
Most DSLRs are diffraction limited to around f/11 so if you go much narrower than that, you'll actually lose sharpness (I tend to only shoot narrower when i need less light) its the one thing film still has in spades over digital _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
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