f/8 and be there.
besides scratches, there are also other elements like old/chemical that can eat into the coating. not a line but more like a smudge patch.
Put it this way:
Replace a filter - $15-80
Replace a lens front element group - $100-$800 or so.
It's cheaper to replace a scratched filter than a front element group, so I'd rather just be safe than sorry.
I might add, as a testament to using a filter for protection. I once dropped my Canon 35mm f/2 on the ground from waist height, while it was in a lens case. The lens was perfectly fine but the filter's element cracked. Without the filter as the first surface meeting the ground, I think my lens' internals would have been more badly affected.
uv filter in a way works as the first line of defense against the **** the world throws at you, be it scratches, dirt, oil, unidentified fluids or any corrosive stuff that eats through the delicate coatings of the front element. there are times u realise u cant really clean certain stuff off the filters, imagine those kena your front element of your unprotected $$$ lens. tio filter just throw and buy new one, tio unremovable stuff on front element of expensive lens = shiok only LLST go service centre and burn wallet
but for stuff like 50mm 1.8 i wont really be bothered with protective filter (buy 10 dollar filter which screw IQ might as well dont buy, buy 50 dollar filter also not justifiable) as its front element is rather recessed, spoil just throw n buy new one
well if you only shoot inside a cleanroom, i doubt you will need one
i said spoil can throw because if you can do any actual damage to this tough little lens it would be totally gone case already. or imagine paying repair cost of probably 3/4 of the cost of a new unit. 70-80 dollars i might as well get a new unit for 125 or a 2nd hand for 110.
Last edited by keast; 1st June 2008 at 07:35 PM.
i have 2 lenses now.
18-200 costs me $1200, so i use 72mm Kenko Pro1 Digital UV filter ($50) and CPL ($100).
For my $160 50/1.8, u think i bother?? no filter in front
Sony ɑ55V || Sony 16-105mm F3.5-5.6 || Minolta 28mm F2.8 || Minolta 50mm F1.4 || Minolta 70-210mm F4