"frederick" wrote in message
news:1186622322.925846@ftpsrv1...
Dave wrote:
i did a ton of travelling earlier this year and got my camera lenses
quite dirty at times. (did my best to keep them clean but i was in
crazy places...)

i wiped them gently with anti-static cloths but i didn't feel good
about it.

should i buy "Multicoated" lens covers (i believe a.k.a. Neutral
Density Glass Filters)? has anyone used them?

i own the Canon 30D, and so far all Canon lenses.

thanks, dave


There's always arguments about filters. I tended to dismiss the
significance of image degradation from filters as exaggeration.
But I've got a couple of 77mm UV filters, one a Hoya Multicoated one, the
other an uncoated Kenco (supposed to be Hoya Glass?).
On a wide angle lens, I can't normally see any image quality difference
between the filters. If flare/ghosting is a problem with the uncoated
one, it's only reduced by using the multicoated one - not eliminated, in
which case results are much better with no filter at all.
At 200mm f2.8, I thought that my lens was faulty, as images were
significantly blurred. I was very surprised to see that when I changed to
using the MC filter, image quality was much better. It seems to me that
filter quality is much more critical as focal length increases.
I will buy only multicoated filters in future. But, as they are
expensive, I'm less inclined to want to clean them when working in
dusty/dirty/wet environments with the corner of a shirt or whatever
happens to be handy. For now, I leave the uncoated filter on my wide
angle lens, but remove it when ghosting is a potential problem. Because
the wide angle lens front element and filter is so exposed, it gets dirty
very quickly in outdoor environments, and using just a lens cap and no
filter would be very inconvenient having to remove and replace it between
shots.
YMMV

It is absolutely true that as focal length increases filter quality becomes
more important. You can convince yourself of this by shooting first through
window glass and then in the open with a wide angle and then tele lens,
blowing up to 100% and comparing the results.

That being said, I recently did a series of tests with a normal MC lens
protector on a 17-70 zoom at 70 and compared pix with the filter on and off.
If there was a slight degradation it was almost invisible, and the slightest
focusing error masked it.

While a few small scratches on the front element of a lens are not really
critical, I personally keep filters on all my lenses, and no one has ever
complained about sharpness.

Toby