I just bought a almost brand new 200/4 zuiko a few days ago,and
the salesman was kind enpugh to throw in a hoya(hmc) skylight filter
to go with it.I told him that I don't use filters on all my lenses
and he got a shock.He said "Sir,this lens is too good to be bash and
I think it is a good idea to have one in front of the lens element
in case you accidentally scratch it!"
Well,I think he is quite right and I think this is one of the
most favourite question/dilemmas facing everyone of us everyday.
Do you really need UV/Skylight filters?I think they are just
marketing idea.The often cited reasons for having them are to cut
out UV light and protect the front lens element.I don't know of
anyone who specifically wants UV light in any photograph so why
don't lenses have the necessary coating to prevent UV light in the
first place?
No doubt,the glass of our lenses absorbs a good deal of the UV
light,as does the cement between grouped elements.The coating may
also have a function in suppressing UV light transmission ,but I
don't know whether is this an explicit design consideration for
coatings.I shoot most of my photograph at or even below sea
level,where UV light levels are relatively low.Therefore I don't
bother with UV filters .A UV filter can be useful though at higher
altitudes,where UV light levels are much higher.
Well I never found a difference in the image quality with and
without filters,sometimes I did find a image degradation in the form
of unsharpness or filter flare.Cheap filters,Rodenstock filters,B+W
filters ,they all affect the image under these conditions.
The idea of protecting the front lens elements is also pretty
weak.Having another glass element just adds to the number of
surfaces that can cause flare or vignetting.I can see a use for a
filter when it would prevent dust from gaining access to the inside
of the lens if the front element moves during focusing,but imaging
you buy the most expensive lens that you afford and then find
yourself screrwing a 10~20dollars filters in front of it.Hmm.. come
to think of it, why can't the front lens element be coated with
some scratch proof material that will last forever?
In practice I never bother with protective filters.So far I've
never damaged the glass of a lens and I consider myself an average
user,not careless but also not extremely careful.
So what do you guys think?Did you ever come across any camera/lens
maker that strongly recommend the use of a protective filters on
their lenses?
(it is scorching hot here in singapore 30-33 degree celcius and
humidity is about 70-85% as contrast with being shower with snow in
north america/canada!)
Jonathan Tan
I realized after more years than I care to say of taking pictures,
even in unsheltered backpacking, rock scrambling situations that I
have never scratched one of my filters. After seeing the degradation
of sharpness caused by filters measured by Gary Reese I decided not
to use them at all, unless for a special purpose. That said, I have
never liked skylight filters because they are pink and I do not like
what they do to the color balance. I liked UVa filters because they
are clear and I felt that they made a visible improvement in the
image at altititudes above 6 or 7 thousand feet where UV radiation is
strongest - a reduction in the appearance of haze and blue in the
shadows without adding color in other places. If you use a good
filter and keep the sun off it with a good hood or a hat you really
do not have to worry about flare. If you use the lens cap when
squeezing by a rock face or in a sand storm you do not need a filter
for protection. And to balance Gary's findings one must consider that
almost all of those spectacularly huge enlargements of Ansel Adams
were taken with red filters.
--
Winsor Crosby
Long Beach, California
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