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Urban Fredriksson  wrote:

> I use UV filters only when I think they're needed, which
> isn't very often. (For a couple of my newer lenses it's even
> specifically stated by the maker that they don't need any.)

My thoughts: I had no UV or Skylight filters on my lenses for years because
of some bad experience years ago with lesser grade (and non-multicoated)
filters.  What I also didn't realize at the time, was that a filter needs
to be 'squeaky' clean on each side or it is just another surface to reflect
off of, especially since the flat filter is at a different angle to most
spherical front lens elements (this and any slight residual film on the
filter is where 'ghost' headlights come from).  That residual film can be
emitted from your camera bag padding and plastic camera parts, so just
because you put your filter on new and clean, doesn't mean that it will
stay that way.  The best liquid cleaners that I have found is the ones that
are made for cleaning multi-coated lenses.  I use a white cotton dark room
glove for this.  Then I get out my micro-woven lens cleaning cloth (Leica
or Pentax) and carefully wipe it perfectly clean.  Fogging the glass with
your breath works in a remote location, but this leaves something behind
too, even after you wipe it to what looks like clean.  If your filters look
clean, but they are 'slippery' or not 'squeaky' clean, then you have a film
on them which can cause ghosting, reflections  and increase lens flare.

And use a lens shade or hood all of the time!  I can move all of my lenses
around to see a difference with and without them, so they do matter.

Anyway, in the past couple of years, I put all Nikon brand UV filters back
on all my shorter lenses, and I clean my gear when necessary (at least once
a month or more), and have not had any flare, ghosting or reflection
problems with them recently.  The longest lens I have a filter on however
is my 105mm 2.5, because I shoot into locomotive headlights and I have had
problems with those pesky 'extra' headlights in the past with telephotos. 
Never have I had a ghost headlight with a Nikon lens though that had no
filter on it.  (I'm not picking on any one lens manufacturer here, but the
most headlight ghosting I have seen has been in shots taken with Canon
400mm 2.8 and 300mm 2.8 lenses.  I don't think there are filters on the
fronts of these, just the little ones in the filter drawer that are part of
the lens design and not to be used without).  

Maybe I worry about this too much, because my current 300mm 2.8 has, and my
recent 500mm 4.0 had a built-in (non-removable) UV filter in front of the
first lens elements, and I have never had that problem with those (see my
500mm CSX shot on the web site - no headlight ghosting at all: those extra
'mystery' headlights - film type is irrelevant - have noticed though that
E-6 gives you 'light trails' or oval headlights more, while Kodachrome
blows lights out into flare more like in this CSX shot - very noticeable
around top headlight).

I don't have a UV in front of my 180mm or 80-200mm zoom right now.  Anybody
on this list having any headlight ghosting problems with filters on those
focal length lenses?

Dave Cohen
Photographer
Action Photographic Webmaster
[EMAIL PROTECTED]
http://www.anet-stl.com/acphotog/home/

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