Miha Valencic wrote:
> Hi Peter!
>
> > glass type they use, but its probably L39. At one time I
> used Sky filters
> > exclusively until I understood the true differences, from that
> > point onward
> > sold off and never bought another sky filter.
>
> Would you explain the true difference between sky and UV filters?
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Sure Miha,
The difference is the UV filter cuts out more of the "invisible" UV luight
and does not have any coloring. Key word here is invisible. You will not see
the UV light with your eye but it will appear on film.
The Sky Filters have a slight pink tone which is designed to warm colors
very slightly in shade and only cuts out half the UV when you compare it to
a true UV filter. For example, at sea level you would be hard pressed to see
a difference. The only difference you may see is that the pale skin tones on
people taken with a Sky filter underneath a tree or in the shade of a
building, etc., would have a very very slight warmth to them. At higher
altitudes or near the ocean where UV is far more prevalent, images with the
Sky filter would have a slight blue cast while those with the UV would not.
It is important to note that B+W & Heliopan labeled KR1,5 filters are NOT
really sky filters but slight warming filters with the R meaning a RED
factor of 1.5 on a decamired scale. KR3 is a RED 3, etc. The 81A and 81B
filters are wratten filter designations for warming filters. Each increase
the color temperature. Take a look at
http://www.schneideroptics.com/filters/filters_for_still_photography/tempera
ture_chart/
and the chart will highlight what I am saying. Note, these filters do little
when it comes to filtering UV light. Note UV filters are not listed on the
chart as they are neither warming or cooling filters.
These days I strictly use warming filters when I want that effect (on
overcast days, etc.) and UV filters all other times. Hope this explains
things, if not let me know and I will try to explain further.
Peter K
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