Chip Louie wrote:
> I'm wondering if this information is posted anywhere. I'm
> aware that there
> are differences in the wave length of the filtered light but
> have not seen
> which filters use which glass. Also, is it only above L41
> type glass that
> the yellow tint is visible? I have Hoya SMC, HMC and B+W UV
> filters and
> have not noticed any differences but now I have to go look!
> Thanks for any
> other info you can post here.
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I do not think this information is posted anywhere. The charts that
accompany some of the filters show the chart for the cutoff. I learned much
of this from several optical engineers I know while I was doing some
research on UV filters a while back. Each filter will cut out different
percentages of UV at particular points (wavelengths).
Hoya uses L39 as their UV standard, L41 is designated on the better Kenko
(Hoya makes Kenko) filters, but my friends at Hoya explained L41 is used
exclusively in the Super HMC Pro UV filters. B+W has never confirmed which
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.
As to Yes, glass that cuts off above 410 nanometers will have a yellow tint.
You can see physially see this on a B+W's UV415 and more so in their B+W
UV420.
Peter K
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