I just did a little measuring and research.
First, to whoever posted saying that Hoyas have brass threads, the info
I found says they are anodized aluminum. That's what a worn one I have is.
I compared 2 49mm UV filters, Oly and Hoya:
Hoya Oly
Front thread 2mm 2
Shelf to hold glass from front 1 0.5
Glass 2 1.8
Glass to rear 1.7 1.4
Total 6.7 5.7
The Oly uses a shelf half as thick to hold in the front of the glass, a
thinner snap-in retention ring on the back and slightly thinner glass to
save 1mm of thickness. I suppose it may use a stronger mount to maintain
the same strength, shich may, slong with the thinner glass, mean greater
production cost. I don't have a Hoya thin filter, but the spec says it
is 3mm thick, whereas the Oly without the front thread would be 3.7mm,
so they do a little more "thinning" than on the Oly.
Hoya does make what you want, filters using 1mm thick glass with front
threads and overall thickness of 3mm, but only in UV and 1A. They are
called Hoya Pro 1 and are SMC coated.
Just 'cause it was sitting here, I now know a B+W 72mm UV filter is
8.7mm thick.
Moose
julian_davies@xxxxxxxxxxxxxx wrote:
Like the OM 49mm doesn't? My point is that if they can OEM the thin 49s for
Oly, with a thread, why not for themselves? I've never seen the Hoya thin
mount, so if it's thinner in 49mm than an Oly, apologies, but their standard
ones are thicker overall for no apparently good reason. They don't seem to be
of a cheaper construction, just bigger.
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