Hey - one of you bro's care to reveal the nomenclature
for the 67mm bayonet filters for 6x7 lenses???
The Pentax filters for bayonet mount 6x7 lenses are called
_Pentax SMC for 6x7_.
The filter ONLY fits on a lens with a front bayonet lens, it will not
fit on a screw-only filter mount lens. The filter itself has both
a bayonet and a screw mount on the objective side. This allows both
screw mount and bayonet mount lens hoods to be used.
The 6x7 filters are rather more hefty than the normal Pentax filters.
I think it is due to the front/aft space required for the bayonet.
Even though the bayonet filters could stack, Pentax recommends not
doing so for reasons of vignette -- after all the filter rings are
larger than normal.
A screw-in (non 6x7) filter will fit in a lens with bayonet mounts.
However if the lens hood has a bayonet on it, you won't be able to use
it with the screw filter. The non-bayonet filter lacks the front bayonet
to attach the hood with. Screw in hoods will work with either filter.
In general, most Pentax 67 lenses have combination bayonet/screw
front filter mounts. The exception are lenses with 77mm front filter
threads. Many of them lack the bayonet mounts -- and remember the
bayonet filters won't fit. To be more precise, the Pentax filter sheet
says that 67,82,100 mm filter lenses will accept the bayonet. The 77
and 95 mm filter lenses can be either screw or bayonet, depending
upon the lens. The sheet reflects common practice in 1982, so it
could be quite out-of-date with respect to modern production lenses
and presence of bayonet mounts. I don't know which kind of filter
is used on lenses which accept rear-mount filters; I don't have any
and the manuals don't really say.
That's all I know right now -- I hope it helps.
Bolo -- Josef T. BUrger
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