Similarly, the Zenitar 16mm f/2.8 FE includes a set of screw-in
filters that fit at the back of the lens. One must always be fitted
for the lens to achieve proper focusing and correction. This is
different from using a front-mounted filter that was not designed in
as part of the optical design.
Godfrey
On Apr 3, 2006, at 9:40 AM, John Francis wrote:
Really? Both my A* 300/f2.8 and my FA* 250-600/f5.6 came with a
set of drop-in filters (albeit different sizes for each lens) that
included what appears to be a plain glass filter. I'm pretty sure
it's recommended practice to have a piece of glass in the optical
path there - why else would there be a filter blank included?
One or two lenses (300/2.8?) require a filter "blank" (filters at
the back of the lens) to focus properly in the first place.
