[MF3D.FORUM:1128] Re: Sputnik ground glass

[Paul Talbot <ptww@xxxxxxxxx>]

PABigelow@xxxxxxx wrote:

> Has anyone sucessfully replaced the
> "ground glass" Sputnik viewfinder lens
> with a ground glass panel?

I know a lot of people have said they want to, but
haven't yet heard anyone report about a successful
effort.

One issue that could cause some difficulty is the
shape of the glass.  It appears for some reason to
have a (convex) lower surface.  A flat replacement
at a minimum would require recalibration, which would
not be a big deal by itself.  The question that remains
is whether there would be an adverse side effects (e.g.,
can the three lenses in fact still be synched?  Would
the magnifying lens still work correctly with the
new focus surface?

> If so, where does one find suitable ground glass?

I was amazed not to be able to find any at micro-tools.
Someone suggested Edmunds to me, but their on-line
site search only turns up the opal glass.

I've seen some "photo quality" acid etched glass on e-bay.
8x10 pieces have gone unpurchased with starting bids as
low as $5.99 (chipped edges) or $8.99.

> So far, in my searching, local glass shops have:
> 1) Sandblasted glass (too coarse)
> 2) Acid etched glass (not coarse enough)

The e-bay seller mentions using these in large format
cameras, so I would think the coarseness should be suitable,
but I haven't tried any yet.

Paul Talbot