No more Velvia

Chadwick writes:

I just read in Amateur Photographer that Fuji are to permanently cease
production of Velvia 50 in a year's time. Apparently they can't get one
of the magic ingredients.

There will be an ISO 100 replacement (not to be confused with the
already existing 100F) which will have all the saturation of Velvia 50.

What about grain and resolution?

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Alan Browne writes:

One rule of thumb (and probably more myth than fact) is that for every 10°C
below fridge temp, the storage life of unexposed slide film is doubled. So at
-17°C the storage life would be something on the order of 10 years.

This assumes that you manage to protect it against cosmic rays, which
ultimately determine the shelf life of film.

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Alan Browne writes:

One rule of thumb (and probably more myth than fact) is that for every 10°C
below fridge temp, the storage life of unexposed slide film is doubled. So at
-17°C the storage life would be something on the order of 10 years.

This assumes that you manage to protect it against cosmic rays, which
ultimately determine the shelf life of film.

--
Transpose hotmail and mxsmanic in my e-mail address to reach me directly.

Mxsmanic wrote:

Alan Browne writes:


One rule of thumb (and probably more myth than fact) is that for every 10°C
below fridge temp, the storage life of unexposed slide film is doubled. So at
-17°C the storage life would be something on the order of 10 years.


This assumes that you manage to protect it against cosmic rays, which
ultimately determine the shelf life of film.

Wrap in a dense blanket of polyethelyne and put into a thick walled
aluminum can. Put the can in a deep freezer.

Heat is the more pressing deteriorator of film. By chilling it, its
deterioration is slowed down markedly. It will deteriorate quicker at
room temp or even fridge temp. Assuming nothing can stop cosmic rays,
at least this step extends the life significantly.

As to cosmic rays, I've shot 1600 film 3 years after being left in the
fridge (in a tin can), and other than the fact that 1600 (Fuji negative)
is a pretty crappy film (color) to begin with, exposed at 800 the
results, colorwise, were acceptable (and no worse than the usual awful
result), and the grain was as should be expected. If I can find the
negs, I'll scan a few frames and post them. (Perhaps in the scan we'll
see some cosmic ray evidence).

Shielding from cosmic rays is a complex subject. A quick web search
shows:
1- a lot of people working on it, primarilly for space exploration;

2- any effective shield deteriorates as it gets bombarded, rendering it
slowly less effective with time and in some materials it produces
undesirable byproducts.

Aluminum is one 'blocker', polyethylene is another. So wrap in dense
poly and put in an aluminum can. Can- freezer. Neither material is a
perfect blocker.

Cheers,
Alan

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"Mxsmanic" wrote in message
...
Walter Hofmann writes:

No. The glass in lenses (and elsewhere) is still liquid! Is just flows
very slowly.

Not true. That's an urban legend.

See: http://math.ucr.edu/home/baez/physic...ass/glass.html

"Mxsmanic" wrote in message
...
Walter Hofmann writes:

No. The glass in lenses (and elsewhere) is still liquid! Is just flows
very slowly.

Not true. That's an urban legend.

See: http://math.ucr.edu/home/baez/physic...ass/glass.html

Bandicoot wrote:

old window and you'll find every pane is thicker at the bottom than the top,
due to flow. Of course, this takes a couple of hundred years before it's
practically measurable.

"A lump of molten glass was rolled, blown, expanded, flattened and
finally spun into a disc before being cut into panes. The sheets were
thicker towards the edge of the disc and were usually installed with the
heavier side at the bottom. Other techniques of forming glass panes
have been used but it is only the relatively recent float glass
processes which have produced good quality flat sheets of glass."

-- http://math.ucr.edu/home/baez/physic...ass/glass.html

Same webpage leaves some opening for a not perfectly solid glass, but in
the main, glass is a solid and does not flow, and the "old window"
explanation is just a misinterpretation of the facts of mediaevil

Cheers,
Alan


--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.

Alan Browne wrote:

-- http://math.ucr.edu/home/baez/physic...ass/glass.html

Same webpage leaves some opening for a not perfectly solid glass, but in
the main, glass is a solid and does not flow, and the "old window"
explanation is just a misinterpretation of the facts of mediaevil

[I guess I should finish the sentence... went off to check spelling...]

.... of mediaeval glass making.






--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.

"Alan Browne" wrote in message
. ..
Bandicoot wrote:

old window and you'll find every pane is thicker at the bottom than the
top,
due to flow. Of course, this takes a couple of hundred years before
it's
practically measurable.

"A lump of molten glass was rolled, blown, expanded, flattened and
finally spun into a disc before being cut into panes. The sheets were
thicker towards the edge of the disc and were usually installed with the
heavier side at the bottom. Other techniques of forming glass panes
have been used but it is only the relatively recent float glass
processes which have produced good quality flat sheets of glass."

-- http://math.ucr.edu/home/baez/physic...ass/glass.html

Same webpage leaves some opening for a not perfectly solid glass, but in
the main, glass is a solid and does not flow, and the "old window"
explanation is just a misinterpretation of the facts of mediaevil


Ahh, now that might make sense: since I know for a fact that these panes do
tend to be thicker at the bottom., the idea that they were installed thick
edge down (which I didn't know) would reconcile the differing
interpretations!

Mind you, cylinder glass was pretty flat too, ditto plate glass. Just both
cost more than float glass, and you come across them much less often.


Peter

Glass is a "liquid". A colloidal mixture. Glass is a "liquid" of high
density. It flows very very slowly. It can take from hundreds to a
thousand years (or more) depending on quality of its.
Today we have many types of glass (with high quality too) that have a
great life without deforming. There is equipment and procedures at the
Universities to measure that and estimate the life of a glass.
Glass is different from crystal, that have more durability (millions of
years to form and millions to decompose).
In really glass isn't a liquid is more like a plastic, but glass have
liquid characteristics. You will see some technical explanations on
physics and chemistry books.

Alan Browne wrote:
Bandicoot wrote:

old window and you'll find every pane is thicker at the bottom than
the top,
due to flow. Of course, this takes a couple of hundred years before it's
practically measurable.


"A lump of molten glass was rolled, blown, expanded, flattened and
finally spun into a disc before being cut into panes. The sheets were
thicker towards the edge of the disc and were usually installed with the
heavier side at the bottom. Other techniques of forming glass panes
have been used but it is only the relatively recent float glass
processes which have produced good quality flat sheets of glass."

-- http://math.ucr.edu/home/baez/physic...ass/glass.html

Same webpage leaves some opening for a not perfectly solid glass, but in
the main, glass is a solid and does not flow, and the "old window"
explanation is just a misinterpretation of the facts of mediaevil

Cheers,
Alan



--


Carlos A. B. Coutinho
Rio de Janeiro, RJ
Brasil