The glass of a lens should be about the same Moh's hardness as quartz, 7,
since it's predominately quartz. I have no idea about the hardness of
coatings, but aren't they only a few molecules thick?
Bill
Pentax says its SMC coating is harder than glass. Very hard molecules...
Andre
På 20. feb. 2004 kl. 19.02 skrev Andre Langevin:
The glass of a lens should be about the same Moh's hardness as
quartz, 7,
since it's predominately quartz. I have no idea about the hardness of
coatings, but aren't they only a few molecules thick?
Bill
Pentax says its SMC coating is harder than
I have no idea how the typical lens coating material compares in
hardness, quantitatively speaking.
We only know SMC is harder than the glass under it (dixit Pentax).
Andre
This is absolutely not true concerning lamp or bone black. Carbon comes in
many forms, polymorphs, e.g. crystalin as in diamond which is very hard
indead, in sheet form as in graphite and only weakly bonded where it is very
soft and will not wear bearings when used as a lubricant. Graphite
It is much harder than talc. Think about it.
From: Rothman, Aric [EMAIL PROTECTED]
Interestingly, carbon (graphite) is both the softest (tying with talc),
and hardest (diamond) mineral, per Moh's
hardness scale. Depends on its molecular structure.
I have no idea how the typical lens
a vigorous
cleaning with graphite would do nothing more than yield a very clean lens.
Aric
-Original Message-
From: Bob Blakely [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 19, 2004 10:37 PM
To: [EMAIL PROTECTED]
Subject: Re: Lens Cleaning Problem - Volatile Liquids
It is much harder
: Thursday, February 19, 2004 10:57 PM
Subject: RE: Lens Cleaning Problem - Volatile Liquids
What is much harder than talc? Lens coatings, or graphite? Obviously,
lens
coatings are much harder than either. I stated I had no idea how to
quantify the difference. I referenced Moh's hardness scale
That's an interesting idea. I am always reluctant to use a powder
because most have some abrasive effect. Is this not a problem?
[EMAIL PROTECTED] 02/18/04 10:27AM
The problem I've had with volatile liquids (alcohol, acetone, etc...)
is
that while they'd dissolve many oils greases, they'd
The stuff is as soft as talc. No harm will come to your lenses or coatings
from the lamp black. FYI, this is the substance preferred by photographers
of yore.
Be very careful not to spill it. If you do, and it's on the carpet, and you
are married, you will probably soon be single.
Regards,
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