On 12/10/2012 8:51 AM, Darren Addy wrote:
On Wed, Oct 10, 2012 at 2:46 PM, William Robb
<[email protected]> wrote:
One day at the studio, I did a little experiment. I took an old UV filter,
drew a small circle in it with a felt pen and measured it's transmission
properties within that circle on our densitometer . I then emptied an ENTIRE
can of Dust-Off at the circled paert of the filter, and them measured it
again. There were no differences at all in the two readings.
That's a nice experiment, but it provides only one data point for one
can of one brand of "dust cleaner" that was produced under one set of
meteorological conditions (at the factory) and sprayed under another
(one) set of meteorological conditions (humidity/barometric
pressure/etc. at your location).
In addition, we've all cleaned glass before and understand that there
is a difference between clean glass and clean glass with a smeary film
on it (that you can see from the side). I'm guessing your densitometer
couldn't tell the difference between the two, but I know which I would
rather be shooting through.
Why do you insist on making crap up. Do you really think I wouldn't be
able to see a "smeary film" on a filter?
Are you so ignorant of the technology that you don't think a "smeary
film" wouldn't register as a density difference to a status densitometer?
There was no residue and no measurable discoloration. A densitometer is
more sensitive than the human eye to this sort of thing.
I think it is always inaccurate, and potentially dangerous, to "paint
with a broad brush". When you say "canned air", for instance you are
generally using a misnomer and people may tend to lump anything in a
similar looking can with similar functionality together in their
minds. "Dust Off" in particular is refrigerant-based propellant
cleaner, which is not compressed air and incorrectly called "canned
air". Calling it "canned air" sounds so harmless, doesn't it? And it
may be harmless. "Dust Off" went through a bit of a PR scandal with
"huffing" and so a "bitterant" has also been added to the mix. You
aren't spraying just air.
Go back and read my posts on the subject. I very carefully call the
product "canned gas". Why? because I know that it isn't air inside the can.
People can misuse anything by using it for what it isn't designed for.
We have problems here with young people huffing gasoline and Lysol. This
doesn't mean the products aren't good for powering a car or cleaning a
floor.
Ignoring the potential problems with moisture and humidity (the
nozzles are designed to try to cut down on the moisture droplets that
can be sprayed) you have a *potential* problem with temperature
differences between your equipment and the temperature of the air
coming out of your can of refrigerant. Fast expansion/contraction
(particularly if it is on just a small part of a surface) can be a Bad
Thing.
In some 40 years of using this particular product, I have yet to have a
problem. The temperature difference is negligable, unless one is stupid
enough to hold the can upside down and spray liquid propellent.
There is also the logical fallacy of "since I've done *something* X
number of times and never experienced a problem" then that is the same
as: "doing *something* is not going to cause a problem". There is a
reason that they call them Best Practices.
40 years of not having a problem goes way beyond doing something x
number of times and not having a problem.
On the other hand it is worth remembering that you aren't touching the
surface of the sensor itself, but a filter that is in front of it. I
wonder how sensor cleaning works on cameras with no anti-alias filter.
Is there still a hot-filter in front of the sensor (for IR)?
Not a concern for me, every DLSR camera I own has a cover glass. of some
sort.
However, the bottom line in all of this was well-spoken by the Isley
Brothers in their 1969 hit: "It's Your Thing (Do What You Want To
Do)". If you ask the question, you may get a wide range of answers but
it is up to you to decide what you are comfortable with for your
equipment.
As I said, my cleaning methods do cause some people to jerk their knees
and curl up into little foetal balls and make mewling kitten noises. You
appear to be one of the ones affected badly.
--
William Robb
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