On Wed, Oct 10, 2012 at 2:46 PM, William Robb <anotherdrunken...@gmail.com> 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. 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. 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. 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. 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)? 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. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
