So, some words on dust control for for film negative scanning. I think I can now succinctly state the general rule and best compromise approach for home film negative scanning. Dust setting is related to air flow. You can observe this from a vernacular layperson perspective easily. If you set an object out on a table in a typical indoor room, after a month or so, you’ll notice a significant amount of dust will accumulate on the object’s horizontal surfaces. But, if you place the same object inside a drawer for a month, you’ll notice it won’t be quite so dusty after the same amount of time. Why? Well, with air flow, that’s easy to explain. The open room gets more air flow than the inside of a drawer. The air carries dust, and out of the air the dust settles on surfaces, a little bit at a time.
In this understanding, you can also make some very interesting analogies to explain dust in air. Dust in air is not dissimilar to a suspension in a liquid. A suspension, unlike the other mixture types, colloids and solutions, has particles that can settle if the liquid is left stationary. The settling of dusts is not dissimilar to water carrying sediments that settle onto the ground. Another great example is mixing some kinds of drinking beverage powders into water. If you just pour it in to your glass of water, it may settle to the bottom and just get stuck there. But, if you are more forceful with the liquid motion by stirring it up, the powder that settled to the bottom with mix more evenly throughout the liquid for a short time. But, if then left to unstirred for a long time, the powder will settle back to the bottom of the liquid.
Now, you can explain the settling of dust by analogy of the settling of powders you might want to mix into your drink. More forceful air motions, like blowing on a surface with compressed air, swept these dust particles up into the air, but as the air moves more calmly and gently through the interior of a room, the dust particles swept up in the air are more prone to settling on surfaces as the air moves through the room. Finally, we must note that it is only because of air movement can increasingly larger amounts of dust settle onto a surface. Were the room sealed air-tight, the only dust that would settle would be that dust already in the air, and once settled, no more dust would come in. It would also mean that humans wouldn’t be able to breathe in such a room, which is why every indoor room designed for humans has positive air flow and therefore the potential to cause dust accumulation.
Okay, so what does the Internet have to say about dust. Well, I couldn’t find very much pertinent to what I was searching for, but one important point that is worth noting. Modern street sweepers are designed to pick up even very small dust particles due to the potential that the micro-scale dust particles have for water pollution. Beyond that, I found some other info sources, but I wouldn’t say they are particularly informative, accurate, or scientific on the issue of dust.
I guess I have to say that I like my own explanation the best.
20181027/DuckDuckGo how to reduce air flow dust settling in a space
20181027/DuckDuckGo air flow dust settling
20181027/https://en.wikipedia.org/wiki/Dust
20181027/https://en.wikipedia.org/wiki/Street_sweeper
So, what is my solution, then, for film scanning? I decided to build a small mostly enclosed cardboard box to do all of my film scanning work in. It is 4.5 inches tall, and large enough to contain at least two 8.5 x 11 inch papers side-by-side. A little bit wider than that to leave some working room, of course. This space is where I first bring my film sleeves inside to remove and insert into my scanning apparatus, which is my cardboard film holder that mounts the film in front of my DSLR camera. I use a regular 50mm prime lense with extension tubes that measure just under 50mm, and the lens near-focus is used to reach 50mm. This enclosure is large enough for me to put only my hands and forearms through the 4.5 inch tall opening for working, so that ought to keep the dust out well. In order to see what I’m doing when removing the film from the sleeves but still keep the dust out, I have a window on the top surface made out of plastic wrap. Yes, the plastic wrap having an electric charge attracting dust can be a problem, but mainly it’s only a problem if the dust falls down. If it gets attracted but stays on the surface of the plastic wrap, that’s okay. Besides, some other plastic options seem to have a worse problem with accumulating static charges than plastic wrap, so overall the plastic wrap window is good enough, plus it’s cheap.
One thing to be aware of, however, is that your box must also be strong enough to withstand a few puffs of compressed air from your blower brush. Yes, I’ll be using my blower brush inside the box to sweep any accumulated dust off the surface of the film, and the goal of the rest of the box then is to prevent too many new dust particles from entering by the means of the room-scale air circulation. That being said, I’ll need to regularly sweep any dust out that may have accumulated inside the box.
I still have yet to test my box to see if it delivers better results than the old method, along with making finishing touches to my box too.
With this box built, another thing I’ve found it useful for is using it as a clean chamber to make lens changes on my DSLR camera. Hopefully using the box when changing lenses on my DSLR camera can help keep dust out of the mechanism, which some has gotten into my camera and onto my sensor at this point in time. Then again, maybe the main cause of that was trying out a non-weather-sealed zoom lens on my DSLR camera just one time. Just a few times, but apparently enough zooming to bring enough air flow through the mechanism for that same forced-air dust settling effect I pointed out to happen inside my camera.