That image was just one from a sequence of text and images. The snapshot showed the moment when solder was being raised away again after applying a sufficient amount to the joint already. The solder wire was "in the air" between the lens and the joint, and was not resting on the iron itself. That's just when the radio trigger caught it on camera.
In the accompanying text that unfortunately you did not see, I explained that the soldering iron has to heat all parts of the joint and solder is then applied to the joint. I also explain the basics of conduction, power ratings and heat sinking out of the iron, so that beginners get to understand what's happening when they choose and use a soldering iron for the first time.
I don't claim to be the world's greatest at anything but after 40+ years I'm not a beginner either! :)
@Max, You mean like this? A little excess solder, but it worked and has apparently survived the summer at overnight camp. The pull-up-resistor lets a mini-USB cable charge an mp3 player. Customer Is Happy, but I'm Not.
These days, my problem with solding has nothing to do with solder, but the fact that I can't see the parts very well. If I take off my glasses, then my face is so close to the hot soldering iron that I can feel the heat. Even a soldering iron with LEDs doesn't help.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.