We had six fantastically well informed photographers this evening.
Lee had sent me an e-mail earlier asking me to bring in my "spinning thingy" which I took to mean my Arctic Butterfly. Using his camera I showed everyone what the sensor looked like (without the mirror in the way) with both room light and with my LED flashlight, which is more eye-catching. I then demonstrated how to clean dust and debris off a sensor. I was mostly successful but there was one speck that must have had something sticky on it. For this I suggested a q-tip and 99% alcohol, though there are other ways available. My Arctic Butterfly is a couple of years old and cost about $70 at the time. You can still buy that model at that price but the company has other models for more. It's expensive and I only use it 3-4 times a year but, with my older camera and frequent lens changes, I find it well worth it to get a good cleaning in a very short amount of time, even in the field.