Sorry, not trying to blow you off. I promised my daughter that I would take her hiking, and I needed to get her out the door. Three year olds can be very tempermental; it's best to go when they are willing rather than to wait and risk them changing their mind.
I think others have actually answered fairly well, but let me talk more about why I chose the test conditions I did (fuel, temperature, elevation, etc.).
First, my objective: Test the Soto OD-1R Microregulator stove in cold induced low canister pressure conditions. I wanted to answer the question, "can a Soto Microregulator compensate for loss of canister pressure due to cold?"
Now, at what point does canister pressure really start to fall off? Well, generally about ten Fahrenheit degrees (about five Celsius degrees) above the boiling point of the fuel. And what are the boiling points of the fuels inside a canister? Well, regular butane boils at 31F/-0.5C, isobutane at 11F/-12C, and propane at -44F/-42C. So, adding about 10 Fahrenheit degrees to the boiling points, we get our critical test temperatures: 41F/5C for butane, 21F/-6C for isopbutane, and -34F/-37C for propane. Note: I could also use a blend of fuels, but the computations necessary for calculating the boiling point are beyond me.
Now, I live in Southern California. Temperatures like those described above are a little hard to come by -- but in the mountains such temperatures abound. There's just one catch: Boiling points fall by about 2 Fahrenheit degrees for every thousand feet of elevation (about 1 Celsius degree for every 300m of elevation). I went to 6000' of elevation, therefore the boiling point will be 12 degrees lower than at sea level (and the critical temperature, boiling point + 10).
Now, I can use any fuel I want, so long as I am at the critical point (about 10F above the boiling point). The easiest to use is butane for someone in Southern California simply because the temperatures are relatively warm here. It's hard to find temperatures cold enough to really test isobutane and propane here.
Basically though, it doesn't matter which fuel one tests with, so long as one tests at a temperature appropriate for that fuel. Again, the point is to test at the point where canister pressure is really going to fall due to cold.
I believe I did just exactly that. Look the flame in the "long" video on my blog. It is robust. That means there was good canister pressure. But at the end of the video, the flame was very small. That means there was poor pressure. What happened in between? The canister got cold. The regulator valve was not able to compensate for the loss of pressure in the canister.
I'm really tired after my hike, so I hope I'm making sense.
Adventures in Stoving