Congrats on getting the first roast under your belt.
They do look very light in colour, but as you say, it might just be the flash.
Did you hear 1st of 2nd crack at all? If not did you get much smoke? Smell and smoke are good nonvisual indicators of roast level.
Fairly standard (wise) advice for a first roast is to continue roasting right through the various stages until the beans are pretty much black. This extended roast allows you to see first hand what happens to the beans at the various roast stages.
It is also a good idea to break open a couple of the roasted beans to check for even colouring.
One other thing you could do is weigh the roasted beans. Generally you lose 15-17% (generalistation) of the green beans mass through roasting.
Did the mesh sock thingy work well?