Setting the camera and taking the stack
why on earth would anyone want to take handheld image stacks?
for me this is a simple one - I want to go out for a walk and if I see an insect I can take its image. Yes, I generally go out with the purpose of taking shots of insects, but I like to take shots of whatever I come across when I'm bumbling aimlessly through an area which can be rich in wildlife with numerous photo opportunities. Because I'm out and about during the time when the insects are generally active I doubt that many of my 'models' would have the patience to wait around for me to setup the tripod and lighting requirements. Taking the stack is usually less than 30 seconds in duration but stalking the beast can be considerably longer and it's at this stage you decide whether or not the wee beastie is sitting still enough to make the effort worthwhile.
So what does 'still enough' actually mean?
Well it's fair to say that if the creature takes off at a rate of knots, either legging it under the nearest rosette of decaying vegetable matter or flying off into the sunset (metaphorically speaking) then that would be considered not very still at all. It's worth saying at this point that different insects do behave differently, even within groups of similar looking things. Try stalking a Large Red Damselfly vs. Common Blue Damselfly and I'm sure your success rate at getting to within a couple of inches of a Large Red is far higher than getting to within the same distance with the Common Blue. If you do get very close to a Common Blue you should
a) consider yourself a skillful stalker (in the insect stalking sense)
b) take a stack of the beast before it flies off, and
c) after you've taken the stack, poke it with a stick to make sure it's actually still alive (this is just my attempt at humour - you shouldn't really do this, Sir David Attenborough might be watching you from within the confines of the nearest hawthorn shrubbery)
I've alluded to taking a stack but prior to that I suppose I should mention something about the camera settings. I generally start with the camera on manual focus at iso-400 on shutter priority and usually try at 1/100. If there's not enough light through the lens then I'll step down to no slower than 1/60 (I find camera shake is just to obvious below this). If there still isn't enough light at this speed I will do one of two things; either step up the iso until there is sufficient light through the lens, but unless it was a particularly interesting shot, I'd be more likely to just wander off and look for my next victim.