It may be stating the obvious but to all of you who use magnifying lenses of any sort please be careful where you leave them especially while the sun is low in the sky at the moment.
I had a VERY lucky escape yesterday,I had recieved a new magnifying lamp & had put it on my workbench & then went into lunch.When my wife went out an hour later she shouted for me & I ran out to find that the pinboard I have on the wall behind my bench was merrily smouldering away to itself,luckily it was underlay board for laminate flooring so just smoulders rather than bursting into flame so I ripped it off the wall & threw it out.Effect of all this ...a scorched area on the concrete wall under the pinboard,a rather smelly workroom & an additional fire extinguisher in the workroom to complement the one in the garagy part of the garage,next job will be a fire alarm!!
So please guys be careful how you put things down,this could have been a lot worse than it was & I hate to think how bad it could have been in the house.

A lucky escape Rob.
I've got a smoke alarm right above my bench, because that's the sort of thing I'm really good at (trying to burn the house down, that is).

That's very sound advice! It's very often the 'couldn't happen to me' mistakes which prove not only costly but prove the point 'yes it could!'
Most people would probably regard the sun through a magnifying glass conflagration as an old wive's tale but this warning shows otherwise.
My own workroom is up in my attic with just a small skylight which doesn't allow direct sun onto my bench except for a short period during the summer evenings, (flaming blinds me when I'm on this computer though!
But I still have a smoke alarm and fire extinguisher fitted up there, just in case!
My biggest problem is ventilation when there's a westerly gale blowing, I need fresh air not a scale model hurricane!

Stay safe everybody

Robin