I always tell people how impractical it is to paint from life as shadows change and the appearance of the subject changes as the light changes. So I use my iPod a lot to take photos and then paint the subjects back home in my studio (my lounge actually but it's more like a workshop!).
But, for "quick and dirty" watercolours, nothing beats actually looking at the thing that I'm painting - there's simply no comparison between that and using photos. I went out for a walk a couple of days ago to the next village, Juiá, as the sun was low in the west after a day of rain. The cumulus clouds were spectacular against a pale blue sky with their edges a dazzling white as they caught the rays of the sun. I found a bench and sat with the paper on my knee. This is the result:
I added the lower half of the trees, the field and house later at home. I included a plane landing at Girona Airport. For the sky I used Cerulean Blue. There's a watercolour of Puig de Misa in Ibiza which I use as a kind of trade-make on my business card (I sold the picture recently) and this was also painted rapidly on my knee on location.
Typically I spend one day painting an A4 size watercolour so that has to be done from a photo but this is a different kind of painting and it's great fun!
So, inspired by my Juiá sunset, I bought myself an aluminium folding stool with a canvas seat. It was marked at €32 in Servei Estació in Girona which I thought was rather steep so I persuaded them to knock €5 off the price. Even then it was quite pricey as it's a very simple device (they called it a fisherman's chair) but I wanted to capitalise on my new enthusiasm for painting outdoors again.
I think I prefer this painting on the knee to taking an easel and painting standing up but both have their merits. One problem is that walking along, one sees a nice view but, on sitting down, it all changes!