Currently I'm not painting finished large paintings. The weather is glorious and hot, and stably so, which is rather rare up here in "ultima thule" of the 60th latitude. So I'm out there, painting small sketches, almost colour notes, that will be used as reference material together with photographs when I paint in the comfort of my studio and have a wider range of pastels at hand. The colour notes will give me the accurate colour temperature and intensity of light, and also indicate how much or little of details I really need in a bigger painting. As we all know, the camera is a fantastic tool, but it certainly doesn't have the flexibility and range of the human eyes.
Making small colour notes/quick sketches is an easy way to go plein air. I only need a piece of paper I clamp to a support (a pastel paper pad), and a handful of small bits of pastels, and I'm ready to sketch. This is different from painting a finished painting outdoors, which would require more equipment, like the easel, more pastels, a parasol, a stool, hat, water, knife to sharpen pastel pencils, etc. That can be quite a bit of stuff to tote around. A strict plein air painter does that, and finishes the painting on location, but when time or inclination doesn't allow for it, the easy way works very well. I'm a slow painter, so while I can catch the essentials in colour notations, it would be hard for me to take a work to full completion in the time-window of normally 60 to 90 minutes a plein air painter has before having to start a new painting because the light has changed too much. Some effects last only for a couple of minutes: Monet painted one of the paintings in his Poplar series in the 7 minutes the light was just right as the sun set. He had to return to the spot for several days in a row, and just hope a cloud wouldn't sail up at those crucial minutes.
Making sketches that are colour notations will also tell me if the scene is worth wile the time spent on a full painting. Sometimes what seemed perfect isn't, and sometimes what seemed not so exciting will make a good painting.