High flying gliders seen from my stall

It was quiet early this morning at the Shambles market so when I saw these gliders flying very high in the sky I thought I'd see how my iPhone coped.  I was inside the church hall adjacent to St Laurence church in the centre of Stroud which has very high windows on both north and south sides.

The gliders launch from one of two local gliding airfields, the Cotswold Gliding Club at Aston Down and the Bristol & Gloucestershire Gliding Club on the Cotswold Edge near Nympsfield at the head of the Woodchester valley. On some days they just launch and fly in the local area, whilst at other times they actually race, though how it is judged I have no idea. 

As I looked up through these high windows at one time I could see at least four gliders circling near each other. I handheld my phone and tried to zoom in to focus on a glider, and was really quite surprised at the results.