Two woodpeckers

I hope you are not bored with bird photographs but I couldn’t resist this one.

TWO woodpeckers on the feeders. They are very wary birds and fly off if they detect the slightest movement. I saw them through a glass door and took this photo. The glass door has a thin, protective film on it, followed by a double glazed window. What is the point of having a finely ground and polished expensive lens and then placing layers of material between the subject and the lens?

So my image is not terribly sharp but I forgive myself.