|female Purple Finch, window open, 20' distance|
|female Purple Finch, window closed, 20' distance|
I've been happy enough with the quality of images taken through a single pane of glass all winter. With the Harris' Sparrow and Golden-crowned Sparrows visiting the feeders (both rarities in SE Michigan) in November - December I've been hesitant to photograph them with the windows open.
If you need to photograph birds through window panes, know that image quality will suffer, so keep them as clean as possible!