Tuesday, February 9, 2016

Digiscoping Through Windows - 06 Feb 2016

female Purple Finch, window open, 20' distance
I've been photographing birds at the feeders from inside the house since the end of October. With cold weather it is difficult to photograph birds with the windows open. One problem is that heat escaping a warm house can wreak havoc with image quality; convection currents can make images appear as if lenses were smeared with vaseline!  Another problem (in my case) is a cat or two that wants to jump out an open window...

female Purple Finch, window closed, 20' distance
This morning a female Purple Finch was posing nicely in the morning sun, so I took a few digiscoped images from inside the house with the window closed. I then opened the window and took a few more for comparison. I was lucky that it was mild outside, so convection currents weren't bad. The difference in image quality is subtle, but significant! What appears to be motion catchlight in the eyes of the second image (window closed) is actually a double-catchlight from the window pane. Feather detail is a bit better with the window open, as well.

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!

1 comment:

Mark Wloch said...

When I got my first telescope 35 years ago, the instructions warned of degraded views when using the scope through a window because the glass of the objective lens was thousands of times smoother than the glass of any window. Commercially available telescopes(and camera lenses for that matter) are configured to a peak-to-valley smoothness of at least(at most?) 1/4 of a wavelength of green light (1/4 of 20 millionths of an inch) whereas window glass has no such specifications. It would be interesting to the difference between the two types of glass under the high magnification of say, a scanning electron microscope. If only we knew someone who had access to such a device.

Blog Archive