#heat diffraction

Another birding attempt skunked by the weather.  I attempted to hike out to ʻaimakapā fishpond at Honokōhau to find aeʻo (Hawaiian stilts).  Unfortunately, it was hotter than I was prepared for.  And the hike was a mile across an old lava flow, with zero shade or cover.  86-90ºF and super high humidity.  It was HOT.  I can usually handle these temps, but I just went through LA’s coldest winter in 30 years and I am acclimated to the wrong end of the spectrum.  I was feeling a bit lightheaded as it went on.

I made it about a half mile--just within sight of the fishpond--before I bailed.  I might have continued on, but I could scan the fishpond with my binos from that distance and it was pretty much empty birds.

I did spot this kolea (Pacific Golden Plover), though, in a leafy area.  And the photos I took of him reinforced my decision to bail on the hike and go back.

This MIGHT have been a great shot.  Clear view, good lighting, was able to use a low ISO and a high shutter speed.  SHOULD have been great, right?

Well... there’s a thing called ‘heat diffraction.’

If you’ve ever seen heat waves rising off hot pavement, you’ve seen what causes heat diffraction in photography.  At close up distances, this isn’t too much of a problem.  But when you start using long glass (500mm, 600mm, and longer), heat diffraction becomes a big problem.  And the result is blurry photos.  My focus was spot on for this bird, but because of the heat creating a disturbance in the atmosphere, you get a somewhat greasy blur effect.

I’ve encountered this before, shooting tule elk in the heat of summer out in Owens Valley and Bakersfield.  But in those cases, it was at a much greater distance.  And despite the greater heat (probably around 100ºF in those cases), I wasn’t shooting across the equivalent of blacktop pavement.  I was shooting over grass and dirt, which reflects less heat.

Unfortunately, the old lava flow here absolutely radiates heat in this weather.  So even though this kolea was only perhaps 30 feet away, it got hit hard by diffraction.  Resulting in this... very disappointing photo.

Even my AI sharpening algorithms couldn’t save it.  Alas.