Heat wave distortion and long lenses

[Ladislav]

I visited two airshows this weekend (Flying Legends and Air tattoo) and had a lot of fun bringing home thousands of pictures. It was almost clear sky and very hot both days.

When reviewing my pictures I noticed that with long distances and longer focal lengths all images become out of focus / distorted. This weren't my first airshows and I didn't notice this problem before. Shots with long focal lengths on close flypasts did not exhibit the same issue.

The issue looks similar to heat waves usual when planes are taking off or landing and there is a lot of heat from tarmac. Is the same effect happening in skies as well? I noticed that a lot of photographers didn't bother to take pictures of planes in distance. I'm fine with the result, just want to check for the next time that I didn't do something wrong or that there isn't some issue with my equipment.

Example of distant shot (whole picture and 1:1 detail). I think this one was done with: 1/1250, f6.3, 160 Iso, 562 mm - Canon 5D IV and Sigma 150-600 C OS, AI Servo, sequential shutter, single point AF

I have some more striking examples but those may be combined with some motion blur or bad focus as well.

 

[AlanF]

It's standard heat haze - currents of air have different temperatures and diffract the light in a rapidly fluctuating manner. It's a common problem with telephotos in hot weather. There was posting some time ago when someone eliminated it for a static subject by using a 10x ND filter over a long exposure so the fluctuations averaged out.

 

[stevelee]

It's really a nice shot when you don't pixel peep. Obviously the 100% crop is useful for your asking the question.