I discovered something really cool today. I was shooting some Fracking platforms and noticed how bad the heat shimmer is here during the summer. Unfortunately, a Daytime shot was required and the simmer was making it difficult to use longer lenses to flatten the subject against the sky.
Thanks for sharing your observations!
Years ago I observed that 1/400 second gave me much more detail than 1/30 second exp time - o.k., I had some shimmer showing regions of much detail, some regions blurred but the impression was as sharper image overall. 1/30 second integrated sharp and blurred regions into a mushy overall experience. But I have NOT tried to exaggerate exp time beyond a second.
Focal length was 640mm equiv. - I set my 40D to ISO 1600 to reduce exp time despite ISO 1600 for a 40D is its outer limit quality wise.
Your example shows - IMO - the same detail in both shots but the 30 second shot is undistorted which makes it more attractive. One remark: The left shot seems to be in full sunlight, the right shot doesn't show the bright contrasty light - was that caused by the 30 second exposure or did you have changing light?
Thanks again - Michael