Dealing with Ground Heat

[Chris Sgaraglino]

I shot some footage this weekend with 4 different cameras ranging from $1,000 to $5,000.
I shot horses in a pasture across a pond and some antelope in a field.

All the cameras recorder the ground heat radiating up and causin "rippling" footage when on the longer end of the zoom.

Is there anyway to deal with this, other than the obvious (shoot when it's cooler out)?

[Warren Kawamoto]

Get as close as you can to your subject. The longer the lens, the more pronounced the rippling effect will be.

[Chris Sgaraglino]

Thanks Warren,

However, sometimes getting closer is not an option.

Here is a clip form the shoot where I am shooting across a lake.

Ground Heat Effects on Vimeo

[Bill Davis]

QUOTE: All the cameras recorder the ground heat radiating up and causin "rippling" footage when on the longer end of the zoom.
Is there anyway to deal with this, other than the obvious (shoot when it's cooler out)?

The simple answer is no.

But other than the annoying birds in the frame causing the average viewers brain to be constantly distracted by many small objects in motion, there's essentially nothing wrong with one of these shots used as a short establishing shot within a larger work.

Also consider investing in a better tripod head if you're going to need to pan at this kind of zoom length - the inconsistencies of motion in your pans would be another significant distraction for a viewing audience.

But the shot itself is perfectly acceptable other than these issues.

[Chris Sgaraglino]

Thanks for the response.

This is not a clip intended for production - this was only to capture the rippling. I thought it might have been the lens choice I was using, so I tried a different lens. Again, it got it on all cameras no matter what lens.

The "pan" was just moving from one area to another. I do have a Manfrotto Fluid Head on Manfrotto sticks, I just didn't care about the movement in this shot.

[Jim Andrada]

The rippling is a real physical phenomenon. It's really there, so no combination of camera/lens etc will eliminate it. It also depends on what's in the air - watch carefully as you fill your gas tank and you can sometimes see rippling caused by fuel vapors mixing with the air. Or water vapor for that matter. Moist air mixing with dry air, warm air mixing with cool air - rippling guaranteed,

Index of refraction of a material depends on temperature as well as wavelength and in the case of air, obviously with what is mixed in with the air such as water vapor.

But as Bill said it isn't distracting or even particularly noticeable in this clip.

[Brian Drysdale]

Yes, it's a real physical effect and you'll need to find a time of day when those conditions don't apply. However, the heat rippling wasn't that noticeable in your example.

The heat rippling effect can be pretty good looking, especially when used to reinforce a point about the environment that animals have to survive in.

[Dustin Moore]

If you find an in camera solution to this problem the military will pay you a lot of money.

The turbulence is driven by the sun heating the ground. If you wait until very late in the day
the sun will eventually be unable to keep the ground hot enough and there will be an
hour or two of relative calm where you can get a long shot off and not see shimmer.
On the downside, you probably have very little light to take the picture in.

Getting back to the daytime: you may find that a higher shutter speed sharpens the picture
slightly. You can't remove the lateral translation of points in the image but you can mitigate
the blurring caused by that motion during the exposure interval.

Most atmospheric blurring effects can be frozen out above 1/1000 or 1/2000 of a second.
Your picture already looks pretty crisp so this might not help much. If you start using
a much longer lens and framing individual animals the exposure trick might help.

One other thing, you are shooting over land-water-land it looks like, The land and water
have different heating properties and at the boundary between these regimes there is likely
to be extra turbulence. You may find that if you move your kit on to a boat all on the
water you can skip the extra turbulence caused by the first land-water transition. I probably
wouldn't go to expense of actually trying this but it is something to think about it.

Actually, if you could just move everything (animals, camera, etc.) on to the water that would
be your best bet. The water does not heat up much during the day and this minimizes the
turbulence near the ground. I don't know how deep the water is there but the horses might be
alright in it.

[Jim Andrada]

Or you could don full scuba gear and immerse yourself in the lake.

As Dustin said, the number of ground/water transitions doesn't help, Also, the presence of varying amounts of water vapor in the air will cause a bit of the same problem.

This is all part of the reason astronomical telescopes are on mountain tops - to get above as much of the atmosphere as possible. Think of stars twinkling - the star isn't twinkling at all, it's caused by the atmosphere which is also refracting the light in such a way that the stars aren't really exactly where they seem to be, IIRC this is called "seeing" in astronomical terms.

You'll often see this effect purposely emphasized in films of Africa or the Sahara to give the impression of heat.

[Jon Fairhurst]

One of the reasons to get a long lens is to produce that "posse in the road" heat wave effect. To avoid it and keep your framing, use a wider lens closer to the action - when possible, of course.