I would love to hear what you long-lens users do to avoid or minimise the effects of heat shimmer. So far all I can come up with are (1) get closer to reduce the amount of air between the subject and me, and (2) come back another day Is there anything else ?
Shoot BIF high up in the sky.
Hit the trail very early in the morning.
Go to grassy/shaded areas where the ground doesn't heat up much.
Accept the shimmer in your images as an artistic expression device.
One thing that has not been mentioned is to get higher. In many cases heat shimmer diminishes quite a bit as you get further from the hot ground that is causing it, especially if you are shooting across a lot of flat ground. If you can find a location that is higher, even a few feet, it may help. If the situation allows it, shooting from a ladder or from the bed of a truck are possible ways to get more height.
Thanks everyone. Looks like I couldn't have done much to avoid it at the time.
Roland, I think your tip about getting higher might work better at shorter shooting distances than longer distances. I'm afraid I'd leave a dent in my car if I got on top of it - they certainly don't make 'em like they used to And I think the car itself would cause a lot of heat shimmer.
I was traveling across Australia back in August and came across a couple of Kangaroos having a prolonged punching and kicking fight (not totally unlike Thai kick boxing). I'd never actually seen this before except on TV and so I had to try to get some photos. I was too far away to get a detailed picture but later on I found the heat shimmer had ruined most of what detail was left. The weather was warm but not especially hot, and so I was surprised at how bad the shimmer was. It was far worse in the photos than it seemed to be in the viewfinder. Add a few too many of my own basic errors and I ended up with a whole lot of crappy shots instead of some gems.
My next trip will likely be in hotter weather, so maybe I won't need to take my long lenses after all.
Alan321 wrote:
I would love to hear what you long-lens users do to avoid or minimise the effects of heat shimmer. So far all I can come up with are (1) get closer to reduce the amount of air between the subject and me, and (2) come back another day Is there anything else ?
- Alan
nothing else to do
perhaps shooting from higher up might help at times if you can get a high angle or something (or more rarely from lower down)
Alas, it's a PITA and you have to try very early or very late or get in closer.
The heat difference between land and air only needs to be a few degrees to start seeing the effects of refractive index gradients, which is what is the origin of the shimmer. If you used Schlieren photography you would be shocked to see how bad the effect is. Once you get differences in temperature of several degrees the shimmer is a deal breaker, over long distances. Even on relatively cool days it's ruined shots and even shooting over water the effect can be large.
Pixel Perfect wrote:
... If you used Schlieren photography you would be shocked to see how bad the effect is...
Thank you for sending me on a little exploration of science history, Mr. fluid dynamics! Enjoyed it.
As mentioned already "heat" shimmer isn't really a good description as you get the effect on both hot and cold says. All you need is a difference between the ground temperature and air temperature for things to go wavy on you. Happens on sunny winter days all the time.
The only two things I've found to help the situation are:
- Get higher, the less of the air column close to the ground you shoot through the better. If you can find a higher vantage point to shoot from do that.
- Shoot when the air and ground temperatures match. There are a lot of variables to this, though often at some point in the morning the air and ground temperatures will be close to each other. Cloudy days often easier to deal with as there is no solar load on the ground to heat things up.
The only solve for you at this time are the combinations of what the previous posters have suggested. The actual solve for the situation you have witnessed is adaptive optics (de-formable/active optics), which are commonly used for ground to space imaging, and some very specific military (LASER) applications. I hope to see this trickle-down someday to our level of use...within my lifetime that is... .
DocsPics, luckily for me there's probably a very good reason that I could not come up with that solution - thank goodness However, it is the correct solution - i.e. don't bother taking what will inevitably be a crappy photo.
Andrew, I don't believe that local area contrast will work with heat shimmer. It certainly works with haze but haze shows up as just a loss of contrast. Heat shimmer is different because it is causing optical distortions (e.g. straight lines appear as wavy lines) that cannot be fixed by enhancing contrast.
Stand, rather than kneeling. Shorten the distance between yourself and the subject (not always practical). Stop down; I think that the suggestion was f5 or 5.6 will give you better results than a wider aperture. Shoot later or earlier in the day; as the angle of the sun becomes more acute, the effect diminishes.
Interestingly, I gave the new 400 f2.8 II a workout on a brilliant sunny day on field turf where the heat waves were visible - everyone's nightmare. Shot from five yards behind the goal posts, sitting directly on the turf. My original 400 and 600 would have given me frame after frame of oof shots; in these conditions, I usually go with a 300 and chase the action along the sidelines until later in the afternoon when the sun is at a lower angle. The new lens had some heat haze issues at 100-80 yards away, but only intermitently and then it rapidly cleared up as the subject got closer, a benefit I never expected.
I really wonder how the lens has an impact on AF *accuracy*, as long as the aperture is the same and the speed is sufficient with the "slower" (older) lens to track action. I mean, the camera makes all the decisions about where to move the focal plane, not the lens; the camera tells the lens to move x steps forward or backward. The lens just does it (at whatever speed it can do). If the max aperture is the same the AF sensor is getting the same amount of light to work with...
Is there anything else ?
