Just before Christmas I was shooting a product with a wire mesh in my studio. On 100% loupe I could see that parts of it were out of focus. So I naturally checked the CCD and lens for dirt. Couldn't see anything so I took another shot. Still had out of focus areas but wierdly in different places. After 30mins of head scratching and more cleaning and check software settings, I suddenley thought that may be the two propane space heaters blowing across the studio were causing thermals. Turned those off took another shot and bingo, all 100% in focus! I'm not sure if it was purely a themal issue or droplets of water or CO2, flying across the field of view (propane gives off a lot of water and CO2 when it burns), but it really had me going.
I've now taken a closer look at these and you can see quite a lot of distortion going on in the images from shot to shot. Pretty much like you'd expect in a mirage. I've uploaded some shots of the loupe layered up in a PSD file.. www.kingbridge.co.uk/temp/mirage.zip (http://www.kingbridge.co.uk/temp/mirage.zip).
You learn something new everyday! I guess that multi shot shooters see this all the time, but that was a new one on me.
100 Mega Pixel resolution? Great, but not if you've got the heating on! 8)
Andre Regini
www.regini.com
www.kingbridge.co.uk
Yes, hot air mixed with cold does it all right. A jet turbine is the best example :)
thanks for sharing!
Thanks. its an itressting issue. I never tought about that problem ;)
Got to laugh.... Was visiting a large studio here last week and saw their space heaters, so I recounted this incident to the guy running the place. Today one of his teams was shooting a car and they were scratching their heads for ages trying work out why a headlamp was drifting in and out of focus.... Yep... turned out he could point to them straight to the thermal from an Arri sitting below the headlamp! LOL! :D