EF600/4 lens hood image distortion

John Sheehy wrote in post #19437314
Exactly. I saw my worst thermal distortion that I ever noticed the first day I tried my RF800/11, on a very cold morning with bright sunshine. I thought that my lens was defective, it was so bad. I checked again a little later, and I could see the distortion changing through the viewfinder in real time, and then realized that it wasn't the lens.

John Sheehy wrote in post #19437314
Exactly. I saw my worst thermal distortion that I ever noticed the first day I tried my RF800/11, on a very cold morning with bright sunshine. I thought that my lens was defective, it was so bad. I checked again a little later, and I could see the distortion changing through the viewfinder in real time, and then realized that it wasn't the lens.

Interesting. It must be the long glass or the lens + camera didn't have time to evenly cool off. I've had my camera set up on a tripod shooting the northern lights at -42 C with no apparent distortion. That said, at that temperature it is wise to put gloves in before touching the tripod.

Rod

RodS57 wrote in post #19437504
Interesting. It must be the long glass or the lens + camera didn't have time to evenly cool off. I've had my camera set up on a tripod shooting the northern lights at -42 C with no apparent distortion. That said, at that temperature it is wise to put gloves in before touching the tripod.

Rod

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Rod, heat distortion doesn't normally have anything to do with the lens or camera being warm. . The lens hood issue this thread is talking about is a real outlier.

Heat distortion, typically, is about the air itself and the way it interacts with direct sunlight.

Of course you didn't have heat distortion when you were shooting the northern lights, because heat distortion normally only happens when there is full sun. . Just a little overcast and the distortion is a complete non-issue, despite the varying relative temperatures of the air and the ground.

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Tom Reichner wrote in post #19437507
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Rod, heat distortion doesn't normally have anything to do with the lens or camera being warm. . The lens hood issue this thread is talking about is a real outlier.

Heat distortion, typically, is about the air itself and the way it interacts with direct sunlight.

Of course you didn't have heat distortion when you were shooting the northern lights, because heat distortion normally only happens when there is full sun. . Just a little overcast and the distortion is a complete non-issue, despite the varying relative temperatures of the air and the ground.

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Yes, this is true.

Sunlight warms objects up, especially dark objects. Years ago Canon make their big teles white (whitish) to reduce warming of the lens. But lens hoods were still black. Now they have seen the light and made a white lens shade for the Canon 100-500mm lens. That should reduce cool/warm air mixtures in the vicinity of the lens hood and improve sharpness in sunlight.

Those white lens hoods are really conspicuous.

John Sheehy wrote in post #19437314
I saw my worst thermal distortion that I ever noticed the first day I tried my RF800/11, on a very cold morning with bright sunshine.

Yes, and that's why it will help coming here. Especially in the winter, when we just barely see the sun at all, and not at all in the far north of the country.

We see a lot of grey skies with clouds, though, if you like them!

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This morning, while doing research for an upcoming photography trip, I was watching a wildlife video, and heat distortion was very visible in one of the short takes. . I immediately thought of this thread and thought I would post a link to the video. . Heat distortion is much more apparent in video form because you can see the "waves" as they dance in the air.

For those who seem to be having trouble understanding what typical heat distortion is and what causes it, watching this will make it quite obvious that such heat distortion has nothing at all to do with a lens or camera being warm, nor with the outside air being warm.

https://www.youtube.co​m/watch?v=PnSEivYt-VU

The part with the heat distortion is when a Snowy Owl at a good distance is shown. . The clip is about 5 seconds long, starting at the 12:39 mark and running until the 12:44 mark. . The distortion is primarily occurring behind the owl, and causing the background vegetation and snow to look quite blurry.

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Tom Reichner wrote in post #19437507
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Rod, heat distortion doesn't normally have anything to do with the lens or camera being warm. . The lens hood issue this thread is talking about is a real outlier.

Heat distortion, typically, is about the air itself and the way it interacts with direct sunlight.

Of course you didn't have heat distortion when you were shooting the northern lights, because heat distortion normally only happens when there is full sun. . Just a little overcast and the distortion is a complete non-issue, despite the varying relative temperatures of the air and the ground.

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Yeah, I have to suffer through what you are talking about every spring: ice + water + sunshine makes for fuzzy pictures when any distance is involved.

Edit: that said, I spend a lot of sunny winter days shooting in temperatures below -20 C with no adverse thermal effects. Just my experiences with what can be a complicated issue.

Rod

You definitely don't need sun for heat waves. Large bodies of water hold nearly constant temperature. It changes with seasons, but over 1 day at least, it's constant. I experienced severe heat distortion over Botany Bay in Sydney. It's roughly 4km radius. In the moring, air was very clear. There was sun, but the sun does not heat up this amount of water in any measurable way. About mid day, there was a sudden cool change. Air temp dropped from about 22 degrees C to about 15. The water was 17. So now the water in the bay became like a huge hot plate and predictably, the air above the water reacted to the hot plate.

I have photos which demonstrate my cool change better than these, but I just grabbed these off Flickr. (Photos that show the problem better did not make it to Flickr).
Both photos taken from the shore, ie, not over any land.

Morning, full sun, background looks quite good.

Have you tried the half-length Zemlin hood? Does it also show the distortion effect? (I see Canon also makes a half-length version)

https://www.zemlinphot​o.com …se&q=false&cate​gory_id=99

I've been using the Canon half-size hood when condtions are dry and the long hood only when it's rainy and haven't seen the blurring I originally reported. That blurring most often occurred when I first put the camera/lens on my window mount and immediately started making exposures. It then tended to clear up after a few minutes of use.

Until I recognized the effect of that self-contained atmospheric disturbance within the lens hood, I thought it was in the distant atmosphere or some kind of mechanical/electical effect that ruined those initial frames.