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Canon 600d with Canon 100-400mm - strange effect on bokeh

Started Nov 13, 2012 | Discussions
nplion New Member • Posts: 5
Canon 600d with Canon 100-400mm - strange effect on bokeh

When I use digital zoom x3 on my Canon 600d with the 100-400mm lens, on the result videos I have the strange "movements" on the bokeh and sometimes little bit on the focused object. Shooting on tripod with IS and AF always OFF. All settings is manual.

check this test video (view it in 720p):

www.youtube.com/watch?v=Qjuu24QnaXM

Somebody have any idea what is wrong?

Canon EF 100-400mm f/4.5-5.6L IS USM Canon EOS 600D (EOS Rebel T3i / EOS Kiss X5)
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Paul B Jones
Paul B Jones Veteran Member • Posts: 3,107
Heat wave?

The nicely out of focus vegetation is clearly bouncing around in the breeze.

The movement in the grey unicolour background may be from heat shimmer as warmer and colder air interact. Telephoto lenses really pick this up, even when it is not so visible to the naked eye.

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OP nplion New Member • Posts: 5
Re: Heat wave?

When the subject is far, ok, I understand, but it's happen also in about 10 meters. Summer and winter to.

RobNZ Forum Member • Posts: 70
Re: Canon 600d with Canon 100-400mm - strange effect on bokeh

Did you have  a filter on the lens?

The 100-400 is known to do odd things with IR filters.

Rob.

OP nplion New Member • Posts: 5
Re: Canon 600d with Canon 100-400mm - strange effect on bokeh

No filters, no IS, no AF. Just clean video shooting only with x3 digital zoom that has only 600d.

OP nplion New Member • Posts: 5
Re: Canon 600d with Canon 100-400mm - strange effect on bokeh

Totally zoom is 400mm*1,6 (crop factor)*3 (digital zoom) = 1920mm. Only 2 times I had no problem, but all the rest it was. Sometime is more, sometime is less. Maybe the IS OFF not locks very good? Is it possible?

photonius Veteran Member • Posts: 6,895
Re: Canon 600d with Canon 100-400mm - strange effect on bokeh

nplion wrote:

Totally zoom is 400mm*1,6 (crop factor)*3 (digital zoom) = 1920mm. Only 2 times I had no problem, but all the rest it was. Sometime is more, sometime is less. Maybe the IS OFF not locks very good? Is it possible?

I doubt the IS lock is that bad.

What is more likely is atmospheric conditions. As you say, 1920 is really "long". In winter, if you shoot from inside the house to the cold outside, you have a huge temperature differential and big area where cold meets the warm air and you get turbulence. People here have posted samples like shooting from the inside of a car through an open window into the colder outside, and the image was substantially affected.

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Canon EF 100-400mm F4.5-5.6L IS II
OP nplion New Member • Posts: 5
Re: Canon 600d with Canon 100-400mm - strange effect on bokeh

Thanks, photonius, I think you are right. For the next time I'll avoid shooting in the midday or in sunny day.

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