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T2i video zoom exposure

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tom.skier
Posts: 817 - Karma: 392
I have been trying to make video with my 550D/T2i whilst using the zoom and even with everything set to manual and the aperture set so that it doesn't change I get variations in exposure as I zoom. The manual does advise that this may be an issue and I notice on all of the 550D videos I have watched on YouTube that nobody uses zoom - presumably for this reason.

Is there a solution to this - settings/different lens etc?

Any advice would be much appreciated.
Thanks
Oct 11 2010 7:25AM
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J-Evs
Posts: 6387 - Karma: 1,615
you need a fixed aperture lens

such as one that says f2.8
unlike the kit lens which is 18-55 f/3.5-5.6
Oct 11 2010 9:54AM
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207
Posts: 8969 - Karma: 3,846
one of the many reasons the kit lens blows
Oct 11 2010 11:07AM
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TheGreen
Posts: 504 - Karma: 41
yup.. what happens is the lens can't handle the low aperture when fully zoomed in (or zoomed out not sure) so as you zoom in the aperture goes up. I suggest getting a new lens with fixed aperture, but if you insist on keeping the kit lens, you'd have to set the aperture at 5.6 or whatever the lowest aperture that the camera can keep all the way through the zoom is.
Oct 11 2010 1:19PM
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tom.skier
Posts: 817 - Karma: 392
I did think a fixed lens would be the solution, but I don't think I've got the extra cash for a new lens now. I'll have to experiment with using a track/dolly for now instead of zooming to get the same effect.

Thanks everyone for the advice!
Oct 11 2010 2:15PM
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WillStart
Posts: 3955 - Karma: 3,192
true, the kit lens changes the aperture as you zoom. but also, the T2i has some sort of problem where it sometimes changes exposure even if you're using a kit lens. they did a firmware update to correct this problem. you might have it already, but if you don't, you should download it
Oct 11 2010 4:06PM
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[~_~]
Posts: 20239 - Karma: 1,273
Completely different effects actually. Zooming keeps foreground/background spatial relationship constant, whereas tracking separates them.
Oct 11 2010 4:09PM
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TheGreen
Posts: 504 - Karma: 41
yeah way easier than that would be setting the aperture to 5.6 or a higher number
Oct 11 2010 10:38PM
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IanAvery-Leaf
Posts: 9926 - Karma: 9,344
that does not fix the problem, the iris still opens/closes when you change focal lengths
Oct 12 2010 12:36AM
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TheGreen
Posts: 504 - Karma: 41
really? Cause I've tried it with the exact same lens he has (yeah I was stupid and bought the t2i kit) and the f/number stays at 5.6 all through the zoom, does this mean the iris opens and closes but the f number doesn't change?
Oct 12 2010 10:30PM
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freshlyDIPPED
Posts: 1160 - Karma: 121
not if youre in the right manual settings.
you have to set the aperture to a value that all focal lengths are capable of on the kit this would be 5.6 plus.
Oct 13 2010 12:24AM
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assface
Posts: 4319 - Karma: 2,031
just zoom slower and it should auto-correct. you can hear the clicking, ive tested and thats how mine works
Oct 13 2010 1:43AM
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assface
Posts: 4319 - Karma: 2,031
just zoom slower and it should auto-correct. you can hear the clicking, ive tested and thats how mine works
Oct 13 2010 1:46AM
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Beach
Posts: 237 - Karma: 26
True the exposure will remain the same in a constant aperture lens but the focus will still be thrown off as most camera lenses are varifocal. You would need to get a parfocal lens such as a proper cine lens, unless you plan on not ever zooming with a shallow depth of field (in general f8 or below).

But zooming with a SLR lens will give never give you a particularly smooth result, I personally would never bother unless you get a specialist lens.
Oct 13 2010 2:23PM
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mak
Posts: 700 - Karma: 167
I also believe that even if you do set a constant aperture, the lens will still flicker as you zoom. Supposedly, constant aperture lens do not have the same problems. But if you really want to zoom with a variable aperture lens...http://photo.net/canon-eos-digital-camera-forum/00WepW
Oct 13 2010 5:21PM
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