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#1 |
New Boot
Join Date: Aug 2005
Posts: 24
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problem with aperture value when i zoom ?
Hi! In video mode When I zoom with my 15-85mm the aperture value changes automatically (exposition ?) ... how to avoid it or disable this function !
Because of that i can' t zoom and make video without light changing ! Thanks ! Daniel |
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#2 |
Major Player
Join Date: Sep 2009
Location: Bakersfield, CA
Posts: 232
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Daniel,
The 15-85mm is a variable aperture lens. As you zoom it HAS to adjust the aperture accordingly due to the design of the lens. The way around this is to purchase a fixed aperture lens (it will say something like "f2.8" rather than "f3.5-5.6"). |
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#3 |
Inner Circle
Join Date: Mar 2003
Location: Billericay, England UK
Posts: 4,711
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Dan - the aperture value only changes automatically if you're shooting at full wide and max aperture. Try it the other way around - shoot at full tele and max aperture - then zoom to full wide - you'll see that the aperture doesn't change.
Craig's right, you need to buy a fixed aperture zoom lens (usually a lot dearer than the vari-aperture lens you've got) tom. |
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#4 |
Regular Crew
Join Date: Jun 2008
Location: New Orleans, LA
Posts: 57
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Weeell... You don't NEED to...
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#5 |
Inner Circle
Join Date: Mar 2003
Location: Billericay, England UK
Posts: 4,711
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he needs to if he wants to (quote) 'make video without light changing'.
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#6 |
New Boot
Join Date: Aug 2005
Posts: 24
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I understand now !
I must to purchase a fixed aperture lens : maybe the 50mm f1.4 or 1.8 ! Thanks a lot for all of yours ! Daniel |
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#7 |
Inner Circle
Join Date: Mar 2003
Location: Billericay, England UK
Posts: 4,711
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Well you'll find it difficult to find a fixed aperture lens, but I know what you mean.
No - you want a constant maximum aperture zoom. Yours is probably 15 - 85 mm f/2.8 to f/5.6, something like that. What you want (what we all want) is a 15 - 85 mm lens that has a maximum aperture of f/2.8 throughout the zoom range. tom. |
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