Camera Labs

when i set a low aperture when i go to take the shot the aperture i set changes to a higher number canon lens canon camera EOS rebel 550D
what is the reason for this

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canon rebel 550D 100mm micro, 15-85mm 85-300mm

That's because you have a variable aperture lens. (example F/3.5-F/5.6) So it will change aperture according to the focal range. Fixed aperture lenses (like a Tamron 17-50mm F/2.8 ) will mentain F/2.8 in AP troughout it's focal range.

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Gear: Nikon D80, 18-105mm, 35mm F/1.8, 85mm F/1.8, SB-600
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In other words, if you zoom with that lens. The biggest aperture wil become smaller.

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550D + 18 - 55mm kitlens
50 mm F1.8
I apologize in advance for my poor spelling..

Thanks very much very useful

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canon rebel 550D 100mm micro, 15-85mm 85-300mm

unless it's the macro lens you're using....

Then your aperture will change when you close focus...

not on all lenses though only with the ones you that don't extend when focusing... (but that is unimportant)

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nikon d90 --->af-s dx 18-105mm; tamron 90mm macro

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or macros

phil i was referring to your post when you said that macro lenses change aperture when focusing. this is the case with nikon/canon lenses that do not extend during focusing. in other hand tamron or sigma macros extend to almost double the lenght of the lens while having a fixed aperture.. (should be like that at least)

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nikon d90 --->af-s dx 18-105mm; tamron 90mm macro

add me up on:

flickr:
http://www.flickr.com/photos/bakica/

deviant art:
http://tbensic.deviantart.com/

----:>bakice ce vladati svjetom<:----