Beginner's lens questions for K-x

Started Jun 26, 2010 | Discussions thread
audiobomber
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Re: Dan: Not on my lens.
In reply to djedi, Jun 29, 2010

Your headline should read "not on my camera".

djedi wrote:
RE:

I think there's been a misunderstanding. The 17-70mm does not hold f2.8 until 35 mm. Aperture is not stepped, it is gradual. If the 17-70 is f2.8 at 17mm and f4 at 36mm, then it passes through other aperture values as it zooms. It would only be f2.8 for the first mm or two. As soon as you start to zoom the aperture starts to decrease.
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Dan

Mine switches from 2.8 to 3.5 at about 33mm.

You have your camera set for 1/2 steps. If you set it for 1/3 steps, you would notice your lens changes from 2.8 to 3.2 to 3.5. If your camera could show even closer aperture steps, then it would show 2.8, 2.9, 3.0, 3.1 etc. The lens doesn't hold 2.8 aperture and then suddenly jump a step (or half a step). A zoom with variable aperture opens up constantly as you zoom.

It would only be f2.8 for the first mm or two.

That's probably overstated. It would be f2.8 for several mm's.

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Dan

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