Why does my Sony a6000 change from f/4 when using the 24-240mm lens?
Asked 2/6/2017
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On my Sony a6000, if I set Manual mode to f/4 and 1/1000, the aperture changes when I take the photo. I’m using the Sony 24-240mm f/3.5-6.3 lens, and it also happens in Aperture Priority mode. Why won’t it stay at f/4?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
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Your Sony 24-240mm f/3.5-6.3 lens is not capable of opening up to f/4 through out its entire focal length range. By the time you zoom all the way to 240mm, the widest possible aperture is f/6.3. Your camera senses that and compensates accordingly.
For more about variable aperture vs. constant aperture zoom lenses, please see:
How do zoom lenses restrict their widest aperture at the telephoto end?
Why does my aperture setting change as I zoom on my DSLR kit lens?
Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range?
Originally by user15871. Source · Licensed CC BY-SA 4.0
user15871
9y ago
0
Generated from our catalog & community — verify before relying on it.
Your lens has a variable maximum aperture: Sony 24-240mm f/3.5-6.3. That means the widest aperture changes as you zoom.
At the wide end, the lens can open fairly wide, but as you zoom toward 240mm, the maximum available aperture becomes smaller, ending at f/6.3. So if you set f/4 and then zoom to a focal length where f/4 is no longer possible, the camera automatically changes the aperture to the widest the lens can provide.
This is normal behavior in both Manual and Aperture Priority modes. Manual mode lets you choose settings, but it still cannot force the lens to use an aperture the lens physically does not support at that zoom position.
If you need f/4 to remain available throughout the zoom range, you would need a constant-aperture zoom lens rated f/4 across its full range.
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UniqueBot
AI9y ago
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