RX-1 Interesting Aperture Observation

Started Feb 2, 2013 | Discussions thread
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jlf
jlf
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RX-1 Interesting Aperture Observation
Feb 2, 2013

I'm sure others have made the same observation, but I hadn't seen it mentioned so figure I'll share it here.

I often shoot in Aperture-Priority mode (A) or Manual (M) and was observing my AF speed and preview speed would change when I select smaller apertures for better DOF. Coming from a DSLR, I was a little surprised that the aperture was not changing just when depressing the shutter button but also as I changed it during preview.

This means the AF performance on the RX-1 depends on your chosen aperture, as the lens is actually stopped down during focus and preview. So, AF speed at f/8 is quite a bit slower in low light than f/2.8, for example.

But, it means the preview is truthful to the resulting DOF of the selected aperture.

For Program (P) and Shutter-Priority (S), the maximum aperture is f/4 so it's using at least two stops less light than the camera's maximum aperture for focus.

One of the benefits of f/1.4 and f/2.8 lenses on DSLRs is their focus speed and accuracy in low-light conditions is improved due to the increased amount of light entering the lens during focusing.

Certainly an interesting difference with the RX-1 coming from a traditional SLR.

j.

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