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Slow lenses focusing in dark rooms

Started Apr 16, 2018 | Discussions thread
OP Lou Cohen Regular Member • Posts: 499
Re: Slow lenses focusing in dark rooms

Sheacash wrote:

My guess is that the max aperture at a given focal length is the key. Even though the 25mm is longer than the 14mm, because it's capable of a faster aperture for focusing it focuses faster. If I'm right, a 35-100 f2.8 should focus much faster than the 14-140 at 100mm even if both are set at f5.6.

Unfortunately, much as I want to be able to validate that theory, I don't have a 35-100 to do it. If someone wants to fund this research, I'll gladly take donations

Yep. Exactly right. The more light, the faster it focuses.

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