X-T4 - I`m really disappointed

Started 3 months ago | Discussions thread
fujiian
fujiian Regular Member • Posts: 200
Re: X-T4 - I`m really disappointed
1

rlx wrote:

ikaika777 wrote:

TheWhiteDog wrote:

Apparently, in manual/AF-ON it makes the lens focus at its widest aperture. This does two things: it limits DOF giving the AF less to confuse it. Also it allows the maximum amount of light in which helps the AF system to "see". In regular BBF the lens doesn't open to its maximum aperture. Having said that, BBF does improve things as it separates the AF from AE which normally would be handled together by the shutter button, so less for the camera to do at each step. Also BBF is the only option when using AF-C, which I don't tend to use, but for those who do BFF makes a great deal of sense.

I guess what’s confusing me is when you say, “it makes the lens focus at its widest aperture.” How can it do that if you’re in Aperture priority mode or am I completely missing something? Same goes for “In regular BBF the lens doesn't open to its maximum aperture.”

When shooting in aperture priority mode the camera ends up setting the shooting aperture to the aperture you have selected. However the AF system has its own strategy that is independent of that. There are apparently three different AF strategies depending on the position of the front switch.

  • AF-M opens the the lens aperture as wide as it can while focusing.
  • AF-C stops down to the shooting aperture.
  • AF-S stops down the lens to some intermediary aperture between wide open and the shooting aperture.

One can check easily by looking into the lens while AF is working.

Once the focus is set, the camera sets everything according the selected shooting aperture to take the picture. So that's a two step process.

I've noticed AF does cause the aperture to open up (the lens 'chatters', people often complain about this), but have never noticed the subtle differences between the three modes until following this thread.

Am I the only one that finds this absolutely bonkers – especially if one is clearly superior? Possibly a trade-off between AF speed and pinpoint accuracy?

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