>>4306679With meme narrow DOF, yeah maybe f1.2 or such can be a problem. Stopping to f2.8 for AF assuming there's enough light probably isn't a bad idea.
In low light, I would be surprised if they don't allow wider apertures though. Cameras usually pick an aperture and crank ISO up to whatever and AF based on that, in the old days people didn't realize this with DSLRs but this leads to flashes in EVFs or the LCD momentarily showing a brighter image as you engage the AF, if lighting isn't good.
>They are awesome for actually taking photos of small, distant fast moving objects though.Or just really anything, another prime benefit of a big element and wide aperture is you can effectively see through some objects, like fine mesh screens, screens, chainlink fences, or a dirty window.
Obviously you aim to not have to shoot through such things but sometimes you just have to, and the difference between f2 and f5.6 is quite extreme, it's kind of exponentially better, to a ridiculous degree. Even f2.8 isn't as good, but this is a niche use. If you're not wide as f2.8, then f4 or f4.5 or anyhting simply doesn't really cut it and you can live without trying to blurbust through obstacles. Nice feature to have, if you have it, though.
Anyone with a fast prime can try it out. Infinity focus, set auto ISO, set like 1/250 shutter and go to f1.4 then f4 with a pencil 6" from your lens. At f1.4 it will be totally gone, at f4 it'll be more noticeable and a distraction but not too bad and f5.6 (which most cheap teles go to, or higher at the end if a zoomer) and above you can no longer really do it well.
