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A TC 2 video (going live now)

I made a quick thing for the second channel.  This is really just a ramble about autofocus and nighttime, as well as a little bit of trivia regarding Chicago airports.  

A TC 2 video (going live now)

Comments

On OnePlus camera app, when recording video or taking photos, tap and hold the screen and it will lock AutoFocus!

Joshua Doades

As the OnePlus 3 uses phase detection autofocus, what I suspect is that it only monitors a certain number of points in the picture for focus. In this case if there are not enough points of light in the areas it uses for phase-detection, it then tries refocusing the image. When I had the OnePlus 2, I ended up buying a third party app (Cinema FV-5) just so I could lock the focus as the default camera app was terrible for focus hunting even in good light.

Seán Byrne

Regarding SW Airlines. I flew SWA into a small Texas airport one time and the chief steward came over the intercom after we had landed.. "Thank you for flying SW Airlines, we know you have a choice .. Nah, who am I kidding - we're the cheapest and besides, no-one else flies into this airport.. But thanks anyhow"..

Gordo

The autofocus algorithm may be looking for edges in its contract detection - points of light would require a different algorithm. At that distance, it's effectively infinity and manually focussing would be the obvious choice but I think you said your camera doesn't support it so not an option. I also wonder if the aircraft window might be playing tricks on the autofocus system.

Gordo

Dallas Love Field and Houston Hobby Airport are also both almost exclusively Southwest Airlines. I think SWA just likes coming in and taking over smaller airports in big cities for whatever reason.

Jason McMillon

FWIW, my assumption of this unstable focus on lights in the dark has always been that the camera is unable to focus down to sharp enough that the lights cover a single pixel, so it periodically guesses "surely I can do better" and hunts for focus again. The lack of single pixel focus being possible here is simply due to light spreading (in the atmosphere) over distance -- they don't look pixel-point sharp to our eyes either (except maybe if you're talking about, eg, laser light). Presumably the camera moving relative to the lights (eg, in a plane or car) makes this problem worse, so the camera discovers its "marginal" focus is even more marginal, and is more likely to try hunting again. One might hope the camera would,eg, recognise that it's tried this pattern of "can I do better than this marginal focus" N times, and decide not to try again... but my impression is that the focus systems on most contrast detect cameras just do not have that level of memory of past actions/outcomes. Some cameras have a "lock focus" option on their autofocus (eg, hold down for a longer period than "tap to focus") for stills mode, which can reduce this focus hunting, and might help in this situation; but I'm not sure if that works in video mode on (m)any of them. Ewen

Ewen McNeill


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