LumoLabs: Pentax K-5 low light focus study is published

Started Feb 23, 2011 | Discussions thread
dlacoutu Contributing Member • Posts: 811
Re: LumoLabs: Pentax K-5 low light focus study is published

Just so my findings are not only for the other forum, here is what I found tonight:

Following Falk's suggestion, I've made some tests involving shining a flashlight into the viewfinder while focusing...

And guess what : using a tungsten flashlight into the viewfinder, my camera focused properly!!! (note that a "daylight" LED flashlight had no effect upon focus).

Test case:

  • find a target/light level where you get consistent FF

  • M mode, 400 iso, flash on (to be able to better judge focus)

  • do pics without the flashlight, pics with it...

I've even found another test, faster and more "obvious"...

"Dynamic" test:

  • AF-C (the behavior will be obvious!!!)

  • while half-pressing the shutter, intermittently shine the flashlight into the viewfinder.

=> you'll see the camera adjust the focus for tungsten light...

So, under a given light level threshold, the camera will revert to "daylight focus", and not properly compensate for tungsten lighting anymore...

I guess the reports of misfocuses in "low daylight" situations are actually based upon the false assumption that when the sun just went down, the WB is still "daylight", whereas in reality there is an heavy shift toward blue...

 dlacoutu's gear list:dlacoutu's gear list
Samsung NX100 Pentax K-5 Samsung NX200 Pentax smc FA 50mm F1.4 Samsung NX 30mm F2 Pancake +6 more
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