Nifty fifty STM - focus issues, or human error?

TMHKR wrote:

archiekar wrote:

-you dont have to go out to 5.6, should be consistent just above F2

-for test being a little close can help with bias, note that focus should be 1/3 in front and 2/3 behind.

-FYI focos and recompose at 1.8, 1.2, 1.4 is going to give you poor consistency it is really hard to nail shots when moving and trying to keep the focal plane fixed especially with a depth of field of centimeters (depending of course on how close you are to your subject). Getting that eye pin sharp EVERY time is just not going to happen under 1.8.

-looks like the issue however is sorted, glad if what I suggested helped.

Well, I'm not sure it's consistent before at least F3.5. Focus jumps are still noticeable, but not as noticeable as with F1.8 and F2.0. The more I stop down the lens, the jumps are less noticeable (there are virtually no jumps by F4.0).

If I keep half-pressing the shutter button several times (while holding focus point on target), the lens jumps a tiny bit at each half-press. It attempts to refocus, but instead it just jumps a millimeter here, a millimeter there (half-press = focused, half-press = unfocused, and so on). I believe that's just how it works.

Yes it is in part how it works, the focus ring has play as do the teeth that control it so there is a lack of precision. The jump is quite fast and I believe it uses an inerpolation algo of some sort so it is not just a move in one direction but rather just past and back.

I have a copy of the 50 F1.8 ii (not STM) that becomes quite good at F2.2 and consistent shooting a 5D mkii if that makes a difference.

We are really nit picking here, what we get out of this lens is truly great, and that statement does not need the " for the money" thing before it...even though it is a bargain at its price around $100. After understanding its limitations you can still use it to effectively capture many types of scenes SO enjoy it, I do, hope you do now as well!