Nikon d3300: Is this photo normal?

Started 8 months ago | Discussions thread
MOD Mako2011 Forum Pro • Posts: 23,570
Also normal

tommy48 wrote:

There's one other thing I noticed that I didn't want to mention to Nikon or here because I thought it would just start getting too complicated. But I noticed, and I'm sure I'm not the first person, that there is a lot of leeway in what the camera reports as being in focus, as indicated by the green dot lighting up when things are supposed to be in focus in OVF mode.

That's also normal and somewhat related to the 2-D nature of the focus arrays trying to lock onto a 3--D target.  There are often vertical and horizontal components to the FoV the Array you can get a range of "in focus"   The parameters for the green light also have a range.  Each camera model differs.

The focus ring can actually be moved (turned) quite a bit and the green dot will stay lit, even though the image cannot really be in optimum focus for the whole range. Couple that with the fact that the image focus is extremely sensitive to any change in the position of the focus ring, and you can see that the camera can think that it's in focus when it's really not.

Yes...PDAF is not designed to be perfect regards focus accuracy.  It's a balance between speed, accuracy, and practicality. there when perfect focus is a must

The real focus is at a specific position within that turning range, not the entire range or the endpoints.

True....but by design you need a "range" with PDAF or you might never get a solid green light in many scenarios.

I think when the lens focuses it will reach one of the endpoints that says it is in focus and stop moving.

Normally that's not the case.  It does go for the center...but there are hardware limitations in the focus drive system.  And different lens will have different tolerances as well.

But it's really not in focus. The real focus is somewhere between the two endpoints, not necessarily in the middle, and probably more toward one endpoint than the other.

It..tries for the middle.

I believe this because I noticed that depending on which way the focus ring turns to get into focus has an affect on how sharp the image is. If the focus ring turns so that the lens contracts to focus, then the focus is poor. However, if the focus rings turns so that the lens expands when focusing then the image will be sharper, I think because it is closer to the real focus position. I don't know if I'm making myself clear.

Clear as a bell.  It's a known limitation of PDAF.  It's also why folks will AF calibrate a lens from a front and a back focused start point.

I think my next camera will be one that has micro adjustment built in, like the D7200. Maybe the price will come down after the release of the D7500. Or I might try Canon. I hear their cameras are better for video, also.

I like micro adjust.  It really wasn't that critical when sensor resolution was small.  Now that we are at 12mp and higher...I find it a must.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)

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