50mm 1.8d problem ?

Hi guys, anyone using this lens found a problem AF when camera held in portrait position ?
ive been taking shots of grandaughter , OK the ambient wasn't all that good , but the 50 seems to lock
on quickly in landscape but struggled in portrait , anyone notice this
Going to try with 35 , and 18-105 see if the same , which prob would then lean towards not enough ambient to lock on
Thoughts please

Do you mean viewfinder or Live View? Very different focus methods.

Are you using the center focus point in the viewfinder?

There are two types of focus points in the viewfinder, cross type and otherwise type (don't know a better name).

Cross type is a dual sensor, and detects focus phase in either vertical or horizontal orientation. Otherwise type is horizontal only, less sensitive in some cases. I think it basically matters about if the edge seen is horizontal or vertical.

Camera models with only a few focus sensors may have only one cross type, in the center. Models with many more focus points have several more cross types, but still mostly more in the central areas. The specs chart in rear of manual (section Focus) will specify number of focus sensors , and the number that are cross type.

Check to see which of the focus points is being used, whether the camera chooses it or you've manually chose one.

I'm using the 7100 , thru viewfinder and moved the focus point using the pad, high up on the screen to focus on her eyes
I thank you for any info , and I have to say I'm pretty experienced with the camera so will understand most of your replies
I expected the cross hair , horizontal , vertical thing and now wondering if it's not just as sensitive away from the centre
cross hair points
i suppose if it picks up focus better from centre point it's no big deal to just focus and re compose , just like to know if others find it struggling in the lowish light off centre point in portrait orientation

Just checked on PC screen , out of 20 or so 2 are way out , prob me , the rest are nailed on it just took some seconds to get there

Use one of Nikons software.... View NX2 or NX-D... they can display which focus point(s) were used.

Thanx sparky done that, focus points where they should be , focus is bob on and where I put them ,
eyes mainly
as I said focus is good when it got there just wondered if others had similar with off centre focus point or portrait orientation in not too god ambient light

Do your camera have the ability to adjust focus for front/back focus?

Cheers Sparky , but maybe you misunderstand and I'm not putting it over well
The focus is perfect , focus point is where I put it , the issue is it takes some seconds to lock focus
especially in portrait and off centre , I think it's probably not enough ambient light and using manual
the focus assist light doesn't deploy
hope that's a bit clearer , will try other lenses tonight in similar light and see what happens

Skwaz said:

I'm using the 7100 , thru viewfinder and moved the focus point using the pad, high up on the screen to focus on her eyes
I thank you for any info , and I have to say I'm pretty experienced with the camera so will understand most of your replies
I expected the cross hair , horizontal , vertical thing and now wondering if it's not just as sensitive away from the centre
cross hair points
i suppose if it picks up focus better from centre point it's no big deal to just focus and re compose , just like to know if others find it struggling in the lowish light off centre point in portrait orientation

Click to expand...

The D7100 says it has 51 focus sensors, and 15 are cross type, more than some models. However this link
Nikon | Imaging Products | Capturing power - Nikon D7100 (the viewfinder with the red cross type)
shows those 15 to be three vertical rows down the center of the horizontal viewfinder, at least, NOT at the ends where portrait eyes are (not more than one away from center row).

My D800 is pretty much the same, and it gives me a little trouble too (in same vertical portrait and eyes situation). Usually OK, good enough, but sometimes it takes 2 or 3 shutter buttons to get it to trigger. I use single point, but moved to top of vertical frame.