Can't focus when shooting portrait orientation vs landscape?

[lay-z]

Hi All,

I did a studio photoshoot today and noticed that I was experiencing trouble with getting the focus right when shooting on a "portrait" orientation compared to landscape.

Although I focused exactly on the model's eyes, the focus point always appears elsewhere, such as the garment and even in some cases, the model's feet!

I was using the vertical grip's shutter release when sooting the portrait orientation if that's any useful information but have never experienced this problem when shooting other portraits in the past!

Camera Settings:

Nikon D80
Sigma 30mm f/1.4 @ f/4
1/80 sec (or was it 1/100th?) shutter
centred metering
spot focus selected


I've posted two unedited, uncropped photos as reference. The landscape format is great and in focus as I wanted. However, the portrait seems out of focus on her eyes, which is where I aimed the focus point to be.





Could someone please provide some insight as a few shots are completely unusable due to this problem!

Cheers,

Alan.