How is this SD1m portrait photo shot ?

Scottelly wrote:

xpatUSA wrote:

adrianashoots wrote:

I found on this page some very nice photos of Sigma SD1

https://timgm.eprice.com.tw/tw/dc/img/2011-05/23/17202/oscar210_5_Sigma-SD1_2415914c6d0ac5f92b2ee209f74dcde8ori.jpeg

How it is this Merrill photo shot ?

The skin looks smooth, and colors are pure. Not leathery, dry in any way, but healthy.

Most of the skin is out of focus which is why it looks smooth with not much detail:

GIMP edge detection filter - black equals no edge equals out of focus,

Ted, I'm sorry to disagree with you, but it sure looks to me like most of the skin would be in focus. Just look at the hair that is showing as in focus in your image, and on the left side that hair is obviously behind her cheek, while the hair on the right side is obviously in front of her face, so in front of her cheek. It looks to me like the focus is perfect on her eye, making most of her cheek, nose, chin, lips, and some of her hair in good focus, but for some reason your image is showing mostly just some of her hair, lips, and eye in focus, when we know that most of her nose has to be in focus, because all but the tip of her nose is behind the hair on the right, and in front of the hair on the left. Most, if not all of her cheek falls into the same plane of focus, yet your image makes it look like neither her nose nor her cheek are in focus.

For the above, I applied Gaussian edge detection, then Levels, then Threshold conversion to pure B&W. From Scott's comments the threshold  settings may be too high.

Here are some Edge Detections - without threshold conversion:

In many modern cameras, focus "Peaking" uses a similar method of edge contrast, as does CDAF.

The top left is too much ... the entire cheek and all the hair appears to be in focus!

Of the other three, I lean toward 'Gradient' at top right, followed by the other two.

Knowledgeable comments about edge detection always welcome.