Focusing using manual lenses

gaetanonline wrote:

Hi!

I love my Pentax and I sometimes use manual lenses with it.

I have da problem about focusing. I use catch-in-focus and all settings are fine.

I see camera always use center point to focus.

I think this has always been the case, if the lens is manual you get center point confirmation - it's true on the K1 and I think it was true right back to film

When I shoot half-lenght portraits at f.2/8 eyes are out of focus.

The simple answer is to shoot with a smaller aperture and more depth of field but I am guessing that you want shallow depth of field to isolate the subject from the background.

I tried to "focus and recompose technique" but I still have the same problem.

In my opinion that's because the focus point is not the head (the eyes) but it's lower, so even if focus plane is in focus, focus point is not.

I think it is more to do with the field of focus of the lens, if you focus on a brick wall 2M away, the bricks at the edges of the frame are sharp but they are further from the camera than center brick. So the field of focus isn't an arc from circle 2M in radius, it is flattened (but not perfectly flat either). If the middle of the frame is focused at 2M something exactly 2M away at the edge is just a little too near the lens. So focus and recompose is not perfect , and will vary from lens to lens.

Maybe I could solve the problem using smaller apertures f.5/6 or shooting only headshot for portrais

Shooting only headshots and moving closer would mean you had a shallower d.o.f so the problem might be worse.

How do you suggest to solve the problem if I want to go on using manual lenses?

Two ways. One is to just live view and/or a magnifier, or any other focus aid you can get. The other is through practice to know that if focus a little short when you recompose things will be right, but you need to learn how short to focus.