Focusing Issue

[dhead]

Ok, I'm not a pro, but isn't the sharpness of an image supposed to be as good, or better, as you stop down the aperture??  I have X2D, 2 lenses:  38V, 55V.  I'm seeing the same thing with both lenses - tripod or handheld - IBIS on or off - auto focus or manual.  The more I stop it down, the more out of focus it gets.  What am I missing?  I took each of these with the 55V from the same spot, about 50 feet from the light - focusing on the light.  The effect with the 38V was even more noticeable. 

[Ralf]

Diffraction blur occurs at very small apertures. This is also the case with the high-quality Hasselblad XCD lenses. However, I can use my XCD 38mm up to F16 without any problems and without observing diffraction blur.

[MGrayson]

You are likely seeing diffraction effects. A theoretically perfect lens is sharpest wide open at its plane of focus. Real lenses aren't mathematically ideal, so they often get sharper up to f/5.6. Past that, and while the Depth of Field increases, so does softening due to diffraction. Only a very bad lens is sharper at f/16 than at f/11. OTOH, if you need the Depth of Field, you may be willing to sacrifice maximum sharpness. Large Format film often uses f/64 because of the inherently very shallow DoF of that size (and the lesser need for magnification in printing).

This is a big subject, and none of it is obvious.

Matt

[dhead]

Thank you both.  f13-f16 was about where I was beginning to see the effect of this, so it matches what you have both said.  I hadn't noticed it, until I started using a tripod - thought I needed a new tripod!!
I learned something today, and I can certainly shoot without going over f-13.  Visiting Yellowstone & Grand Tetons in September, so depth of field will be what it is - but in focus!
Thanks, again.

[Paul2660]

It also might be due to Focus Shift. There has been a lot written on focus shift with the newer V lenses. Lloyd Chambers seems to feel the 38V had considerable shift, however Jim Kasson  reported he was not able to notice any. Here is a link to Jim's work up.

https://blog.kasson.com/x2d/focus-shift-in-the-hasselblad-xcd-38-2-5/

For sure by F22 some of the softness is due to diffraction.

Paul

[Domip]

Try with electronic shutter and compare if it gets sharper.

[davidjiang]

Thank you both.  f13-f16 was about where I was beginning to see the effect of this, so it matches what you have both said.  I hadn't noticed it, until I started using a tripod - thought I needed a new tripod!!
I learned something today, and I can certainly shoot without going over f-13.  Visiting Yellowstone & Grand Tetons in September, so depth of field will be what it is - but in focus!
Thanks, again.

If you really want big DOF when f/13 below can't achieve, you can try focus bracketing both 38V & 55V can, of course with a tripod. Try it with f/11, f/8 even f/5.6, you can have better IQ with enough DOF

[dhead]

Try with electronic shutter and compare if it gets sharper.

The effect with electronic shutter was pretty much the same.