Spherical Aberration

[chrysoberyl]

Several sharp lenses - Samyang 14mm XP, Samyang 50mm XP, Sigma 28mm Art and Sigma 40mm Art – have noticeable spherical aberration. I have the Samyang 14mm XP and Samyang 50mm XP, and I want the Samyang 35mm XP, but I hesitate because I suspect it will have this characteristic also.

These are all fairly high quality lenses and I understand that compromises must be made when designing lenses, so I am curious what compromise results in spherical aberration.

If there is already a thread on this topic, please post a link.

 

[Joules]

As far as I'm aware, correcting spherical abberations causes out of focus areas to appear less smooth and can make the transition are unpleseant to some people.

The lenses you mentioned are all quite fast, so I would assume that if they are not perfectly corrected for spherical abberations, that serves to keep they bokeh good when used wide open.

See http://bokehtests.com/styled/index.html as an example of a site going into some detail on this. There are probably better ones out there though.

 

[chrysoberyl]

Thank you, Joules, very informative. As far as I know, Canon cameras always focus wide open. Is there a way to force the camera to focus at the set aperture? That would resolve my problem nicely.