Originally posted by Derridale Just two examples taken with the 180 from quite a distance......
Impressive shots!
Originally posted by Derridale Anyway - back to the original topic - I have the 8-16mm on pre-order with Adorama,
Awesome. Can't wait to read about your first impressions.
Originally posted by Derridale ...given that I already have a Pentax 77mm LTD, I'm wondering if there is anything to be gained by trying the Sigma 85/1.4?
Well, it is a different focal length. You get a different perspective for the same framing and for portraits this can result in a more flattering look. The greater focal length also helps with blurring the background. Finally, the Sigma is faster. However, it is impossible to say whether you'd be gaining anything without knowing the 85/1.4's performance. The FA 77 is a fantastic lens and it will be difficult to come close or even surpass it. On the other hand, if you asked someone if there is something to be gained by having a Pentax A* 85/1.4 in addition to an FA 77/1.8 I reckon most would answer "Yes".
Originally posted by Digitalis Zeiss lenses are well known for doing it and they are supposedly designed to be relatively unscathed by such egregious lens design bloopers.
CA is not a design bloop. It is impossible to avoid. You can minimise it by using exotic and very expensive glass but I reckon at the expense of other qualities (in addition to affordability).
Originally posted by Digitalis I don't like it when a company labels a lens APO when it really isn't.
Fair point. The same can be said about the "Macro" designation which is also often used in a liberal manner. However, Sigma is not know to have inflated prices, using false pretences.
Originally posted by Digitalis But the aberrations are still there - you can correct and image till the cows come home but it isn't going to look as good as an image taken with a lens that didn't have the same flaws.
I think you are throwing CA and spherical aberrations and other imperfections all into the same pot. To the best of my knowledge CA can be very well corrected, often by very simple means (just scaling a colour channel, i.e., reversing what the lens did in the first place). If the lens has more complex behaviour, then there is software like DxOMark which applies a much more complex correction (where the local correction depends on the position in the image).
Originally posted by Digitalis ...focused at infinity
How did you focus at infinity?
I'm sure you are aware of the fact that you cannot use the infinity marker on the lens, let alone the end position of the focus ring. Perhaps your lens needs AF adjustment near the infinity region? BTW, the fact that is optically fine at near distances does not rule out a potential problem near infinity. It could still need an alignment of some sort.