LensTip.com

Lens review

Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA

27 August 2016
Arkadiusz Olech

7. Coma, astigmatism and bokeh

Coma and other aberrations of higher order which deform points of light in the frame corners are corrected well only for the APS-C sensor area. In the corners of full frame the deformations of diode images are distinct even on stopping down the aperture by one full step. Still you have to state clearly that the image remains better than that provided by 1.8/50 Canon and Nikkor constructions. Their deformations were far more noticeable.

Center, f/1.8 Corner APS-C, f/1.8 Corner FF, f/1.8
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh
Center, f/2.5 Corner APS-C, f/2.5 Corner FF, f/2.5
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh


Starry sky proves to be even more ruthless challenge for the tested lens. Only after applying the f/3.5 aperture the stars in the frame corners become point-like; still even after stopping down the lens so significantly the images of very bright stars feature residual coma effects. It tallies well with our conclusions from the resolution chapter where we suggested it might be necessary to stop down to near f/4.0 in order to get fully useful images across the whole frame.


Please Support Us

The coronavirus crisis has been adversely affecting many businesses and, sad but true, ours is not an exception. Despite that difficult situation we would like to preserve continuity and high quality of publications available on all our websites. Still, we are now aware it might be impossible without additional financial help. That's why we would like to ask all those who visit, read, and care about Optyczne.pl, LensTip.com i Allbinos.com for support - it's enough you send us a small sum of money via PayPal. If a lot people decide to support our websites we think we'll stand a chance and survive next months without any lasting harm. We count on your support and understanding, stay safe and be healthy.

- - - - - - - - - - - - - - - - - advertisement - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

A7R II, JPEG, f/1.8, lewy górny Corner kadru 1:1
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh
A7R II, JPEG, f/2.5, lewy górny Corner kadru 1:1
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh
A7R II, JPEG, f/3.5, lewy górny Corner kadru 1:1
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh

The photos of the sky, downloadable from sample shots chapter, show another aberration mentioned before, the longitudinal chromatic aberration to be more precise.

The optical construction of the lens deals with the astigmatism well. That aberration, understood as an average difference between horizontal and vertical MTF50 function values amounts to 5.6% so a level considered by us as low.

It would be difficult to criticize any out-of-focus areas, generated by the lens – they are very pleasing to the eye. The appearance of defocused light circles proves that much: they feature no significant local extremes, even the rim which often appears on stopping down the lens, is of very low intensity.

Still mechanical vignetting should be mentioned at this point. The circle in the frame corner is noticeably truncated. What’s more, that truncation remains perfectly visible even on stopping down the lens by two full aperture stops.

Center, f/1.8 Corner APS-C, f/1.8 Corner FF, f/1.8
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh
Center, f/2.5 Corner APS-C, f/2.5 Corner FF, f/2.5
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh
Center, f/3.5 Corner APS-C, f/3.5 Corner FF, f/3.5
Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA - Coma, astigmatism and bokeh