Carl Zeiss Distagon T* 25 mm f/2.0 ZE/ZF.2
7. Coma, astigmatism and bokeh
The astigmatism is not corrected in a perfect way because the result of 6% doesn’t deserve to be described so but it can be certainly considered good. Overall, no major reservations.
Please Support UsIf you enjoy our reviews and articles, and you want us to continue our work please, support our website by donating through PayPal. The funds are going to be used for paying our editorial team, renting servers, and equipping our testing studio; only that way we will be able to continue providing you interesting content for free. |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Let’s look at the defocused images of a point-like diode which was put in different parts of the frame and photographed by different apertures.
Also in this case the lens’s performance falls a bit short of perfection. Many images show diversities in the form of concentric rings which signal some problems with the spherical aberration correction. These problems are real- they can be noticed in the resolution measurements as well. When you set the resolution by f/2.0 and reach the best possible result and then reset the aperture to f/2.8 the resolution level doesn’t improve sharply. If you want to see that improvement you must to move the focus ring a bit. This effect might be small but it remains measurable.