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Voigtlander APO-Lanthar 125mm f/2.5 SL - Review / Test Report - Analysis |
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Lens Reviews -
Canon EOS (APS-C)
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Page 2 of 3
Distortion
As to be expected from a moderate tele lens the level of distortion is very low (very slight
pincushion distortion).
The chart above has a real-world size of about 120x80cm.
Vignetting
On the EOS 350D with its reduced format (APS-C) the (full format) lens exhibits slight
vignetting at f/2.5 which shouldn't be problem in most scenes. At f/2.8 the issue is
already negligible.
MTF (resolution)
The 125mm APO Lanthar exhibited an excellent performance straight from f/2.5
up to f/8. Beyond diffraction effects are the limiting factor but it remains
easily usable till about f/16.
The lens showed a very even performance across the frame without any obvious
centering issues.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
The Voigtlander is virtually free of lateral chromatic aberrations (color shadows at harsh
contrast transitions). An exceptional and also very rare characteristic these days.
Longitudinal Chromatic Aberrations (LoCA)
LoCAs (greenish to reddish halos in front and behind the focus field) are practically absent as you
can see below - a positive side effect of the (true) apochromatic design.
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