Just MTF Charts

Just MTF Charts: Sigma Prime Lenses

Published April 4, 2019

This is the third post publishing all of our MTF results so that methodology is consistent and they are easy to find. No comparisons, no commentary, just the test results for you to use and abuse as you see fit. We’ll continue today with the Sigma prime lenses.

For those who wonder, the results presented are for EF (Canon) mount lenses, but we do test them in F and FE mount also (with appropriate glass for the mount), and there is no difference.

A Quick How to on Reading MTF Charts

If you’re new here, you’ll see we have a scientific methodology to our approach, and use MTF charts to measure lens resolution and sharpness. All of our MTF charts test ten of the same lenses, and then we average out the results. MTF (or (or Modulation Transfer Function) Charts measure the optical potential of a lens by plotting the contrast and resolution of the lens from the center to the outer corners of the frame. An MTF chart has two axis, the y-axis (vertical) and the x-axis (horizontal).

The y-axis (vertical) measures how accurately the lens reproduces the object (sharpness), where 1.0 would be the theoretical “perfect lens”. The x-axis (horizontal) measures the distance from the center of a lens to the edges (measured in millimeters where 0mm represents the center, and 20mm represents the corner point). Generally, a lens has the greatest theoretical sharpness in the center, with the sharpness being reduced in the corners.

Tangential & Sagittal Lines

The graph then plots two sets of five different ranges. These sets are broken down into Tangential lines (solid lines on our graphs) and Sagittal (dotted lines on our graphs). Sagittal lines are a pattern where the lines are oriented parallel to a line through the center of the image. Tangential (or Meridonial)  lines are tested where the lines are aligned perpendicular to a line through the center of the image.

From there, the Sagittal and Tangential tests are done in 5 sets, started at 10 lines per millimeter (lp/mm), all the way up to 50 lines per millimeter (lp/mm). To put this in layman’s terms, the higher lp/mm measure how well the lens resolves fine detail. So, higher MTF is better than lower, and less separation of the sagittal and tangential lines are better than a lot of separation. Please keep in mind this is a simple introduction to MTF charts, for a more scientific explanation, feel free to read this article.

 

Sigma Prime Lenses

14mm f1.8 DG HSM Art

Lensrentals.com, 2018

20mm f1.4 DG HSM Art

Lensrentals.com, 2018

24mm f1.4 DG HSM Art

Lensrentals.com, 2018

28mm f.14 DG HSM Art

Lensrentals.com, 2019

35mm f1.4 DG HSM Art

Lensrentals.com, 2018

Sigma 40mm f1.4 DG HSM Art

Lensrentals.com, 2019

50mm f1.4 DG HSM Art

Lensrentals.com, 2019

85mm f1.4 Dg HSM Art

Lensrentals.com, 2019

105mm f1.4 DG HSM Art

Lensrentals, 2019

135mm f1.8 DG HSM Art

Lensrentals.com, 2019

 

For a look at all the Just MTF Articles we’ve done so far, be sure to check them out here.

 

Roger Cicala, Brandon Dube, and Aaron Closz

Lensrentals.com

March, 2019

 

 

Addendum: The Digital Picture is hosting the MTF charts on their comparison tool, putting them up as we publish them here. It’s a great way to compare two lenses for the one or two of you who like to do that. The Canon and Zeiss primes are already up, the Sigma should be added by tomorrow.

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in Just MTF Charts
  • Mike Cropper

    Holy cow! Sigma 40mm. That’s impressive.

  • Gerard R

    What the hell is with that Sigma 14/1.8? Is that the sharpest Sigma of the lot? I’m just surprised I haven’t read more hype about it.

  • Andreas, I never have 10 copies of Leica lenses for that. But Zeiss SLR lenses are somewhat similar and they still have some optical imperfections, although never a lot.

  • Andreas Werle

    Thanks for this explanation and the link, Roger. It is revealing, that adjustable lens elements are “only” compensation the errors of the other lens elements. One would at once think, that lenses, which are composed of very few elements like the MACRO-ELMAR-M 1:4/90 mm (4 elements, no aspherical, no cemented elements, no IS, no autofocus) should show fewer errors. Will you ever show us Olaf-Data of those lenses?
    Greetings Andy

  • Tyler Mercer

    No worries. Thanks again!

  • I don’t have data on that one, I’m afraid.

  • Tyler Mercer

    Thanks very much for the MTF charts for so many lens and getting them integrated into the Digital Picture comparison tool! Very useful (& fun) info. If you ever have the chance, please consider adding the sigma 105mm 2.8 macro MTF chart.

  • DrJon

    When I had the Canon 100mm f2.8 USM Macro it was really good for macro work but I really didn’t like it as a 100m lens for normal use. The 100mm L however is a fabulous lens for general use.

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