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Just MTF Charts

Just MTF Charts: Sony FE Mount Prime Lenses

This is the fourth post publishing all of our MTF results so that methodology is consistent and they are easy to find. The previous have been by lens brand. This one is by the mount, since the Zeiss Batis and Loxia lenses fit more naturally here than with the Zeiss SLR lenses. Otherwise, no comparisons, no commentary, just the test results for you to use and abuse as you see fit.

Oh, wait. One commentary. You’ll notice the Sony 28mm f/2 lens does not have 20mm results, it stops at 18mm. This lens has a small amount of copy-to-copy variation of distortion that makes the very edge results of our automated testing seem to have more variation than is real. Faced with the option of presenting questionable results or testing 10 copies by hand, I voted to just not present that data. I do want to emphasize this a technical testing issue, not something that would affect photography.

With that out of the way, here are the Sony FE mount prime lenses, followed by the Zeiss Batis and Loxia lenses. (The Sony FE 24mm f1.4 and Sony FE 35mm f1.8 have been recently added.)

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.

Sony FE Prime Lenses

Sony FE 24mm f/1.4 GM

Lensrentals.com, 2019

Sony FE 28mm f/2

Lensrentals.com, 2019

Sony FE Sonnar 35mm f/2.8

Lensrentals.com, 2019

Sony FE Distagon T 35mm f1.4 ZA

Lensrentals.com, 2019

 

Sony FE 35mm f1.8

Lensrentals.com, 2019

Sony FE Planar 50mm f1.4 ZA

Lensrentals.com, 2019

Sony FE 50mm f1.8

Lensrentals.com, 2019

Sony FE Sonnar T 55mm f1.8 ZA

Lensrentals.com, 2019

Sony FE 85mm F1.4 GM

Lensrentals.com, 2019

Sony FE 85mm f1.8

Lensrentals.com, 2019

Sony FE 90mm f/2.8 Macro G OSS

Lensrentals.com, 2019

Sony FE 135mm f/1.8 GM

Lensrentals.com, 2019

Zeiss FE-Mount Lenses

Batis

Batis 18mm f2.8

Lensrentals.com, 2019

Batis 25mm f2.0

Lensrentals.com, 2019

Batis 40mm f2

Lensrentals.com, 2019

Batis 85mm f1.8

Lensrentals.com, 2019

Batis 135mm f2.8

Lensrentals.com, 2019

Loxia

Loxia 21mm Distagon f2.8 

Lensrentals.com, 2019

Loxia 25mm f2.4

Note: this is data from only 3 copies. I have no excuses. I was lazy, the lens didn’t interest me much when it first came out, and I never went back and completed the testing.

Lensrentals.com, 2019

Loxia 35mm Biogon f2.0

Lensrentals.com, 2019

Loxia 50mm Planar f2.0

Lensrentals.com, 2019

Loxia 85mm Sonnar f2.4

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, Aaron Closz, and Brandon Dube

Lensrentals.com

March, 2019

 

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
  • All our tests are at widest aperture and focused at infinity

  • leh

    What f are these lenses shoot?
    Close distance or infinity?

  • Jimmy Andino

    The charts alone make me want to buy the GM 135/1.8 – Holy Smokes!! Sony really did whip up something truly special with that lens… can’t wait to see the results for the GM 24/1.4….

  • ZaltysZ

    It would be interesting to see Tokina FiRIN 20mm tested. Any chance?

  • DrJon

    The Sony’s sharper than the Sigma at the same apertures?

  • Neal G

    On the flip side, it seems like most 35mm 1.4 have pretty poor results.

  • Brandon Dube

    The apertures are more moderate (F/2) and the fields of view smaller (17.5 degrees full diagonal). This makes control of geometric aberrations a /lot/ easier. At the same time, the focal lengths are not extremely long as in, say, a 400/2.8, so the use of lots of exotic materials is not strictly necessary to get good color correction.

    It’s a goldilocks focal length / F-number.

  • Federico Gallinari

    I understand, and unfortunately I imagine the stupid fanboys crusades, knowing both the canon and the nikon 400 I asked out of curiosity to understand how much the price was justified in terms not only of construction and lightness but also of optical quality.
    tnx anyway

  • Mike Cropper

    Interesting. Batis 18 and Sonar 55 are very impressive in overall resolution and falloff. Also, Batis generally outperforms the Loxia.

  • Frederico, it was an experimental trail run of a few copies Brandon did when he was here. But fanboys took it way out of context so i won’t be republishing them.

  • but 1 is the loneliest number

  • Probably both.

  • xWidget

    The 50/1.8 really is a tragic lens. I don’t think I’ve ever returned something to Amazon so quickly.

    Will you be updating these pages as new lenses come out like the Sony 24/1.4 or will they go on new posts?

  • capitanG

    Roger, will you ever test the Voigtlander FE lenses?

  • capitanG

    1 is not a prime number… 2 is the first prime number…

  • DrJon

    ??? Their Canon primes post only went to 200mm and said:
    “That’s all the Canon primes we have done except tilt-shifts, which will come out separately.”
    Did they publish the official Canon MTF chart in an article somewhere?

  • Neal G

    That seems a bit hard to believe, but I know nothing about lenses 😛

  • j.a.

    Numbers on the Loxia 85mm are fantastic, I love shooting with that lens, results are so pleasant

  • Andrew Gordon

    I agree. Mine is wicked sharp.

  • Federico Gallinari

    but I saw the canon 400’s MTF. Was it a different system?
    thanks

  • I think it’s because the focal length is the first 3 prime numbers and that causes magic. Don’t believe me? Well the Sony is the sharpest of the 135mm and it’s actual focal length is 135.7

  • It’s too big for the bench. We already published a disassembly.

  • Federico Gallinari

    Hi roger, why no one give MTF about the 400 2.8GM???
    You have it, but you have not done tests unless disassembly, are restrictions imposed by Sony?

  • Andreas Werle

    Thanks for the kind responses, Roger and Brandon. This is a nice lens with a great performance in the center – and pretty expensive. I did BTW look at the respective official MTF-Charts of the lens. It does not show this behaviour. My guess is, that the Zeiss/Sony-MTF chart is an “idealised” presentation. If you correct the focus in the out of center region, the resolution should improve. Correct?

    Sorry, can not post the link. Your firewall caught me again. 🙂 You my find it by googling with “Planar T* FE 50mm F1.4 ZA” at the Sony-homepage.

  • Neal G

    What is it about the 135mm length that makes those lenses so sharp? Seems like this is common regardless of the manufacturer.

  • Brandon Dube

    A lot of Coma in this design too. Very strong third order that balances with fifth order in field at the extreme.

    At least comparatively. The MTF is still higher than a lot of other lenses on the market.

  • Justin

    Really great stuff Roger. Thank you. Notice we didn’t get 100 GM. Plans for those?

  • Andreas, that is almost certainly why. When there’s significant field curvature, you see this pattern often.

  • Max Manzan

    I’m surprised by the MTF-curves of the Loxia 21mm f/2.8. Not in a positive way.

  • Andreas Werle

    A lot of beautyful Data, Roger. Thanks for that. One Question. There is a strange behaviour of the MTF-curves in case of the Sony FE 50mm f/1.4 ZA. The lowest contrast for 50 l/mm, ca 20%, is at ca. 12 mm image height and then increases to ca 40% at the edge of the image circel. Is this due to field curvature?

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