Just MTF Charts

Just MTF Charts: Nikon Prime Lenses

We’ll continue our just MTF chart series of posts with the Nikon brand prime lenses. For those of you who have been asking, The Digital Picture is going to add all our MTF graphs to their comparison tool as we release them. That will let you do logical comparisons like ‘is the Sony 135mm f/1.8 GM sharper at the edges than the Sigma 14mm f/1.8‘ to prove your brand is the absolute best in online forum wars.

Three quick answers to questions that I’m sure will be asked:

  • Z lenses testing requires sacrificing a camera and lens for electronics, machining a new mount for the bench, and wiring everything together. It’s a long and expensive process and we won’t have Z-lens test results for at least months. 
  • No, we don’t test stopped down. Lensrentals is willing to pay the cost for 10-copy tests wide open to establish standards for QA testing (which is always done wide open) and we share them. If you really want stop-down results, a 10 lens series costs $5,500. Email me and I’ll tell you where to send your check.  
  • The 24mm f1.8 isn’t missing because I forgot. I didn’t have enough results to post a 10-copy average.

 

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.

 

Nikon MTF Charts

Nikkor 20mm f/1.8G ED

Lensrentals.com, 2019

Nikkor 24mm f1.4 G ED

Lensrentals.com, 2019

Nikkor 28mm f1.8G

Lensrentals.com, 2019

 

Nikkor 28mm f1.4E ED (by special request)

We didn’t put this in originally because I didn’t have 10 copies to test. Here’s the results for 5 copies, it’s all I could get to.

Lensrentals.com, 2019

Nikkor 35mm f1.4G

Lensrentals.com, 2019

Nikkor 35mm f1.8G ED

Lensrentals.com, 2019

Nikkor 50mm f1.4G

Lensrentals.com, 2019

Nikkor 50mm f1.8G

Lensrentals.com, 2019

Nikkor 58mm f1.4G

Lensrentals.com, 2019

Nikkor 85mm f1.4G

Lensrentals.com, 2019

Nikkor 85mm f1.8G

Lensrentals.com, 2019

Nikkor 105mm f1.4E ED

Lensrentals.com, 2019

Nikkor 105mm f2.8G IF-ED VR Micro

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

April, 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
  • It’s a really good lens.

  • Naveen Kailas

    The Nikon 28/1.4 ED appears to be the sharpest lens of the bunch, and may be the sharpest lens under 50mm in any of your recent runs of MTF tests. Very surprising.

  • Ayoh

    Thanks Roger, that is great information. Seems some companies have very short-sighted management. Manufacturing variation data is very useful for robust design. They don’t have to publicise the variation, or do anything about it but it still is much better to have that information than not

  • Ayoh,

    That is, indeed, the question. The answer is that some do. We have had engineers from several manufacturers come over and exchange methodologies and data. Others choose not to and some are testing exactly the same way they did in the 60s.

    They all could, of course, the expense would be trivial for them. Why they don’t varies. In a couple of instances we’ve had a company’s engineers come over and they were very excited and couldn’t wait to use the techniques. The company’s managers absolutely denied there was any need for such testing, the way they were doing it was just fine, and refused to invest any money in testing.

    These are very large companies with different departments wanting different things. Marketing departments don’t want test results released, they can’t possibly be as good as the computer generated theoretical MTF tests. Accounting departments don’t want to ever spend money. Some optical engineers love bad metrology (lens testing) because if there design looks great on computer but doesn’t manufacture well, bad metrology won’t reveal that. And most large companies have a lot of resistance to any idea of ‘you’ve been doing it wrong’.

    My favorite example is a company who has zero interest in improving their in-house testing and has told us our testing is of no value. Yet their R&D department pays us to do testing of developmental products for them.

    Before you ask, I can’t name name’s; if they have had interactions with us we’ve signed non-disclosures.

  • Ayoh

    Thank you Roger for the very candid reply, much appreciated.
    Based on comments you have made at other times it seems you are pretty confident that your test system is much superior to that of lens manufacturers. Why do you think this is the case? it seems that for someone like Canon/Sony/Sigma/Nikon the costs above would be trivial compared to the cost committed to in lens manufacturing and cost associated with failure to control quality. It seems it would not be a question that they can’t do it rather than that they feel they don’t have to. Give the engineering expertise in those companies they could probably easily design and build their own OLAF-grade testing system if they committed to it. After all if comparatively small lens rental shop with a few guys and interns can do it surely a large scale lens design and manufacturing house can. Why would they not do that themselves?

  • Ayoh

    Thank you Roger for the very candid reply, much appreciated.
    Based on comments you have made at other times it seems you are pretty confident that your test system is much superior to that of lens manufacturers. Why do you think this is the case? it seems that for someone like Canon/Sony/Sigma/Nikon the costs above would be trivial compared to the cost committed to in lens manufacturing and cost associated with failure to control quality. It seems it would not be a question that they can’t do it rather than that they feel they don’t have to. Give the engineering expertise in those companies they could probably easily design and build their own OLAF-grade testing system if they committed to it. After all if comparatively small lens rental shop with a few guys and interns can do it surely a large scale lens design and manufacturing house can. Why would they not do that?

  • Ayoh,

    Start with the optical bench is a $200,000 piece of equipment that requires about $20,000 a year in maintenance and upkeep. Add in $50,000 worth of mounts for various lenses and another $60,000 in custom software, rent and utilities on a building to keep it in and the bare breakeven cost to run it is about $50 an hour (it doesn’t last forever, and I’m not doing what a business would do and depreciating it over 3 years and adding in the interest on the loan to buy it — hence my cost only, not what I’d actually charge which is way more).

    Plus it takes a skilled tech to run it, which is another $40 an hour (they don’t make $40, but employment costs, benefits, and taxes put that as a bare minimum). So $100 an hour ($720 a day) to break even; 276 days estimated to complete the testing = $198,200.

    But that’s unrealistically low. During that same 276 days we’re supposed to be doing testing to fulfill contracts, etc. I’d lose way more income than that estimate if we were to just do stop-down testing. And before you get all excited about how rich optical testers could get, Olaf optical testing (which owns the machine and all) has never made a profit and never paid me a dime.

    Roger

  • Ayoh

    Why is it so expensive?

  • Thank you for your reply Roger. The information you provide was very interesting and worth asking. I fully understand that commit to a single project for 276 days is not the best for businnes.

  • Patrick Cligny

    Thank you Roger for your work on the 28mm/1.4E which confirm the FTM given by Nikon for 10 and 30 lines pairs (https://imaging.nikon.com/lineup/lens/f-mount/singlefocal/wide/af-s_28mmf14e_ed/spec.htm).
    Nikon did a real work on 105 and 28mm/1.4. But the Sigma pressure, on performance and price is terrific…

  • Lance Blackburn

    Thank you very much for your efforts, Roger. Always much appreciated. It would be good to have a comparison to the original Nikon published theoretical MTFs side by side.

  • Matti6950 .

    Thanks a lot Roger 🙂 Hmm choice between Sigma art and nikon harder now.

  • Thanks for adding the 28/1.4E results Roger! It looks like the black sheep in the family even compared to the 104/1.4E, and if you’d hid the label and told me that was a recent Sigma Art, I’d totally believe you. Many of the Nikons’ results look like they’re a few generations old, which is ironic since they were the ones to push high-resolution DSLRs. (FWIW, I use many of the f/1.8 and f/1.4 Nikon primes including the 28/1.4E on a D850 and am happy with them.)

  • Chris in NH

    How about the 200mm Micro F4 IF-ED? It’s still legendary for macro use, astonishing for a 20+ year old design, and I believe the oldest lens still active in Nikon’s lineup.

  • Mattr

    Interesting how differently the two 85mm primes respond to stopping down (when compared to your wide open results). The main improvement with the Sigma Art seems to be better sagittal resolution in the outer parts of the image circle. Thanks for posting!
    BTW, I understand that this is a lot of work/money. But even single copy stopped down results are informative.

  • They all get better, and most primes will resolve 0.5 at 50 lp in at least the center 1/2 of the image by f/4. They aren’t all equal by any means, especially in the outer 1/3, and wide-angles generally struggle more to get there.

    Newer design (last 5 years or so) high-quality f/2.8 zooms will get there in the center by f5.6 but few of them will reach 0.5 at 50 lp in the outer 1/3.

    Couple of f5.6 examples, a Sigma 85 Art gets there, a Canon 85mm f1.2 doesn’t quite but it’s close, a Canon 70-200 f2.8 isn’t close away from center. Also a good example of why I’m always laughing when people tell me their zoom is ‘as good as a prime’.

    https://uploads.disquscdn.com/images/301e96d0545a4cc9d08a040a35801bf3d2a2fe1b95cfff7d9d42341e47039c0a.png https://uploads.disquscdn.com/images/d5bd9429ad9b39c44f7c55f00c48b1eab85590b1fa031ea4786b70e6efb3b713.png https://uploads.disquscdn.com/images/67d043c7b3c79f2197f0dd7b189433266fb593ee85f8e954fdba7263498398ca.png

  • Rokoko

    Thank you Roger!

  • bdbender4

    Ah, good to know, I also wondered about this.

    I also was curious about Nikon Z mount lenses, but am grateful for and not surprised at the explanation.

    As for the rest, it’s the same as it ever was. Thank you!

  • Ernest Green

    I assume all these tests are done wide open. Can/does a typical prime lens (or any lens for that matter) easily score at or above a “5” on the 50 line pair test when stopped down? Say to 2.8, F4, F5.6. In other words do all modern quality lenses perform similarly at 5.6 when it comes to the 50 line pair? I’d like to see just one example of a stopped down lens test.

  • P. Jasinski

    The kickstarter idea does not really sound that abstract. I would most definititely back that up, as this might spare many people a lot of trips to camera shops attempting to test their lenses on shop displays, small AF targets and random camera store items 😀

    If you count the time (or man-hours), I’d rather pay someone who actually knows what they’re doing 🙂
    A 100$? cound me in.

  • OK, I did the 5-copy run I was able to do and posted the results above.

  • Brandon Dube

    A million isn’t even a third of the funding it would take…

  • Brandon Dube

    No… MTF is just a thing. Whether lens A and B are the same model or different models is not relevant. If lens A and lens B differ at 20lp/mm by 0.1, one is going to look substantially better than the other.

  • Andreas Werle

    Sorry for that.

    Of course the statement, that “Two that differ that much …” refers to copy variance, not as a guide to compare different lenses (50/1.4 from Brand A compared to 50/1.4 from Brand B).

    I understand, that this would be an oversimplification of your Data and i respect, that you want to avoid it. Peace! 🙂

    Greetings Andy

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