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Equipment

Sony FE 50mm f/1.8 MTF and Consistency

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Sony has cranked out a bunch of new lenses lately, and one of their latest got my attention: the FE 50mm f/1.8.  It did so for a couple of reasons. First, I wasn’t expecting it, since they already have the really good FE 55mm f/1.8 ZA lens in their lineup. Second, I’ll admit I expected them to suffer from the inevitable comparisons with Canon’s ‘nifty fifty’ the 50mm f/1.8 STM lens.

The Canon lens is small, inexpensive, quite sharp, and has some of the lowest copy-to-copy variation we’ve ever tested. Copy-to-copy variation has been a weakness in the FE lineup. While Sony was clearly making progress with that I wasn’t sure they were ready to take on the reigning variance champion. The sony lens is a little larger and more expensive, but then again, if you shoot Sony FE you’re kind of used to ‘a bit more expensive’ lenses and at $250 this is a really affordable lens.

As always, I remind you that this isn’t a review of the lens, simply a lab test of multiple copies on our optical bench to assess MTF and variation.

MTF

Well, we’ll go with the logical comparison first, the Canon 50mm f/1.8 vs the Sony 50mm f/1.8. The Sony actually does better at the lower frequencies, indicating it’s probably a more ‘contrasty’ lens, while the Canon is better at higher frequencies, so it may have superior fine detail resolution. Both are really quite good, though, and I should really use ‘different’ rather than ‘better or worse’ to compare them.

OlafOpticalTesting, 2016

OlafOpticalTesting, 2016

 

Of course, a lot of Sony shooters want to see the FE 50mm vs 55mm comparison. There’s quite a price difference and while there’s a lot more to a lens than MTF curves, people probably want to see what the MTF differences are.

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

 

The 50mm is a very good lens and quite a bargain at the price. But there are reasons the 55mm costs more. It’s clearly better across the field than either of the ‘nifty-fifty’ lenses. But the usual rule of ‘increasing resolution is increasingly expensive’ does apply. You get a better lens, but you pay a lot more.

Sample Variation

This is the portion of the test where I just expected Sony to not compare very well. But guess what? The copy-to-copy variation on the FE 50mm f/1.8 is superbly low. Remember, the Canon 50mm f/1.8 STM is the standard against which all other lenses are measured. It’s amazingly consistent. The Sony is very close to that. In some ways (center sharpness variation) it’s actually a bit better. So hat’s off to Sony, they’ve made an FE lens that from a copy-to-copy variation standpoint is as good as anything on the market.

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

 

Let’s show you how good by comparing the variation of the new 50mm with the 55mm, which has a lot of sample variation. (I’ll go ahead and add, because desperate fanboys continue to ask, the variation for 55mm lenses is the same now as it was then.)

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

 

To summarize, then, if you buy a 50mm f/1.8, chances are it’s going to be just about like every other 50mm f/1.8. Sure, there will be a few bad copies, there always are. But they’re very consistent.

We’ll probably tear one of these down soon and take a look inside to see if we can determine just why sample variation is so low. The Sony is a ‘unit focus’ lens with no separate focusing element, if I read their release information correctly, which may have something to do with the lower sample variation.

 

Roger Cicala and Aaron Closz

Lensrentals.com

May, 2016

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 Equipment
  • Hmm, I thought it made sense when I read it. ?

    So, to ask what I thought he asked, I would absolutely love to know what your take is on DXO’s “perceptual megapixel” calculation? Whether it’s bogus or brilliant, it factors into so many debates online between those of use who aren’t smart enough to think (and test) for ourselves… or just lack the time.

    The second part of what I thought he asked is, What’s your take on the optical performance when using a full frame lens on a crop sensor camera? My experience has been that (usually) I’m better off, in terms of IQ, using a lens that matches my sensor’s size. What is your quick take on that? I know this question is a bit thick, but where I hang out on the web, it’s constantly debated.

    Thanks so much for any insight you’re willing to shell out!

  • Well, I didn’t really understand the question. 🙂

  • Is this a telephone pole or power line support? At f/8 would I be able to tell? ?

  • You are wiser than most of your peers. If the lens looks great to you based on your teat(s), then you do indeed have a “good” copy. The desperate hunt for theoretical or speculative quality gains suggest that those hunting don’t actually have a “real” standard by which to compare lens quality or performance (or they are engaging in neurotic behavior). It’s nice to see someone set the standard them self in a time when specs and numbers often mean more to people than what’s behind them.

  • Please answer this Roger… 🙂

  • Neroon

    At 1.8 the lens is softer and slightly less contrast. At 2.8 my Bokeh test looks great.

  • Neroon

    I contacted Sony today and they have no answer and not even a confirmation that there is a firmware update coming. I am returning mine tomorrow. If and when they get their shit together on this lens I might repurchase it.

  • Roger- thank you for this article. Question for you, what are your thoughts about DXOs “perceived megapixels” as relates to system image sharpness? There are many photographers out there who believe a FF lens on a crop body changes the optical performance of the lens to be less sharp because this invented metric includes resolution into its calculation. I respect your thoughts and insights, what is the truth of the matter?

  • Y.A.

    That is a bummer man! I was very happy with the AF performance of my A7 + Techart + 50 STM. Looks like I’m keeping the STM

  • Danny, we’ve gone to +/- 1 SD to try to make the graphs not overlap so much.

  • Danny Wilson

    Hey Roger, are you still using ±1.5 standard deviations for your shaded regions?

  • ChuckMz

    “foregone conclusion”

  • S.Yu

    I just don’t know what degree of sharpness I should be expecting, my current 50mm used for years is an old Contax, and I suspect it’s already decentered…

  • Just buy in a store where you can try a couple copies before purchase.

    Or use an online retailer with a solid return policy. For all of Amazon’s faults, they’re at least good for that.

    I paid $550 for mine used. I don’t know where it falls on the spectrum. I’ve tested centering and it looks good, but I can’t know for other things. Still, for what I paid, I’m content.

  • S.Yu

    Yeah, but it looks as though there’s a pretty significant chance a ~$800 FE55 you get would be even less sharper than this $250 FE50, so at least in my personal opinion it wouldn’t be worth it until they get QC solved.

  • gggplaya

    Love my FE 55mm, so sharp and the bokeh is so smooth. I had a sigma art 50mm before on my canon, the zeiss is definitely nicer.

  • gggplaya

    Canon is clearly a better “VALUE”. But not necessarily a better performing lens. I happen to own the canon 50 stm and the sony FE 55mm which is an incredible lens.

  • I know. But in terms of bokeh, it still looks fairly close. It’s certainly not planar OOF blur, that’s for sure. And the difference is still worth something in choosing lenses. My point was simply that independent of the quality (resolution) of a given copy FE55, there are still reasons to choose it.

  • revaaron

    How much is Pentax’s nifty fifty?

  • S.Yu

    Keep in mind that’s not the typical Sonnar, the ZM 50/1.5 is pretty much typical Sonnar (though it lacks the cemented triplet it gets very close) and any typical Sonnar should look like that. Sony’s just using the name because it’s obviously not a Planar nor a Biogon nor a Distagon but still allegedly Zeiss. Everything’s non-Distagon non-Planar non-Biogon(not many symmetricals in the Digital age in the first place though) is sort of Sonnar these days, because it’s the only name that wasn’t properly defined in the beginning. Zeiss used the name for Ernostar type lenses for a short period too.

  • That would sum it up nicely 🙂

  • This is a really important point — and makes this a good reminder that what we’re doing is analyzing the heck out of just the optics of a lens. Good optics are necessary in a lens, but not by a long shot the only important aspect when considering it.

  • D. Garlans

    If you buy into a Sony system, complaining about the price isn’t really an argument that holds any water. Everything Sony makes is more expensive than their competitors. It’s just the nature of the beast. If you want good pricing, get a Pentax…

  • D. Garlans

    How does the lens compare to the old Sony E-mount 50/1.8 OSS lens for the crop sensor cameras?
    Obviously crop vs full frame makes the comparison rather difficult, but it’d still be interesting to see how the old model stands up.

  • sickheadache

    Yes, I went over the Paper Work and Rented from LensRental and came up with the far gone conclusion….Sigma 50mm 1.4 Art is the Best 50 Hands Down. Otus is 55mm lol and 4 Grand. lol

  • June angelus

    So it costs twice the Canon 50 STM but only a “different lens”, not better?

  • Totally agree!

  • Neroon

    I have it and debating returning it. The AF speed is terrible. It’s better on the A7RII. On the A7II and older, not so much…

  • David Braddon-Mitchell

    Sure; but the worst case scenario would be a sending back scenario. Annoying – very – but not the end of the world.
    I got used to it with Canon in the early 2000s before they upped their game.
    But I’m so pleased Sony seems to be getting better; here in Australia returning lenses is a real pain and usually involves citing chapter and verse of the consumer law, and talking to managers, which is all quite stressful.

  • Looking at the difference between the FE55 and the new FE50, it seems that your worst case scenario for a bad copy of the FE55 is that it does no better or slightly worse than the new lost cost lens. Not an encouraging prospect.

    Still, sonnar bokeh vs. planar bokeh should also come into the equation for the decision.

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