Equipment
Sony FE 50mm f/1.8 MTF and Consistency
![](https://www.lensrentals.com/blog/media/2016/05/590255796186.jpg)
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](https://www.lensrentals.com/blog/media/2016/05/MTF.jpg)
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](https://www.lensrentals.com/blog/media/2016/05/SonycompMTF.jpg)
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](https://www.lensrentals.com/blog/media/2016/05/sonyvar.jpg)
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](https://www.lensrentals.com/blog/media/2016/05/Sony-var-comp.jpg)
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.
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