In this lab testing article I will be covering the wide angle Sony FE 20mm f/1.8 G Lens and FE 24mm f/1.4 GM Lens, using the Sony A7 III for the full frame camera body. Basically I want to know, and more importantly, show you all how each lens performs in the lab. This way you can make an informed decision when it comes to buying one wide angle lens or the other if in the market.
For example, what does that extra 4mm of wide angle actually get you? What does the faster f/1.4 aperture of the GM lens get you? Is the GM lens noticeable sharper? How does the bokeh rendering compare between the two lenses? At the ends of the day do you really need the faster and more expensive f/1.4 GM Lens?
The Lab testing will give us a great baseline as to how these lenses actually perform in a controlled environment. I also plan on making a video for my youtube channel on this topic so be sure to stay tuned for that by Subscribing Here >>
This equipment was provided to me courtesy of BHPhotoVideo, so do me a solid and be sure to check them out for all you photography and video gear needs.
Comparing the Basic Specs:
These lenses are very similar in a lot of respects and when holding them in my hands they both have excellent build quality in my opinion. The FE 20mm f/1.8 G Lens is noticeable lighter weight and smaller in size which is worth noting.
Sony FE 20mm f/1.8 G Lens vs Sony FE 24mm f/1.4 GM Lens
14 Elements in 12 Groups vs 13 Elements in 10 Groups
Special Lens Elements:
Two Aspherical Elements, Three ED Elements vs Two XA Elements, Three ED Elements
Dual XD Linear Focus Motor system vs Direct Drive Super Sonic Wave AF Motor
Rounded 9-Blade Diaphragm vs Rounded 11-Blade Diaphragm
Minimum Focus Distance:
7.09″ / 18 cm vs 9.45″ / 24 cm
67mm vs 67mm
13.16 oz / 373 g vs 15.7 oz / 445 g
Lab Testing – Minimum Focus Distance (MFD)
As you can see above in the basic specs section of this article, the FE 20mm f/1.8 G Lens has a 18 cm MFD and the FE 24mm f/1.4 GM Lens has a 24 cm MFD. This is pretty significant when it comes to close-up photography and actual magnification as you will see in the images below.
I shot all these lab testing photos in RAW quality and made zero adjustments to them. So NO lens correction, contrast, sharpness, or color adjustments were applied in Lightroom. Just the defaults that Adobe applied on import to be clear.
FIrst I want to show you what the full frame looks like from each lens at the maximum aperture, then I will show you 100% Crops for a more detailed inspection of each lab test.
F/1.8 vs F/14 @ Minimum Focus Distance
Now here are the 100% crops of each image. 1500px is the actual crop for reference.
So as you can se based off this test, you can clearly get more magnification with the FE 20mm f/1.8 G Lens, due to the closer minimum focus distance, and the captured detail on both lenses is excellent. Also, the out of focus renderings look awesome on both lenses in my opinion, but the f/1.4 GM lens is yielding larger bokeh ball renderings as you would expect with the fast f/1.4 max aperture. The bokeh balls are nice and round on both lenses. I do see a slight advantage in sharpness on the FE 20mm f/1.8 G Lens in this test and the color/ contrast appears near identical on both lenses. In addition I don’t see any fringing at all on this high contrast lab test scene which is very impressive in my opinion.
F/1.8 vs F/1.8 – 100% Crops
Since the FE 20mm f/1.8 G Lens has a max aperture of f/1.8 I wanted to show you how it compares to the FE 24mm f/1.4 GM Lens @ f/1.8 for reference. In theory, the more expensive GM lens should arguable look a little better one might think, since it’s stopped down to f/1.8 and the G lens is at its max aperture plus costs a lot less money. Well let’s find out!
What I am seeing here is near identical results other than the magnification differences of course. Since the FE 20mm f/1.8 G Lens is much closer to the quarter, the out of focus rendering is a little different and more exaggerated. So the bokeh balls are larger and render a bit different. However, as far as sharpness goes, they look pretty much the same to my eyes with perhaps a slight advantage to the 20mm.
20mm VS 24mm
Next I want to show you the difference between 20mm and 24mm. In other words, what does that extra 4mm get you when the camera is in the same exact spot.
As you can see that 4mm makes a pretty significant difference. So, for somebody in real estate photography for example, you would be able to get more of the scene if frame if your back is to a wall. As far as distortion goes, both lenses are well controlled overall I would say. The out of focus bokeh rendering is as expected with the faster FE 24mm f/1.4 GM Lens yeinding more separation and larger bokeh balls. VIgnetting is noticeable on both lenses at their max apertures, and that will go away as you stop down the aperture.
100 % Crops – f/1.8 vs F/1.4
Now let’s take a look at the scene so we can check for sharpness and other details that we might see… I focused on the dollar bill for reference.
Looking at the center of the frame both lenses are producing very sharp results as you can see on the dollar bill where I focused. Due to the shallower depth of field the FE 24mm f/1.4 GM Lens is capable of producing, the quarter and background are more out of focus when compared to the FE 20mm F/1.8 GM Lens.
One noticeable lens flaw I am noticing with the FE 24mm f/1.4 GM Lens is the bokeh balls have a green fringe ring around them which is not very pleasing to the eye in my opinion. I don’t see any of that on the more affordable FE 20mm f/1.8 G Lens. Now Let’s check out the corner areas…
I cropped in on the Monster energy drink can to compare both lenses in the same area, but clearly the actual corner on the 20mm lens is further out than the 24mm lens. However, I wanted to show you the distortion on the can and also the very slight reddish fringing you can see on the FE 24mm f/1.4 GM Lens. It’s most noticeable on the “E” in Monster.
As far as sharpness goes, both lenses appear to be very good, although the 24mm GM lens looks a bit softer on the can. However, this is due to the extremely narrow depth of field the f/1.4 max aperture produces. The can is about 2 1/2 inches thick or so and I focused on the dollar bill which is at least 2 inches behind the can. So that softness you are seeing is the depth of field. Just like on the quarter in the center of the frame for example.
For reference and a more fair comparison, here is the upper right corner of the FE 20mm f/1.8 G Lens. As you can see below it appears a little soft as well due to the depth of field difference. The wall where the picture is hanging is actually about 8 inches behind the dollar bill distance wise, and the quarter is about 5 inches in front of the dollar bill. Therefore the depth of field is a factor you must note when viewing these test photos when it comes to judging the corner sharpness.
F/1.8 vs F/1.8 – 100% Crops
I also want to show you the f/1.8 renderings from both lenses so you can see how the 20mm vs 24mm effects the results.
As you can see the extra 4mm does make a difference in the out of focus renderings and depth of field. I am honestly surprised to see at f/1.8, the FE 24mm f/1.4 GM Lens is still showing the green outline on the bokeh balls which is certainly worth noting.
F/8 vs F/8
So lastly for this lab test I just want to show you what f/8 vs f/8 looks like for those curious about overall sharpness in this particular scene.
100% Crops @ f/8…
Lab Testing Conclusions
So based on this lab testing I would conclude that the FE 20mm f/1.8 G Lens is fantastic and absolutely worth the money when compared to the 24mm f/1.8 GM lens as far as sharpness, bokeh renderings, and overall optical quality in this scene. The closer minimum focus distance is a nice advantage, and the wider field of view the 20mm lens produces is also a nice if you require such a view.
The faster f/1.4 aperture of the GM lens is clearly better for lower light situations and a slightly more out of focus rendering as you can see in the testing.
As far as optical performance goes, both lenses are very sharp and well controlled when it comes to distortion. However, when it comes to fringing, the FE 20mm f/1.8 G Lens has a clear advantage based on this lab testing. You can see on the bokeh balls and the Monster can that the GM lens suffers from som fringing, but I am not seeing any of that on the G Lens in this test.
If I were to base my opinion on this lab testing alone, I would consider the much more affordable FE 20mm F/1.8 G lens over the FE 24mm f/1.4 GM Lens. With that being said, I can’t afford either of these lenses so take that for what it’s worth. The deal breaker on the FE 24mm f/1.4 GM Lens for me was that green fringing on the bokeh balls. I do not like the way that looks, and for my purposes f/1.8 is fast enough considering the Sony A7 III and all the other recent full frame e-mount cameras have stabilization built in. In addition the high ISO performance is fantastic these days compared to just a few years ago.
With that being said this was not real world testing, and the FE 24mm f/1.4 GM Lens is know for that “magic” look. Therefore you must stay tuned for the full review and real world sample photos before making a fully informed decision on that matter.
That is about it for this article, but please stay tuned for the full reviews of both these lenses which will also have video testing and real world photos. I will also make a comparison video for these lenses, but I need to get more real world photos and sample video with the FE 24mm f/1.4 GM Lens still.
I would love to hear your thoughts about these lab test photos and please let me know if you think I missed anything.
On a personal note I wish all of you the very best in these crazy Coronavirus times we are currently living in. It’s hard to comprehend it all, so I am just trying to take the obvious precautions and ride this storm out as best I can. On a positive note, it is very nice to spend more time with my kids and have some awesome gear to play with 😉
I will catch up with you all later and please have a wonderful day, Jay