Panasonic Gh4

Jan 292015

Canon EFS 24MM STM

Don’t want to read the entire 24mm STM review? Here is the gist: I love it, I love it, I love it, go buy one.

So why do people buy pancake lenses from Canon? Four main reasons:

  • They are cheap
  • They are small
  • They are sharp
  • They have better focusing than Canon’s other entry lenses.

In other words, for the dollar, you can’t go wrong with a Canon pancake lens. The Canon 40mm STM was a knockout success. Read my review of that lens here. The 24mm STM is, in my opinion, even more freaking amazing. It only costs $150, making it the second cheapest Canon lens available for DSLRs (only the Canon 50mm 1.8 is cheaper). The 24mm STM is the only prime you can get in the wideish/normal focal range for under $400 dollars.

So here is the lens… box…

IMG_6944Canon EFS 24MM STM Box

It will only fit EF-S cameras. So it will fit any Rebel (like the 3T, T5, T3i or T5i), 60D, 70D, 7DmkII, etc… Basically as long as you have a crop sensor and not full frame it will fit (unless you have the EOS-M, then you need an adapter).

It has the same dimensions as the 40mm STM, but is bit lighter. It makes your DSLR look smaller and also makes things more balanced, allowing most of the weight to reside in your hands.

The 24mm fills in a big gap. The only cheap way you can shoot at a 24mm focal length is via a 18-55 kit lens, getting an old used Canon EF 24mm f/2.8, or finding some other random zoom lenses. These options will generally run you over $150 (unless you get the 18-55mm used). So, the Canon 24mm STM lens fits in nicely at 24mm, providing a sharp focal length that is equivalent to 38mm on a full frame sensor (good for interior photography, close up portrait, etc…). It is not a low light monster, but f/2.8 is good enough in low light situations, I have stopped plenty of my lenses down to f/2.8 in low light situations. The 24mm is a wide(ish) prime, and so you can afford to have a longer exposure than with a 40mm or 50mm prime.

What comes in the box:

Canon EFS 24MM STM BoxCanon EFS 24MM STM Packaging

This lens is shipped in a small box. It sits in a plastic shell looking thing and is tightly packed with bubble wrap. In the box you find the 24mm STM, lens cap, an instructions manual, and warranty information.

Images of the lens:


Canon EFS 24MM STM Macro .52ft

Canon EFS 24MM STM Front Lens Element

Canon EFS 24MM STM Rear Lens Element

A bit on STM Technology

STM technology uses a focus by wire mechanism. With STM, the focusing mechanism is not physically attached to the lens, instead the physical focus ring and lens focusing are linked through electronic circuits, kind of like remote control. So whats the big deal about STM? Nothing really. It does provide better focusing than Canon’s other cheap lenses such as the 50mm 1.8 and 18-55mm. Manual focusing is smoother, and autofocusing is much quieter (but a bit slow). If you plan to shoot videos, STM is popular (because of the smooth focusing).

Canon EF-S 24mm STM Specs

Focal Length: 24mm
Maximum Aperture: f/2.8
Aperture Blades: 7
Blade Type: circular aperture blades
Lens Construction: 6 elements in 5 groups
Diagonal Angle of View:    59°10′
Focus Adjustment: full lens extension
Closest Focusing Distance: 0.52 ft. / 0.16 m
Filter Size: 52mm
Max. Diameter: 2.7 inches
Length: 0.9 inches
Weight:    4.4 oz. / 125 g

Notes: Good luck finding 7 circular aperture blades for this cheap. 7 blades is two more than the Canon 50mm 1.8! Plus, the blades are rounded; resulting in circular bokeh when you stop the lens down. Filter size is a good common 52mm, and the lens is significantly larger with its lens caps on; I’d say it measure to be about two inches long. Construction feels very solid. The plastic seems more solid than what you will find on 50mm 1.8 (seriously that lens feels so frick’n cheap), you get a metal lens mount, and the lens has a dense feeling. Not bad for $150.

24mm STM Sharpness Test

It is pretty sharp at the center, and loses a bit towards the edges. Wide open, it is very usable; more usable than my 50mm 1.8 and at f/5.6 it is slightly better than the 18-55 kit (at f/5.6). How do I know it is sharp? Well the first thing I like to do is shoot the night sky. If the stars retain their pinpoint shape decently well, I consider the lens to be sharp. If I see bloated stars and coma near the edges I consider the lens “meh”. The 24mm is sharp, not “meh”. Its more, “ooh, not bad”. The following image is of a star cluster called the Peliades, located at the center.

Canon EFS 24MM STM Sample Photo #5

Click on the above image to see it full size (~5,000 pixels by ~3,000). You can see how sharp the lens is at the corners. Keep in mind, this exposure was several seconds and so the stars move a bit in that time, so they are not as sharp as they could be (astrophotography without tracking results in star trails).  You might see some vignetting. This little lens vignettes fairly aggressively, though the full moon was out (on the left part of this image if I recall correctly, so this image is a bad test for vignetting). After seeing the nice results of this photo, I decided to take a picture of the moon through the eyepiece of my telescope. Basically I held the 24mm lens right up to my eyepiece and took a picture of the moon handheld:

Canon EFS 24MM STM Sample Photo #2

I have a lens resolution chart that I had printed via AdoramaPix. It’s not the real deal, and the print quality isn’t amazing, but I figured it would yield somewhat decent results in a controlled environment. So, here are the result for my crappy resolution test, the upper right corners of the images are the actual center of the frame and the lower left corner is the lower left edge of the frame (basically I cropped the original images down to the lower left quarter):

Canon 24mm STM f/2.8

Canon 24mm STM f/2.8


Canon 24mm f/5.6


Canon 40mm f/2.8


Canon 40mm f/5.6


Canon 18-55mm f/5.6 II

The 40mm is the sharpest, and the 24mm and kit are neck and neck, with the slight advantage going to the 24mm (in my opinion). If you look close, maybe the 18-55 will look better to you? I don’t know. The 24mm looks a bit dark at f/2.8, I don’t know if that was my fault or just severe vignetting/poor light transmission. I’m guessing it’s a bit my fault compounded with vignetting (this lens vignettes pretty hard at f/2.8). Keep in mind these test images are the lower left quadrant crops of the full resolution images. So the upper right corners of these images are the actual center and the lower left corners are lower left corners.


Pretty aggressive.

Vignetting at f5.6

Vignetting at f/2.8

Vignetting at f/2.8

Vignetting at f/5.6


Truly surprising bokeh for such a cheap and wide lens. You don’t really expect nice bokeh at 24mm because lenses at 28mm and below just always seem aesthetically harsh. For a 24mm prime, the STM does fine. The bokeh is nice and round as I stop the lens down, beating the 18-55 kit and beating the 40mm STM.

24mm bokeh at f/8

24mm bokeh at f/8

40mm STM bokeh at f/8

40mm STM bokeh at f/8

Holy heptagons! The 24mm kills the 40mm in terms of circular bokeh. Which is crazy, because the 40mm STM kills the 50mm 1.8 in terms of circular bokeh. The advantage the 40mm does have is that overall, the bokeh is more creamy and less harsh. This is a natural result of longer focal lengths. here is another shot of the 24mm STM bokeh:

Canon EFS 24MM STM Bokeh

When you shoot up close with this lens you get a nice shallow depth of field. I shot the above image at f/3.5 and was very close to the grass. As you move away form the subject and stop down the lens you lose that shallow DOF and nice bokeh.

Spherical Aberration / Spherical Distortion:

Canon 24mm has a bit of barrel distortion

The Canon 24mm has a bit of barrel distortion

The 24mm STM has a decent amount of barrel distortion. When I edit my photos in Lightroom, I generally apply +6 to the distortion slider to fix the problem. Not a big deal. In the above photo you can clearly see how the table appears to be curved. Pretty aggressive for a non super wide angle lens.

Chromatic Aberration:

Not much CA

Not much CA

This image is a pretty crappy test of CA, I had a better image that I believe I deleted. Basically you can definitely see some violet fringing under the right circumstances, but as far as major chromatic aberration; this lens doesn’t exhibit any extreme false color.


Focuses  faster than the cheap Canon 50mm 1.8 and 18-55mm kit. The Canon 50mm 1.4 beats the STM in terms of focusing speed and accuracy. But take my word’ the 24mm STM focuses very well and reletively silently. If you are happy with the 40mm STM focusing you will be just as happy with the 24mm STM focusing. The STM lenses are great for autofocusing video. If you have a DSLR that can use STM for autofocusing, you will enjoy the 24mm STM. Manual focusing for video? Not very practical (though manually focusing for still images is fine), more on that later.

Auto-focus Sound:

Pretty effing quiet. I’ll upload a sample eventually.

Macro Photography with the Canon EF-S 24mm f/2.8?

One thing that is cool about the 24mm STM is how close you can get to the subject. This thing feels like a wide angle macro lens! I’d say the closest I can get on my Canon 50mm 1.4 or 1.8 is about 16 inches. The 40mm can focus down to about 12 inches. The 24mm STM focuses down to about 6 inches! I think I will have to buy some extension tubes to try pseudo-macro photography with the 24mm. I’ll post some close up pictures when I get around to it.

24mm STM vs 18-55mm

You may think that owning a 18-55mm fills your needs across the 18-55mm focal range, but lets be honest any modern Canon prime will outperform the 18-55 at an individual focal length. And sure enough the 24mm STM beats the 18-55mm @ 24mm. The sharpness is ever so slightly better (in my view), it can go down to f/2.8 (the lowest the Canon kit will go down to is f/4 @ 24mm), and it does not have a rotating filter mechanism. Serisously, spinning filters are the worst! and every time I focus with the canon 18-55, the filters spin. The 18-55 does have some advantages; it has IS, a wide focal range, and is about as sharp as the 24mm STM. If you own the 18-55mm kit, you don’t really need the 24mm STM. Personally, I think that with the new super cheap Canon 10-18mm, the 18-55mm is becoming a bit outdated. There are too many lenses that, when combined, form a high performance/low cost setup:

24mm STM
40mm 2.8 (or 50mm 1.8)
55mm – 250mm

This pretty much covers your entire range (minus something around 28-35mm), for a very modest price. The 55-250mm has good image stabilization which is vital for videos and stills throughout that telephoto range. So while the 18-55 is cheap and versatile, I think the 24mm is more fun has its place in anybody’s lens arsenal, especially if you plan to rock the setup I mentioned above.

24mm STM for Video?

Yes and no. If you shoot with auto-focusing; its great. If you shoot manual its not so great. Basically STM focusing prevents your from rack focusing effectively. You can’t mark the lens and have precise stops. You may mark a spot on the lens, focus to it and find that it is not in focus! This is because the focusing is done by a wire rather than precise gears. The result is nice fast and quiet auto focusing, but frustrating manual focusing. Definitely go for non STM lenses if you need precise manual focusing for video. For stills?! Its fine. I sometimes focus manually and it is not as frustrating as trying to shoot manual video.

24mm STM vs 24mm f/2.8 IS USM

Canon has released three lenses that are wonderfully cheap (relatively speaking) and effective for video work; the 24mm f/2.8 IS USM, 28mm f/2.8 IS USM, and the 35mm f/2 IS USM. I don’t own these lenses so I can’t tell you how the 24mm STM compares to the 24mm f/2.8 IS USM. But, judging from my personal research the IS USM lenses all focus better, are sharper, and have IS, which is why they cost 4x as much. So umm…. it’s an apples to oranges comparison. Plus, if you are into video, the 24mm IS is a no brainier; you get image stabilization plus you don’t have to deal with the clunky STM manual focusing issues I mentioned above. Image stabilization is useful at all focal lengths for video. Even at 24mm.

Personally, I think I will keep my 24mm STM and not upgrade to the Canon 24mm IS USM. I will, however, get the 35mm IS USM eventually. It sports a bigger aperture f/2, which when combined with IS is an ultimate low light/video lens. Moral of the story; as a video lens the 24mm STM is okay, nothing to write home about – it lacks IS, and the focus ring is a small but solid(ish) plastic ring  (it is a nice improvement over the 50mm f/1.8).

24mm STM vs 40mm STM

How does the 24mm stack up to the 40mm STM? It’s flat out harder to make sharp wide angle lenses. Everything below 28mm tends to get soft easily in my experience. Hell, even my Tokina 11-16mm which is considered sharp looks like a mess in the corners at f/2.8. So don’t expect anything razor sharp, especially wide open. But, the 40mm isn’t really in the same league; it is a step up. Better sharpness, no severe vignetting and it fits on full frame cameras (5D, 6D, etc..). Do you like your 40mm STM? If you do, you will like the 24mm STM.

Who Should Buy the 24mm STM

Well, this thing only costs $150 brand new so really it’s not a life or death situation. I say don’t stress over this lens. If you are curious, buy it. If it looks too mediocre skip it and save up for something better. It’s f/2.8 so it is not a killer low light lens, but you will get better bokeh and a more shallow depth of field than on the 18-55 kit. If you don’t have a 24mm lens in your arsenal you should buy this lens. You can get real close to your subject. I think it would make a fine wide angle portrait lens (I’m not into that). As a video lens, it’s serviceable. Manual focusing is doable. The ring is small, but if you have worked with the Canon 50mm 1.8 or 40mm STM you will be fine with the 24mm STM. If you want value – this lens is it. I have the 40mm STM, and I like the 24mm STM more, though that could be explained by the lack of 24mm lenses I have (I have four prime lenses between 40mm and 50mm!).

Who Shouldn’t Buy the 24mm STM

If you own a full frame camera, or own a Nikon, or Pentax, etc.. this thing won’t fit. If you demand exceptional performance, you will likely think the 24mm STM is underwhelming and should either get the Canon 24mm IS USM or an L series. It’s a $150 lens. It can shoot 24mm @ f/2.8. Its the working man’s lens. It won’t win any awards for optics, or for auto-focusing speed, or for low light performance (it ain’t f/1.4). It is what it is: good enough. If you need something more versatile, or higher quality don’t shop for $150 lenses! The 24mm STM is all about value. If you own a 18-55mm kit, you might not need this lens. But it is small cute and relatively sharp, so uh… ???

My 24mm Conclusion

I bought this lens because I needed something in the 24mm range, not because I wanted to review it on my website, or because it was cheap. I would often get pissed that I had to lug my 18-55 kit around strictly for the 24mm-35mm focal range. I own an old 28mm prime, but it is soft so I never use it. The 24mm STM fixes my predicament extremely well. No more kit lens for me (unless I can’t pack all my lenses and just want some casual shots). The 24mm is sharper than the kit, better in low light (particularly for video), is easy to pack, quieter, and only gives up IS. Better bokeh and shallower depth of field as well. I can survive without IS at 24mm.

This baby has a nice build quality to it. Like the 40mm, they are small but weigh roughly the same as the 50mm 1.8. So they are beefy and dense. The rear mount is nice – made out of metal. It means when I drop this lens only the lens elements will break and not the rear connection area. :P

This is a super fun lens. It is small and quiet, so no one pays attention to you. Being able to stick it right in the face of my subject is fun. I get so close to things that I become afraid I might bump my lens. I like the 24mm STM more than my 40mm STM, probably because 24mm is more versatile than 40mm on a crop sensor. I can take the 24mm anywhere; it’s a focal length that always finds use. If you buy this lens you will definitely put it to work.

If you are used to shooting manual videos on the Canon 50mm 1.8 (like I am), you will be annoyed with STM lenses for video. This is the only true annoyance with this lens (same deal with the 40mm STM). Because it is using focus by wire (STM), your focus points are never identical, and the speed with which your focus is not constant – pretty awful for manual focusing. You don’t get the instantaneous response of a conventional focusing system and you don’t get the precision either. (When you focus manually, the lens focuses only after you have turned the focus ring a bit, kind of like a delay). It is not a big deal for still, but is cumbersome for manual video. If you shoot video with autofocus on, then this problem does not apply to you.

Anyway, I hope you liked my totally awesome 24mm STM review. I have lots of personal gear I’d like to review but I am real slow, so check back in the future :P  Here are some recent shots with my nifty little 24mm:

24mm STM Review Sample Image 1 24mm STM Review Sample Image 2 24mm STM Sample Image 6 24mm STM Sample Image 4 24mm STM Sample Image 3 24mm STM Sample Image 5

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