The 40mm Focal Length Is Just About Perfect

Oct 11, 2023

I've used a 40mm (equivalent) lens for years, and while I first discovered this weird focal length more than a decade ago with Micro Four Thirds, it's become a staple of my collection enough to move it from "weird" to "wonderful."

The focal length has also just been discovered by photographer and YouTuber and photographer Robin Wong, as he starts exploring it via the (sadly, recently discontinued) Canon EF 40mm f/2.8 STM lens, a cheap and versatile lens with a quiet stepping motor that even makes it a decent option for video. It's a secret focal length Micro Four Thirds shooters have known for years, and while he's holding off on a full review and test for now, I guarantee he'll love it.

Panasonic did a weird thing when Micro Four Thirds as a new-ish system. In 2009, they launched the Lumix GF1, a highly desirable and portable camera at the time, with an odd lens choice, a 20mm f/1.7 pancake lens that was the predecessor to the current Panasonic Lumix G 20mm f/1.7 II ASPH lens. Seeking the ultimate in portability at the time, I bought it. I wasn't disappointed. It was not just the lens quality (which on both new and old versions is excellent) but the fact that it was a "Goldilocks" focal length. Not too long, like a 50mm often feels, and not too short, like a 35mm always feels to me. It allows to get just enough background with just enough bokeh to make things interesting. Here's an example, of a nice moment with the son I was able to capture with the lens:

The f/1.7 aperture of the 20mm lens for the Micro Four Thirds system can just start to wipe away the background with some bokeh.

While it's not a background-taming monster like an 85mm f/1.8 might be, the focal length is able to get just enough bokeh to make a clean photo with context. This is even more so with the combination that Wong is using, a Canon 5D and the full frame 40mm lens, compared to a 20mm on a Micro Four Thirds body.

It helps that this focal length seems to lend itself to relatively cheap, pancake-style lenses. As such, if I'm grabbing one lens for the day, it's often this one, whether it's full frame or Micro Four Thirds.

Have you shot with a 40mm lens before? What do you think of the focal length versus the more traditional street photography lenses, such as the 50mm or 35mm? Leave your thoughts in the comments below.

Wasim Ahmad is an assistant teaching professor teaching journalism at Quinnipiac University. He's worked at newspapers in Minnesota, Florida and upstate New York, and has previously taught multimedia journalism at Stony Brook University and Syracuse University. He's also worked as a technical specialist at Canon USA for Still/Cinema EOS cameras.

In the case of the 42mm equivalent being a little too long compaired to the 35mm you were used to couldn't you generally just... take a step back?

I understand the compression is slightly different and all, but all things considered those are really similar focal lengths.

Just to be pedantic (and hopefully not wrong!) 27mm on Fuji is equivalent to 40.5mm (it is a 1.5x 'crop factor', I believe)

I got the EF 40 when it came out. While it was compact and a great walk around lens, I felt it just wasn't wide enough. I ended up giving it to a relative. I prefer 35mm, and if I want a little longer, 50mm. It just seemed lost between two common sizes. Luckily everyone has their preferences and there are no right or wrong answers.

I have two 40mm lenses, the featured EF 40 f/2.8 pancake and the behemoth Sigma 40 f/1.4 Art. I love the little pancake on my APS-C body (64 equivalent is very nice for portraits), but for some reason I’m often disappointed with the images I get with it on a full frame body. The Sigma is a whole different story. On full frame, the rendering is truly beautiful. So far, I’ve mostly used it for full length and environmental portraits. It pairs really well with an 85 f/1.2 for the close-up stuff.

Love it for traveling where a small and/or discrete camera works best and 40mm is good for the working distance. Friends got all the attention with their 'lens monsters' while my setup went nearly unnoticed.

I do not own this lens however, I own the EF-S 24mm on my crop sensor camera. The 24mm on an APS-C gives the field of view almost equivalent to the 40mm on a full frame camera. Believe me, I love the results. Being a street and candid shooter this lens / focal length is just brilliant. I found this little gem after searching for almost 4 months in pristine condition. You can’t say it’s used. It’s lovely, handy and easily fits in my trousers. Check out some of my shots using this on my IG at monochromestories. Happy shooting everyone.

For me, I always found 18mm to be the best .... so much for the "just about perfect" focal length.

Still one of the best lenses for Sony E-mount imo is the Zeiss Batis 40/f2 CF lens. Beautiful typical Zeiss-look in terms of contrast and color rendition plus the ability to close focus. Very nice universal lens for all day carry around. I wish they made this for Z-mount too.

I agree, there is no universally perfect focal length. When I got into Sony now 3 years ago, in addition to the usual af sony zooms, I purchased 3 Voightlander mf prime lenses. Two, wide angle and one in particular the 40 1.2 is a dream. When I shoot it, the experience reminds me of my Canon FD days. And even at 1.2, the image quality is good, not Leica Summilux good, but well worth what I paid for it. It slows me down, and keeps my focusing eye well exercised. The 40 is actually my favorite lens to shoot with, but not competitive in very fast, follow-focus scenarios.

I had this lens on my 60D. It's really really good. Fast quiet accurate focusing and very sharp especially for the price. It's also the smallest and lightest lens I've ever owned. It made my 60D WAY more portable than if I had just about any other lens. I could go out with just my 60D and this lens and have a blast shooting all day with it. I really miss it. Makes me want to get another canon camera. I also love the EF 85mm f1.8. It is my favorite 85mm i have ever used.

You know what is perfect? 43mm 🙃😉

I sold my Sigma Art 50mm because I felt it was too tight . Then I used that money to pay for the Sigma Art 40mm . I thought it would feel normal or just right or something.I struggle with this lens for “that feel”Maybe because I really have to make sure it’s hitting focus . My Sigma 40mm missed so often and I still bought the Nikon f mount in 4 and 28 mm of the Sigma Art lenses. I really like the rendering of the Sigma Art 28mm and when it hits focus I’m stoked . I struggle to get a look and feel for the sigma Art 40 . It’s rendering is so bland and dull. It’s so so perfect the look is almost too normal might is say .I purchased the Sigma 65mm f/2 in the e mount and that lens feels “just right” it feels NORMAL but renders beautifully.I think I’ll dig out the Sigma Art 40 and just shoot with it for a bit and see if I start to get a feel for it .I love most all focal lengths and have never struggled with and except the 40 and 50 mm focal lengths. And oddly I love 55 f/1.2 .I have been so so tempted to get the Sigma Art 35 f/1.2 , Voigtlander 40f/1.2 is what I was dreaming to get then I start going through Flickr and I look at tons of pictures. I get drawn to the Voigtlander 35 f/1.2 and definitely the Sigma Art 35 f/1.2 .It’s all about the lenses rendering first then the focal length fov .