P.K. Frary
I enjoyed shooting with pancake lenses on my Olympus Pen and wanted one for my EOS gear. The EF 40 2.8 STM--Canons first DSLR pancake--debuted Summer 2012 and caused a stir due to low cost and reputed high optical quality. Heres my take on this able little optic. CONSTRUCTION: Although a small lens, it feels solid in hand, boasting excellent build: metal mount, beefy plastic barrel and comely industrial satin finish. STM AF is not silent but makes a soft electronic intonated "sheeeeet," resembling a sound effect from Tron. Most built-in camera mics will pick it up during video recording. The work around is to use an external mic or prefocus before the clip. Focus is slower than ring-USM but silky smooth. The motor uses "focus-by-wire" manual focus. The focus ring isnt mechanically coupled to the lens, but is a simply a switch for activating the focus motor. MF is smooth and accurate, albeit slow. The gotcha is it is only active when the shutter button is half depressed. The nested barrel extends during focus operation. I use the EF 40 2.8 STM on a 6D, 5D MKII and SL1. AF is dependable on the 5D MKII and 6D, but randomly misses focus on the SL1 about 15 or 20% of the time. Other lenses are fine on the SL1. IMAGE QUALITY: Wide open at F2.8 my first copy was sharp in the center of the frame but suffered with extremely soft corners on both full frame and APS-C. Corners improved when stopped down to F8 but were still unacceptably soft. Night images with points of light exhibited severe coma (comet-like tail) at F2.8. Stopping down reduced but didnt eliminate coma. For the above reasons, I returned my first copy and bought a refurbished EF 40 2.8 STM from Canon Direct (with a big discount!). What a difference! Wide open, it was even sharper--deadly sharp--in the center. Corners were greatly improved but still slightly soft on full frame. On APS-C the corners were nearly as sharp as the center. And coma was greatly reduced: no coma center frame at F2.8 and only slight coma along the periphery. So second time around a home run! Defocused areas (bokeh) have a pleasantly smooth swirl to them at F2.8, helping offset subjects from background. I find 40mm a natural snapshot FOV for full frame cameras like the 6D. The slightly wide view is perfect for landscapes and environmental portraits. Keep in mind, on APS-C cameras, e.g., 60D, 70D or Rebels, FOV is a 64mm equivalent, falling within the realm of short telephoto. LENS HOOD: Canon makes a dedicated hood for this lens, the Canon ES-52 Lens Hood . Its just a 52mm aluminum filter ring around a disk with a hole in the center. It provides some shade but not much. The 40 2.8 is so popular theres a Chinese knockoff of the ES-62 available for a few bucks less: RainbowImaging HES52 Metal Lens Hood for Canon EF 40mm F2.8 STM . If you want more protection, a generic screw-in type like the RainbowImaging HM52 52MM Metal Lens Hood is better but will spoil the minimalist pancake vibe. I elected to use the ES-52, buying when the price drifted down to $18. LAST BLURB: Normally $150 doesnt buy much in terms of optics but the EF 40 2.8 STM is the exception to the rule. This lens is sturdy, renders beautiful images and is barely larger than a body cap. If you get a good copy, its an excellent optic. A basic 6-element design and offshore manufacturing (Malaysian factory) helped reduce costs but compromises in quality control were obviously made to maintain this price point. Test your lens for sharpness and coma before the return period is up. If Amazon delivered a sharp lens the first time, this would be a 5-star review. Nevertheless, I got a great sample the second try so it ended well after some toil and hassle.