Canon RF28-70mm F2.8 IS STM Review: Small, Fast, and Sharp Performance

Introduction

A cou­ple of months ago, I tran­si­tioned back to the Canon sys­tem after an eight-year fling with Fuji­film. My most-used zoom lens dur­ing that peri­od was the Fuji­film XF 16–55mm F2.8 R LM WR. Weigh­ing 655 grams, it had robust con­struc­tion and deliv­ered superbly sharp images, cap­tur­ing many of my favourite pho­tos. How­ev­er, its size and weight were bur­den­some, and I con­sid­ered its bokeh dis­ap­point­ing, espe­cial­ly in the tran­si­tion­al areas between focus and blur.

Upon return­ing to Canon, I sought an equiv­a­lent lens with a sim­i­lar focal length and max­i­mum ƒ/2.8 aper­ture. The Canon RF24-70mm F2.8 L IS USM was the obvi­ous choice. How­ev­er, at 900 grams, it was even heav­ier than the Fuji­film lens I want­ed to move away from. I car­ry my cam­era almost every­where, so its weight and bulk gave me buyer’s remorse with­in days. 

Then, in mid-Sep­tem­ber 2024, Canon released the RF28-70mm F2.8 IS STM. Com­pared to the RF24-70mm F2.8 L, it los­es 4mm on the wide end but sig­nif­i­cant­ly reduces weight, com­ing in at 495 grams (a 45% reduc­tion!). Its com­pact­ness and rel­a­tive light­ness imme­di­ate­ly caught my atten­tion. Despite a dearth of reviews from my usu­al trust­ed sources, I decid­ed to take the plunge, sell the RF24-70mm F2.8 L, and pur­chase the new RF28-70mm F2.8 instead.

As I antic­i­pat­ed (and hoped), the loss of 4mm on the wide end has­n’t been sig­nif­i­cant in my shoot­ing. The ben­e­fits of reduced weight and size have made a sub­stan­tial dif­fer­ence, espe­cial­ly dur­ing long out­ings. The RF28-70mm F2.8 IS STM offers a bright con­stant ƒ/2.8 aper­ture and image qual­i­ty that is dif­fi­cult to dis­tin­guish from the RF24-70mm F2.8 L, strik­ing an excel­lent bal­ance for ama­teur pho­tog­ra­phers, trav­ellers, or any­one look­ing to light­en their kit with­out sac­ri­fic­ing per­for­mance.

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RF28-70mm F2.8 Build Quality & Design

Canon’s RF lens­es across all price points use plas­tic for most of their exte­ri­or parts, and the RF28-70mm F2.8 is no excep­tion.  Aside from the met­al lens mount and ribbed rub­ber zoom ring, com­po­nents like the fil­ter mount­ing thread (67mm diam­e­ter), hood mount, dia­mond-tex­tured focusing/control ring, exte­ri­or bar­rel parts, and all switch­es are plas­tic. I’m fine with plas­tic bar­rels when they reduce weight, but I can’t help feel­ing cheat­ed by Canon’s use of plas­tic for the fil­ter thread and hood mount; this design choice offers no con­sumer ben­e­fit and increas­es the poten­tial for mis­thread­ing a fil­ter.

Canon claims the RF28-70mm F2.8 has dust- and weath­er-resis­tant con­struc­tion. The most notice­able aspect is the rub­ber gas­ket around the lens mount. Canon’s mar­ket­ing shows inter­nal seals high­light­ed in red, but there’s no evi­dence of seals around the focus and sta­bi­liz­er switch­es.

Despite its large­ly plas­tic design, the lens feels reas­sur­ing­ly sol­id in hand. It’s nei­ther too dense nor too hol­low. Tap­ping the bar­rel reveals more den­si­ty towards the base than the front. Shak­ing the lens pro­duces a slight audi­ble rat­tle from the image sta­bi­liz­er unit—an improve­ment over the loud knock­ing from shak­ing a Fuji­non lens with lin­ear motors.

Although almost half the weight and price, the RF28-70mm F2.8 feels more sol­id than the RF24-70mm F2.8 L. Although the plas­tic and rub­ber com­po­nents seem iden­ti­cal, the new lens deforms less when I squeeze the bar­rel below the zoom ring. There’s a small amount of play in the ful­ly extend­ed bar­rel when the lens is zoomed to 70mm; I feel the move­ment but can’t see it in action. Over­all, it’s a stur­dy design. 

Aes­thet­i­cal­ly, the lens is quite hand­some. I’m par­tial to designs that main­tain a con­stant diam­e­ter through­out the body, and the RF28-70mm F2.8 achieves this ide­al.

RF28-70mm F2.8 Features

Weight and size are rarely high­light­ed fea­tures out­side of pan­cake lens­es and extreme tele­pho­tos with dif­frac­tive optics. A lens’s mass and dimen­sions are often con­se­quences of oth­er design deci­sions. How­ev­er, it’s clear that both were promi­nent con­sid­er­a­tions in Canon’s design of the RF28-70mm F2.8. The RF sys­tem already had two lens­es with sim­i­lar aper­tures and focal lengths: the equal­ly bright RF24-70mm F2.8 L and the equal­ly wide RF28-70mm F2.0 L. Both are large, heavy, and expen­sive. The RF28-70mm F2.8 serves as a com­pro­mise between the two and pro­vides a wel­come reduc­tion in size.

Its com­pact size is part­ly due to its col­lapsi­ble design, about which I was ini­tial­ly appre­hen­sive, fear­ing it would hin­der my pho­tog­ra­phy by get­ting in the way or slow­ing me down. Thank­ful­ly, my fears haven’t mate­ri­al­ized.

A col­lapsi­ble zoom lens is designed to be com­pact and portable when not in use. It retracts to a small­er size by rotat­ing the zoom ring clock­wise past the min­i­mum focal length of 28mm. To take a pic­ture, you rotate the zoom ring counter-clock­wise into the shoot­ing posi­tion, start­ing at 28mm. There are robust detents at two points in the zoom ring’s rota­tion: one at the lens retract­ed posi­tion and anoth­er when cross­ing the 28mm index. Both require just the right amount of effort to over­come, pre­vent­ing inad­ver­tent retrac­tion and exten­sion, and negat­ing the need for the tedious zoom lock levers found on many Canon L zooms.

Inside the lens is an image sta­bi­liz­ing (IS) sys­tem that Canon claims achieves 5.5 stops of sta­bil­i­ty on cam­eras with­out in-body image sta­bi­liza­tion (IBIS). When mount­ed on cam­eras with IBIS, it coor­di­nates with the body to achieve a claimed 7.5 stops of sta­bil­i­ty at the cen­tre and 7 stops at the cor­ners. While impres­sive on paper, I would­n’t get my hopes up. Test­ing this claim on my Canon EOS R6 Mark II yield­ed dis­ap­point­ing results. If we fol­low the old rule of thumb for deter­min­ing the slow­est real­is­tic shut­ter speed for hand­held pho­tog­ra­phy, we would use 1/30 sec­ond for a 28mm focal length. Slow that down by sev­en stops of coor­di­nat­ed sta­bi­liza­tion and we have a 4‑second hand­held expo­sure. Sor­ry, Canon, but those sta­bi­liza­tion fig­ures are wild­ly opti­mistic.

There are two phys­i­cal switch­es on the left side of the bar­rel: the focus mode/control selec­tor and the image sta­bi­liz­er on/off. They’re wel­come inclu­sions as acti­vat­ing and deac­ti­vat­ing such com­mon func­tions via the cam­er­a’s menu is inef­fi­cient, time-con­sum­ing, and can lead to miss­ing fleet­ing moments.

Last­ly, the RF28-70mm F2.8 is an inter­nal­ly focus­ing lens with a step­per motor (STM). Focus dis­tance infor­ma­tion is record­ed in the EXIF meta­da­ta. A pecu­liar aspect of this lens, which I’ve nev­er encoun­tered in oth­ers, is that its min­i­mum focus­ing dis­tance (MFD) varies depend­ing on whether you’re using aut­o­fo­cus or man­u­al focus mode. For exam­ple, at its widest focal length of 28mm, the aut­o­fo­cus MFD is 27cm, but the man­u­al focus MFD is 24cm. This strange dis­tinc­tion con­tin­ues until 64mm, when the MFD of both AF and MF modes unites at 35cm. Fur­ther­more, my R6 Mark II’s help­ful Focus Guide func­tion is dis­abled when sub­jects are clos­er than the aut­o­fo­cus MFD. Canon devotes four pages to explain­ing this behav­iour in its 20-page man­u­al but pro­vides no expla­na­tions for why it exists.

RF28-70mm F2.8 Handling & Ergonomics

The plas­tic com­po­nents of the lens bar­rel have a tex­ture akin to fine-grit sandpaper—non-abrasive, of course—that pro­vides enough fric­tion for gloves and resists fin­ger­prints effec­tive­ly.

The RF28-70mm F2.8 con­forms well to my aver­age-sized hands dur­ing shoot­ing. The place­ment and width of the zoom ring nat­u­ral­ly accom­mo­date my thumb on the left and my index and mid­dle fin­gers on the right. As men­tioned ear­li­er, there are uni­di­rec­tion­al detents at the lens retract­ed posi­tion and at the 28mm index mark. You must over­come the detent to move out of the retract­ed posi­tion. There’s a hol­low clunk when you effort­less­ly slide past 28mm. Sim­i­lar­ly, when you’re done shoot­ing and ready to col­lapse the lens, you must over­come a slight­ly stronger detent to rotate the zoom ring clock­wise beyond the 28mm mark, with an audi­ble snap con­firm­ing you’re in the retract­ed posi­tion.

The zoom ring rotates rel­a­tive­ly smooth­ly, requir­ing uni­form effort through­out its range. There’s just enough fric­tion, sim­i­lar to what I feel on my RF70-200mm F4 (and the RF24-70mm F2.8 L). I sus­pect this is caused by the retractable inner bar­rel slid­ing against what­ev­er mate­r­i­al Canon uses for ingress resis­tance. Over­all, there’s no zoom creep under nor­mal cir­cum­stances when the lens is extend­ed.

The RF28-70mm F2.8 fea­tures Canon’s stan­dard zoom ring with a ribbed rub­ber tex­ture, which feels great—though time will tell if it suc­cumbs to whiten­ing oxi­da­tion. Anoth­er Canon stan­dard is the dia­mond-tex­tured focusing/control ring. Serv­ing dual roles, it has no clicks and rotates smooth­ly and even­ly.

The image sta­bi­liz­er and focus mode/control selec­tor switch­es are with­in easy reach of my thumb. How­ev­er, the focus mode/control selec­tor switch is a bit fid­dly. Tiny slid­er switch­es with more than two options irri­tate me because select­ing the inner posi­tions requires a lev­el of dex­ter­i­ty that I don’t pos­sess in my left thumb.

RF28-70mm F2.8 Image Quality

Over­all, I’m sat­is­fied with the RF28-70mm F2.8’s opti­cal per­for­mance and would char­ac­ter­ize it as the spir­i­tu­al full-frame suc­ces­sor to the well-regard­ed Canon EF‑S 17–55mm F2.8 IS USM. It’s rel­a­tive­ly sharp across all focal lengths and aper­tures, has inof­fen­sive bokeh, and demon­strates good con­trol of flare and ghost­ing. How­ev­er, no lens is with­out com­pro­mise, and the RF28-70mm F2.8 has a few draw­backs, most notably a con­sid­er­able reliance on soft­ware cor­rec­tions for vignetting and dis­tor­tion.

Let me start with its favourable aspects. One of these is bokeh—the aes­thet­ic qual­i­ty of the out-of-focus areas in a pho­to­graph, par­tic­u­lar­ly how the lens ren­ders them. It describes the shapes, smooth­ness, and over­all appear­ance of the defo­cused regions, as well as the tran­si­tion from sharp focus to blur. The bokeh pro­duced by the RF28-70mm F2.8 is pleas­ing for a stan­dard zoom and is rem­i­nis­cent of the RF24-70mm F2.8 to my eyes. It’s a bit hec­tic por­tray­ing con­trast­ing inter­sect­ing ele­ments, such as blur­ry over­lap­ping branch­es, and shows some onion-ring pat­terns under some con­di­tions, but it’s oth­er­wise inof­fen­sive and does­n’t stand out neg­a­tive­ly.

Since impres­sions of bokeh are entire­ly sub­jec­tive, I’ll let you form your own judge­ments.

The sam­ples below show back­ground blur at ƒ/2.8 with focus dis­tances of MFD, 1m, and 1.75m, at both 28mm and 70mm.

Sharp­ness is anoth­er strength of the RF28-70mm F2.8. Based on my analy­sis of real-world images, cen­tre and mid-frame sharp­ness are excel­lent across all focal lengths from ƒ/2.8 onward. The extreme cor­ners lose some of that bite at ƒ/2.8 across all focal lengths, but you’d have to pix­el-peep to notice. There’s an unde­ni­able yet slight reduc­tion in micro-con­trast and a minor loss of fine detail. Stop­ping down to ƒ/5.6 or ƒ/8 increas­es sharp­ness, but it does­n’t com­plete­ly approach cen­tre lev­els. 

The images below com­pare cen­tre and cor­ner sharp­ness across sev­er­al focal lengths and aper­ture val­ues. The enlarge­ments are tak­en from 600px by 600px crops.

28mm cen­tre sharp­ness:

28mm cor­ner sharp­ness:

50mm cen­tre sharp­ness:

50mm cor­ner sharp­ness:

70mm cen­tre sharp­ness:

70mm cor­ner sharp­ness:

I must empha­size this isn’t a dif­fer­ence you’ll read­i­ly notice at nor­mal view­ing scales, even on high-DPI mon­i­tors. For the uncropped ref­er­ence images above, I used the ƒ/2.8 ver­sion, and they all look fan­tas­tic when enlarged to fit my 27-inch 4K mon­i­tor. If sharp­ness were my only con­sid­er­a­tion, and I was shoot­ing sub­jects at hyper­fo­cal dis­tances, I’d be sat­is­fied using ƒ/2.8 across the focal range to cap­ture detailed what­ev­er-scapes, such as in the fol­low­ing shots.

Unfor­tu­nate­ly, that’s a big “if” for two rea­sons. First, at ƒ/2.8, slight­ly out of focus cor­ners exhib­it unre­fined bokeh that looks like astig­ma­tism. In the library exam­ple below, tak­ing the shot at ƒ/8 brings the cor­ners into the depth of field and pro­duces sharp results.

Sec­ond, I sus­pect Canon made sig­nif­i­cant com­pro­mis­es in the RF28-70mm F2.8’s design to pri­or­i­tize sharp­ness and com­pact­ness while ful­ly embrac­ing the mot­to of fix­ing the rest in post. The RF28-70mm F2.8 depends on lens cor­rec­tion pro­files to man­age its heavy vignetting and strong opti­cal dis­tor­tions, and, to a less­er degree, mild chro­mat­ic aber­ra­tions. In this regard, it devi­ates sharply from its L‑series coun­ter­part. When exam­in­ing raw files with these cor­rec­tion pro­files dis­abled, the lens exhibits pro­nounced vignetting at ƒ/2.8 through­out the focal range. Vignetting is espe­cial­ly egre­gious at 28mm, where the uncor­rect­ed cor­ners are almost black. Uncor­rect­ed raw files also show notable bar­rel dis­tor­tion from 28mm to approx­i­mate­ly 37–38mm, beyond which they grad­u­al­ly trans­form into pin­cush­ion dis­tor­tion. 

Last­ly, the lens cor­rec­tions address some minor lat­er­al chro­mat­ic aber­ra­tions, that are more promi­nent towards the wide end of the zoom range. Stop­ping down the aper­ture doesn’t dimin­ish their inten­si­ty, so the lens pro­file is an effec­tive solu­tion. At this point, I feel Adobe deserves tremen­dous kudos for cre­at­ing cor­rec­tion pro­files for such a new lens so quick­ly. All of the pho­tos accom­pa­ny­ing this review were processed in the lat­est ver­sion of Adobe Light­room Clas­sic (affil­i­ate link).

Lens cor­rec­tion pro­files con­tin­ue to spark debate in the pho­tog­ra­phy com­mu­ni­ty. Emo­tion­al­ly, I find myself frus­trat­ed by man­u­fac­tur­ers’ grow­ing reliance on these cor­rec­tions in mir­ror­less cam­eras; it feels like I’m miss­ing out on a lev­el of qual­i­ty and thought­ful engi­neer­ing that should inher­ent­ly be part of the lens design. Intel­lec­tu­al­ly, how­ev­er, I rec­og­nize that these cor­rec­tions allow engi­neers to con­cen­trate on more press­ing chal­lenges that pro­files can­not address, such as improv­ing res­o­lu­tion and devel­op­ing more com­pact designs. Ulti­mate­ly, the res­o­lu­tion lost by shift­ing pix­els to cor­rect dis­tor­tions is min­i­mal and often goes unno­ticed by most pho­tog­ra­phers. Sim­i­lar­ly, the increased noise intro­duced by cor­rect­ing periph­er­al shad­ing is neg­li­gi­ble at typ­i­cal view­ing scales. 

The RF28-70mm F2.8 ren­ders attrac­tive sun­stars at ƒ/16. How­ev­er, you need to be mind­ful of bright light sources shin­ing at oblique angles into your lens, espe­cial­ly since Canon can’t afford to include lens hoods for non‑L glass. With­out a lens hood, you’ll have to keep an eye on the Sun’s direc­tion. I noticed fair­ly con­sis­tent flar­ing with the Sun in the frame, and the amount var­ied depend­ing on the angle. The Sun can also pro­duce small, some­times colour­ful ghosts that I find charm­ing. Pic­tures includ­ing oth­er bright lights, such as the truck head­lights below, can cause inter­nal reflec­tions between the opti­cal ele­ments, lead­ing to their ghost­ly images appear­ing on the invert­ed side of the frame.

There’s some very minor coma in bright points of light against dark back­grounds.

RF28-70mm F2.8 Focusing and Autofocus

The Canon R sys­tem fea­tures closed-loop aut­o­fo­cus­ing, which means it con­tin­u­ous­ly checks focus accu­ra­cy and makes real-time adjust­ments using feed­back from the image sen­sor. In con­trast, open-loop systems—like those found in most DSLRs—rely sole­ly on ini­tial mea­sure­ments from the aut­o­fo­cus mod­ule, set­ting the lens focus based on those cal­cu­la­tions with­out any ongo­ing feed­back.

The Canon RF28-70mm F2.8 IS STM has quick and accu­rate aut­o­fo­cus. Based on my mea­sure­ments, the lens focus­es from infin­i­ty to the AF mode MFD in about 1/3 sec­ond. The STM dri­ving the focus group runs qui­et­ly and with min­i­mal hunt­ing.

The man­u­al focus­ing expe­ri­ence is ful­ly elec­tron­ic (i.e., focus-by-wire) because there’s no mechan­i­cal con­nec­tion between the focus­ing ring and the lens ele­ments. Rotat­ing the focus­ing ring in man­u­al focus mode trans­lates the move­ment into elec­tron­ic sig­nals. These sig­nals com­mu­ni­cate with the lens’s inter­nal motors, which then adjust the posi­tion of the lens ele­ments to achieve focus.

Focus breath­ing refers to the slight change in the angle of view as you adjust focus, which can be notice­able in video work or prob­lem­at­ic for focus stack­ing. The Canon RF28-70mm F2.8 has min­i­mal focus breath­ing as demon­strat­ed in the exam­ples below.

Focus breath­ing at ƒ/2.8:

Focus breath­ing at ƒ/5.6:

RF28-70mm F2.8 IS STM Price & Value

The Canon RF28-70mm F2.8 was announced on Sep­tem­ber 12, 2024, and became wide­ly avail­able in Octo­ber. The release price in Cana­da was $1,500. Although I pre­fer buy­ing used lens­es, giv­en how recent­ly it was released, I could­n’t find any on Toron­to’s sec­ond­hand mar­ket. Thus, my retail pur­chase totalled $1,694.99 after tax, mak­ing it nei­ther a cheap nor a bud­get lens. As I write this, it shares sec­ond place as the most expen­sive non‑L lens in Canon’s EOS R Sys­tem.

The RF28-70mm F2.8 is well worth its MSRP, espe­cial­ly since it’s about $1300–1500 cheap­er than a new RF24-70mm F2.8 L. The extra 4mm on the wide end, ded­i­cat­ed con­trol ring, and less dis­tor­tion and vignetting don’t jus­ti­fy the L pre­mi­um for me. What tru­ly mat­ters is the enhanced porta­bil­i­ty that encour­ages me to take the cam­era along instead of leav­ing it at home. All of this makes it less sus­cep­ti­ble to buy­er’s remorse, so I would­n’t be sur­prised if the RF28-70mm F2.8 takes a while to show up on the sec­ond­hand mar­ket.

Conclusion

In con­clu­sion, the Canon RF28-70mm F2.8 IS STM offers a blend of per­for­mance, porta­bil­i­ty, and val­ue. While it relies heav­i­ly on soft­ware cor­rec­tions for vignetting and dis­tor­tion, its sharp­ness across all focal lengths and aper­tures, fast and accu­rate aut­o­fo­cus, effec­tive image sta­bi­liza­tion, and pleas­ing bokeh make it a com­pelling choice. All these fea­tures are neat­ly pack­aged in a com­pact design that boosts porta­bil­i­ty, mak­ing it easy to take your cam­era along instead of leav­ing it behind. 

Buy­ing sec­ond­hand lens­es saves you mon­ey, but if you’re mak­ing deals on Face­book Mar­ket­place, it helps to know what to check when buy­ing a used lens. Unfor­tu­nate­ly, the RF28-70mm F2.8 is quite new, so it might be tough to find used options at the moment. If you’re set on buy­ing new and found this review help­ful, con­sid­er using the affil­i­ate links below. It won’t change your price, but it does give me a small com­mis­sion to help keep these reviews com­ing. Thanks for your sup­port!

Sample Photos