This week we bring you a review of a Canon full-frame mirrorless mount lens, the all-in-one RF 24 to 105mm IS STM.

And for those of you wondering what a mirrorless camera is: It’s just a fancy way of saying that engineers figured out how to get rid of the mirror that was used to bounce light to either a viewfinder or a sensor. Now, in our digital age, everything just goes straight to a sensor, and a small screen acts as a viewfinder. With that mirror gone, these cameras weigh less, are smaller, and actually are a bit more effective at collecting light when everything else is equal, which it really never is. So, let’s go with this type of camera is lighter and smaller than your standard DSLR camera.

And as for this RF lens? Well, Canon carries two lines of lenses — RF and EF. If you have older Canon lenses for film or digital camera bodies, they are probably EF. The RF lenses are for the full-frame mirrorless cameras only. Canon has another mount for crop mirrorless, but we don’t need to get into that. That’s it. No more fancy acronyms.

And now to actually review the lens.

I tested the Canon RF 24-105 mm IS STM on my R6. Build quality-wise this lens is good. Like many lenses today, the outside is plastic, while the lens mount is, of course, metal. Because it’s so small, the lens does not have room for separate focus and control rings, so they are combined. The zoom ring takes up most of the lens’ length and is grippy and close to the camera body for ease of access. It moves smoothly, though it’s a little stiffer at the telephoto end. The control ring has a different texture so you can tell which one you’re using even through gloves.  It has two switches on the side — one for the control/manual focus ring and the other for turning on or off the optical stabilization.

Mounted on my R6, the lens balances quite nicely; however, on the Canon RP I used to own, it was somewhat uncomfortable because the weight was balanced towards the lens. On the other hand, with either body the total system is light enough that I was able to easily use a simple wrist strap rather than having it around my neck, improving portability without fatigue. Fitting a body with a lens on it and a neck strap in one of my small camera bags has been a problem, solved by this lens and a neck strap.

The compromise to having such a small/light/inexpensive lens is a non-constant aperture range of f/4 at 24mm to f/7.1 at 105mm, a full two-thirds of a stop slower than the EF equivalent. This means you’ll need a longer exposure time to get the same photo. 

This lens has optical stabilization, so longer exposures are easy. The R6 has sensor stabilization as well, further increasing the long exposure performance of this lens.

For folks capturing motion, those longer exposures could be a problem. You can compensate with a higher ISO speed if you don’t mind noise, and for some – especially hikers and people out walking –  this lens’ smaller size will matter more than the visually hard-to-see added noise.

Image quality was decent, but this lens definitely works best in the middle of its focal range, with the image decaying at the extreme widest and longest. Lens corrections cleaned up distortions nicely. I did notice a little color fringing even with those corrections, but it was gone by 50mm. These corrections can be applied in-camera, making it easy to get good images.

One of the mirrorless-specific features of this lens is a higher reproduction ratio of 1:2, compared to the 1:3 of the EF equivalent. Put another way — if you focus just right on an object 54mm long, it will fill the frame. In this mode, the minimum focus distance is then reduced to about an inch from the front of the lens.

And, if you can get your camera within one inch of a living bug, it makes for an amazing shot. Good luck not scaring the bug though.

For those of you who want more in-depth info on the lenses’ more eclectic features, I have a longer review on Medium. Links are available on DailySpace.org.

Overall this is a nice small all-in-one lens that you can tuck away in the corner of your camera bag for when you need a shorter focal length lens, or carry in your hand when you just want to go on a walkabout in search of a not scared bug. It is perhaps a bit expensive at $400, but you can buy refurbished ones from Canon for $250.

Enjoy the spring with your camera. Look up. Look down. And remember — all of it is held together by the same science.