Another lens review this week, and it’s one more for Canon’s full-frame mirrorless RF mount: the Canon RF 600mm f/11 super-telephoto lens. One of my main interests is wildlife photography, which is why I bought one of these for myself a few months ago.

Now the first thing you may notice about the lens is that smaller aperture of f/11. This really isn’t a concern with modern digital sensors that perform well at higher ISO settings, such as those that you might need to use with a slower lens.

The Canon RF 600mm f/11 lens is intended for wildlife photographers on a budget. Weighing just 930 grams means you can leave the monopod at home. The lens has optical image stabilization which has allowed me to shoot sharp images at 1/15th of a second without needing a monopod.

The autofocus is pretty fast. When shooting birds, it tends to hunt for focus a lot before locking on, but I’m pretty sure that is because of user error and the limitations of the autofocus capabilities of my entry-level Canon EOS RP, as I see this with other lenses, too.

The lens has three switches on the side and separate focus and control rings. The switches control focus distance limiting, image stabilization, and focus mode. Like with all R-system cameras, manual focus override is only available if you set the camera upright. If you grab the manual focus ring with autofocus set, it does nothing since the manual focus ring is an encoder that tells the autofocus motor how much to move.

A downside of the aperture is you can only use about the center eighty percent of the frame to autofocus compared to all the way to the edge as with other lenses, an advantage of the mirrorless design. it’s not that big of a deal, at least for me.

Another feature of the RF 600mm f/11 is its collapsible design. It gets about eight centimeters shorter, which is good for storage in a reasonably-sized camera bag. There’s a locking ring at the base of the lens that you must put in its closed position before using the lens, but that becomes muscle memory after a while. It has a fixed ¼ 20 threaded hole for attaching a quick release plate for a monopod instead of a removable tripod shoe like on other super-telephoto lenses. I don’t use a monopod since this lens is stabilized, so I put a strap mounting plate on the thread. I learned early on that it’s more comfortable to have cameras with large lenses facing backward as you’re walking, and that’s mostly true with this lens, though the balance is a little off because half of it is a hollow tube.

Image quality with the 600mm f/11 is great. The Diffractive Optics design works; there isn’t any visible distortion or chromatic aberration, and what small aberrations there are are corrected automatically in-camera. Because of the smaller aperture, you need to use higher ISOs to be able to use fast shutter speeds. I regularly use up to ISO 12,800 without a significant decrease in image quality, so I limit the ISO to that using the Auto ISO setting. I’m really happy with the images I can make with it given all of its advantages and compromises. Enthusiasts on a budget like me don’t usually get this much focal length.

Personally, I don’t use teleconverters but you can use one of the available RF teleconverters, which Canon calls “Extenders”, with the 600mm f/11 to obtain either 840mm at f/16 or 1200mm at f/22, using the 1.4x or 2x teleconverters respectively, though Canon notes that the lens might not autofocus at f/22 using the 2x converter.

Although Canon also makes a big brother to this lens, an 800mm f/11, I decided to get the 600mm version mainly because of its shorter minimum focus distance of 4.5 meters, compared to the 6 meters on the 800mm, which felt limiting to me because I might end up too close to the subject to focus and scare it off by backing away. As it stands, the first time I used this lens, I had to back up to get my subject in focus because I was closer than 4.5 meters.

Another consideration was the size. The 800mm version is about 40% longer than the 600mm, measuring at 281mm when retracted compared to the 199mm of the 600mm. In addition to being smaller than the 800mm version, I can use more affordable 82mm filters, compared to the more expensive 95mm filters used by the 800mm lens. But the biggest consideration for me was the price. At $699, the 600mm f/11 fit my budget compared to $899 for the 800mm f/11 model.