Light artillery: Canon RF 600mm and RF 800mm tested

Lenses with an ultra-long focal length would sometimes be very practical. For example, to photograph birds. But the 500-millimetre or longer gun tubes are so big, heavy and expensive that I never seriously considered buying a super telephoto lens. One afternoon with a three-kilogram monster was enough for me.

Now, however, Canon has two new lenses with focal lengths of 600 and 800 millimetres respectively, which are relatively small, light and inexpensive. The smaller of the two measures less than 20 cm in length when retracted and weighs less than a kilo.

The obvious catch is the poor light intensity of f/11. Birds move quickly and therefore need to be photographed at shutter speeds of 1/1000 of a second or even faster. High ISO values are therefore necessary with a low-light lens. The autofocus also gets relatively little light. Is that even possible?

By the way: The aperture is fixed at f/11. It can therefore not be reduced.

I am very excited about this test. But also very sceptical.

First look

First, I fiddle around with the 800mm lens at home. The closest focusing distance is 6 metres. From the far corner of the living room, I barely manage to focus on the reading lamp at the other end of the room. The lamp completely fills the picture.

At 1/400 of a second, the hand-held image is sharp, with a bit of luck also at 1/125 of a second. Not bad for an 800 millimetre focal length. For static subjects, you can keep the ISO values relatively low.

The two lenses are relatively short when retracted. The disadvantage of this is that they have to be extended before each use. To do this, first turn one ring slightly to the left, pull out the lens and turn the ring to the right again.

Normally, I don't care whether or not a bag is supplied with the lens. I do here. The bag is very practical. The carrying handle also serves as a handle for the double zip. With the removable strap, the bag can also be carried comfortably over the shoulder.

Contrary to my earlier information, the lens hood was also included in the scope of delivery.

Both lenses have a wide focus ring and a narrower function ring that can be freely assigned. There is also a switch that can be used to limit the focus range so that the focus motor has to travel less distance.

Fully extreme in the first attempt

I drive to the lake in the morning and take the tripod with me. Unfortunately, without the plate that connects the camera to the tripod. So I have to take all the shots by hand

A good opportunity to immediately test the limits of what is possible. I screw the 1.4x teleconverter onto the 800 mm lens. This extends the focal length by a factor of 1.4, i.e. to 1120 mm. The aperture is reduced by the same factor and is now f/16. Fortunately, the closest focusing distance remains at 6 metres.

Even the 2x teleconverter would be compatible with the 800mm. This would give you a focal length of 1600 mm at a speed of f/22, but I wasn't able to try it out.

Well, 1120 mm and f/16 sound pretty absurd. But to my surprise, I realised that the pictures came out okay. All freehand, not a single one out of focus.

I set the shutter speed to automatic and the camera set it fast enough. With a focal length of 1120 mm, they are typically 1/1000 or 1/1250 of a second. This means that the images would be sharp even without image stabilisation.

I also set the ISO values to automatic. This leads to values between 500 and 12,800 ISO at aperture f/16. Even in sunshine, I'm usually in the four-digit range. Here is a picture with 5000 ISO.

I use the lens together with the Canon EOS R5. At full magnification (eye) you can see that the image is a little noisy. But with the 45 megapixels, you practically never need the full magnification. As soon as the photo is zoomed out, the noise is no longer a problem.

The focus area

The autofocus sometimes struggles a little. Is it due to the low amount of light that the lens lets through or the autofocus itself? Or even the photographer?

At home, I notice that with both Superteles, the field of focus is limited to a relatively small area in the centre of the image. With the other lenses I was allowed to try out, the 15-35mm and the 24-70mm, the entire image can be focussed. In the two screenshots, you can recognise the focusable area by the white frame corners.

This is confirmed when photographing animals. With the Canon EOS R5, subject tracking with face and eye recognition basically works well. But with the Superteles, the animal's head must always be in the centre of the image. This is not desirable in terms of image composition and sometimes not even possible, as the movements of the animals are often unpredictable.

Here the eye is still in the focusable area. The camera recognises it and focuses on it.

A split second sooner or later, the eye is out of range, and the subject recognition focuses on something in the centre of the image - the eye becomes slightly out of focus.

Photographing animals with the RF 600mm

I take the smaller of the two Superteles with me to the zoo: The RF 600mm. The automatic system favours shutter speeds of around 1/600 of a second. This prevents camera shake, but you are usually in the four-digit ISO range. This image under a cloudy sky has 3200 ISO.

Shots taken at 1/200 second are still sharp for the most part with the image stabiliser. If an animal is only moving slowly, you can keep the ISO sensitivity relatively low.

This image of the bear in the shady forest has an exposure time of 1/250 second. However, with 12 800 ISO. Reduced to this size, the image is usable, but the image noise is noticeable when zooming in.

It's even darker in the lynx's enclosure. The upper limit of the automatic ISO is set to 12,800 ISO. If this is not enough, the camera exposes for longer. The photo with the lynx therefore has an exposure time of 1/100 second. The animal is definitely moving too fast for this, and even the image stabiliser no longer guarantees sharp images. Especially as the teleconverter is also used here - the focal length is therefore 840 mm.

The video recordings clearly show that the image stabiliser does a great job. In this clip, I couldn't even rest my elbows on the camera, but the image is still reasonably steady.

A fixed aperture naturally restricts the design options. But that didn't bother me during testing. At a focal length of 600 or 800 millimetres, f/11 offers a reasonable depth of field in almost all situations. The background stands out nicely, while the main subject remains more or less sharp. Sure: If an animal is standing directly in front of a busy background, it doesn't look nice, but that wouldn't be significantly better even with a slightly larger aperture.

Conclusion: Amazingly good

The RF 600mm and RF 800mm are niche products, but they are no joke. I wouldn't have thought so before testing them, but I seriously recommend these two lenses. Especially the more versatile, cheaper and handier RF 600mm. In normal daylight, even when the sky is overcast, the light is sufficient to take good pictures. Only in the depths of the forest or at dusk is the fun over. The autofocus still works, but the exposure times are then too long for moving subjects - or the ISO is too high.

But that was clear from the start. The only negative surprise for me was that the subject tracking and the autofocus in general is limited to a square in the centre of the image.

How much is possible with the two lenses also depends on the camera. The Canon EOS R5 delivers what these superteles need: it is fast, has a low-noise sensor and super autofocus. The lenses on the EOS R6 would also be a pleasure to use, as it is also fast and low-noise. Its autofocus is even more sensitive to light. However, I would be more cautious with the EOS R and RP. Image noise, autofocus and continuous shooting speed are clearly worse there.

The better the cameras get, the better inexpensive superteles work. I hope that other manufacturers will soon design something similar. <p