Canon RF mount full frame lens shootout Primes vs Zooms 16 December 2022

 

I own and use 11 full frame RF mount lenses, 5 primes and 6 zooms.  Each has its uses but I thought it might be interesting to compare them side by side at each focal length.

The standard doctrine is that zooms offer more versatility while primes usually offer smaller size, a greater maximum aperture and better optical quality.

I compared the lenses under controlled conditions using a fixed flat test chart and also gained experience photographing a range of subjects in the real world. I used a Canon EOS R5 camera and CRAW capture, processed in Adobe Camera Raw, with and without the relevant Adobe lens profile.

Let us begin at the ultrawide end of the focal length range.

15/16mm

Not so many years ago full frame (a.k.a. “35mm”) ultrawide lenses were rare and expensive things used by few photographers. These days with advances in lens technology and post capture file processing they have become readily available to amateur and enthusiast photographers at an affordable price.

I compared the RF 16mm f2.8 prime to the RF 15-30mm f4.5-6.3 zoom at 15mm.

Strange as it may seem the 16mm prime gives a wider angle of view than 15mm on the zoom. Both exhibit massive barrel distortion, color fringing  and peripheral shading with the lens profile disabled.  The profile for the zoom leaves some barrel distortion in the file. This can be corrected manually if desired for architecture.

With each lens at its widest aperture sharpness is equal in the center and on the short side of the frame but the zoom at f4.5 is sharper on the long side and in the corners than the prime at f2.8.

At f5.6 I see no significant difference in sharpness between the two lenses.

It appears the standard doctrine holds good here.  In practice the main advantage of the prime is its compact dimensions and lower price. Peripheral image quality from the prime is poor at f2.8 so we would need to be selective about using the lens at that aperture.  If we don’t mind the extra size and higher price of the zoom it gives us the option of 15, 20, 24, 28 and 30mm focal lengths, a very handy range.

24mm

This time I compare the RF 24mm f1.8 prime with the 15-30mm, 24-105mm L, 24-105mm STM and 24-240mm USM, each tested at 24mm. We have many options at this focal length.

I rate the 24-105mm f4L zoom the best of the bunch overall looking at sharpness, clarity, distortion, peripheral shading and color fringing. At f5.6 my copy of the 24-105mm L is just a touch better than the 24mm f1.8 prime. Next best is the 15-30mm although the widest aperture available to the ultrawide zoom at this focal length is f5.6. Bringing up the rear we have the 24-105mm STM and the 24-240mm USM, both of which are just fine in the center of the frame but fall away in the periphery with softness, shading and prominent color fringing.

When viewed without the Adobe profile the 24mm prime, 24-105mm STM and 24-240mm each exhibit massive barrel distortion. The 24-105mm f4L has mild barrel distortion, the 15-30mm none at this focal length.

The 24mm prime is quite disappointing here showing as much barrel distortion as the two least sharp zooms.

The 24mm prime obviously is the most compact of the bunch and the only one with an aperture wider than f4. So if those two qualities are important the prime is the clear choice. If the size, mass and price are not a problem the 24-105mm f4L is the best of this bunch at 24mm.

35mm

Now I compare the RF 35mm f1.8 with the three zooms, 24-105 STM, 24-105 L and 24-240.

Overall there are fewer differences between the lenses at 35mm than we saw at 24mm.  Even the 24-105 STM and 24-240 which were rather soggy around the edges at 24mm clean up nicely at 35mm.

Each of the lenses delivers equal sharpness in the center of the frame.

Without the Adobe profile the 24-105 L shows mild pincushion distortion, the others mild barrel distortion.

At the widest available aperture sharpness is about equal for all four lenses across the frame. The prime is at f1.8 and showing the greatest amount of peripheral shading and some loss of contrast although sharpness is retained right into the corners. This is a noticeably better performance in the image periphery than we saw from the 24mm prime.

At f5.6 the prime and the 24-105 L are slightly better in the periphery than the 24-105 STM and the 24-240.  The 24-240mm in particular leaves substantial color fringing in files requiring more attention in post processing than the other lenses in this group.

As expected,  the prime delivers the most compact package with the widest aperture. It is also arguably one of the most versatile prime lenses.

50mm

Here the index prime is the RF 50mm f1.8 “nifty fifty” which is the smallest, lightest and least expensive RF lens in the catalogue.  

How does it fare against the larger, heavier and more expensive zooms ?

The 24-105mm f4 L costs 6 times as much and has 4.5 times the mass of the 50mm prime.

Most modern lenses which I test these days are just about as sharp in the center wide open as they will ever get. But the RF nifty fifty is a modern version of an old 6 element double gauss design which typically is not as sharp in the center wide open as when the aperture is closed down a stop or two.

And so it is with the RF 50mm f1.8. This lens is not quite tack sharp in the center at f1.8. The periphery holds up quite well for sharpness but there is considerable shading and loss of contrast towards the corners. Things improve noticeably by f2.8 and by f4 everything looks very sharp, clear  and contrasty right across the frame.

The zooms are sharper across the frame than the prime at their maximum apertures but we are talking about f4 and f5 here compared to f1.8.

At f5.6 the prime is better than each of the zooms although the 24-105mm L comes close. The 24-105 STM and 24-140 trail behind with the 24-105 STM delivering the worst result. Even so that lens is not a bad one. I have used it quite frequently and been quite pleased with what it can do.

So, there are no bad choices at this focal length but if we were to estimate an image quality to cost ratio the RF 50mm f1.8 would come out way ahead.

100mm

This time I pit the RF 100mm f2.8 L macro against a group of zooms, each at 100mm focal length.  These are the 100-500mm L, 100-400mm f5.6-8, 24-105mm f4 L, 24-105mm STM and 24-240mm USM.

With each lens at its widest aperture the 100mm L macro at f2.8 is sharper and more contrasty across the frame and into the corners than any of the zooms at f4, 4.5, 5.6 and 7.1 respectively.

The 100mm macro also exhibits virtually no distortion, color fringing or significant other deviation from optical excellence. On top of that when mounted on the R5 the RF 100 L macro has super fast AF and an excellent stabiliser. It is much more than a super macro lens. It would be very suitable for sport/action or portraiture or anything else requiring a 100mm focal length.

Next best lens in this group is the RF 100-500mm L which delivers excellent image quality across the frame at all apertures and focal lengths. 

The rest of the zooms are also-rans in this company. Somewhat disappointingly, this includes the RF 24-105mm f4 L which at 100mm is not a great performer. It is by no means a bad lens but is no better than the 24-240mm at this focal length.

All six lenses deliver equal and excellent sharpness, clarity and contrast in the center of the frame at f8. But there are significant differences between them as we approach the periphery of the frame.

Summary and comment

Are the primes in this shootout  better than the zooms ?

Hmmm………….In some respects yes. With the exception of the RF 100mm f2.8 L macro they are smaller, lighter and less expensive and they all offer a wider maximum aperture. 

On the other hand the zooms are more versatile, that being the raison d’etre  of zoom lenses.

Image quality is a mixed festival. At some focal lengths and apertures the primes offer better imaging capability but sometimes one or other of the zooms might be better.

Recommendations ?

If I were on a budget and limited to just one lens, what would it be ?

I rate the RF 24-105mm f4L the best all purpose, do most things choice among the lenses tested here. It is some way off perfection but looking at what it can deliver across the whole focal length range the 24-105 L gets my recommendation.

Among the primes I recommend the RF 35mm f1.8 or 50 mm f1.8. These offer excellent imaging capability with compact dimensions at a budget price.

The 100mm f2.8 L macro is outstanding as a macro or general purpose lens although large and expensive.

The 100-500mm f4.5-7.1 L zoom is also outstanding optically and functionally for sport/action/wildlife. Or anything else requiring a long lens. This lens is by far the largest, heaviest and most expensive in this group but has become a firm favourite with wildlife/bird/sport/action photographers because it delivers such good results.

The RF 24-240mm f4-6.3 USM is one of the few decently competent full frame 10x zooms available for any camera system and I can recommend it for occasions when maximum zoom range  is required from a single lens.