Canon EOS R7 lens options. Primes or zooms ?

 

 

 

Last year I sold all my full frame gear in favour of the Canon EOS R7, a crop sensor mirrorless interchangeable lens model with 32 megapixels.

My preference and practice is to work with zooms, many of which offer excellent sharpness with good optical characteristics and great versatility.

But I started to wonder if maybe I could tease out even more image detail from the R7 with one of the prime lenses which are now available for Canon APSC cameras.

So I ran a series of tests using my usual test chart with the camera on tripod and some complex and highly detailed landscape subjects, mostly shot hand held.

I chose two primes, the Canon RF 24mm f1.8 IS Macro which can cover full frame if desired  and the Sigma 23mm f1.4 DC DN which only covers the smaller APSC sized sensor.

The zooms are the Canon RF-S 18-150mm f3.5-6.3 IS STM and the Sigma C 18-50mm f2.8 (constant) DC DN.

I made many photos with the lenses covering the full range of apertures and focal lengths with a final round of tests at 23/24mm and f2.8 (not available for the RF-S 18-150mm), f4 and f5.6 for close comparison.

The Sigmas do not have an image stabiliser, the Canons do.

The actual tests are boring so I will just offer my conclusions, but before doing so I need to make some observations on sample variation in lenses and testing variation in the hands of various photographers using different methods.

The effect of all these variations is that we can find one reviewer stating lens A is better than lens B and another reviewer saying the opposite. I believe it is not necessary to invoke fault or fraud to explain the range of opinions about any lens model but to acknowledge that there is more sample variation in making lenses than camera bodies and more variation in lens test procedures than in measuring camera parameters such as digital noise or dynamic range.

The main aim of my tests is to discover which lens gives me the sharpest rendition of fine subject details but I also looked at other lens characteristics along the way.

Canon EOS R7 with Sigma 18-50mm f2.8 at f9.  Extremely complex bush scene with difficult backlighting rendered nicely here. 

Results:

My copy of each lens is well centered with no significant difference in sharpness between the left and right sides of the frame. Each lens focusses accurately and quickly on the R7.

Each of the lenses is equally very sharp in a large central area of the frame and toward the edges on the long side of the frame. In this area I could not pick which lens made which test frame without the exif data.

Most of the differences between the lenses are on the short side of the frame and in the corners.

Files from the RF-S 18-150mm have slightly lower contrast and acutance than the Sigmas but contain the same amount of actual visual information which responds to a touch more contrast and sharpening in Adobe Camera Raw.

The least satisfactory lens of the group is the Canon RF 24mm f1.8 Macro IS STM. This delivers the softest edges and corners.  When the test files are viewed side by side the RF 24mm is obviously worse than the other three lenses.

I cannot recommend this lens for Canon APSC cameras. I have also used and tested it on full frame with the same disappointing results.

Next comes the Sigma 23mm f1.4 DC DN.   From f2.8 the 23mm offers no better sharpness across the frame than the 18-50mm f2.8 zoom.  

I can recommend this lens only if our use case absolutely requires an aperture of f1.4-f2.  Interiors, low light situations, stage performances and the like spring to mind.    I find that most of the time, even indoors in low light, f2.8 is quite good and these days with Adobe Denoise AI and other denoise software available, high ISO settings are not the problem they once were.

The Sigma 18-50mm f2.8 DC DN  is a welcome addition to the catalogue of good quality zooms now available for Canon RF mount crop sensor cameras. At the time of writing it is best used on the R7 which has an in body image stabiliser as the lens does not have an optical stabiliser. It is very compact for a constant f2.8 zoom, delivers good to very good sharpness across the frame at all focal lengths and apertures down to about f11 when diffraction at the aperture diaphragm starts to degrade image quality.

This is, in April 2025, my choice for low light and indoor work with the Canon R7. It is also good for landscape, street and documentary.

The Canon RF-S 18-150mm IS STM has three times the zoom range of the Sigma, an optical stabiliser, the best close-up capability of the four lenses tested here and good to very good image quality across the frame at all focal lengths and apertures up to about f11. My copy of this lens is a bit better than the Sigma at 18mm and just as good from 23-50mm, bearing in mind my comments about contrast and acutance above.

This is the most versatile of the four lenses and the best for any outdoor work and travel. The extra reach of the 18-150mm is very welcome in many situations.  This lens is also good indoors at the wide end of the zoom with f3.5 being only 2/3 stop smaller than the Sigma zoom.

Canon EOS R7 with RF-S 18-150mm f3.5-6.3.  A good combination for street and lifestyle documentary work 

Summary

My three lens kit for the Canon R7 consists of:

* Ultrawide:

Sigma C 10-18mm f2.8 DC DN  (Full frame equivalent 16-29mm)

* Standard:

Canon RF-S 18-150mm f3.5-6.3 IS STM (Full frame equivalent 29-240mm)  or

Sigma C 18-50mm f2.8 DC DN.    (Full frame equivalent 29-80mm)

* Telephoto/sport/action/wildlife: 

The Sigma 18-50mm  can be complemented by the very compact Canon RF-S 55-210mm f5-7.1 IS USM. (Full frame equivalent 88-336mm) Lens test specialists usually ignore or denigrate this modest little lens but I find it delivers very good image quality over a useful range of focal lengths.

If our standard lens is the Canon RF-S 18-150mm, then the Canon RF 100-400mm f5.6-8 IS USM. (Full frame equivalent 160-640mm) is the ideal telephoto for our kit. This is a full frame lens which gives very good results on either full frame or crop sensor bodies.

For greater reach I also use the Canon RF 100-500mm f4.5-7.1 L IS USM however this lens is much larger and more expensive than the others mentioned here.

My preferred lenses are all zooms. I have nothing against prime lenses having used them exclusively for many years. But zooms have become smaller, lighter and much better optically than they were a few years ago. The main advantage of current model primes is their greater maximum aperture which may be desirable in some low light situations and when visual separation between subject and background is desired.

Footnote:  The sharpest Canon APSC lens I have ever tested is the EF-M 32mm f1.4.STM which delivers excellent to outstanding sharpness right from f1.4 on a Canon M6.2 camera body. Unfortunately it lacks an image stabiliser and autofocus on the M6.2 is slow and jerky. If Canon introduced an updated version of this with better AF for the RF-S system I think it would be well received.

Another EF-M lens I would like to see with the RF mount is the 22mm f2 STM. The selling point of this little lens is its very compact size together with good sharpness across the frame. When mounted it hardly protrudes beyond the front of the camera handle.