Last year, I decided to switch all my full-frame gear to the Canon EOS R7, a mirrorless model with a crop sensor and 32 megapixels.
I prefer shooting with zoom lenses, as they provide excellent sharpness, good optical qualities, and considerable flexibility.
However, I began to think that I might be able to extract even more detail from the R7 using prime lenses now available for Canon’s APSC cameras.
To investigate, I conducted a series of tests using my standard test chart, mounted on a tripod, and also took some intricate and detailed landscape shots mostly handheld.
I selected two prime lenses for this test: the Canon RF 24mm f1.8 IS Macro, which can also cover full-frame, and the Sigma 23mm f1.4 DC DN, designed specifically for the smaller APSC sensor.
The zoom lenses I used were the Canon RF-S 18-150mm f3.5-6.3 IS STM and the Sigma C 18-50mm f2.8 DC DN (which has a constant aperture).
I took numerous photos at various apertures and focal lengths, concluding with a final comparison at 23/24mm and f2.8 (not applicable for the RF-S 18-150mm), as well as f4 and f5.6.
The Sigmas lack image stabilization, while the Canons are equipped with it.
Since detailed test findings can be tedious, I will provide my conclusions. However, I want to touch upon sample variation in lenses and discrepancies in testing methods among various photographers.
These variations can lead to conflicting reviews—one person may favor lens A while another prefers lens B. It’s not about fault or deceit, but acknowledgment that there is often more variation in lens samples than in camera bodies and more difference in lens testing than in measuring camera attributes like digital noise or dynamic range.
My primary goal during these tests was to pinpoint which lens offered the sharpest detail reproduction, but I also noted other lens characteristics along the way.
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Using the Canon EOS R7 with Sigma 18-50mm f2.8 at f9. A highly intricate bush scene captured effectively here, despite challenging backlighting. |
Findings:
Both lenses I examined are well balanced, showing no noticeable difference in sharpness from left to right. Each one focuses quickly and accurately on the R7.
In the central area of the frame, all lenses are consistently sharp, with good edge performance on the long side. I found it impossible to distinguish between the test images without referring to the EXIF data.
Most of the variations between the lenses appear on the shorter side and in the corner areas.
The RF-S 18-150mm images exhibit slightly less contrast and acutance than those from the Sigmas but retain an equal amount of visual information that can benefit from additional contrast and sharpening in Adobe Camera Raw.
The least impressive lens among those tested is the Canon RF 24mm f1.8 Macro IS STM, which shows softer edges and corners. When comparing test images side by side, the RF 24mm distinctly trails behind the other three lenses.
I cannot recommend using this lens with Canon APSC cameras. My experiences on full-frame systems were similarly underwhelming.
Next in line is the Sigma 23mm f1.4 DC DN. Starting at f2.8, it offers no greater sharpness across the frame compared to the 18-50mm f2.8 zoom.
I can only recommend this lens if you specifically need an aperture of f1.4-f2. For instance, for interiors, low-light conditions, or performances, it may be necessary. However, I often find f2.8 sufficient, even indoors in lower light. With tools like Adobe Denoise AI and other noise reduction software, high ISO settings are much more manageable these days.
The Sigma 18-50mm f2.8 DC DN is a notable addition to the collection of quality zooms available for Canon’s RF mount crop sensor cameras. Currently, it is best utilized with the R7, which features in-body image stabilization, as this lens does not have its own optical stabilization. Despite being compact for a constant f2.8 zoom, it provides good to very good sharpness at all focal lengths and apertures down to about f11, beyond which diffraction begins to affect image quality.
As of April 2025, this lens is my top pick for low-light and indoor shooting with the Canon R7. It also performs well in landscape, street photography, and documentary settings.
The Canon RF-S 18-150mm IS STM boasts three times the zoom range of the Sigma and features optical stabilization. It offers the best close-up capabilities among the four lenses in this review and delivers good to very good image quality across the board at all focal lengths and apertures up to around f11. My copy of this lens performs slightly better than the Sigma at 18mm and is on par from 23-50mm, taking into account my previous comments about contrast and acutance.
Overall, this lens is the most versatile option and excels for outdoor photography and travel. The extended range of 18-150mm is particularly beneficial in many scenarios. It also provides good performance indoors at the wider end of the zoom, with f3.5 being only two-thirds of a stop smaller than the Sigma zoom.
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Canon EOS R7 with RF-S 18-150mm f3.5-6.3. |
A Great Lens Setup for Street and Lifestyle Documentary Photography
Overview
For my Canon R7, I use a three-lens kit which includes:
* Wide Angle:
Sigma C 10-18mm f2.8 DC DN (Equivalent to 16-29mm on full frame)
* Everyday Lens:
Canon RF-S 18-150mm f3.5-6.3 IS STM (Equivalent to 29-240mm on full frame) or
Sigma C 18-50mm f2.8 DC DN. (Equivalent to 29-80mm on full frame)
* Telephoto/Sport/Action/Wildlife:
The Sigma 18-50mm can be paired with the compact Canon RF-S 55-210mm f5-7.1 IS USM. (Equivalent to 88-336mm on full frame) Although lens testers often overlook this budget-friendly option, I find it provides great image quality across a versatile focal range.
If we consider the Canon RF-S 18-150mm as our standard lens, then the Canon RF 100-400mm f5.6-8 IS USM. (Equivalent to 160-640mm on full frame) would be the best telephoto option for our kit. This full frame lens performs excellently on both full frame and crop sensor cameras.
For extended reach, I also use the Canon RF 100-500mm f4.5-7.1 L IS USM, though it is considerably larger and more expensive compared to the previously mentioned lenses.
My lens preferences lean towards zooms. While I’ve extensively used prime lenses in the past, the newer zoom options have become lighter, more compact, and optically superior. Primes do offer a significant advantage in maximum aperture, which can be useful in low light conditions or for achieving a pleasing separation between the subject and the background.
Note: The sharpest APS-C lens I’ve tested is the EF-M 32mm f1.4 STM, which provides outstanding sharpness starting from f1.4 on a Canon M6.2 body. However, it lacks image stabilization, and autofocus on the M6.2 tends to be slow and rough. An updated version with better autofocus for the RF-S system would likely be well-received.
Another EF-M lens I’m eager to see adapted for the RF mount is the 22mm f2 STM. This lens is appealing due to its compact size and excellent sharpness throughout the frame. When attached, it barely sticks out past the front of the camera’s handle.
