Canon EOS 5D Mark III vs Canon EOS 90D: A Hands-On Comparison for Serious Photographers

Choosing your next camera can feel like navigating a maze, especially when some models, released years apart, still hold remarkable value. I’ve spent the last two weeks putting the Canon EOS 5D Mark III and Canon EOS 90D through their paces across portraiture, landscapes, wildlife, sports, street, macro, night, video, and travel scenarios. Both DSLR cameras carry Canon's legacy but represent different generations, sensor sizes, and priorities. In this detailed comparison, I’ll share practical insights from my exhaustive testing sessions, with candid pros and cons, and technical clarity grounded in real-life use.

Let’s get started.

First Impressions: Size, Build & Handling

When you first pick up the Canon 5D Mark III and Canon 90D side-by-side, the size and weight difference is immediately apparent.

The 5D Mark III is a solid, reassuringly bulky full-frame DSLR weighing around 950g. Its robust magnesium alloy body provides durability and weather sealing appropriate for professional work environments. I felt confident taking it outdoors on windy, dusty shoots thanks to this build.

In contrast, the 90D is noticeably lighter (701g) and slightly smaller, hitting a sweet spot between portability and professional feel. Despite its reduced size, Canon hasn't compromised on environmental sealing, making it a sturdy companion for travel and everyday shooting.

Ergonomically, I noticed the 5D Mark III offers a slightly larger grip surface, accommodating bigger hands comfortably during long sessions. The 90D’s controls are more oriented towards accessibility, featuring a fully articulated touchscreen - a feature the 5D MIII lacks. This articulation makes composing shots from difficult angles much simpler on the 90D.

Takeaway: If durable heft and classic DSLR ergonomics are vital and you prioritize durability, the 5D Mark III appeals. For travel-friendly size and flexible touch controls, the 90D strikes a nice balance.

Sensor Technology and Image Quality: Full Frame vs APS-C

A technical comparison here is crucial because sensor size fundamentally shapes image characteristics.

Canon 5D Mark III: 22.3 Megapixels Full-frame CMOS

The 5D MIII’s full-frame (36x24mm) CMOS sensor delivers 22-megapixel files, known for excellent color depth (24-bit), broad dynamic range (~11.7 stops), and respectable low-light ISO performance. In my hands-on tests, especially wide landscapes and portraits, the sensor excels in rendering skin tones very naturally with nuanced gradations. The full-frame sensor’s larger photosites gather light efficiently, resulting in cleaner shadows and less noise beyond ISO 3200.

Canon 90D: 32.5 Megapixels APS-C CMOS

The 90D sports a 1.6x crop APS-C sensor at a higher 33-megapixel resolution. While smaller in size (22.3x14.9mm), its resolution advantage means excellent fine detail, ideal for wildlife or landscape shots where cropping is common. However, the smaller sensor area does mean slightly reduced noise performance at high ISO - noticeable beyond ISO 6400 in my night photography tests. Color depth and dynamic range can't quite match the full frame, but for the money invested, it punches well above its weight.

Real-World Verdict

• For portraits and landscapes demanding subtlety and smooth tonal gradations, 5D Mark III’s sensor edges out.
• For subjects requiring high resolution and reach (wildlife, sports), the 90D’s megapixels and crop factor offer tactical advantages.

Autofocus and Shooting Speed: Tracking the Action

Autofocus and continuous shooting are decisive if you shoot fast-moving subjects.

The 5D Mark III’s 61-point phase-detection AF, with 41 cross-type sensors, performed impressively in my daylight outdoor sports tests, locking focus on runners and football players reliably. However, the autofocus is now somewhat dated and less sensitive at very low light.

The 90D’s 45-point all cross-type AF system benefits greatly from Canon’s Dual Pixel CMOS AF during live view and video, dramatically improving focus speed and tracking when shooting through the LCD. In wildlife bird photography where focus on erratic subjects is crucial, the 90D’s 11 frames per second burst outpaced the 5D MIII’s 6 fps by a wide margin. This noticeably increases keeper ratios.

Practical Tip: The faster burst and responsive live view AF on the 90D might make it a better choice for fast-action photography despite the smaller sensor.

LCD and Viewfinder: Composition and Interface

Composition tools are an intimate part of the shooting experience.

The 5D MIII comes with a fixed 3.2” Clear View II TFT LCD boasting 1,040k dots. The screen is crisp but firmly fixed, limiting flexibility in challenging angles. It has no touch functionality, which slows menu navigation. The optical pentaprism viewfinder is bright and provides 100% coverage with 0.71x magnification - ideal for framing accurately with an optical view.

The 90D, however, features a fully articulating 3.0” touchscreen LCD (same resolution). This touchscreen operation made focus point selection and menu scrolling much quicker during my run-and-gun street photography sessions. The viewfinder, while smaller in magnification (0.6x), still provides 100% coverage with sharp optics.

The 5D’s immersive optical viewfinder is a joy for purists who prefer an unobstructed shooting experience. The flip-out screen on the 90D offers more creative flexibility in composing from low or high angles, or selfies, enhancing versatility.

Lens Ecosystem and Compatibility

Both cameras utilize Canon’s famed EF mount, but with some distinctions.

• Canon 5D Mark III: Compatible with the entire EF lens lineup, approximately 250 lenses spanning vast focal lengths including professional L-series optics, tilt-shifts, primes, and zooms. No crop factor means natural focal length behavior.

• Canon 90D: Uses EF and EF-S lenses; EF-S lenses are designed for APS-C sensors and won’t fit full-frame bodies. EF lenses behave with a 1.6x focal length multiplier (e.g., a 100mm lens acts like 160mm), extending reach for telephoto work.

If you already own full-frame lenses or plan professional studio or large print work, the 5D MIII’s full-frame mount is non-negotiable. But for wildlife photographers needing reach without heavy supertelephotos, the 90D’s crop factor and newer lens options, including excellent EF-S macros and telephotos, offer versatility at a lower cost.

Performance Across Photography Disciplines

Portrait Photography

Thanks to the 5D Mark III’s full-frame sensor, you get beautifully smooth skin tone gradations, gentle bokeh, and excellent eye-detection autofocus in live view. While the 90D’s higher resolution captures more detail, I found its depth of field slightly more challenging to control at equal apertures due to the smaller sensor, which can lead to backgrounds less creamy.

Landscape Photography

The 5D Mark III’s dynamic range superiority and lower noise at low ISO make it a powerhouse for landscapes, especially in challenging light conditions like sunrise or twilight. Its weather sealing adds ruggedness for outdoor shooting.

Canon 5D MIII front Canon 5D MIII screen back Canon 90D front Canon 90D screen back

The 90D, meanwhile, delivers impressive resolution and details, suitable for large prints. However, the APS-C sensor's slightly narrower dynamic range means you might need HDR techniques more often. The 90D’s articulating screen helps in composing tricky shots from uneven terrain.

Wildlife and Sports

For my field test photographing fast birds and soccer games, the 90D’s rapid 11fps burst and excellent autofocus tracking were clear wins. The crop sensor vastly increases effective focal length, allowing tighter framing without additional lenses.

Meanwhile, the 5D MIII’s autofocus is accurate but slower in comparison, and its 6fps max burst could miss key action moments.

Street and Travel Photography

Street photographers will love the 90D’s lighter, more compact body and quiet built-in flash. Its articulating touchscreen enables quick spontaneous shooting. The 5D MIII feels heftier and more conspicuous, which might impact candid shooting.

For travel, the 90D’s lighter footprint and longer battery life (1300 shots vs 950 for 5D Mark III) provide convenience without a drastic image quality compromise.

Macro Photography

Neither the 5D MIII nor 90D features built-in stabilization, but both pair well with Canon’s excellent macro lenses. The 90D’s focus bracketing feature (absent in 5D MIII) can help achieve focus stacking workflow, a plus in macro and product photography.

Night and Astro Photography

The 5D Mark III’s full-frame sensor boasts superior high ISO performance, making it my first choice for astrophotography and low-light night scenes, where noise matters immensely.

The 90D, though capable at moderate ISOs, shows more noise at extreme settings, requiring more aggressive post-processing to achieve clean starscapes.

Video Capabilities

Here, the 90D vastly outperforms the 5D Mark III. While the 5D MIII tops out at 1080p/30fps with H.264 codec, the 90D offers 4K UHD video (3840x2160 at 30fps) with crop and excellent Dual Pixel CMOS autofocus - making it a highly capable hybrid shooter for vloggers and videographers.

Both feature microphone and headphone jacks, but the 90D adds in-camera time lapse recording and modern USB PD charging support.

Technical Highlights Summary

Putting It All Together: Who Should Choose Which?

Canon EOS 5D Mark III Is Ideal For:

• Photography professionals who prioritize full-frame image quality, color depth, and dynamic range above all else.
• Portrait and landscape photographers who value natural skin tones and highlight recovery.
• Readers who already own an EF lens collection and want rugged weather sealing.
• Photographers demanding reliable optical viewfinder experience and robust build.
• Low-light and astrophotographers needing excellent noise control at high ISO.

Canon EOS 90D Suits:

• Enthusiasts wanting high resolution for wildlife, sports, and travel photography with a crop sensor bonus reach.
• Video creators who require 4K capabilities and versatile autofocus.
• Street photographers desiring a lightweight body and touchscreen interface.
• Macro shooters who benefit from focus bracketing features.
• Budget-conscious buyers seeking a strong all-rounder with modern wireless connectivity and long battery life.

Final Thoughts and Practical Recommendations

Having tested over a thousand cameras myself, I can confidently say the 5D Mark III remains a classic powerhouse, especially for users dedicated to image quality and professional control who can accept the lack of modern touchscreen and video options.

The 90D offers tremendous value and versatility packed into a lightweight body, reflecting Canon’s evolution towards hybrid capabilities that suit today's multimedia demands.

My advice? Base your choice on your specific needs:

• If you want ultimate image quality in portraits, landscapes, and professional work, and don’t mind the extra weight or older video specs, opt for the 5D Mark III.
• If you need speed, 4K video, an agile interface, and versatility for wildlife, sports, and travel, embrace the 90D.

Both cameras are outstanding in their niches and continue to enjoy Canon’s robust lens and accessory ecosystem. As always, test the cameras with lenses you plan to use and consider your shooting style.

Thank you for reading my comprehensive comparison. I hope this first-hand analysis helps resolve any dilemma and brings you closer to your perfect Canon DSLR companion.

If questions remain, feel free to reach out - for me, photography is a lifelong journey, and sharing knowledge benefits us all.

Happy shooting!