Canon EOS 40D vs Canon EOS 6D: A Deep Dive into Two Generations of DSLR Excellence

In the rapidly evolving landscape of digital photography, Canon has consistently maintained a strong presence across a spectrum of enthusiast and professional cameras. The Canon EOS 40D and the Canon EOS 6D, though separated by over five years of technological innovation, both occupy significant niches within Canon’s DSLR lineup. Understanding their relative strengths and limitations requires not only a review of specifications but also a real-world, practical comparison across multiple photography disciplines.

Having personally tested these two models extensively over thousands of shots and under varied shooting conditions, I provide here an exhaustive comparison tailored for photography enthusiasts - and professionals contemplating either an upgrade or a considered purchase of a DSLR suited to their specific needs.

Size, Build, and Ergonomics: Which Fits Your Hands and Workflow Better?

Physical handling and camera layout are often underestimated factors in long-term user satisfaction and productivity. The Canon 40D and Canon 6D are both aimed at mid-size DSLR users, but their design philosophies reveal notable differences reflective of their eras.

Canon 40D - Robust Mid-2000s Workhorse

Introduced in 2007, the 40D features a body dimension of 146 x 108 x 74 mm, weighing approximately 822 grams. Its magnesium alloy chassis with weather sealing (though not waterproof or dustproof in the strictest sense) offers solid durability for demanding outdoor usage. The body has a slightly boxier shape which some photographers find provides a reassuring grip in challenging conditions, although the rubberized grip is moderate by modern standards.

Canon 6D - Lighter and Optimized for Extended Use

The 6D, announced in 2013, is slightly smaller at 145 x 111 x 71 mm and lighter with a weight of 770 grams, thanks largely to lighter materials and design optimizations for portability. While it also sports environmental sealing, Canon emphasizes it more strongly as “weather resistant” compared to the 40D, making it better suited to adverse conditions with less bulk.

Practical Implications

Users who prioritize ruggedness and firm grip for long hiking days or outdoor shooting may prefer the familiar heft and ergonomics of the 40D. Conversely, photographers who travel frequently or shoot handheld for extended periods will appreciate the 6D’s lighter, sleeker build which reduces fatigue and fits better in more compact bags.

Top-Panel Controls and User Interface: Streamlining Your Shooting Experience

User interface can dramatically affect efficiency, especially in dynamic photography genres like sports or wildlife.

The 40D provides a dated but intuitive control layout typical of Canon's DSLRs from its era, with a top LCD display that shows vital shooting parameters - aperture, shutter speed, ISO, and remaining shots. However, this LCD is monochrome and quite low resolution (230K dots on the rear screen), limiting real-time image review clarity.

In contrast, the 6D integrates a more updated control scheme combined with a 3-inch Clear View II TFT rear LCD at 1,040K dots resolution. Despite lacking touchscreen capability, the interface benefits from higher visual fidelity, making image review and menu navigation more satisfying and efficient. Notably, the 6D foregoes the top LCD panel, relying entirely on the rear screen for parameter visualization - a shift catering to the trend of more interactive rear displays.

The 6D’s shutter speed dial maxes out at 1/4000s compared to the 40D’s faster 1/8000s, a trade-off that may influence shutter priority shooting, particularly under bright conditions with wide apertures.

Sensor Technology and Image Quality: Resolution, Dynamic Range, and ISO Performance

Arguably the heart of any camera decision, sensor attributes dictate initial image quality and downstream processing flexibility. Here the gap between a 2007 APS-C sensor (40D) and a 2013 full-frame sensor (6D) is pronounced.

Canon 40D’s APS-C 10.1MP Sensor

The 40D sports a 10.1-megapixel CMOS APS-C sensor (22.2 x 14.8 mm), offering a crop factor of 1.6x. While sufficient for web and moderate print sizes, its resolution and pixel density pale compared to modern standards. The in-camera anti-aliasing filter ensures moiré reduction but slightly softens fine detail.

Tests with DXOmark rate the 40D’s color depth at 22.1 bits, dynamic range at 11.3 EV, and low-light ISO sensitivity around 700 ISO equivalent. While solid for its time, the data reveal considerable noise and dynamic limitation, particularly beyond ISO 800. These factors impact low-light usability and highlight roll-off in shadow recovery.

Canon 6D’s Full-Frame 20.2MP CMOS Sensor

The 6D introduced a full-frame sensor measuring 36 x 24 mm, with 20.2 megapixels, effectively doubling the area capturing photons compared to the 40D’s sensor. The larger sensor allows for greater pixel area, resulting in lower noise levels, better highlight/shadow retention, and more nuanced color reproduction.

DXOmark benchmarks show the 6D’s color depth at 23.8 bits, dynamic range at 12.1 EV, and outstanding low-light ISO performance rated around ISO 2340, with a maximum native ISO reaching 25600 (and expandable to 102400). In practical terms, this means the 6D produces cleaner images in dim settings, more latitude in post-processing highlights and shadows, and sharper detail retention.

Practical Outcome

Landscape and portrait photographers relying on subtle tonal gradations and maximum image quality should favor the 6D for its sensor excellence. The 40D remains competitive for daylight and well-lit scenarios but reveals its age under tough conditions.

Autofocus System: Speed, Accuracy, and Versatility in the Field

Critical to all photography forms except long exposures and conceptual still life, autofocus technology impacts your hit rate and creative flexibility.

The 40D’s 9-point AF system was commendable when launched but now seems restrictive and basic. The lack of eye or face detection and no AF during live view severely limits performance for portrait and action shooting with the rear screen.

The 6D upgraded to an 11-point sensor, including one cross-type point at the center, improving accuracy in various lighting. More importantly, the inclusion of face-detection AF while in Live View enhances precision for portraits and video. Despite improvements, neither camera offers animal eye detection or high-density AF point arrays favored in modern sports and wildlife cameras.

Real-World Implications

For wildlife and sports photography where tracking moving subjects is essential, both cameras lag behind modern standards, but the 6D offers better base AF coverage and Live View focusing capabilities. Street photographers shooting handheld can appreciate the 6D’s quicker and more reliable AF in challenging situations.

Burst Rates and Buffer Capacity: Capturing the Decisive Moment

Shooting speed is indispensable for fast-action genres such as sports and wildlife photography:

• Canon 40D: 6.5 fps continuous shooting
• Canon 6D: 4.5 fps continuous shooting

Here the 40D takes a small edge with a faster frame rate, an unexpected advantage given its older release. However, this speed comes with a lower resolution sensor, meaning smaller files and less data to process, helping maintain faster shooting.

The 6D’s slower 4.5 fps burst is modest but paired with a far higher resolution sensor and larger files. Moreover, the 6D’s buffer handles approximately 10 RAW images before slowing, whereas the 40D’s buffer is roughly 12 RAW images - a trade-off reflective of the era’s technology and data volume.

Overall, if relentless high-frame capture is a priority over resolution, the 40D may pull ahead, though in modern terms even 4.5 fps can be limiting.

Viewfinder and LCD Screen: Framing and Reviewing Your Shots

The optical viewfinder experience affects framing comfort, especially in bright sunlight or fast-moving conditions.

• 40D: Optical pentaprism, 95% coverage, 0.6x magnification
• 6D: Optical pentaprism, 97% coverage, 0.71x magnification

The 6D offers better scene framing by providing marginally more coverage and larger, brighter optics enhancing manual focus accuracy and composition assessment through the viewfinder.

The rear LCD of the 6D is superior, with over four times the resolution of the 40D, facilitating image review, menu navigation, and live view shooting.

Lens Ecosystem and Mount Compatibility

• 40D: Canon EF/EF-S mount - compatible with Canon's extensive range of EF and EF-S lenses
• 6D: Canon EF mount only - supports full-frame EF lenses exclusively

If you own a collection of EF-S lenses built for APS-C sensors, the 40D is your go-to. However, the full-frame 6D unlocks access to Canon’s full-frame EF lens lineup, offering superior optical qualities and a wider field of view on equivalent focal lengths.

Because the 6D lacks EF-S lens compatibility, users attracted to the budget and size benefits of EF-S lenses must weigh this limitation. Nonetheless, the EF lens lineup remains vast, and many consider the 6D’s full-frame sensor benefits worth the lens transition.

Battery Life and Storage: Keeping You Shooting Longer with Convenience

The 6D offers better battery life, a decisive advantage for travel and event photographers who need longevity without carrying multiple spares. The shift from now less-common CompactFlash cards to SD cards on the 6D enhances compatibility and convenience, as SD cards are more affordable and ubiquitous.

Connectivity, Video, and Additional Features

The 40D predates the video capabilities era, offering no video recording, no HDMI output, and no wireless connectivity.

The 6D marks a significant leap here: it supports Full HD 1080p video at 30fps, includes a microphone port for better audio capture, built-in GPS for geotagging, and integrated Wi-Fi connectivity for remote control and wireless image transfer - features considered critical to modern photography workflows and content creation pipelines.

While video enthusiasts may find the 6D’s video features modest compared to dedicated mirrorless models, its presence is a huge step forward compared to the 40D.

Durability and Environmental Resistance

Both cameras are weather-sealed but not explicitly waterproof or ruggedized to military specs. Photography outdoors in moderate adverse conditions (dust, light rain) is feasible, though neither should be subjected to harsh environments without protective covers.

Sample Images and Performance Across Photography Genres

Canon 40D front Canon 40D screen back Canon 6D front Canon 6D screen back

Extensive shooting comparisons reveal strengths and compromises in practical photography contexts:

• Portraits: The 6D’s full-frame sensor excels with natural skin tones, smoother bokeh, and more accurate eye detection autofocus. The 40D’s APS-C sensor produces decent portraits but with slightly harsher skin tone gradations and less shallow depth of field at equivalent focal lengths due to crop factor.

• Landscape: The higher dynamic range and resolution of the 6D render it superior for fine detail capture in expansive scenes with high contrast. The 40D performs admirably in bright conditions but suffers shadow noise and highlights clipping under tough lighting.

• Wildlife/Sports: The 40D’s faster burst rate can yield more action shots, but overall AF system limitations constrain effective tracking. The 6D's better ISO handling facilitates low light shooting in wildlife or dusk sports events, but its slower burst rate hinders capturing fast sequences.

• Street Photography: The 6D offers discreetness with quieter operation (no built-in flash), better low-light ISO performance, and compactness; the 40D’s integrated flash and heavier body are less ideal here.

• Macro: Neither camera has inherent macro focusing advantages, but the 6D’s better sensor resolution aids capturing minute textures.

• Night/Astro: The 6D’s low noise at high ISO and greater dynamic range make it vastly preferable for astrophotography and long exposure night scenes.

• Video: Exclusive to the 6D, 1080p recording with external mic input is sufficient for casual filmmaking and vlogging.

• Travel: The 6D’s lighter weight, longer battery life, and wireless features make it the better travel companion.

Overall Performance Scores and Evaluation

Analyzing aggregated sensor and system benchmarks, the Canon 6D commands a substantial advantage in overall image quality and features, scoring notably higher in color depth, dynamic range, and low-light capabilities. The 40D holds its ground regarding shooting speed and durability.

Genre-Specific Performance Breakdown: Matching Camera to Your Photography Focus

Value Assessment and Pricing Perspective

At original launch prices in USD:

• Canon 40D: Approximately $1,099 (body only)
• Canon 6D: Approximately $1,699 (body only)

The 6D commands a premium justified by technological leaps over half a decade, including sensor size, connectivity, and usability upgrades. However, depending on user requirements and budget constraints, the 40D may represent a more economically viable option for those prioritizing ruggedness and burst speed over advanced features.

Recommendations: Who Should Choose Which?

Choose the Canon 40D if:

• You require a reliable mid-range DSLR with a faster burst rate for action photography.
• Your lens collection includes many EF-S format lenses you wish to continue using.
• You prioritize rugged, heavier body ergonomics for outdoor shooting.
• Video and wireless connectivity are not priorities.
• Budget constraints favor a more cost-effective, older model.

Choose the Canon 6D if:

• You want the advantages of a full-frame sensor with superior image quality, dynamic range, and low-light performance.
• Video capture, Live View with face detection, and wireless features are important.
• You prefer lighter gear for travel and extended shooting.
• You use EF full-frame lenses or plan to invest in them.
• You seek better integration with modern workflows, including GPS tagging and HDMI output.

Final Thoughts: Balancing Legacy Strength with Modern Innovation

While the Canon EOS 40D remains a venerable camera, respected for its durability, shooting speed, and dependable performance, the advances embodied by the Canon EOS 6D firmly place it as the superior choice across nearly all technical and practical aspects except burst rate. For enthusiasts and professionals looking to future-proof their kit or elevate image quality, especially in portrait, landscape, and low-light applications, the 6D is a worthwhile investment.

For photographers focused on budget, burst action, and compatibility with APS-C lenses, the 40D still offers compelling value as an advanced DSLR.

By thoroughly considering your primary genres, shooting style, and feature priorities, this detailed comparison should enable you to make a confident camera choice grounded in tested experience and technical expertise.

If interested, please consult with Canon’s broader lens and accessory offerings that complement your chosen body, ensuring maximum versatility and creative potential on every shoot.