There maybe some good reasons to buy a Canon or Nikon cropped sensor dSLR including:

• they are cheap and still take great photos
• you have lots of Canon or Nikon lenses and want a 2nd camera body as backup or for telephoto reach, or plan to compliment it with a full frame dSLR
• you desperately need radio TTL remote flash capability using Pocket Wizard modules

Hate to disappoint you but they are really the ONLY reasons now, and for the rest of us who can afford a Panasonic GX7, Olympus E-M5 or the new Olympus E-M1, you will find they offer far more versatility with much less weight, size, the same or better image quality and they are much more fun to use as they don’t have the archaic noisy, annoying mirror.

Top of the range cameras from each camp:

The Olympus E-M1 vs Nikon D7100 vs Canon 7D (although this is well overdue for a replacement being 2009 technology).

The advantages of the E-M1:

• the best sensor dust cleaner – I have never had to clean my Olympus cameras yet my Canon 1D Mark III plagues me continuously
• in-camera 5 axis image-stabiliser which is the most effective of ANY camera AND works on ANY LENS even old legacy manual focus ones AND is very effective in movie mode negating the need for heavy, expensive stabilising rigs
• much reduced need to carry a tripod – the image stabiliser even allows hand held shots as slow as 1 second with wide angle lenses for those flowing water or moving crowd shots – awesome indeed!
• the highest level of weather protection – it is almost waterproof as long as it is not subject to underwater pressures – just check out the videos online of using it under a shower and in a puddle of water! Makes it easy to clean, and you will feel much more comfortable in dusty places or in the rain!
• an awesome electronic viewfinder which offers some great advantages over optical dSLR viewfinders including:
  • live histogram so you can keep an eye on blowing out highlights
  • image stabilised live magnification to make manual focus far more accurate and easier
  • focus peaking for an alternative mode of accurate manual focus
  • the EVF is far better than optical for accurate manual focus of tilt lenses
  • can set most settings without your reading glasses or taking your eye away from the viewfinder
  • ability to still visualise the scene and focus when using a dense filter such as a Hoya R72 infrared filter or a ND400 filter.
  • ability to pre-visualise effects such as Art Filtered or monochromatic images with filters applied and various levels of contrast and desaturation
  • ability to see panoramic stitching guides
  • ability to pre-visualise different aspect ratios
  • you can hold the camera to your eye for better stability in movie mode
  • NB. other EVF functions in other Micro Four Thirds cameras:
    • the GX-7 and some forthcoming cameras can use truly silent electronic shutter mode with potentially even faster burst rates with camera held to viewfinder
    • the GH-1 and presumably other GHx cameras also allowed pre-visualisation of shutter speed effect, displaying the extent of flowing water effects, etc
• far more autofocus points when using the viewfinder – 800 CDAF + 37 phase detect easily beats 51 phase detect for the Nikon and 19 phase detect for the Canon – this means you can AF on ANYWHERE in the frame
• faster, more accurate AF for slow moving subjects – on sensor AF sensors means that AF does not need microcalibration as with dSLRs and the AF is incredibly fast
• ability to accurately and quickly AF on the closest eye of your subject anywhere in the frame – this is awesome and one of my favorite functions!
• quiet shutter – much, much, better for shooting in quiet events such as wedding ceremonies, classical music concerts
• no mirror-induced camera shake at high magnification – no need to go into clunky mirror lockup modes
• extended shutter speed range to 60sec – great for astrophotography
• unique Timed BULB and Live View BULB modes – long exposures are now much easier – just watch the image “develop” on the screen and terminate the exposure when you are happy with it
• 10fps burst rate (w/o AF or IS) with up to 50 RAW shots (the 7D will only do 15 RAW in a burst and limited to 8fps)
• automatic hand holdable HDR modes as well as traditional HDR bracketing modes
• WiFi built in allowing almost full remote control and wireless tethering to smartphones or Apple iPads – you can see the LIVE image on your device, change settings and then even touch a subject and the camera will AF on that subject then take the shot – absolutely awesome capability which will allow new creative imagery to be achieved, placing the camera in dangerous situations or spots where a human cannot control it directly, yet still be fully controlled by WiFi.
• tiltable touch screen – again, you can just touch the rear screen and it will AF and take the shot  – the screens on the Nikon 7100 and Canon 7D are fixed and do not have touch capability, and even if they did, AF is very slow in Live View mode
• light – the E-M1 is only 497g, yet very nicely laid out for ergonomic use even with larger lenses. The dSLRs are around 800g.
• smaller – 130.4 x 93.5 x 63.1mm
• ability to convert almost any full frame legacy lens into an image stabilised tilt or shift lens
• more telephoto reach for same size telephoto lens
• ability to use a wider range of legacy lenses such as the superb Leica M rangefinder lenses, as well as a new range of f/0.95 manual focus lenses, and have them image stabilised.
• ability to use the superb, cropped sensor optimised Olympus Four Thirds lenses with fast AF.

Advantages of the dSLRs:

• don’t need to turn camera on to see through viewfinder
• slightly better C-AF tracking but not in movie mode – however, C-AF will only get better as technology improves with mirrorless cameras
• in addition to 30p movie mode, 24p movie mode plus 60p on the 7D – however, if you want the best video – look at the GX-7 or GH-3 Micro Four Thirds cameras
• full compatibility with their respective full frame lenses albeit in cropped view – although the new Metabones Turbo EOS adapter may give this capability to Micro Four Thirds as well
• radio TTL remote flash option not just light-based remote TTL flash – however, hopefully this will be addressed soon, although there is already a 3rd party option
• a very cheap portrait lens option – the 50mm f/1.8 lens but no eye detection AF as with Olympus (~$199 vs $349 for the Olympus 45mm f/1.8)

The all important standard zoom lens:

Let’s compare the E-M1 with the 12-40mm f/2.8 lens with equivalents on the Nikon 7100 (Nikon DX Nikkor 17-55mm f/2.8G lens) or Canon 7D (Canon EF-S 17-55mm f/2.8 IS USM).

The additional advantages of the Olympus kit include:

• 24mm wide angle of view in 35mm terms instead of only 26mm for the Nikon and 27mm for the Canon
• 4 stops image stabilisation compared to 2-3 stops with the Canon and NONE with the Nikkor lens.
• yes, that means you could hand hold this lens down to half a second, perhaps 1 second at the wide angle range, while you would be lucky to achieve similar results on the Nikon at 1/20th second.
• almost waterproof
• lens is almost half the weight at 382 g compared to 755g for the Nikkor and 645g for the Canon
• lens is more compact being only 84mm long compared to 111mm and when mounted on the camera the differences are even greater as the E-M1 is not as thick
• cheaper filters as you only need 62mm instead of 77mm for the Nikon and 72mm for the Canon
• closer focus of only 0.2m giving 1:3 macro compared to 0.35/0.36m respectively for the Canon and Nikon
• movie silent fast CDAF autofocus as well as phase detect AF capability – the Canon and Nikon lenses are not optimised for CDAF and are quiet but not movie silent
• customisable lens function button on the lens which can be assigned to a range of roles
• superb image quality – it will be interesting to see how the Canon and Nikon compare, but given the reviews I think I know the answer!
• despite all the benefits above it is a similar price to the Canon and significantly more affordable than the Nikon ($999 vs $1399 for the Nikon)

To be fair, there is ONE advantage of the Canon and Nikon zoom lenses – 1 stop more depth of field versatility, however, this is easily addressed by supplementing the Olympus with one or two very small, affordable prime lenses such as the Olympus mZD 17mm f/1.8, Panasonic 25mm f/1.4, Panasonic 42mm f/1.2 (coming soon), or Olympus 45mm f/1.8, or if you really want a different lens to compliment the zoom, add the awesome Olympus mZD 75mm f/1.8.

Autofocus macro lenses:

The main options designed for the cropped sensors are the Olympus mZD 60mm f/2.8, the Nikkor DX Nikkor 85mm f/3.5G and the Canon EF-S 60mm f/2.8.

The Olympus lens has it all over the competitors with advantages such as:

• better image stabilisation (although IS is not as effective in the closest macro ranges but still can be handy)
• almost waterproof (neither of its competitors have any weatherproofing)
• almost half the weight at 185g vs 355/335g – this is really important for hand held macro work as tired hands waiting to time the shot start shaking!
• movie silent fast CDAF autofocus as well as phase detect AF capability – the Canon and Nikon lenses are not optimised for CDAF and are quiet but not movie silent
• optimised for live view mode, and when combined with the E-M1’s tiltable screen means getting down low or high for those macro shots are far easier and far more fun
• focus limiter switch included which further speeds up AF and allows immediate access to 1:1 focus – neither of its competitors have this
• more affordable than the Nikon ($449 vs $635) and higher quality than the similarly priced Canon

Low light urban street walking capabilities:

When travelling, one of the great experiences for photographers is to walk the streets at dusk and capture a very different view of the cities – without a tripod and with a small discrete kit.

The GX-7, E-P5, E-M5 and E-M1 cameras blow away the dSLR competition for this purpose as they are much smaller, even jacket pocketable, have similar high ISO image quality, have much better image stabilisation for longer hand held shots in the dark and, particularly, if combined with the 12mm f/2.0 lens or 17mm f/1.8 lens, make awesome night time hand holdable street cameras.

The E-M5 can hand hold a 12mm lens down to 0.3secs comfortably while the E-M1 can do 1sec or perhaps more.

What wide angle low light autofocus primes are available for the dSLRs?

Canon offer an EF 24mm f/2.8 IS or the much more expensive EF 24mm f/1.4L lens or the 14mm f/2.8L but neither of the latter have image stabilisation.

Nikon offer 20mm f/2.8, 24mm f/2.8 or the much more expensive 14mm f/2.8 or 24mm f/1.4 lenses but NONE have image stabilisation.

There are no cropped sensor optimised EF-S or DX wide angle prime lenses, let alone image stabilised versions of these!

Neither Canon nor Nikon offer affordable cropped sensor dSLR low light solutions with AF with effective focal length wider than 30mm even without image stabilisation!

The Micro Four Thirds absolutely eats the cropped sensor dSLRs for this very common need.

More details:

I have created a detailed comparison table of the above and more on my wikipedia – see here.

For those concerned about the marginally less shallow depth of field in certain circumstances, they can resort to f/0.95 lenses, or consider the future technology – already the E-M1 uses intelligent jpeg sharpening of only the in-focus areas so it would not take much imagination to assume it won;’t be long before the user can “dial-in” a degree of extra blurring of the out-of-focus regions.

The end of the cropped sensor dSLR is nigh – I would be surprised if they exist in another 10 years.

Furthermore, one has to wonder what Canon and Nikon will do with their lens range which is generally NOT compatible with CDAF when CDAF becomes increasingly important with the advent of full frame mirrorless cameras.

There is a limit to what can be achieved with on-sensor phase detect AF alone compared to what can be achieved with CDAF combined with phase detect AF.

If I was a betting man, the whole range of current Canon and Nikon lenses,  just like the Olympus Four Thirds lenses will lose substantial value in 10 years because they are not CDAF compatible and will be replaced with more versatile lenses.

 You have to ask yourself – why would I even think of buying a cropped sensor dSLR – get a full frame dSLR if you really need that extra shallow depth of field  or go Micro Four Thirds for much more fun and versatility.