see also:

• Canon EOS camera system
• Canon EF lenses
• Canon EF-S lenses
• Canon R full frame and APS-C mirrorless camera system
• Canon EOS-M EF-M mirrorless system
• CanonEOSAPSC
• timeline of Canon EOS camera and lens development
• digital SLR cameras
• professional sports / journalistic dSLRs

• Canon have a range of 35mm full frame digital SLR cameras which, along with Nikon F dSLR system have been their main pro camera line
• none have a built in flash and currently none have sensor based image stabiliser or articulating screens
• according to DxOMark:
  • peak 18% S/N is similar for all models listed below although the 5DIV is marginally best and the 1D mark II the worst, however at ISO 6400 the 5DIV and 1DII have some 1-1.5Ev better noise than the 2012 models and 0.5EV better noise than the 5DS
  • peak dynamic range is best with the 5DIV at 13.6EV and 1DII at 13.5EV while the other models are significantly worse at around 1EV less dynamic range with the 5DIII being the worst and the 6D only marginally better at 12.1EV (this is 0.5EV worse than the Olympus OM-D E-M1) - this places the 5DS / 5DSR with 12.4EV at only average dynamic range capability which impacts its utility as a landscape camera
• for most people a smaller, lighter, less expensive camera kit is a better option - such as Micro Four Thirds system but many want the benefits of full frame's ability to capture shallower depth of field (DOF) and have better image quality (1.5-2EV less noise), and for these people on a budget, the now outdated but more affordable Canon 6D may make good sense as long as they are not shooting sports, although its minimalistic AF functionality will make shallow DOF work such as portraits difficult to obtain accurate focus away from the centre, while the lack of 1/8000th shutter speed will require use of ND filters to allow wide aperture, shallow DOF images outdoors in the sun.
• not included in the table below is the 2011 model 18mp Canon 1D X sports dSLR which in Jan 2017 still lists at $AU7100.
• the long awaited Canon 6D Mark II is thought to be coming Q2 of 2017 and we could reasonably assume it may have the following specs:
  • a much improved 24mp sensor, Dual Pixel AF in LiveView, an improved AF system but no 4K video and presumably will cost $US2000 which would make it around $AU2700 - almost twice the current price of the mark I - will the sensor image quality and improved AF system be enough to justify that?

• one of the main reasons to buy full frame cameras to gain shallower depth of field (DOF), particularly for portraits, weddings, and whilst all full frame cameras will be equal in the ability to have shallow DOF, the actual technical ability to achieve accurate focus when DOF is only 2-5cm is not so easy!
• if one reviews photos on the net of models taken with shallow DOF on full frame dSLRs, a significant portion have inaccurate AF - that is, the focus is not on the subject's closest eye
• there are several reasons which contribute to this problem:
  • unlike mirrorless cameras, dSLRs require manual microcalibration for each lens to adjust for variances of the systems AF mechanisms which are not on the sensor
  • most dSLRs have AF points mainly in the centre of the frame whereas most of us like the subject's eye away from the centre, this means that unless the camera can detect the closest eye and choose the AF point for you (which none of these Canon dSLRs can do), you must either:
    • use a centre AF point to focus on the eye and recomposing which introduces errors (either you move a little or the subject moves a little while recomposing), or,
    • selecting an off-centre AF point and compose with that point over the subject's eye which limits composition options
• the Canon 6D only gives 11 AF points which are all crowded in the centre so not so great for accurate shallow DOF portraits, and the other cameras fair only little better with a still rather small spread of AF points across the frame
• a further issue in bright sun, is that when using wide aperture lens settings to achieve this shallow DOF, you need a low ISO and fast shutter speed to avoid over-exposure - the 6D only gets to 1/4000th sec and so you will need to use ND filters
• a major issue also arises with telephoto primes such as the 135mm f/2L lens - as soon as you turn a flash on for fill, the flash sync forces you to a slower shutter speed (1/180th sec in the case of the 6D) and without image stabiliser in the camera body or the lens you are at great risk of camera shake unless you resort to tripod use or are very careful in holding the camera.
• if you want just enough shallow DOF for most portraiture without having ultra-shallow DOF, then a Micro Four Thirds system camera with wide aperture prime lens will address all of the above issues and provide more consistently accurate and easier AF, and as the latest iPhones, show, there will soon be selective in-camera software based blurring of the scene distinguishing your subject
• another alternative is the Sony a7 II full frame mirrorless camera which is a 24mp full frame mirrorless camera with sensor based image stabiliser which can do slowish AF with Canon lenses via a Metabones adapter and will provide better manual focus experience however, you will not have compatibility with the Canon flash system

• another reason to buy a full frame camera is that they are available with higher megapixel count sensors which potentially allow single shot high resolution images such as the Canon 5Ds / 5DSR full frame dSLR which offers 50mp albeit with sacrifice of reduced dynamic range, more high ISO noise, larger file sizes, slower burst rates
• the problem is that to get 50mp of image detail you must have all of:
  • stationary subject (there is a good reason sports photographers are happy with 20mp or even 10mp)
  • no camera shake (you need a tripod with mirror lockup and self-timer, and preferably electronic first shutter, or a fast shutter speed to get the most detail)
  • superb optics (hence Canon is updating most of their pro lens range)
  • accurate focus
  • no anti-alias filter on the sensor (hence the Canon 5DSR version) - but this may introduce moire artefacts
• the question you need to ask yourself - are you prepared to accept the compromises and address the above issues - or will the 50mp camera be a waste of money for you?
• the Olympus OM-D E-M1 mark II has a 50mp high resolution mode with minimal moire, full electronic shutter mode, wireless smartphone remote control and live view, and no need for mirror lock up but does still require a tripod and a static scene as it shifts the sensor between each of 8 shots which are then combined - this makes it better for product shots and negative or slide reproductions.

• full frame cameras using similar generation technology will give 1.5-2EV better high ISO noise characteristics than a cropped sensor camera such as Micro Four Thirds system
• this is great for moving subjects (including Milky Way astroscapes) where a high ISO to allow a faster shutter speed is required and image stabiliser will not be as useful
• bear in mind though that there is a big price to pay for shooting at high ISO even with full frames and this is not just image noise but perhaps more importantly, loss of dynamic range - shooting at ISO 1600 with a 6D or 5D Mark III and you have lost 1EV dynamic range - and these two cameras do not have a lot of dynamic range to start with
• HOWEVER, if you need wider depth of field (DOF), then there is little advantage over a Micro Four Thirds system which can combine a 2EV wider aperture to keep the ISO down by 2EV which negates the full frame sensor noise advantage, as well as having better image stabiliser

• 35mm full frame cameras as well as APS-C, APS-H and DX sensors have the old analog 35mm x 24mm film 3:2 aspect ratio (1.5x) which is longer and thus narrower than the 4:3 aspect ratio (1.33x) of Micro Four Thirds system and many picture framing formats
• 1.5x aspect ratio print sizes include 8“ x 12” and 20“ x 30”
• international paper sizes such as A4 are 1.414 ratio
• one can crop a 3:2 image to 4:3 image for 12“x 16” but then a 20mp image becomes 17.7mp
• an 8“ x 10” print is 1.25x ratio and so requires further cropping