Top Tips and Tricks for the Canon 5D Mark III

OK, I admit, I’m being a bit deceptive.  While this post will include “tips” for taking full advantage of the Canon EOS 5D Mk III, it won’t really contain any “tricks.”  That is because with digital photography, especially a camera as powerful and complex as the 5D3, there really aren’t any tricksTricks implies shortcuts, and to paraphrase Euclid, there is no royal road to dSLR photography.  Instead there are techniques and camera controls that can and should be learned.  These will then allow you to adapt not just to a specific situation or emulate a certain image or style, but will give you the tools and knowledge to adapt to any situation and create the images you desire.

I spent several intimate weeks with the Canon 5D Mk III as I researched and wrote my dSLR camera guide, Canon 5D Mark III Experience, the first (and hopefully best!) book available for the 5D Mk III.  In the process I learned and discovered a few obvious and not so obvious things about the 5D3 that will help you get the most from your camera.

Canon 5D mark III mk 3 Experience e book tips tricks how to learn manual guide instruction
Detail of the Canon 5D Mark III

Learn and Take Advantage of the Autofocus System

First and foremost is to learn, understand, and make full use of the new 61 Point autofocus system.  This powerful and highly customizable AF system will allow you to capture more sharp images of a variety of moving subjects which was not previously possible with the 5DII, or even the 7D.  But to do this you will need to take control of it in order to focus on, or begin tracking, your intended subject.  This involves making use of the AF Modes as well as the AF Area Selection Modes and AF Points.

For moving subjects you can then employ the AF Cases and their settings to let the camera know what to expect as far as subject movement.  AF subject tracking works in part by predicting where the subject will be when the Shutter is pressed, so if the camera knows the subject is going to be moving erratically about the frame and changing its rate of speed, then it can take measures to better follow this than if it is set for a subject that is expected to move smoothly at a steady rate.  Ten tips could easily be written about the autofocus system alone, but I will limit it to a few (my e-book guide Canon 5D Mark III Experience contains extensive explanation of the AF system and all its elements, if you wish to learn it inside and out.)

Canon 5d mark iii mk 3 auto focus autofocus 61 af point select
Simulated image of the Canon 5D Mark III viewfinder showing the 61 autofocus points, with the desired AF Point shown as the larger black square.

One of the essential steps in taking a successful and sharp photo is controlling where the camera autofocuses.  If you allow the camera to autofocus by automatically choosing its own focus point(s) (such as in Auto+ Shooting Mode or with One-Shot AF Mode and Auto Selection – 61 Point AF Area Selection Mode) it typically focuses on the closest object.  This may or may not be what you want to focus on, so you should select or at least narrow down where the camera focuses using the autofocus AF Points or Zones.  By doing so you are telling the camera exactly where to autofocus or to look to find a moving subject to track.  For example, you often want to focus on a subject’s eyes, but if you allow the camera to choose the autofocus point itself, it may select another part of the face, or somewhere else on the body, or even a raised hand that is nearer to the camera than the face to focus most sharply on.  If you are capturing an image of a bird in a tree, the camera has no idea you want the autofocus system to zero in on the bird so that it is in sharp focus and not the branches or leaves near it or the perhaps even the leaves closer to you.

You will select an AF Mode based on whether the subject is still or moving, and select an AF Area Selection Mode based on how large of an area you want the camera to look at to find your intended subject – ranging from a small spot to a wider Zone to all the available 61 AF Points.  You can set the AF Modes and AF Area Selection Modes in a variety of combinations based on what and how you are shooting.

Activate all the Available AF Area Selection Modes at first and experiment with them all.  Then if you decide that you will never or rarely use one or more of them, de-activate those modes so that you don’t have to “click” through them every time to select your desired mode.

canon 5d mark III mk 3 autofocus auto focus af point zone 61 af area selection mode
Available AF Area Selection Modes of the Canon 5D Mark III

Spot AF is Not Necessarily More Accurate than Single-Point AF.  You may be inclined to use Spot AF all the time, assuming it will be more accurate than Single-Point AF, but this is not advised.  Spot AF is designed for specific situations and autofocusing challenges, where you need to focus on a very precise area and avoid any surrounding or foreground objects that the AF system may otherwise lock onto.  This can include making sure you zero-in on a bird that is sitting among leaves and branches, or perhaps shooting through a fence to a subject beyond.  In those situations you may find that Single-Point AF searches back and forth between the near leaves/ fence and the further subject, because the area it is looking at to find the subject encompasses both potential subjects.  Spot AF will allow you to target in on a more precise area.  Although Spot AF is indicated in the Viewfinder by the tiny square within the larger selected AF Point square, Spot AF will actually pinpoint the focus to an area about the size of the larger square.

So while Spot AF will be more accurate in certain situations as described, it should not be used for general use.  Because it is so precise, the area it looks at to find contrast or a detail on which to focus may be an area of solid color.  For example if you used Spot AF to quickly focus on the general cheek and eye area of a face, it may be aimed at an area of skin without contrast, whereas the Single-Point AF area might encompass the cheek and the eye and thus find enough contrast to be able to properly and quickly focus.

Decide How Many Selectable AF Points you wish to Choose From.  If you are coming from a Canon 5D Mark II, the 60D, or any number of other previous Canon dSLR cameras, you may be used to only having 9 AF Point to choose from.  If you still wish to manually select a specific point or zone, you may find that 61 points are a bit overwhelming at first.  Even if you are used to the 19 AF Points of the Canon 7D, you may not wish to suddenly jump up to 61 AF Points.  So you can limit the number of AF Points you wish to choose from to either 15 or 9, or to just the more accurate cross-type points.  Unfortunately, the 9 points are not in the nice diamond pattern of previous EOS cameras, but you may find them to be more manageable.

canon 5d mark III mk 3 auto foucs autofocus af mode point area selection 61 11
Limit your Selectable AF Points if 61 are too many to deal with.

Choose Your Priority when Working in AI Servo – Focus or Release.  You will need to tell the camera what your priority is when shooting in AI Servo AF mode – is it to ensure that the subject is in focus, or that the shutter is release immediately, whether or not the subject is in focus?  There are two menu items to set the priority for the first image and the second and subsequent images if shooting in Continuous Shooting Mode.

For AI Servo 1st Image Priority, Release priority will prioritize shutter release, or immediately capturing the initial shot at the possible expense of exact focus.  Generally when taking a photo, you are supposed to half-press the Shutter Button, allow the camera to focus, then continue the full-press of the Shutter Button to take the image.  If you simply “mash” down the Shutter Button, this setting will cause the camera to take the photo without bothering to focus first.  Sometimes when photographing sports, news, or events, capturing the “decisive moment” may take priority over exact focus.

Setting for Focus priority will prioritize focus for the first shot, ensuring that the subject is in focus before the picture is taken.  So when you fully press the Shutter Button, this setting may cause a brief, perhaps micro-seconds delay while the camera confirms focus before actually releasing the shutter.

Equal priority is a slight compromise between Release and Focus priorities.  It allows a brief (perhaps micro-seconds) pause for the camera to possibly find focus before releasing the shutter.  It does not guarantee that the image will be in focus, but merely gives it more of a chance to find focus.  It generally seems to make more sense to choose Release or Focus based on your priority.

Canon 5D mark III mk 3 custom setting function control multi controller direct autofocus point
AI Servo 1st Image Priority menu to determine if capturing the shot or getting the subject in-focus is the priority.

AI Servo 2nd Image Priority is similar except that it applies to the second and subsequent images in the burst.  Setting for Speed (Shooting speed priority) will prioritize shutter release, or continuing the high speed burst at the possible expense of exact focus.

Setting for Focus will prioritize focus tracking for the following shot(s), ensuring that the subject is in focus as you continue to take the burst of images.  Again, this may cause a brief, perhaps micro-seconds delay while the camera confirms focus before releasing the shutter for each image.

Equal priority again allows a slight pause before each of the subsequent shots to perhaps give the camera time to find focus before releasing the shutter.  This pause may be slightly more pronounced when shooting in low light or low contrast situations.

These 1st Image Priority and 2nd Image Priority settings should be set in conjunction with each other, based on the type of situation you are photographing and thus your priorities.  Generally, it sharp images are your goal, you will want to set both for  Focus Priority.  You may sacrifice the maximum 6 frames per second (fps) continuous shooting speed (if you have the Drive Mode set for High Speed Continuous) as there might be a  couple micro-seconds or more delays as the camera ensures that the subject is in focus before taking the subsequent shots.  If you are capturing a “decisive moment” such as a runner at the finish line or a goal being scored, you will want to set one or both of the settings to Release Priority/ Speed Priority, but ensure somehow that you have pre-focused on the subject distance so the result is not wildly out of focus.  Again, I go into much more detail about the various combinations and when to make use of them in my e-book.

Set the Custom Controls for Multi-Controller Direct.  This will allow you to manually select your AF Point or Zone more quickly by simply toggling the Multi-Controller thumb joystick, without having to first press the AF Point Selection Button.  You have probably noticed, to the dismay of your muscle memory, that the AF Point Selection Button no longer controls image zoom.  This is because there are many more image review options that are now made possible by Comparative Playback (side by side image review), discussed just below.

canon 5d mark iii mk 3 multi controller direct af auto focus autofocus point select

canon 5d mark iii mk 3 auto focus autofocus multi controller direct af point select zone control custom function setting
Set the Multi-Controller for AF Point Direct Selection for ease and speed.

Take Advantage of Comparative Playback (Side by Side Image Review).  Of course you can instantly review the image you just captured on the rear LCD Monitor, but the 5D Mk III now also offers Comparative Image Playback Mode (Two-Image Display) which gives you the ability to simultaneously compare two images or two different sections of the same image.  Whereas before, one would have to “flip” back and forth between two images and navigate around the images, this feature allows for some extremely helpful and flexible image analysis that was previously only possible once you were back at your computer.

To enter Comparative Playback Mode during image playback or review, press the Creative Photo / Comparative Playback Button (at the top of the row on the left of the camera back), which is also indicated by the side-by-side blue squares icon for side-by-side image playback.  Use the SET Button to highlight which of the two image windows you wish to navigate, then use the Quick Control Dial or Main Dial to scroll or jump to the desired image, the Magnify Button followed by the top Main Dial to zoom in or out of the selected image, and the Multi-Controller to navigate around the selected image frame.  You can press the INFO Button repeatedly to change the Shooting Information Display in order to view shooting information and/ or the Histograms.  If you zoom in on a specific area of one image and wish to zoom in on the other image to the same magnification and same area of the image, press the SET Button to switch to the other image window, then press the [Q] Button.  Also, press and hold the Playback Button to view the highlighted image as a single, full-screen image.

canon 5d mark iii mk 3 view image lcd side by side comparative playback review rear screen
Comparative Playback Mode view of two different images, also showing the images’ Histograms.

There are several different viewing options and potential uses for Comparative Playback, whether you are simultaneously viewing two separate images or two areas of the same image.

-Display the active AF point(s).
-Preview alternate cropping guides.
-View the thumbnail plus the Luminance Histogram.
-View the thumbnail plus the RGB Histograms.
-View the thumbnail plus basic exposure information.

For two different images:
-Compare the compositions of two images simultaneously.
-Zoom in and simultaneously compare a specific area for focus or exposure.
-View the thumbnails along with histograms or basic exposure information of both images.

For the same image:
-Zoom in and simultaneously compare two separate areas of the same image to have a closer look at focus or exposure.
-View the entire image for overall composition while also zooming in to view an area of detail for focus or exposure (see Figure 61).

Set the Default Magnification for Image Review.  In order to immediately review your images according to your preferences, you should set the initial magnification and position that you will view an image during image review (Playback) when you press the Magnify Button.  You can set for no magnification (1x) and then use the top Main Dial to zoom in and out.  This can be handy if you have the image review set to initially show the Shooting Information Display with the Histogram.  Since the image in that view is a thumbnail, you can then press the Magnify Button to show the full size image.  After this initial zoom, you can then use the Main Dial to zoom in or out.

Or set for 2x, 4x, 8x, or 10x magnification and it will instantly zoom to that magnification when the Magnify Button is pressed.  Again, after this initial zoom, you can then use the Main Dial to zoom in or out.  Each of these magnifications will zoom from the center of the image.  Or you can set it to quickly zoom in to full size, 100% view of the pixels, zoomed into the AF Point where focus was achieved, using setting Actual size (from selected pt).  This can be useful to quickly check for precise focus, though note that if you focused with a selected AF Point and recomposed, it will zoom into the final position of that AF Point in the composition, not the actual position where you used it to focus on your subject.  But if you only recomposed slightly, it will often be easy to quickly navigate to the actual area of focus.  The setting Same as last magnif. (from ctr) will zoom in at the same magnification that you last viewed an image at, centered at the image center.

canon 5D mark III mk 3 magnify button lcd view zoom
Magnification menu to set how images are initially viewed during Playback when the Magnify Button is pressed.


I’m still putting this post together but wanted to share what I had already written.  Next week I will go into more detail about the tips below:

Turn on the Viewfinder Warnings

canon 5D mark III mk 3 viewfinder warning custom function setting


Auto Rotate Images in the Camera and on Your Computer

canon 5D mark III mk 3 auto rotate image view lcd


Use the Q Button for Quick Access to a Variety of Features for Still Images

canon 5d mark iii mk 3 q button control edit image view lcd


Make Use of the Silent Control Touch Pad and Q Button for Movie Shooting

canon 5d mark iii mk 3 movie video silent control touch pad q button menu


canon 5d mark iii mk 3 movie video silent control touch pad q button menu


All of the above information – and much, much more – can be found in Canon 5D Mark III Experience, my latest Full Stop dSLR user’s guide e book, which goes beyond the manual to help you learn the features, settings, and controls of the powerful and highly customizable EOS 5D Mk III, plus most importantly how, when, and why to use the functions, settings, and controls in your photography.

Written in the clear, concise, and comprehensive style of all Full Stop guides, Canon 5D Mark III Experience will help you learn to use your Canon 5D Mk 3 quickly and competently, to consistently create the types of images you want to capture. The e-book is available in either PDF, EPUB, or MOBI format for reading on any device.

Learn more about it, preview it, and purchase it here:

As one Canon user has said about Full Stop guides, “I don’t know how I could fully take advantage of all the features the camera has to offer without this publication! It’s well-organized, easy to understand, and succinct enough to keep your attention while still containing a wealth of information to get the most out of your camera.”

Take control of your 5D Mk III, the image taking process, and the photos you create!

Canon 5D Mark III mk 3 book ebook manual guide tutorial instruction bible how to dummies field EOS


Canon 5D Mk III Specs and What They Mean

It is here!

Canon 5D Mark III pre-orders available at and at B and H Photo (my affiliate links – thanks for supporting this blog by using them!):

pre-order your Canon 5D Mk III from Amazon

pre-order your Canon 5D Mk III from B and H Photo


It is expected to be available and start shipping on March 22, 2012.


The long awaited and highly anticipated Canon EOS 5D Mark III has finally been announced!  There has been wide speculation of what the camera will include (including predictions at one time that it would be split into two camera lines for still vs. video).  It seems that the most current leaked specs were accurate, and the new 5D boasts such features as a whopping 61 point autofocus system, improved exposure metering system, fast DIGIC 5+ processor, and dual card slots for CF and SD.

I myself made some educated guesses back on August 5, 2011 as to what the camera was likely to offer.  I have included my predictions below in red, and my reactions and comments are in blue:

Canon EOS 5D Mk III specs:

  • 22.3 MP Full Frame Sensor. (26 to 28 MP Full Frame sensor.)  This is a surprise that they didn’t increase the sensor resolution very much, but as anyone who has used a 5D Mk II is aware, it already has amazing resolution and great high ISO/ low noise performance.  It appears from early test samples that this new sensor is going to show significant improvement in the high ISO/ low noise area, with perfectly acceptable, low noise, usable images all the way up to 12,800.  Yes, 12,800 ISO.
  • DIGIC 5+ Processor. (Single or Dual DIGIC 5 processors).  A nice, fast processor to keep up with the 6 fps frame rate, HD video, and all the image info coming from the high resolution sensor either in RAW or JPEGs that are being processed in-camera to include various settings such as Auto Lighting Optimization, Picture Controls, and other user-set adjustments such as the newly included Lens Aberration Correction.  This higher processing speed will also allow long continuous bursts even with the in-camera processing settings being used on JPEG images as they are being captured.
  • Full HD Movie – ISO 100-12800 H:25600.  (Full HD video at all the frame rates, perhaps with RAW video, perhaps with full time autofocus).  With two different compression formats to choose from, time codes with multiple options, and audio control plus a new headphone jack.
  • 6.0 frames per second high speed continuous shooting.  (7 frames per second high speed continuous shooting.)  Not quite as fast as I expected, but this is actually a much more useful rate for most situations.  This higher fps rate combined with the new 61 point AF system is going to allow the 5D to be used a bit more as a sports and action camera.  It does not appear the this desired feature that I hoped for is included:  Ability to customize Continuous Low and High settings so that you can choose your own rates.
  • ISO 100-25600, expandable to L: 50 H1: 51,200, H2: 102,400.  (ISO 100 to 12,800 or more, and then expandable.)  The new sensor, as mentioned, is likely to have tremendous performance in low light, high ISO situations with minimal noise, and preliminary samples and tests indicate this is indeed the case.
  • 3.2″ 1.04 million pixel Clear View II LCD screen.  Not articulating.  (3” very-high resolution LCD screen – Non-articulating?  Articulating?  Touch screen?)  A nice, high-resolution rear LCD screen, with a wider ratio to match the sensor and great for video shooting.
  • 61 point autofocus system with up to 41 cross type sensors.  (19 point (or more) autofocus system, all cross-type, with numerous configurations and customization options, as taken from the 7D.  Plus the new Autofocus menu system of the new 1D X to make configuring and taking full advantage of the AF system much easier.)  This is the biggest surprise for me.  I expected something like the19 point AF system of the Canon 7D, maybe with 20-30 AF points – but the 61 points is a shock.  While this will be awesome for tracking moving subjects and action, it is also customizable to reduce the number of choosable AF points and make it reasonable workable for “still” photography, as demonstrated in this still grabbed from a Canon video.
      Canon 5D Mk III mark III autofocus points 61 41 15 9
    Still from Canon video on the 5D Mk III

What this is showing is that if you wish to manually select a single AF point – which you should typically do in non-action-tracking situations to ensure that the camera autofocuses exactly where you want – you can limit the number of selectable AF points so that you don’t have to  manually click across dozens of points to quickly get to the one you want.  You can limit it to 9 points (as with the 5D Mk II or 60D), 15 points (similar to the 19 points of the 7D and likely the one I will most often use), just the cross-type points (which will number up to 41 depending on which lens you are using), or all 61 of them.

  • When using Center AF Point with an f/2.8 lens, the 5D Mark III is able to focus in EV -2, which according to Canon, “is the equivalent of shooting by the light of a full moon.”  This is an incredible improvement over the autofocusing abilities of the 5D Mk II, which struggles in low light.
  • 63-zone dual layer metering sensor.  (Improved 63 zone+ exposure metering system)  This is a similar metering system as in many of the current Canon cameras, such as the 7D and 60D, which has proved to be excellent as determining the proper exposure even in challenging lighting situations.  This metering system takes into account color, luminance, as well as information provided by the active AF point(s) to best determine the exposure.
  • Magnesium alloy body with improved durability, water, and dust resistance.  (Magnesium alloy body with weather sealing – already has this, not much improvement required.)  A durable, go-anywhere camera is now even more durable and resistant!

Additional features of the new 5D Mk III:

  • “Intelligent viewfinder” which means it includes the 7D type viewfinder with the LCD grid that can be turned on or off, sensitivity to light and dark to automatically illuminate the AF points when needed, if desired.
  • Silent and Low Vibration Modes.  These are likely designed to enable one to use the camera more stealthily – not just surreptitiously, but in situations such as dance and theater performances where you need the shutter and mirror to be quieter.  Low vibration is handy for optimal sharpness in certain hand-held and tripod shooting situations.
  • Dual memory card slots – CF and SD.  This is a new feature for the 5D line.  (It will likely and hopefully retain the CF card)
  • LP-E6 battery – thankfully they have retained the same battery as the 5D Mk II and 7D.  (It will likely retain the LP-E6 battery)
  • HDR Mode – This is an in-camera feature that will take and combine 3 images, either at auto-levels of exposure or user-selected EV increments.  You can then choose from various options of how you wish the camera to process the final image.  The original 3 images will also be saved for your own use.  The camera also offers an improved 7 stop EV latitude of exposures for auto bracketing, for those who wish to do more with HDR using other software and post-processing themselves.
  • Multiple Exposures – Nikon has had this feature for a while, so it is nice to see it on a Canon.

The 5D Mk III has also incorporated many of the menu and Custom Function features of the 7D, such as the ability to customize many of the buttons and controls of the camera, as well as the new, easier to use and comprehend Autofocus Menu system as the one seen in the Canon 1D X.  By putting all the AF options in one menu, it makes it considerably easier to take advantage of the powerful AF system options without having to access and understand various menus items and Custom Function options (as you do with the 7D).  There are also AF “presets” so you don’t have to remember and set the variables such as “Tracking Sensitivity” and “AF Point Auto Switching.”  The Custom Functions of the 5D Mk III have also been grouped into 3 categories now for ease of use.

There is also an image comparison feature where you can compare two images side by side on the rear LCD to see the effects of your adjustments – double chimping!

Hopefully there will be the options to customize the size of the Center-Weighted, Spot, or Partial Metering circles, and to adjust the Hi Speed and Low Speed Continuous shooting rates, and perhaps some additional WB options such as more Fluorescent option.

Built-in GPS, wireless flash, or wi-fi?  No, they all still require optional, external devices.  But we will see these in-camera features eventually.

I will soon be starting to write an e-book user guide for the Canon 5D Mk III to join my current Full Stop camera guide line-up which includes Canon 7D Experience and Your World 60D. You can check out my Full Stop bookstore website to learn more:

full stop dslr photo photography camera manual guide for dummies canon nikon

If you are interested in pre-ordering your Canon 5D Mk III, please use my referral links to the 5D Mk III on or B&H Photo. Using these links will help support my blog and my work.  Thanks, I appreciate your support!

If you are in the UK, please click here for the UK Amazon referral link.

And if you are in Canada, please click here to use my Canada referral link.

BandH Photo

Direct Link to Canon 5D Mark III pre-order at B and H Photo.

These are retailers that I have purchased equipment from (excluding Amazon UK/ CA), and I recommend them based on my good experiences, their extensive selection, competitive prices, great customer service and responsiveness, and fair return policies.

Canon 5D Mark II vs 5D Mk III

As I recently noted in my post about the eventual release of the 7D Mk II, as an e-book camera guide author, I have to attempt to plan my life and writing schedule around the release of the latest dSLR cameras. And since major camera companies typically give little-to-no advance notice for the announcement then release of a new model, this involves lots of speculation and following of online rumors. And then I subject myself to a few weeks of intense, non-stop research and writing when it is finally announced.

The Canon 5D Mark III has been rumored for imminent release numerous times, including most recently Feb 2011, November 2011, first quarter of 2012, and “any minute now.”  This speculation occurs with every expected new model, so as you can see, there is no telling when it will suddenly be announced.  But based on Canon’s history of model releases, it is sometimes pretty easy to narrow the range down.  For example, the original 5D reigned for 3 years, and then was replaced by the 5D Mark II, which was announced on September 17, 2008.  Add three years to that, and you get an announcement of the Canon 5D Mk III expected in September 2011.  Not so difficult, really.  Except one has to take into account the disruptions to manufacturing and supply caused by the earthquake in Japan, so that could cause a delay of a month or three.  As equally fascinating is the speculation for what features the 5D Mark III will have. Most interestingly, some have wildly suggested that the line will be split in two with a stills version and a video version.  Not likely.  So what is there to improve on this amazing camera?  Well, several of its features can easily be improved, and hopefully there will be a few surprises added.

canon 6d canon 5d mk iii mkiii mk 3 mark 3 mark ii vs compare which one
The Canon 5D Mk II, patiently awaiting its successor, the Canon 5D Mk III – or is it the Canon 6D…

Currently the Canon 5D Mk II offers:

  • 21 MP Full Frame sensor
  • DIGIC 4 processor
  • Full HD video
  • 3.9 frames per second continuous shooting
  • ISO 100 to 6400 (expandable to 25,600)
  • 3” high resolution LCD screen – non-articulating
  • 9 point autofocus system, all cross-type plus 6 assist points
  • 35 zone exposure metering system
  • Magnesium alloy body with weather sealing

Much of this can easily be improved upon, and in fact the current 7D already boasts several upgrades to these features.  The 5D Mark III will obviously take the best of the 7D and improve upon it in some areas.

Canon EOS 5D Mk III predictions:

  • 26 to 28 MP Full Frame sensor
  • Single or Dual DIGIC 5 processors
  • Full HD video at all the frame rates – plus many additional video features and options that videographers have been waiting for or use 3rd party firmware to obtain, but that I don’t know much about since I have yet to enter the video world.  But I can assure you that the 5D Mk III is going to be a videographers dream, perhaps with RAW video.  Perhaps it will even be able to autofocus full time in video mode.
  • 7 frames per second high speed continuous shooting.  I’m not sure of the mechanics of it but it seems that the large mirror flipping up and down is an impediment to a super fast fps, but Canon has done it both on previous film cameras and in the 1D line.  So hopefully it will be significantly higher than the current 3.9fps.  It will definitely boast an improved maximum burst rate (more JPEG or RAW frames captured before the camera pauses to digest them).
  • Ability to customize Continuous Low and High settings so that you can choose your own rates. Please, please, please.
  • ISO 100 to 12,800 or more, and then expandable – while the ISO performance of the 5D MkII is already stellar, the new one will boast even more improved high ISO performance (less noise at high ISOs)
  • 3” very-high resolution LCD screen – Non-articulating?  Articulating?  Touch screen?  It seems that an articulating screen is the way to go for any camera now, but will Canon hold off with putting this on their higher end models?  Touch screen is definitely coming to dSLRs, but will it be on this one?  …maybe, probably not.
  • 19 point (or more) autofocus system, all cross-type, with numerous configurations and customization options, as taken from the 7D – this desperately needs to be improved in the 5D, and the technology is already there in the 7D.  Canon will definitely add the new Autofocus menu system of the new 1D X to make configuring and taking full advantage of the AF system much easier – as opposed to the autofocus menu and C.Fn options on the 7D which make it a bit complicated.
  • Improved 63 zone+ exposure metering system – it will definitely boast an upgraded exposure metering system, perhaps the current 63 zone system, but probably even a bit improved.
  • Magnesium allow body with weather sealing – already has this, not much improvement required.

Additional features:

It will certainly have a several new menu and custom function settings, hopefully including some additional control over Spot, Center-weighted, and Partial metering, like the ability to change the size of the area metered and the ability to link it to the active AF point.  Plus the new Autofocus menu system similar to the 1D X.

Oh yes, and the HDR fans would appreciate more latitude in auto exposure bracketing, such as perhaps 5 exposures over 5 to 9 stops. And maybe some more fluorescent white balance options like Nikon offers.

It will likely and hopefully retain the CF card and the LP-E6 battery.

Built-in GPS or wi-fi?  This will eventually be in all cameras, and maybe this one will have these features.

So, there are my best guesses. Be sure to follow the rumors at Canon Rumors to find out when the 5D Mk III may come out, particularly the 5D Mk III category. And learn about my Canon 7D Mk II predictions in this previous post.