(Video section updated June 2017; rating changed from 4 to 5 stars).

I write this review from the perspective of an advanced photographer who does the occasional video. For three and a half years, I owned the 5D Mark III; its responsiveness and the image quality it delivered with a good lens made it less a camera and more an extension of my mind and eye, faithfully recording the grand landscapes, events, and decisive moments I was privileged to see. The upgrade to the IV was more a personal choice, rather than from being compelled by any major limitation of the III. I've now grown familiar enough with it to write a review.

A 5DIII user or a 7DII user will find the controls very familiar; I was able for the most part to start using it without referring to the manual and all that muscle memory I'd built remained useful. As a practical matter, having the controls and even most of the customizations be similar between different Canon bodies is a great convenience if you happen to be using two different cameras during a shoot, particularly one where you don't control when the action happens. The shutter feels softer and quieter, a design carried over from the 5DS/R to reduce vibration. The viewfinder phase detect AF is everything you expect from a camera like this - I had no problems with my 24-70 II, 70-200 II, 135 or 85 1.8 at maximum apertures. After using this camera for seven months, I can say that tracking is improved over the III. The new metering sensor enables face detection and tracking through viewfinder AF. Combined with Zone AF and using a fast prime like the 135L or a zoom like the 70-200 II, it is excellent for candids and for tracking action. The 135L, in particular, is an absolute joy to use for candids. Light, fast, and precise, the effect is one of the camera virtually disappearing, leaving your eye and the unconscious reflex of your finger to capture one precious moment after another. Perhaps the biggest surprise is the touchscreen. I find myself using it more and more in preference to the joystick when navigating the menu. Dual Pixel Autofocus is as as fast as advertised - certainly as fast as viewfinder AF. What I found pleasantly surprising was that I seem to be able to get sharp shots at exposure times well over 1/focal length seconds using this method. You do have to get past the ergonomic considerations of shooting with a heavy camera held at arms length though, and it is probably better used with smaller lenses versus something like a 70-200.

In terms of image quality - you will certainly notice the extra resolution. For the times you don't need it or are not able to use it effectively, the camera helpfully offers lower resolution RAW modes. I find the 17 MPix MRAW mode is very useful for run of the mill shooting needs giving something reasonably close to the resolution of a 6D or 5D III, generally preferring to use the full resolution mode only for landscape shots using a tripod or portraits in good lighting. The camera's JPG engine is clearly improved over the 5D III. The fine detail mode is a nice addition. I gave up on shooting JPG with the III due to the soft detail and very aggressive NR even at base ISO. On the IV, you can probably shoot JPG in a fairly broad range of conditions.

The dynamic range - which was the main reason I upgraded - is certainly better than the III. The early fall morning shots I took with the camera clearly showed it capturing a greater range of tones than my old III. Shadows are much cleaner - at base ISO, the IV has less than half the read noise of the III. The complete absence of banding or pattern noise makes this an even bigger advantage, and this is easily seen and much appreciated when you work on RAW files. The camera does appear, for the most part, to be ISOless. What I mean by this is that once you know your aperture and shutter speed, you are better off shooting (in RAW) at low ISO and then boosting in post. I've taken shots at ISO 400 and boosted by 3.2 stops in Lightroom (the equivalent of ISO 3675) and get very clean images. The benefit of this is that you preserve the greater dynamic range available at low ISO versus throwing away the highlights during in camera amplification. One application I've found this useful for is when shooting in challenging and changing light conditions such as stage events. I've taken to setting my aperture and shutter speed for DOF and movement and simply shooting at low ISO, with confidence that I will not overexpose highlights, and can easily recover a 3+ stop underamplification of darker regions in post with no noise penalty. This makes me less reliant on metering accuracy gives me more time to focus on composition and timing. I do find this to be a significant advantage versus the Mark III, and one I have come to appreciate very much as I have spent more time with the camera.

It does bear noting that the noise advantage of the IV over older Canon sensors, particularly the 6D, diminishes significantly at high ISO. This is because at high ISO, the dominant read noise is the upstream read noise from the sensor as opposed to the noise from A/D conversion. Increasingly amplified with ISO, it swamps the conversion noise which is the only component benefitting from on chip ADC and which is unaffected by ISO (the upstream read noise of the 6D, once scaled for pixel size, is actually lower than that of the 5D IV; in contrast, the conversion noise of the 5D IV is much lower than that of the 6D) Both the 6D and 5D IV have lower pixel size scaled upstream read noise than the 5D III. This lower upstream read noise of the 5D IV over the 5D Mark III does seem to translate into better high ISO performance. Overall, for the same viewing sizes, I find myself using less noise reduction at high ISO than I was used to before, and color and detail is well retained even at ISOs like 12,800. With this performance, I am looking forward to using this camera for astrophotography this summer.

I decided to update the section on video based on eight months of using this camera plus recent announcements by Canon. Much has been said about the 1.74x crop factor and large file sizes for 4K video, so I won't go over that here. What I will say is that I have been able to take better 1080p videos with far less effort using the 5D IV than my old 5D Mark III. Comparing videos taken in similar lighting conditions and the same lens, the IV's videos seem to show better color rendition and highlight detail. I certainly do not mean to suggest that the III is incapable of making excellent videos - there are plenty of great videos taken using that camera that are publicly available, and Magic Lantern firmware allows shooting of RAW 24 fps 1080p video, something currently unavailable on the IV - only that for a relative novice like me, it is a lot easier to do so on the IV. I've found the autofocus and face tracking in movie mode to work very well; so long as you have a reasonable number of faces (4-5), it has no trouble locking on to a specific face, even from the side, and will easily reacquire focus after a temporary obstruction. What this means is that you can use your fast lenses, particularly those having IS, for grab and go shooting and come away with great videos; you will have no trouble using them wide open. One of the complaints I had when I initially wrote this review was the absence of C-LOG. As of July 2017, this will no longer be the case, since C-LOG will be available as a paid firmware update and is implemented for both 4K and 1080p video. This means that much more of the dynamic range of the sensor will be available for those who don't mind spending time grading and processing their videos. Yes, ideally the firmware update would have been free, but the cost does not seem exorbitant, and quite simply, I would far rather have it than not. Based on my actual experience with using the camera for video, and the recent announcement of C-LOG implementation, there simply is not a reason for me any more to dock a star here.

Overall, the 5D Mark IV is a superbly capable photography tool that addresses some of the shortcomings and improves upon the strengths of what is already a very good camera. Importantly, these improvements are in areas that are meaningful to photographers and will be noticed as they push the camera to its limits - low ISO exposure latitude, tracking, and high ISO noise performance. Like the 7D II and the 5D III, this is a photographer's camera - well thought out, robustly built, fast, responsive, highly customizable, and above all an absolute delight to pick up and use. Like those cameras to which it owes its heritage, it handles and performs beautifully, and is utterly dependable. As I have become familiar with its capabilities and the results it produces, it has inspired the same level of trust and confidence that the 5D Mark III did, the same eagerness to use it, and the same thrill of anticipation when I have a shoot planned with it. And if it feels like a bit of a smaller step up from the 5D Mark III, that says more about what a revolutionary camera the Mark III was when it first came out than it does any shortcoming of this camera. The features in the 5D Mark III made it one you could take into situations where a 5D II simply wouldn't perform. In contrast, you're likely to use the 5D IV in much the same way as you would the III, and the newer camera will do the job better and make your job easier. If you can afford the 5D IV, you'll enjoy the greater shooting and editing flexibility and the ability to capture better photographs in a somewhat expanded range of conditions versus its predecessor. You'll no doubt also find yourself taking more videos due to the convenience and ease of focus tracking through dual pixel AF. Features like the intervalometer, WiFi, and GPS are very useful additions, although they were not primary attributes for me in determining camera choice. If you are upgrading from a 5DII or crop frame and are on a budget, I can attest, through the several tens of thousands of photographs I've taken with the 5DIII, that it remains a great camera and, at current used prices, very good value for your money.

Image notes: The first and third photographs were shot using a 70-200mm f/2.8L IS II - as flawless a lens as I've shot with - the second with an 85mm f/1.8 and the last one with a wonderfully sharp (but unfortunately, rented) 35mm f/1.4L II. The second photograph was shot at ISO 400 and pushed 3 stops in post- something that you really couldn't do with the III - and illustrates the point about "ISOless" shooting. Note that the underexposure applies only to ISO - regardless of camera, you want to maximize the photon signal incident on the sensor - without blowing the highlights - to minimize shot noise as a proportion of the signal, and you do this through maximizing aperture and exposure time subject to other shooting constraints like DOF and movement. This is obviously also the basic premise behind ETTR. The third photograph of the dancer was taken in single shot mode - one shot, one capture - using AI Servo and illustrates the tracking speed and precision of the focusing system.

Additional information: A buy/no-buy decision is yours to make obviously; my goal was to give you enough information based on my experience so you can make an informed decision if this is the right camera for you. If you've read this far, I wanted to share a few resources I've found useful, all publicly available for free: Emil Martinec's 2008 paper on noise and bit depth is truly outstanding. Bill Claff's website is a great resource for data based noise comparisons between cameras as well as technical data on sensors such as full well capacity, read and conversion noise, etc. That data shows that the 5D IV's advantages over previous generation Canon sensors in the 6D and 5D III extends beyond just lower conversion noise due to on chip ADC. Roger Clark's website has some excellent material as well, and finally, DPReview is a wonderful website for real world comparisons and for finding explanations of very technical concepts such as noise, dynamic range, and ISO invariance in layman's terms.

The Canon 5D Mark IV is one of the most anticipated cameras. Mark III users and other camera enthusiasts are pondering if they should make the upgrade or jump ship. I purchased this camera from B&H so it won’t show that I own it and I will updated this review as I continue. Now, a bit about my background, I shoot weddings for a living after retiring from more than 40 years of running my other businesses. I have watched every Mark IV Youtube videos available before its release so that I would know exactly what to look for upon receiving the camera. Here is the good, the bad and the ugly.

Reasons to buy
1. 30.4 MP full-frame provides the ideal file size for wedding photographers who have to process thousands of photos. The image was large enough for cropping but not too large to slow down my workflow. However there is a better choice for landscape photographers, the 5DSR and Nikon D810 with higher resolution. Having a higher pixel count has many advantages and in some way allows the Mark IV to be more effective than the 7D Mark ii other than it is slower at 7fps. The Mark IV has about one stop better ISO and DR (dynamic range) performance and this means I can comfortably use ISO 1600 instead of 800 to double my shutter speed. In wildlife photography, especially birding, the crop sensor 7DM2 is extremely difficult to frame birds in flight whereas the Mark IV allows you to capture a wider image and crop later in post. Please keep in mind that you will not have the same reach with the Mark IV as the 7DM2 when cropped to the same resolution (30/1.6/1.6=11.7 MP). Of course we should always try to fill the frame by using a longer lens or best to get closer to the subject but that is not always possible.
2. Seven frames per second continuous shooting speed. Sounds like just one extra frame improvement from the Mark III but read on, the faster processor and bigger buffer are what made the difference. Buffer did not get filled up if I shot jpg but maxed out at about 40 frames with sRAW and 10fps with RAW (The claim of being able to continuously shoot 21 pure RAW pictures is untrue, at least I was able to accomplish that with the fastest memory card) and it continued to shoot at about 4fps in sRAW (appx only 25% of the Raw resolution, something I would avoid using unless I know they are going to be casually loaded on Facebook and in that case you may as well shoot jpeg, mRAW is a bit better about 57% of the RAW resolution. Even after the buffer was full, the Mark IV continuously shot at 2fps in RAW for as long as I held the shutter. Extra frame over the Mark III is nice because you may just miss that first kiss. But the frame rate is not the biggest improvement, not as important as how fast it can clear the buffer and how it allows you to operate regardless of a full buffer. For wildlife or sports the Mark IV can unload a full buffer 4 times faster than A7Rii, in about 5 seconds vs. 20 seconds. This makes it impossible to use the A7Rii for actions, especially when it drops to 0.5 fps (one frame every 2 seconds, 4 times slower than the Mark IV) after the buffer is full. I tried the A7Rii frame rate in both compressed and uncompressed modes with the same result. The conclusion is I would never use an A7Rii for birding or sports but I would gladly take the Mark IV with me anytime. These experiments were conducted with the 128mb Class 10 U3 Lexar and Transcend memory cards independently in each camera. However for pro sports shooter, I am sure the 1Dx Mark II would be a better choice as it is faster with bigger buffer.
3. Focus. This is the most important feature for my application and it is where Canon shines. It has the same 61-point AF system with 41 cross-type but with expanded vertical coverage compared to the Mark III. But I don’t see much usage for the vertical coverage, may be more horizontal coverage. In low light the mark IV focuses faster than the Mark III, Nikon D810 and Sony A7Rii with higher hit rate which is another big reason for Mark III users to upgrade. In live view, the Dual Pixel focus speed is much faster than Mark III which still uses contrast detection. This works well for photo as well as video. It is very intelligent and tracks quite well even when the subject’s face is turned away. Dual pixel is accomplished when each pixel in the sensor is split in half, capturing a left and a right image. These images are processed and compared in nanoseconds to attain focus. The Mark IV algorism is superior to just face detection. It can track object, for example it can follow the bride's shoe. However it is always going to be slower to focus than spot focus because the processor has to work continuously. Dual pixel AF comes in extremely handy and that alone is worth the upgrade. This is something the A7Rii has but the A7Sii is lacking. In live view, the focus area select is limited to 3 options instead of 7, track, spot and expanded. It can be changed with the "Q" button only in live view mode and can not be adjusted with the AF area select button. IMO, Canon's strength is on focus speed, despite of how much I like the IQ on my A7Rii, it has less focus hit rate on action shots than Mark III or IV. The Mark III and IV will continue to be the go to camera for wedding photographers.
4. ISO range 100-32000 with 50-102400 expansion. ISO noise is improved from the Mark III by about one and half stop, usable at 1600 in my opinion. I noticed there are less color noise than the Mark III and the grains are finer due to a higher resolution sensor. This is really helpful for low light shots which require a faster lens than F2.8. Even though the ISO has improved from the Mark III, a reason to buy but it still has more banding and noise than the A7Rii. The D810, A7Rii and A7Sii are still the low light monsters.
5. Touch-screen LCD monitor. Finally Canon makes it easier for us photographers and you can use both the buttons and the touch-screen simultaneously. Yes, there are certain menu that can be navigated quicker with the dials so it is brilliant you can do both. There is also a confirmation tone after you have tapped the item. The screen is higher res than Mark III and as sensitive and accurate as my iphone. Reviewing photos on camera has never been so easy. Scroll, pinch, swipe and tap, it is so fast to navigate, again a feature D810, A7Sii and A7Rii lacks. Resolution on the screen is 1,620,000 vs Nikon D810 at 1,229,000 and Mark III at 1,040,000.
6. Dual Pixel Raw. With the dual images generated from the split pixel, Canon cleverly processes them as Dual Pixel Raw allowing post micro focus adjustments. This is good to have for wedding and portrait photographers, as you can fix minor focus problem in post at appx. half inch focal range so don't expect miracles and it is a hassle to use with double the size file. Currently, Lightroom does not support this feature at the moment so the workflow is painfully slow using DPP Application. Adobe has announced that they will support Dual Pixel Raw so this is a temporary problem.
7. Weather sealing should be improved but it is hard to prove. But with Canon’s legendary quality, I believe they did borrow the technique from the 7D.
8. DR (Dynamic Range) has been greatly improved. The shadow has a lot less noise than previous models. Increase latitude to push shadow for under exposed area and the ability to retain detail over the 5D Mark III and 6D is truly incredible. Canon's claim on increase DR is 100% true, the difference is so obvious that it makes me hesitates pulling my favorite Mark III out of the bag. DR is still a bit shy from A7Rii but greatly improved from the Mark III and 6D. It can now compete with any full frame head to head. If I am buying a still camera for just the DR, the A7Rii or the Nikon D810 will be the choice but the Mark IV is just so much better in so many other arenas.
9. Wifi and GPS. Uploading photos to phone to share in social media has never been easier and I am glad Canon has finally caught up with the trend. There is a second setting in the GPS menu that let you shut down GPS when power is off. This is extremely helpful in saving power which the 7D Mark ii is lacking.
10. Improve handling. The grip is more comfortable than the Mark III. I have medium size hands, I own and tried many cameras, the Mark IV has the most comfortable grip for me. The rubber has been improved from the Mark III. It is more secure and comfortable to hold.
11. Third party gear. The popularity of the Canon lens system makes owning this camera a dream as it has created an extremely strong third party support. For example the Metabone adapter which works wonders on the Canon lenses, allowing me to share the glass and to use the Sony A7Rii as my main video camera and Canon 5D Mark IV as my still camera. The combination of these two cameras is perhaps one of the best systems to use for weddings. Despite of how much I like Nikon's IQ, I could not share its lenses with Sony to obtain auto focus with an adapter. This is the main reason I purchased this camera. I want to make it clear that I am not associated or paid by any parties for this review.
12. Canon added the extra AF area selection button which can be used for quick ISO adjustment. Under CUSTOM CONTROL on the last icon at the bottom you can set this button to adjust ISO with the front dial. This extra button makes adjusting ISO on the fly a single step process. I change ISO quite often between indoor and outdoor during the reception so this comes in quite handy. Basically Canon has added a third wheel for the ISO similar to that of the A7Rii, except it is better because my A7Rii ISO wheel often gets accidentally bumped.
13. HDR video. I can save blown out highlights shot in this mode for about 1 to 2 stops. However, it will only shoot in 30FPS at 1080P because it actually shoots in 60FPS and combine the 2 frames in HDR. This mode is not available in 4K since the limit is 30FPS.
14. Country of Origin. 5D Mark IV is made in Japan, Sony A7Rii, A7Sii and Nikon D810 are made in Thailand. This can be viewed as a bias opinion but I have always had better luck with products Made in Japan. I think, this is the main reason why Canon is more expensive with less features compared other brands. I am a heavy shooter and my 5D Mark III is 3 years old, never had a single issue and my Sony A7Rii broke twice in less than a year.
15. Multi Shot NR (Noise Reduction). In this mode the camera takes 4 quick consecutive shots and process them to reduce noise. This allows you to shoot in much higher ISO with noticeable improvement in IQ but remember to keep your hands steady (no tripod needed) and it only works in jpeg. How is this different than stopping down 2 stops on the shutter speed? The Mark IV takes 4 images separately, process and align them to produce less noise verses stopping down the shutter which causes motion blurs. When I run out of options in low light, I would switch from RAW to JPG and change to this mode. You will find the photos quite usable even at ISO 3200.

Reasons not to buy
1. LPF- Low Path Filter. Canon could easily remove this filter but chose not to. My take on this, is that Canon is very conservative and they chose to sacrifice sharpness over Moire for many reasons. On my A7Rii I do occasionally see Moire, for example power lines so this is a preference and may not be judged as a defect. Read up on
http://www.birdphotographers.net/forums/showthread.php/126621-Understanding-the-Low-Pass-Filter-Effect-Cancellation-Issue-What-You-Must-Know-About-Canon%E2%80%99s-Two-New-50-Megapixel-Camera-Bodies
However, I would rather choose sharpness and risk Moire such as in the Canon 5DSR design. This is where Nikon and Sony shine, their IQ is sharper without the LPF but with slight risk of Moire.
2. 4K video recording is perhaps the worst feature Canon has added to this camera. Motion jpeg creates a warping appx. 240GB file size in just one hour of record time. Also due to the 1.74x crop, I was unable to shoot wide even with a 16-35mm, not to mention the less than okay low light quality. On the up side the Mark IV allows you to frame grab at 8.8MP which gives me better IQ compared to frame grabbed from A7Sii. My assistant can now shoot backup photos at 30fps continuously in critical moments. If you intend to frame grab, I highly recommend that the shutter speed is set to 1/125 or higher otherwise most of the frames would not be usable. Canon should have given us another codec option with better compression and not worry about cannibalizing their pro cinema line. Their near sight leaves the door open for Sony and Nikon. The way Sony is progressing with Nikon's dependency of Sony's sensor, I estimate both Canon and Nikon's dominance on the pro market will not last more than a decade. For now I would keep my Canon lenses and keep my fingers cross that they will up their game.
3. No Tilt screen. Some may wonder why Canon didn’t put this in the Mark IV. My guess is that the tilt screen makes the camera less rugged, harder to seal and both Canon and Nikon want to make their pro gear bullet proof. The toughness of Canon gear is one of the main reasons I use it exclusively for weddings. It’s sad to say that my Sony A7Rii gave me a “Camera Error” message in just a few months of light usage (I couldn’t fix it even after doing a hardware reset) and my Mark III lasted for years. Do I wish for the tilt screen? Canon and Nikon both should listen carefully, I want the tilt screen even if I have to sacrifice some durability and weather resistance.
4. Weight body only is 800g (Not including 90g battery) appx 2 pounds (1 pound=454g), it is 60 grams lighter than the Mark III and 30g heavier than Canon's lightest full frame 6D but still much heavier than the GH4 and A7Rii (625g including battery). I use the Click Camera Holster from Turbo Ace and the weight is not an issue as I could barely felt it during my entire trip in Africa.
5. The memory card is outdated and slow Canon should have used Cfast.
6. No EVF. EVF has many advantages operating in the dark. You can see what the sensor sees instead of everything pitch dark coming from the mirror which makes composition and exposure harder. With EVF, if you are under exposed by not paying attention to the meter, you will immediately notice and make the correction. Here is a unique idea, Canon can add an EVF next to the current view finder as it will be extremely useful for shooting video under the bright sun. It can be retracted like the RX100 but with Canon I don't think that would ever happen. Most would agree without the EVF, the DSLR will be not be able to compete with Mirrorless in video features. This is one of the reasons that Canon is trying to separate still from video on their DSLR line up and steer video shooters to their cinema line . I am not paid by Canon, Sony or any third party. IMO, Sony is better on video and Canon is better on photos.

Important update: As of 9/24/2016 the raw files from Mark IV is supported in Lightroom CC but not in LR 5. No older versions of LR get any updates when there is a new version available. You can use the newest version of the Free Adobe DNG converter Ver 9.7 to convert the native RAW files to DNG's that LR 5 can read.

In conclusion, the photo quality of the Mark IV has been improved remarkably from the Mark III but if you want to shoot video, this is definitely a “no buy” and I would only use it as a backup. Canon is facing some real competitions on sensor technology but amazingly it is still able to keep up on the photography side. For Canon to survive this market in the long term, it has to either heavily invest in mirrorless technology or to follow Nikon's foot print to use Sony's sensor. But to compete in price with the added features Canon may have to make it in Thailand. It's not Canon does not have the ability to make better sensors, just that it is unable to drive cost down to compete in the DSLR market. Imaging the Mark V with Sony’s video specifications and Canon’s brilliant stills technology, may be a reason Sony will never sell its sensors to Canon. The way Sony and Nikon are progressing, I think they are the choice for the all around video and still cameras. Now Canon is hanging on threats relying on its market dominance created through the decades. Most Canon photographers are ready to jump ship, some already did and Canon engineers absolutely have to get on the edge of their chairs to hold on its crown. I sure hope that they will get their act together with all my investment in all the Canon lenses. The Mark IV in video application has inadequate codec selection (biggest killer is file size), lack of zebra, focus peaking, over cropping in 4K mode which affects not only focal length but also ISO performance. The only advantage is its dual pixel AF but the cons out weight the pros. For now, as a photographer, if you own Nikon, stay with Nikon for its great IQ, the Mark IV features are evolution not revolution and they are still not worth the switch. If you are serious about shooting both stills and video buy this camera and the A7Sii or A7Rii and share the lenses with the Metabone Adapter. One thing that I did not mention about the advantage of DSLR over mirrorless is that the sensor stays clean whereas my A7Rii sensor had to be cleaned 3 times during my last 30 day trip. A lot of my pictures had spots which took hours of Photoshop. In the DSLR, the mirror basically acts as a shield during lens change. Sensor cleaning is a huge hassle (almost impossible without leaving some smear even after trying out multiple sensor cleaners) and I hesitated swapping lens on many occasions on all my mirrorlesses. If you shoot mostly photos buy this camera and never look back, IMO, it is the best all around stills camera in 2016.