topic Re: 5d mark III focusing slowly/etc. in low light wedding receptions in EOS DSLR & Mirrorless Cameras

5d mark III focusing slowly/etc. in low light wedding receptions

ejder — Thu, 10 Apr 2014 14:33:15 GMT

I've been using 5d2s for a long time because I am simply not rich enough (and I don't want the huge body either) to buy 1d-series cameras for work. I've shot about 20 weddings with the 5d3 since I bought it, and I finally sent it in to Canon the other day for an autofocus checkup.

My #1 issue is reception autofocus. My 5d2s beat my 5d3 at reception focusing (with 580EX AF assist always used). They are more reliable for AI servo and faster for one-shot.

My 5d3 struggles to acquire in one-shot, taking probably close to 2 real seconds (it feels like forever) to establish and confirm a lock on a static subject during wedding receptions with lenses like 24L II, 35L, 50L. In contrast, in the exact same lighting conditions and with the same lenses and flash AF assist, my 5d2s all snap right to focus and I click the shutter within about 1 second or less, getting an in-focus image about 90-95% of the time.

With AI servo, the 5d3 is just inferior to my 5d2s in low light. I was hoping, one day, to get a camera that would give me the ability to track subjects well during processionals/grand entrances/reception dances using the outer points, because I'm pretty tired of being stuck with center-point framing for these situations. I thought the 5d3 was supposed to solve that problem, but in fact it took a step backward in low light AI servo accuracy and locking. My 5d2s (center point) both acquire faster and track better in low light than my 5d3 (center point also).

After sending the 5d3 in to get it checked (and so they could charge me $175+), I got a nice copy of the page saying that the camera focus in low light is blah blah etc. etc. use AF assist (which I had noted I did) and the overall feeling was that they were very condescending and disregarding of my equipment issue. To me, a $3500 camera should perform better than a camera that is now worth ~$1300...and so the 5d3 performs arguably better in GOOD light, simply because it has more focus points to choose from which are generally pretty accurate - in GOOD light. However, it performs worse in reception light. Wedding photographers will understand what I mean by reception light.

My 5d2 AI servo is not useless during receptions, but my 5d3 AI servo struggles more in the same reception lighting. My 5d2 one-shot locks quickly and pretty accurately during receptions, while my 5d3 takes significantly longer in one-shot to lock, and sometimes it gives me pretty wild misses, during receptions. Always using AF assist with 580EX, and btw the 5d3 firmware is the latest version (1.2.3 at this time). The camera simply focuses slower during receptions than my 5d2s, and AI servo misses more.

I also don't like that AF points don't light up before focusing, but this is less important to me than a fast, responsive AF system for wedding receptions. I have had to put away the 5d3 on multiple occasions and bring out a second 5d2 for wedding receptions just so I can get good dancing photos, good speech/toasting photos, etc., before all the key moments went by and ohhhh too late, my focus system didn't lock in time...

I have been having this issue with 5d3 performance since I bought it close to a year ago. I do wedding photography primarily, and I have quite a bit of experience shooting weddings and dealing with the various demands of weddings.

Most of my AF experience is with single point, with only a few experiences using the expansion settings. I have never had trouble locking or tracking with single point with my 5d2s as long as there was enough light to do it, and being used to that I expected the 5d3 to be able to perform at LEAST comparably. It does not.

At this point, this critical functional limitation of the 5d3 has left me very dissatisfied with the camera. I thought upgrades were supposed to do everything just as well or better than the previous version, but this newest camera has shown me that more AF points definitely does NOT mean a better (or even comparable) AF system in every situation. Clearly something was traded off when they added a ton of cross-type points, like low light acquisition speed and being able to see your AF points illuminate when you start AF.

I've been playing around with Nikon equipment for a while and am beginning to think that is my forced alternative. I don't like the things I hear about Nikon customer support, and I don't really like the direction they are going with some of their releases or how they handled function issues (focus issues with off-center focus points, oil on sensors, etc.) but Canon isn't innocent of that stuff either. And if I use an all-Nikon setup then I will have excellent dynamic range at low ISOs as well. Too bad Nikon doesn't have the glass I like best (35L, 85L, etc.)...but compromises must be made in some direction, and I'm intensely frustrated with Canon's latest cameras' focusing systems in low light.

It's very specific, mind you: Low light performance is inferior to my 5d2s. In good light, my 5d3 has better AF flexibility for tracking with outer points, and the one-shot focus acquisition is comparable to my 5d2s.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

TCampbell — Fri, 11 Apr 2014 17:54:30 GMT

The 5D III has far far more than simply "one shot" vs. "AI Servo". There's a 47 page document on *just* the focus system for that camera. Specifically, there are a number of options for AF area selection and if you've chosen a sub-optimal mode you could be forcing your camera to struggle to achieve focus.

For example... in just the "one point" style mode, there's:

Spot AF - a reduced AF area designed to be used with HIGH CONTRAST but SMALL focus points (such as eyes). They idea behind this reduced AF area (which the 5D Ii doesn't support) is that you can force the camera to focus on a particularly tight object (such as an eye) at very shallow depth of field without having to worry that the camera will accidentally grab either the eyebrows or nose, etc. which are at a slightly different focus distance and end up softening the focus on the eyes. But when using this mode, the camera needs a subject with high contrast and enough light to make it easy to identify the contrast because you're dealing with a very tiny area.
1 pt AF - this works like the standard 1 point AF mode found on most cameras.
Expand Area AF - this is a 1 point mode except it borrows from points above, below, left and right of the selected point to use as focus-assist points. This aids in situations where contrast is poor (or light is poor) as it give the AF system a larger target target to help find enough contrast to lock focus.
Surround - like Expand Area AF, this mode uses a central AF point but then completely surrounds that point with 8 additional points to expand the AF area even larger.
Zone AF - this mode allows the camera to use a block of AF points in a region of the display. E.g. if you are composing your subject with a "rule of thirds" composition, you could push the AF zone over to the area where you intend to place your subject. It's an auto-select area but the auto-select is constrained to only those AF points in the zone you pick.
Auto-select 61 point AF - this mode allows the camera to use any AF point it wants. However, unlike typical auto-select modes, you actually can use the joystick to tell the camera where you want it to search for it's initial focus point. This is because this mode is commonly used in sports situations where the cameras intelligent tracking & recognition system (iTR) will be used... the camera focus will follow the subject as they move around, but there's a whole set of configurations which control how the camera expects subject movement to behave (this is a highly tunable mode.)

The AF system on the 5D II (and, like you, I also own both 5D II and 5D III cameras) has an AF system that can focus from -0.5EV to +18EV.

The AF system on the 5D III, on the other hand, has an AF system that can focus from -2EV to +18EV. In other words, the 5D III focuses in considerably less light than a 5D II.

The 5D II has only 9 user-selectable AF points (the 9 you can see... one center "cross type" point surrounded by 8 single-axis AF points in the diamond pattern). BUT... it has 6 more "focus assist" points which are hidden (not user selectable). These are not etched on the viewscreen, but they are on the focus sensor. Two points ... one above and one below the center point, are only available at f/2.8 (so not all lenses will be able to use these). Four addtional points form a box around the center point and these work even with f/5.6 lenses.

This means in some situations your 5D II is using a larger focus area then you might guess. Canon does not consider these extra points to be focus points... they are "focus assist" points in that they extend the area the camera uses to help it obtain more a larger target with which to identify enough contrast for focus.

This is why I'm thinking you've picked a sub-optimal AF area mode. You might be using spot-AF and, if you are, you are forcing the camera to focus with a significantly smaller AF area than the 5D II (especially if the 5D II was using those hidden focus-assist points and you didn't know it). Try using expand area AF or surround AF if the camera is struggling with low light.

I hope this is helpful. The 5D III is an amazing camera and easily has one of the very best focus systems in the industry.

The Canon 6D, incidentally, has an 11 point AF system with one cross-type point, but the 6D can focus down to -3EV... a bit lower than the 5D III. However in virtually every other way, the 5D III has a vastly better focus system.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

marcosphoto — Fri, 01 Aug 2014 13:22:32 GMT

I can't say I'm completely impressed with my upgrade to 5D3 from my 5D2 but I can tell you that my 5D3 smokes my 5D2 body any day of the week and sunday with regards to focus speeds - cannot even compare! However at first I did notice some lag with flash installed. I noticed a firmware upgrade early on addressing this issue but I never saw it as a large enough problem to bother doing the upgrade right away (I prefer to do firmware only when absolutely nessesary). However when I had the light leak problem addressed, they did my firmware for me and I can say that YES, the upgrade did improve my performance in low light with flash installed.

Are you on the latest firmware?

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ejder — Fri, 01 Aug 2014 16:38:27 GMT

As I said in my original post, I've been on the latest firmware ever since I got the camera. It's been sent in to Canon to see if it's functioning normally, and according to them it is. The 5d3 focuses slower in low light, period. If your subject moves at ALL (or if YOU move, e.g. the target is the eye vs. the nose or the mouth of the subject just by natural movement), and you're using one-shot mode, it completely restarts the focus acquisition process, goes through the double-checking stuff all over again, and 5 seconds after pushing the AF-ON button you finally get a focus lock that MIGHT be in focus.

AI Servo in low light is basically worthless. My 5d2s track better and in lower light than my 5d3. It's been this way since the beginning, even after Canon received and tested the camera and charged me just to tell me nothing's wrong with it.

That's the #1 reason why I don't really like the 5d3 and actually won't use it at all for several parts of the wedding day. Unless I want 99% out-of-focus photos, that is...

I've used it for 20+ weddings now, same results every time. I don't think the fault lies exclusively in ME - otherwise I probably would not get comparatively much better results with an "inferior" camera like the 5d2.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

marcosphoto — Fri, 01 Aug 2014 21:38:31 GMT

Sorry, missed that part about the version - guess I was just excited to try to help out. I personally cannot agree that my 5D2 was better at focusing low light (flash or not) - than my Mk3. However, as I only do this sort of shooting for personal stuff and on a professional level do motorsports I think its completely possible I have not met those conditions often. Also, I found the Mk3 so good in low light that I hardly use my flash so again I'm not an expert. I will say one thing, repair people (present company excepted 😉 sometimes just assume the owners are crazy and don't bother doing the inspections as deeply as they should. I feel the same about my 24-105L lens which I feel has issues but repeatedly get told it's perfect. Not saying this is the case for you but who knows.

Question, my olden days 430EZ flash used to emit a red beam assist while focusing however I swear my 580EX2 flash does not. Because I don't use the flash often I am curious if these flashes are designed with a visible assist beam and if so, curious why I've never taken notice to it on my flash.

Good luck in your search for the truth.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ScottyP — Sat, 02 Aug 2014 01:34:32 GMT

You are not alone in this.

Peruse the "most kudoed posts" on this site, being sure to select "all time" rather than just those of the last week or month, etc... You will find that of the first 5 pages (75 posts) about 60 of them are the following post and popular responses to this post: http://forums.usa.canon.com/t5/EOS/5D3-AF-assist-beam-slower-focus/m-p/2277

There were 180 responses in all.

I think even this is understating the magnitude because it lists the original post and all its kudos-winning responses as separate posts, rather than as one post with an insane, unprecedented number of kudos for its sub-postings. Also, In addition to this thread there were several other significant threads on basically the same issue, and if you read it all you will see at there were threads on all the other Canon-related forums.

There was a firmware upgrade and that made a lot of people's issues better but some still reported issues catching focus in low light. Weddings did seem to be the scenario most frequently used to describe the problem(s).

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ejder — Sat, 02 Aug 2014 01:39:04 GMT

This singular issue of the 5d3 has ensured that I will never buy another one (unless they fix that, which they won't). Unlike what I did with the 5d2 (upgraded to 5d2s towards the end of their product cycle), the 5d3 is too impaired for low light photography for me to be able to replace my 5d2s with 5d3s. I can only hope the next generation will NOT have the same low light focus delays...otherwise I might have to buy a few 6Ds just to keep up with more current tech (since my 5d2s will wear out eventually). I've heard they don't have the same doublechecking delay, but they also have other limits that I dislike (1/4000 ss, 1/180 flash sync, no pc sync port, SD memory only) and will have to work around.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ScottyP — Sun, 03 Aug 2014 16:49:06 GMT

Is there anyone out there who 1.). Had the low light focusing problem with 5d3 as described in the big thread I referenced above, and 2.). Used the firmware upgrade?

If so, did it a.). Fix the problem or b.) not really fix the problem?

I actually bought the 6d instead of the 5d3 for the sole reason of that problem. I had the money, I was planning on buying the 5d3 on that Black Friday sale, but I changed my mind and went 6d for the low light focusing. I had experienced bad low light focusing with my old T3i and that was the biggest issue for me since I shoot indoors a lot.

I had been assuming the firmware upgrade had fixed the issue, but re-reading the old thread, and looking at some newer posts, I see that may not be the case. I have been thinking of upgrading to a 5d3 at some point, either a used one or maybe this coming Black Friday if there is a great deal to be had. It seemed like half the world chimed in on the old thread, and I was wondering how people, particularly any who actually had the problem, but also those who never did, are faring today, a year or so on.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

linbs — Sat, 18 Oct 2014 14:28:48 GMT

I have the same problem since I bought my 5d mark iii about a year ago... I bought it for concert and music club photography and being a Nikon shooter I couldn't find appropriate camera in Nikon range at that moment and Canon looked reasonable... so am swearing non-stop since... for a long time I thought that I was doing something wrong but after few months of studying all possible sources of information on the camera I believe I understood most of what I need... and my final oppinion is - 5d mark iii is the worst camera I ever used for low light action shooting... it works ok in good lighting and especially in studio... I believe, that for a camera of this level and price range is not good enough...

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

TCampbell — Sat, 18 Oct 2014 15:51:36 GMT

My 5D III performs outstandingly. The OP who created this thread some 6 months or so back, never did address the question of which focus mode was being used, nor which lens, etc.

I'm shooting with mostly all f/2.8 glass (when I do concerts I will also often grab my EF 135mm f/2L) But this means I'm already getting more light and using more focus points than someone with an f/4 lens or a variable focal ratio lens.

HOWEVER... I'm also not using 1 pt "spot" AF. That would be mis-using the equipment. In low-light, llow contrast, use one of the two "expand area AF" modes in which the AF points near the select points behave as AF-assist points to help identify contrast in low-contrast situations. This is one of the reasons why the camerra has a superior AF system.

I also have a 5D II and, yes, it works well in low-light also. But the 5D II has hidden focus-assist points and it's automatically using them (you don't actively switch them on or off like you do on the 5D III).

The 5d III is an "advanced" camera for advanced skill photographers. It's got 6 different variations in how to select and use the AF points. It's also got numerous various in focus-tracking (for servo modes). But the reason I say it's an advanced photographer's camera is becuase it's always going to do what the advanced photographer tells it to do (including when they pick the wrong mode for the situation at-hand.)

While it's somewhat important to understand that there are 6 different variations in how to select AF points... what's even more important is to understand why the camera has so many options. Make sure you understand the difference and in what situation you would want to use "spot AF", vs "single point AF", vs. "surround area AF"... and you'll really start to appreciate the capability of the advanced focus system.

I say this, because owning both cameras, there are pretty much no situations in which my 5D II can outperform my 5D III with AF system performance and regardless of light levels.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ejder — Mon, 20 Oct 2014 16:40:58 GMT

Actually I did say which lenses (24L II, 35L, 50L as primary examples, plus the 85L II for static subjects), and I said which modes (AI servo and One Shot both having different problems).

As for number of points, I have used the expanded (5 and 9 both) and each time I do that it locks on the wrong target far more often than if I keep it down to a single AF point (not the fine/spot point, but the single point without the smaller square inside).

And about preset focus acquisition and tracking modes, I have tried each of the presets in original state and have also modified them, but the results are very similar for me each time - many out of focus tracked shots during receptions. If you were to look at my presets each one would have something altered in the adjustable options, because I have been through MANY different possible options.

I have now shot over 20 weddings with the 5d3, and though my results have improved a small amount, I have given up expecting any different from the camera in terms of general tracking ability/delays in low light focusing. I use my 5d2s when I want fast, reliable (albeit center point only) reception focus locking.

I have done a lot of experimenting with the 5d3. You can say whatever you want about me and I am obviously powerless to stop you, but true experience and fact are all I am going by for my observations.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

TCampbell — Mon, 20 Oct 2014 17:23:52 GMT

I missed your list of lenses on your first post.

If you haven't already seen this, take a look at page 37: http://cpn.canon-europe.com/files/product/cameras/eos_5d_mark_iii/EOS_5D_Mark_III_AF_setting_guidebook.pdf

Your lenses are "Group A", but not every point can take advantage of cross-type AF and f/2.8 glass. There's a column of points in the center which can (excluding top & bottom of the column).

When you use the 5 and 9 point "expanded AF", the camera is really using the center point of the cluster as the AF point. The other AF points are being used as "assist" points... they expanded the AF search area to help the camera find contrast if there is not enough contrast in the center point.

There is a "zone" AF which also uses clusters of points... but it's a bit different than the expand area AF or surround area AF. The "expand" and "surround" really do use the center point, assisted by the others. Zone focus allows any of the points in the cluster to be treated as the AF point (the others are not focus-assist points). It's a bit like using full 61-point auto-selection... except reducing the number of possible points to just the points in one area.

Since I have both systems, I've tested the cameras in very low light using 600EX-RT speedlites with the focus-assist beam enabled. Both cameras lock focus very quickly (typically in about 1/4 to perhaps 1/2 second.) Ultimately the test targets I am using are subjects that offer contrast. The cameras need something with contrast to lock focus. Focus on a flat-ish low-contrast target will make any camera struggle.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ejder — Mon, 20 Oct 2014 20:34:18 GMT

I always look for high-contrast edges (where suit and undershirt separate, eyes, mouths, etc.).

There have been other people reporting similar results as mine with 5d3s, the general feeling I've gotten is that not all 5d3s are created equal. Some of them have delays, miss often in the dark, etc. My 5d3, on its best day, on a TRIPOD (with no movement), with AF assist, with center point or center with expansion, never acquires focus in low light with any of my lenses in under about 0.8-0.9 seconds. In real world conditions, that gets doubled, tripled, quadrupled (yes, quadrupled) regularly because it's handheld, things are moving, etc. AI servo just misses completely about 60-70% of the time. Lighting conditions are 1/100-160, ISO1600, f/1.8ish. My 5d2s track better (center point) and lock faster in low light. My results are extremely consistent. I would not have posted what I did not personally experience, and having used the 5d3 for another 10+ weddings since my first post and seeing the same overall results, I still stand by my experience.

I do suspect not all 5d3s are created equal.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

Yokobash — Fri, 06 Jan 2017 00:58:31 GMT

Im having the same issue! With my both 5d3 in getting crazy of that for nore than a year now and canon lab also told me the bodies are fine, the thing is with my case, it wasnt like this frin the first day, when i just baught my first 5d3 i adored this camera her performanse regarding AF were amazing! But simething happen someday and since then i cant get it back for how it was, for long time now i have similar expirience to what you describe, really frustrating .;(

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

TCampbell — Fri, 06 Jan 2017 02:37:50 GMT

One other point I failed to mention previously...

When I first started in photography (as an apprentice back in the early 80's) the cameras were manual focus only (auto-focus was practically non-existent) and even still... the lighting in a reception hall was typically very dim. Focusing was extremely difficult. We always used flash (absolutely always), often had to preset the focus to a given distance (e.g. 7') with a broad enough DoF that every subject would be in focus.

Later, we got flash systems that had modeling lamps which made it a lot easier to focus.

But today... you can get Canon Speedlites with focus assist beams built-in. Both the 600EX-RT flashes will fire a red pattern that the camera can use to lock focus in ANY level of light and it's very fast.

I typically shoot in Av mode but I the camera offers an option to set the shutter speed range when using the flash in Av mode. The choices are "automatic" (which really uses the range of 1/30th to 1/200th or 1/250th depending ont he capabilities of the camera body) -OR- 1/60th to 1/200th (or 250th if the body can flash sync at that speed), -OR- just lock in at the max shutter flash-sync speed (1/200th or 1/250th depending on the body). I set mine to use the 1/60th-1/250th range BECAUSE that allows the camera to collect ambient light and gives it permission to go down to 1/60th and I can hand-hold a shot at that speed without worrying about camera motion. At 1/30th you may get some blur from camera movement.

This gives you the advantage of the focus-assist beam for fast focusing even in complete darkness with the bonus of getting fill-flash + ambient blended light. It's a fairly high quality result for shooting receptions in extremely challenging light.

Also... make sure your 5D III is _not_ in spot-focus mode. I'd suggest using "expanded AF" or "surround AF" mode.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

linbs — Fri, 06 Jan 2017 12:09:17 GMT

I don't think this is the point. Camera obscura didn't have any focusing at all and no AV mode and people still managed take pictures... We are talking about modern cameras and what they are supposed to do. 5D III obviously failed... I am shooting in low light conditions (concerts, music clubs etc.) where using a flash is not an option, I shot few times with a borrowed D3 (Nikon as you understand) and didn't have a slightest problem at all. With Canon it is a nightmare. I tried all the possible advices and setting variations. It just doesn't do it. At least so far I couldn't find any usefull advice how to do it...

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

Waddizzle — Fri, 06 Jan 2017 13:39:01 GMT

I'd be really curious to know what exposure settings people are trying to use when they experience these issues.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

TCampbell — Fri, 06 Jan 2017 16:28:31 GMT

@linbs wrote:
I don't think this is the point. Camera obscura didn't have any focusing at all and no AV mode and people still managed take pictures... We are talking about modern cameras and what they are supposed to do. 5D III obviously failed... I am shooting in low light conditions (concerts, music clubs etc.) where using a flash is not an option, I shot few times with a borrowed D3 (Nikon as you understand) and didn't have a slightest problem at all. With Canon it is a nightmare. I tried all the possible advices and setting variations. It just doesn't do it. At least so far I couldn't find any usefull advice how to do it...

This is probably not a good example since the Camera Obscura could be moved (it was basically a room), it required a considerable amount of light (subjects typically needed to be in full sunlight), and the images were horribly blurred. Back in the days before autofocus (because I did a lot of weddings back in those days), there were a lot of techniques we used to come away with good results when we couldn't rely on the equipment to get the results. The cameras didn't have auto-focus, period... so focus was all on the us.

But rather than missing the good old days of photography... I'm much happier with our modern equipment. The "keeper" ratio is much better.

In technical specs the 5D III can focus down to EV -2. That's pretty dark and very few cameras outperform that (although the 6D can focus down to EV -3 it's focusing system isn't nearly as versatile as the 5D III.) In comparison, the Nikon D3 only goes down to -1 -- it cannot lock focus in the low light situations that a 5D III can handle. The 5D III can focus with literally just half as much light as the D3. The 6D can focus with literally just 1/4 as much light as the D3.

I cannot explain why a particular user had an issue in a particular situation unless I am there to see what they are doing. I can only say that the 5D III is a more "technical" camera... it does not have the simplisitc focus system of the 5D II, so there's a lot of room for operator error by choosing settings which aren't ideal for the situation at hand. I do know that my 5D III has served me well and while I now shoot with a 5D IV, I still have my 5D III. I recall shooting baby lambs within minutes of being born in the basement of an old barn. It was very very dark, and yet... the camera nailed the focus without fuss (basically a situation I probably wouldn't even try with previous eqiupment). If you own a 600EX series or 580EX series or 430EX series Canon Speedlite, you can attach it, turn it on, then tell the camera to "disable" the flash. It will still use the focus assist beam on the flash to help it lock focus but the flash itself will not fire (just don't forget you set the camera to "disable" the flash or you'll be wondering why the flash isn't working the next time you need it.)

If you haven't already done so, download the AF setting guidebook for this camera (this is information which is not in the owner's manual).

You can grab a copy here:

http://cpn.canon-europe.com/files/product/cameras/eos_5d_mark_iii/AF_guide_EOS5D_MarkIII_eng_January2013.pdf

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

ebiggs1 — Fri, 06 Jan 2017 17:06:06 GMT

I shot 20+ wedding and am unsatisfied... i shot another 10+ weddings and am still unsatisfied.

Really? Why haven't you just bought a Nikon D810? Seems like a simple reasonable solution.

Me personally I only use 1 series for weddings, now, but in the past I owned and used a the 5D, 5D Mk II and the Mk III. I do agree with Tim Campbell, you must know the Mk III insdie and out. It is so complicated.

I will say when I got the 5D Mk III, I almost never used a flash.

Re: 5d mark III focusing slowly/etc. in low light wedding receptions

marcosphoto — Fri, 06 Jan 2017 19:53:27 GMT

I'll chime in on this post, been a long time since I made a comment on it. I still struggle a great deal with my 5D3, it's worse than the 5D2 by far. I've noticed that the 5D3 has a worse EV rating than it's brothers which is the excuse canon canada gave to me on my 3rd complaint of terrible low light performance. Repair center as usual claims no faults found - a standard retort. It almost seems worse with a flash, which was a problem that was supposedly addressed with a firmware update but seemed to make no difference in mine. I hate the low light focus so much, I was very tempted to buy the 5D4 which had absoultely unreal low light focus abilites which I tested in a dark room with an f4L 24-105. So impressed I was going to spend the unreal money on the body but in the end could not sell my 5D3 for anything more than a giveaway price.

For now, we trudge along with a simply good (but not amazing) camera body, but I suppose it is our faults for not going to another brand right?! Canon will continue to claim ignorance of the issues and not put in much effort as long as we keep being lazy and stay with them just because we bought the glass. I don't hate the camera so much, but I question the brand these days.

P.S. I concede that there are smarter, better and more educated photographers out there who say they know the body well enough that it's not an issue for them (although the majority have complaints), but if canon cannot determine why our cameras have these issues - how can we?