Canon 6D Dominates Low Light Focusing Test vs 5Dii, 5Diii & Nikon D600

[Mt Spokane Photography]

The test might be useful as a comparison between models, but there is no measured or controlled light level or color temperature. There is no reason to believe that different camera models respond the same to different color temperatures, so a standard temperature removes any arguement about that. Measurements at various color temperatures might be interesting for comparison sake.
As to time to focus, its not clear as to how that was measured, I did not notice the methodology. I have found the best way to get to focus is to merely press the shutter button all the way down while the camera is in one shot mode. The camera will take the shot when focus is achieved. Some cameras seem to delay turning on the AF light, but the camera is actually focused earlier. A sensitive mike connected to a oscilloscope can record the shutter button press, and the shutter opening so you get a precise measurement, for example.

 

[helpful]

Exposure value (EV) is not an amount of light and it also has nothing to do with ISO. It is simply a definition for relating camera settings which are equivalent to each other in terms of how much light they would let in, if there was the same amount of light available.

Setting your camera to f/1.0 and 1 second exposure is still called an EV of 0 even in complete darkness or in bright sunlight. Setting your camera to f/1.4 and 2 seconds exposure is still EV 0.

By telling someone that you are obtaining proper exposure by an EV of 0 and a certain ISO value, then and only then does the actual darkness or brightness of the scene come into play. In that case, changing the ISO will change the EV needed to obtain proper exposure for the same scene. And vice versa, changing the brightness of the scene will also change the EV needed to obtain proper exposure for the same ISO.

So you might ask why then does Canon present on their 6D product page a meaningless specification about sensitivity at -3 EV? EV doesn't mean luminance, but they are acting like it does.

The answer is that it is well-established practice among photographers to express luminance in terms of their camera settings using the EV terminology, by assuming that ISO 100 is used and that a nominally "correct" exposure is being obtained by the camera settings indicated by the specified EV. Since photographers probably communicate best when talking in terms of their camera settings, EV makes for an easy way to understand the level of available brightness for a photographer when this common practice is used.

Anytime exposure value is used to speak of the amount of available light, the assumption is that a CORRECT exposure will be obtained from that EV of aperture/shutter speed AND a sensor sensitivity of ISO 100.

 

[ishdakuteb]

You're adding a lot of confusion here by arbitrarily defining your own zero. It's like saying you're going to start counting everything from the number 4, so if there are of 2 of something on a table, you're telling everyone there are 6. Makes no sense.

0 EV has a real, absolute definition - an exposure of 1 s, f/1.0, ISO 100.

Technically, your "0" EV is actually EV = 5. That means your -7 EV is really -2 EV (and in fact, the 6D is spec'd to AF at -3 EV, but of course, that may not equate to real world numbers).

It would help avoid confusion if you restate your numbers according to the real definition of EV = 0, otherwise many people will read that you're testing at "EV = -7" and think you're spewing complete bullsh cow manure.

Sorry, but the fact that you don't seem to understand some of the basics, like the fundamental definition of the basis for the specification you are testing, makes me question what you're doing. I definitely appreciate individual testing (and especially the fact that you did post your definition, so the error could be spotted), but post/blogs like this contribute to the vast and growing pool of bad and/or unreliable information out there.

neuro, i have question on this part: base to my conversion of everything back to iso 100, it shows that
- 1/60 f2.8 iso 400 (0) will be equivalent to 1/15 f2.8 iso 100 which is EV 7
- 1/60 f2.8 iso 102,400 (-7) will be equalivant to 2 f1.0 iso 100 which is EV -1

is there something wrong with my conversion? however, taking a look into his images, i guess that he was talking about zone system instead of exposure value, but there is no such -7 zone system, and i am scratching my head over here

 

[dlleno]

...The answer is that it is well-established practice among photographers to express luminance in terms of their camera settings using the EV terminology, by assuming that ISO 100 is used and that a nominally "correct" exposure is being obtained by the camera settings indicated by the specified EV. Since photographers probably communicate best when talking in terms of their camera settings, EV makes for an easy way to understand the level of available brightness for a photographer when this common practice is used.

Anytime exposure value is used to speak of the amount of available light, the assumption is that a CORRECT exposure will be obtained from that EV of aperture/shutter speed AND a sensor sensitivity of ISO 100.

+1 helpful nice summary. now can we get back to discussing the 6D's AF performance in terms that make sense and communicate the right story? Lets use the term "EV 0" as it is nearly universally understood in terms of evaluating important camera capabilities.

 

[MichaelTheMaven]

Ive always been surprised to meet highly intelligent individuals who are completely unable to process the most basic of information, simply because they are too smart to understand the heart of the matter.

Something to think about.

Love ya guys!

MM

 

[Chuck Alaimo]

I thought the 6D autofocus in -3EV conditions was a one stop improvement over the 5d Mark III and a two stop improvement over the 5D Mark II? I don't know about the Nikon.
I don't really get testing beyond the rated limit, maybe I missunderstand further explaination of the -7EV thing would be much appreciated. I also seem to recall a video from DigitalRev (in the boxing ring) where the 5D3 excelled against the D600 no where near -3EV?

I watched that vid ---- it was testing the servo tracking of the 3 though, this is one shot focus mode

 

[Loswr]

I'm always surprised when people put forth results and a conclusion, and then are surprised when others critically evaluate the methods used to generate those results, and weigh the quality of the methods when evaluating the reliability of the results and the strength of the conclusions.

Something else to think about.

 

[Chuck Alaimo]

grrrrr..... Ok, I'll say it, I don't really care about the methodology! What I care about is how well this camera's AF performs in a variety of situations. The definition of EV matters less to me than the results! which in this case seem pretty good. I'd like to see more of this!!!

 

[MichaelTheMaven]

I'm always surprised when people put forth results and a conclusion, and then are surprised when others critically evaluate the methods used to generate those results, and weigh the quality of the methods when evaluating the reliability of the results and the strength of the conclusions.

Something else to think about.

I welcome and appreciate criticism, but how does the discussion of semantics in this test somehow mean that the 6D doesn't focus well in low light?

Some people appreciated the amount of time & energy it took to do this. Some don't. But I do know this:

That center focus square on the 6D is very, very good in low light. Ill grab it before the others for low light situations.

If you cannot walk away from this post/discussion with that very basic, heart of the matter idea, than nothing I can say will matter to you.

No hard feelings either.

Thanks!

MM

 

[Chosenbydestiny]

I'm always surprised when people put forth results and a conclusion, and then are surprised when others critically evaluate the methods used to generate those results, and weigh the quality of the methods when evaluating the reliability of the results and the strength of the conclusions.

Something else to think about.

Makes me think about DXOMark tests

 

[dlleno]

back on topic --

Isn't the 6D rated at -3ev while the 5d3 is rated at -2ev?

the single AF point in the center is rated at -3EV sensitivity, yes. However, per Canon product support the other 10 AF points are -1EV sensitive. so -- the stationary "focus, then frame" approach with only the center AF point should yield a not-surprising one-stop advantage in very low light compared to the 5D3. Note for interests sake that -3EV is four stops less light than requried for the exposure meter itself to perform up to its rated specifications! so you can focus, but you might want to get to know how the metering system behaves under those same conditions.

Someone correct if wrong, but Canon also confirmed to me that all 61 AF points of the 5D3, on the other hand, are sensitive to -2EV.

Don't forget that EV sensitivity is not the only measure of success for the AF system. for example, Roger over at lensrentals put these puppies to the test and discovered a wider variability in AF accuracy (std dev = 28 I believe) for the 6D compared to the more consistent 5D3 at std dev = 17. thats a considerable difference.

 

[Helevitia]

Thanks for the results. I'm considering upgrading from a 7D. How does the 7D compare in these tests? Does anybody know? I'm sure there have been similar tests done between 7D and 5D2/3?

 

[rafaelsynths]

I'm thinking of renting the canon 6D myself . Can anyone help me on my other post it has 3 replies and all of them are from me
I need some pro tips on whether to rent a 6D or 5D

 

[Marsu42]

Thanks for the results. I'm considering upgrading from a 7D. How does the 7D compare in these tests? Does anybody know?

The af is supposed to work from -0,5lv ... my 60d from 0lv, so not much of a difference, and the af slows down considerably and I have to use af assist frequently. So the -3lv from the 6d (or -2lv from the 5d3 for that matter) should make a very, very large difference in speed and low light capability.

Note for interests sake that -3EV is four stops less light than requried for the exposure meter itself to perform up to its rated specifications! so you can focus, but you might want to get to know how the metering system behaves under those same conditions.

Interesting point, I wondered about that, too and would like to see some reviews on that, but afaik it only matters for available light w/o en e-ttl flash.

for example, Roger over at lensrentals put these puppies to the test and discovered a wider variability in AF accuracy (std dev = 28 I believe) for the 6D compared to the more consistent 5D3 at std dev = 17. thats a considerable difference.

... but only if you use a large aperture lens and shoot with a thin dof, for other shots a little variation doesn't matter - 60d and esp. 7d are much less precise than the 6d.

 

[dlleno]

Thanks for the results. I'm considering upgrading from a 7D. How does the 7D compare in these tests? Does anybody know? I'm sure there have been similar tests done between 7D and 5D2/3?

yes, the 7D fared among the worst of all the cameras he tested. FYI pardon my asssumption of background here, but for those unfamiliar, high standard devition is bad. 7D was 41, 5D3 was 17.

http://www.imaging-resource.com/news/2012/08/01/autofocus-reality-part-3b-canon-cameras


and Marsu42 yes good reality check.

 

[Chosenbydestiny]

Thanks for the results. I'm considering upgrading from a 7D. How does the 7D compare in these tests? Does anybody know? I'm sure there have been similar tests done between 7D and 5D2/3?

yes, the 7D fared among the worst of all the cameras he tested. FYI pardon my asssumption of background here, but for those unfamiliar, high standard devition is bad. 7D was 41, 5D3 was 17.

http://www.imaging-resource.com/news/2012/08/01/autofocus-reality-part-3b-canon-cameras


and Marsu42 yes good reality check.

Could it be they had a bad copy of the 7D for testing? I've always remembered my old 7D focusing a bit better than my 60D.

 

[Dylan777]

I'm always surprised when people put forth results and a conclusion, and then are surprised when others critically evaluate the methods used to generate those results, and weigh the quality of the methods when evaluating the reliability of the results and the strength of the conclusions.

Something else to think about.

I welcome and appreciate criticism, but how does the discussion of semantics in this test somehow mean that the 6D doesn't focus well in low light?

Some people appreciated the amount of time & energy it took to do this. Some don't. But I do know this:

That center focus square on the 6D is very, very good in low light. Ill grab it before the others for low light situations.

If you cannot walk away from this post/discussion with that very basic, heart of the matter idea, than nothing I can say will matter to you.

No hard feelings either.

Thanks!

MM

Michael,
I'm not an expert in testing.

I did have a chance to play with 6D outside parking lot, behind business building, around 7PM westcoast. It was quite dark and the light sources were street lights. I compared to my 5D III and I didn't see the advantage of 6D has to offer in term of -3EV AF center point. Maybe it wasn't dark enough? I shot with my 24-70 f2.8 II lens at f2.8. The outer points were bit slower though.

 

[Marsu42]

Could it be they had a bad copy of the 7D for testing? I've always remembered my old 7D focusing a bit better than my 60D.

I guess you didn't do any (semi-)scientific tests? I don't have a 7d, but I've read many times that the af on the 7d is the least precise, and the lensrentals test confirms it - though by a margin you may not notice in day-to-day shooting because unfortunately the 60d is rather unprecise, too, and of course the lens also matters.

I compared to my 5D III and I didn't see the advantage of 6D has to offer in term of -3EV AF center point. Maybe it wasn't dark enough? I shot with my 24-70 f2.8 II lens at f2.8. The outer points were bit slower though.

The good news for 6d buyers is that obviously you didn't see any disadvantage, too - and yes, I guess it wasn't dark enough because -3lv is rather dark, though not different enough from -2lv to tell a difference w/o a lightmeter (or you can look inside your picture files, the measured light value is in there). From kr http://www.kenrockwell.com/tech/ev.htm

LV 3 Brightly lit night street scenes
LV 2 Typical night street scenes
LV 1 Dark scenes outdoors at night
LV 0 LV Zero is defined as the light level that requires a 1 second exposure at f/1 with ISO/ASA100 speed film.
LV-1
LV-2
LV-3
LV-4
LV-5 Scene lit by the full moon
LV-15 Scene lit only by starlight.

 

[dlleno]

...I did have a chance to play with 6D outside parking lot, behind business building, around 7PM westcoast. It was quite dark and the light sources were street lights. I compared to my 5D III and I didn't see the advantage of 6D has to offer in term of -3EV AF center point. Maybe it wasn't dark enough? I shot with my 24-70 f2.8 II lens at f2.8. The outer points were bit slower though.

folks this is not complicated. The way to test the advantage that the 6D has to offer in terms of a -3EV center point, is to test in -3EV light!

were you shooting in that level of light? I would say never mind trying to correlate with KR or Wikipedia or any other attempt to describe qualitatively what -3EV is. Maybe its a firefly in a coal mine during power outage, I don't know -- but none of that matters: it turns out we know what -3EV is! Does proper exposure require 4 seconds at f/2.8 and ISO 1600?

 

[MichaelTheMaven]

Hi Dylan-

I appreciate you taking the time to do some tests of your own. This is what I wanted to read, other low light focusing tests.

It's going to be very difficult to notice the difference between the 5Diii and 6D for single focusing type tests, both are going to focus in low light in just over a second. Even when going for 30-50 rounds of focusing, the 6D was only marginally better in the central point. Set up a timer and focus back and forth between 2 high contrast targets 50 times and then you will start to see the differences in speed easier.

As a side note, most of the 5Diii's central, top to bottom, middle row, did very well in low light, where the 6D's other squares failed.

As a whole the 5Diii's focusing systems are the best of the bunch (not even close), but when it comes to low light, yes, it does seem the 6D has the edge in that one central square. Its a true pity Canon didn't have more of an upgrade, but the 6D absolute dominated the 5Dii and D600 on that central point in low light.

M