Messages

1

Lenses / Re: Confused About 50mm Lens Filter

« on: April 23, 2012, 10:34:39 PM »

Of the B+W options listed, I think you want this one: http://www.bhphotovideo.com/c/product/11990-REG/B_W_66070222_58mm_UV_Haze_010.html

The Digital Pro ones are chrome not black, you don't need a slim (you loose front threads on those) or an extra wide one on the 50, and the other F-Pro 010 filter without the M isn't MRC coated.

2

EOS Bodies / Re: What will be the response to the D3200?

« on: April 19, 2012, 10:42:33 PM »

Canon has nothing to worry about. Canon is still pWning Nikon at cameras and market share.

And copiers and printers..... can't forget the copiers and printers..

3

EOS Bodies / Re: Canon is getting owned in sensor technology

« on: April 19, 2012, 04:55:39 PM »

I'm not convinced that Canon's DR is a result of worse sensor technology and not the result of a deliberate design objective to limit it. There's nothing, AFAIK, in CMOS or CCD sensors fundamentally that would produce the characteristic sloping curve you see from Canon's cameras. Moreover, virtually no other camera manufacturer shares the same kind of curve or the pervasiveness Canon has when you look at DXO's DR charts. In fact the only Nikon cameras that share that pattern that I'm aware of are the D3, and it's derivatives the D3s and D700.

So Far as I know, DXO, contrary to their claims, doesn't measure just the sensor, their measurements cover the whole signal processing chain from sensor though amps to ADCs, to whatever the processor does to the values before outputting it as a RAW file. While this is certainly is more for useful for the images you'll see but doesn't really provide a means to say anything about the sensor tech.

So why is Canon doing this? That's a darn good question.

4

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 18, 2012, 07:28:05 PM »

esi32 ...

... All the EV talk in the world doesn't matter, but since others are making it an issue: f16 for 8 sec is listed as EV = 5, (http://en.wikipedia.org/wiki/Exposure_value), and this is a commonly used setting for landscape, foaming water etc. And, Photogs like Dan Cheung have reported consistent under-exposure using the 5DIII. That too is interesting.

Except it is a serious factor in whether and how much the meter would be incorrect for any given situation. In fact, it is THE factor for any given situation. The problem is we're talking about reality here. If you need to have the camera lit to 20EV to get a 1/3rd stop error on the meter, you're not realistically going to do that in the real world ever. So yes, what you're shooting, and how bright the area you're shooting from really does matter.

So as to your Ev 5 scene, you're going to have to provide more than just "this is used for..." how bright is the actual environment the camera is in? This is crucial to determining whether there's the potential for a metering error. If the camera is in EV12 and you're NDing down the scene to EV5 with a f/16 lens, ya, you're probably going to see a problem with a 5D3. If the camera is in EV12 and you're NDing the scene down to EV5 but using an f/4 or faster lens that doesn't require stop down metering, you're not going to see an error at all. This has been generally born out by my experience in the field with and my testing of my 5D3, and I don't believe my camera is an outlier in any special way on the good side.

Canon is taking it seriously, and that is a good thing. They will decide what to do, and personally I am happy that Canon takes feedback and complaints seriously.

As am I. I'd much rather they promptly acknowledge things, even if they ultimately do nothing, than not acknowledge it at all.

5

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 18, 2012, 03:04:22 PM »

Brilliant. Canon should ignore an issue that they have determined is real.
Well that ought to drive product improvement.

It is attention to detail that makes a product, or an artist, great.

A known issue that might cause an error of 1/3 stop exposure is significant.
Fix it ... it's that simple.

This isn't simply a matter of attention to detail, it's a matter of engineering. The engineering was for a meter that operated correctly form 1 to 20 EV w/ a 50/1.4 (t/1.6) lens. You can ignore that, you can stick your fingers in your ears and scream, "it should be fixed!" over and over all you want, but the simple reality is that the camera was designed to work properly over a specific range of light levels and, so far as I can tell, does so and beyond.

To recall the camera and issue a fix is tantamount to fixing something that literally isn't broken unless you use the camera outside of the designed conditions. It sets a precedent that with sufficient wailing and gnashing of teeth a product's specs can be altered after it was designed and released.

I disagree. Canon (or any other manufacturer) should fix all acknowledged issues. Especially those that they have admitted to and is fairly known to camera users who frequent forums and sites like CR. They can't afford for the word to get out that they won't do anything.

No they shouldn't just fix all acknowledged issues. Only issues where the product is deficient in functioning where it was designed to function, should be addressed with anything more than a workaround. The 5D3 wasn't designed to meter correctly at -10 EV, or -5EV, or 0EV. Under some cases it may, more often than not it performs better than the design specs indicate it should, but if you're relying on the meter outside of the designed parameters you're in undefined territory and may not get an accurate reading regardless. No company should be under an obligation, perceived or otherwise, to fix an issue that only occurs outside the designed operating range.

Turn off the LCD on top of the camera. That solution would work for now. But imagine Ferrari telling the owners of their 458 Italia (has computer displays next to the tachometer). After having shelled out 300k on their dream sports car. "Just turn off the display...you have still the tachometer". I don't think it would go over too well.

Your situation isn't even remotely comparable. A more apt one would be that Ferrari owners were complaining that their car knocks or otherwise doesn't get it's best performance when being run on 87 octane gas instead of the designed 91+. Then go on to insist that Ferrari should actually redesign the engine, and recall the car so that it does run correctly on a fuel it wasn't designed to run optimally on in the first place.

Does that sound reasonable to you?

That's the problem here. Yes, there's an "issue". Yes, Canon has acknowledged it. No the issue doesn't appear to occur inside the specified operating range of the camera, in fact it seems to occur at a point more than 4 stops below the specified operating range. Yet that's not good enough apparently. Well following that line of thinking neither is the ISO performance at 1600 or higher, nor is the AF performance with lenses that have a max aperture of f/16, nor is the fact that the viewfinder doesn't have 5/8" of nose relief. I can make a case that all of those are deficiencies with the camera, should I get enough people to whine about those, should Canon redesign the camera for them too too?

6

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 18, 2012, 03:23:20 AM »

I'll be kicking myself for these comments when I find myself in that decisive Manchester/bedware macro shooting moment. Maybe a product shot of "thread count" at 104k ISO?

I believe we're heralding in a new age of photography, for the first time in history people will truly be able to experience the many shades of black that are present in the world of complete darkness.

7

EOS Bodies / Re: 5D3: ISO 160, 320, 640 etc cleanest ISOs?

« on: April 18, 2012, 03:16:30 AM »

I literally don't get NOTHING of this discussion, simply because maybe I have a misunderstanding how different ISO's in digital cameras are achieved. I always thought ISO settings in digital are only made by different multiplication factors of the amount of sensor information (signal+noise) readout, so for example ISO200 would be achieved simply by boosting/amplifying the number of photons that hit any example pixel by the factor 2 (double) in comparison to the value it would have for ISO100 and ISO320 would be amplified 3.2x the value it would have at ISO100. With this theory there would not be a reason to take the picture at ISO400 but underexpose it by a third or pulling pushing something? OR is this because of FULL stops at aperture and speed? I guess I answered the question already, but I'm not sure if all is that simple. Or hmm, I guess it is?
Please enlighten me! Thanks....

Broad strokes: Photons hit's photo site, some get converted into an electron. The electrons accumulate during the exposure and create a vary small voltage. That voltage is amplified by one or more variable gain amps then fed into the Analog-digital converter (ADC). The number that comes out of the ADC goes to the RAW file.

Now fun part is when you get to doing the amplification. There are several ways to go about doing it, the following 3 have actually been used to my knowledge in cameras.
1) a single amp that has 1/3rd stop steps (AFAIK Nikon does this)
2) a single amp that has 1 stop steps and push and pull via software and adjusting the meter (AFAIK Canon's non EOS-1 bodies do this)
3) 2-stages of amps that handle full and fractional stops in stages (AFAIK, Canon's EOS-1 bodies, at least I know for sure the Mk3s do it this way).

For case 1, lower ISOs are always better (less noise more DR) than higher ones.

For case 2, the +1/3rd stop ISOs are worse for noise and DR than the base ISOs. The +2/3rd stop ISOs are better for noise but not DR than the base ISO, and at low ISOs often better for noise than the +1 ISO. Once you hit unity gain it doesn't matter, things just go down hill anyway and you want to use the lowest ISO you can.

For case 3, below unity gain, IME all +1/3 ISOs are worse than the base ISO, and +2/3rds ISOs are worse than the base and base +1 stop ISOs. Once you hit unity gain ISOs get progressively worse as you'd expect.

Expanded ISOs (L, H1, H2) are merely mathematical manipulations of the highest (or lowest) real ISO setting the camera can do. IMO, these are the "when having a picture is more important than having a good picture" settings, at least H1 and H2.

Unity gain, is the point where 1 collected photon == 1 RAW value step.

8

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 18, 2012, 02:49:55 AM »

I really hope Canon don't offer a fix for this, since seeing more test results.

It seems that this issue is only an issue at 0 or -1EV, which falls outside of the designed 2-20EV range of the meter. At these light levels, you should not be using the in-built meter anyway, so Canon does not have to act on something that does not fall within of the design specifications of this product.

I find myself in something of the same boat. Based on the growing body of testing I've been doing the meter appears to function properly in the specified range—and even some what below it—with pretty much anything lens you can throw at it without getting into teleconverters. And I seriously don't care for the precedent that recalling and "fixing" something that behaves correctly over the operating range it's supposed to work over sets. I honestly think the most appropriate solution would be similar to what they did with the 1D/s mk. 3 and Canon USA service notice dated 03-02-09; provide free service to those who believe their meter is functioning incorrectly.

I'm still writing up a report on this for my site, and I'll be sure to drop a link to the final version, but for the moment this is what my preliminary results look like.

The backlight becomes an issue when the light reaching the meter though the lens hits -6.5EV including transmission looses for the lens. In more practical terms for photographers it plays out something like this.

Lens	Min Light Level	Example exposure settings
24-70/2.8L or 70-200/2.8L IS II	-3	30s f/2.8 ISO 200
24-104/4L IS	- 1-2/3	25s f/4 ISO 100
70-300/4-5.6L IS @ 300mm	0	30s f/5.6 ISO 100
85/1.2L II	-5	1.6s f/1.2 ISO 3200

As for leaking from a light shining on the top LCD instead of the backlight. I'm coming up with about 0.001% transmittance or something like 16-2/3 stops. So as long as you don't have some clown shining the equivalent of the sun at noon on your camera in the dark that shouldn't be a problem either. A light source that will light a surface 5mm away to 35K lx generates only a 1/3rd stop error when the meter sees ~ -4.67Ev from the scene (in my case that worked out to a scene lit to ~ -1-1/3Ev with an 24-70/2.8L lens on the camera).

9

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 16, 2012, 01:49:12 PM »

Have anyone tried setting the DOF button to switch between Ai Servo and One Shot? I aimed at the same spot, but the exposure varied from 1/500s to 1/800s when I switched af-mode. How the hell can that be?

It's not happening 100% of the subjects I shoot at, but 90% and it's 100% consistent at one subject when I push the switch...

In Evaluative, the metering is tied to the AF system to determine the importance of a given zone (in focus or not). It may also be tied to Servo v. no servo because they present different "focuses" on operation (tracking a moving object v. a non moving one).

Moreover, in general the focus affects the metering by changing the light that's incident on it. So does changing the focal length if the aperture doesn't precisely change to compensate. Inner and rear focusing lenses change focal length (which is why the generally breath) when focus is changed. If the aperture isn't precisely compensating for the focus, the result can be a sufficent error in light transmission, hence the meter changes.

Anybody ever tried taking a normal in sunlight shot and another one while covering the LCD to verify this under-exposure issue?

I've both gaffer taped over the LCD and compared the exposures to those on my 1D3 and I get the same reading within a 1/3rd stop. So in my experience, black gaffer taped LCD, uncovered LCD, and 1D3 with similar framing and identical lens, perform nearly identically in practical shooting situations.

As I said a page back I'm going to be going though a much more riggerous testing routine, and publishing my findings, simply because it interests me. But in my un-scientific, but generally way better controlled than I've seen anybody else do, tests I find that in practice the meter is completely unaffected over the design ed 1-20EV range, and maybe a few stops more than that. THough one of the things i'm looking for is the relative difference in power between T-LCD incident light and though the lens light to start skewing an exposure.

I think if people understood the nature of a logarithmic scale, this wouldn't be an issue. Let's say that the backlight lights up the meter sensor the same as a gray card in -6 EV light (which seems to be about what the math suggests). 

So far as I can tell, the meter has a noise floor around -4EV, due to thermal/dark current noise and the fact that there are those LEDs in the viewfinder contributing light. And by the specified design, anything darker that 1EV isn't guaranteed to meter correctly in the first place.

10

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 14, 2012, 10:07:59 PM »

Re. Canon JP's response. As I keep saying, the meter appears to behave normally inside the specified operating range. The camera + a lens cap/body cap + the viewfinder blacked out is not a situation that occors inside the specified parameters for the operation of the meter. People keep ignoring that, but the reality is getting the meter to error inside the designed range requires a considerably high delta in light levels between the top LCD and the subject—and doesn't work on the backlight alone. I'm not convinced yet such a situation will actually happen in practice—hopefully I'll have some actual numbers on that sometime next week.

Someone suggested it already here: if camera knows if lcd is On or Off, it probably could be compensated with firmware. If camera doesn't know lcd light status then it's only fixable by hardware manipulation.

And as I already pointed out that doesn't work because light incident on the LCD, not just the backlight, will also affect the meter reading and the camera doesn't know that the light incident on the meter is actually light incident on the meter. A hardware fix is the only possible fix unless it's determined that the erroneous behavior is only see outside the designed range for the meter's operation.

11

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 14, 2012, 06:11:29 PM »

Since I will be using this camera in many low-light situations, this will probably become a major issue for me.

Low light is a very relative term. Just what do you mean by low light?

For example, as I just noted, in my previous post, with the meter on CWA I see a stable meter in a room lit by 2 24" LCDs monitors and nothing more (meter reading 8s f/2.8 ISO 100, est EV0).

If you want to frame your expectations, look though the images you have, anything darker than about EV1* (meters 4s f/2.8 ISO 100 or equivalent), is below the design range of the meter and may not meter correctly. Anything below EV -4* (2m f/2.8 ISO 100 or equivalent) is below the  meter's hard sensitivity floor. As it stands*, anything between EV -4 and EV 1 have the potential to be thrown off by turning the backlight on. There are of course caveats to this, the actual cases are subtly more complicated but that should put you in the ballpark.

My biggest concern is that Canon Canada has not released any press release whatsoever, and the camera stores still claim (as of today) that this is a rumor and that no real hardware problem exists. I have also not heard of any "new shipments" with design changes coming in.

Keep in mind Canon is a big company, and the regional Canon divisions aren't all in complete sync with each other. Things take unequal amounts of time to work their way though the bureaucracy in different places. There may also be various legal implications with posting something like that in different places, which likely means each region has to run the service notice though legal and that doesn't happen instantly either.

From the various websites covering this, the issue goes well beyond the LCD screen (as the US website describes) to the top display and even the viewfinder, so this is pretty substantial.

I would urge you to be very careful what you consider valid information while reading about this. The barrier to entry for publishing something on the Internet is incredibly low and there are no safeguards to stop the blind from leading the blind so to speak.

The behavior seen in the CameraTown video, where the meter changes as you move your eye away from the viewfinder, is typical and expected behavior in an SLR where the metering sensor is in the viewfinder—read all of them. Some may be less susceptible to light intrusion because they have a smaller viewfinder, a viewfinder that is more recessed,  or there are other differences in the internal design (different reflectivity of the focus screen for example). But make no mistake, under the right conditions, and those aren't just "with the sun at your back", removing your eye from the viewfinder will change the meter reading.

I was planning on purchasing this camera this week (prior to my upcoming vacation) but as I will ultimately spend upwards of $6000 on this (kit, accessories, etc), I am pretty concerned about buying this if it is defective? What about all of your thoughts on this? For those of you have who have yet to purchase, has this issue now put you on the fence?

Well it's probably pretty clear that I already own a 5D3, and I'm using my 5D3 with little concern with the reported issue as it doesn't actually seem to be a problem in practice. My 5D3 meters virtually identically to my 1D3 in any situation where I've had the two side by side. Worst case scenario, if Canon determines that they must fix something, there will be a recall and a fix will be made for free, you'll just have the hassle of sending the camera in for the work to be done.

In fact, in practice, the biggest problem I've had with the 5D3 is the missing battery grip, lack of an RRS's L-plate for said missing grip, and having to run release candidate software (LR4.1 RC) to be able to work on the images.



* Based on my testing (though EV1 is the lower design limit for the 5D3's meter) and I reserve the right to adjust those numbers based on further testing.

12

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 14, 2012, 05:36:09 PM »

Throwing more caution to the wind, I should have a engineering lux meter in my hands early next week, and I'm going to rerun though my tests with ambient light measured by the lux meter instead of just trying to get it right.

Moreover, it's worth remember that depending on the metering mode there's more than just simple metering going on. In evaluative, the metering is tied to the AF points and will change as the camera feels that one AF point or another is more or less in focus and therefore more or less relevant. Likewise, for some lenses (especially macro lenses) the effective aperture will change as the magnification is increased (e.g. see the effective apertures for the MP-E 65 at various magnifications).

I was playing with the camera in the dark earlier and seeing stabling metering in CWA down to what I'm guessing was close to EV 0 or EV -1 (was metering 8s, f/2.8 ISO 200, the only appreciable light source in the room was a pair of mostly black 24" LCDs) but varying the focus—and not over the full throw either—on the macro lens I happened to have on the camera was sufficient to change the metering by more than a stop. I'd really love to be able to get my hands on a ZP.2 EF or Canon CN-E Cine lines with t-stops since they account for actual light loss, but that's outside my budget.

One think I just though of is that metering seemed much more stable in CWA than Evaluative, it's possible that whatever leak exists, only affects certain peripheral zones but does so enough that in low light situations that the camera alters the overall exposure. Stability in various metering modes is on the list of things to test.

My concern is when shooting outdoors of something dark in the shade while standing under the bright sunlight, whether the leak would cause inaccurate metering. But I am still not sure how much light would go through the LCD compared to the viewfinder.

Doesn't seem to be much of an issue in practice. One of my test was shooting from under an relatively bright overhead lamp into the darkest part of the room (I'd guesstimate a 4-6 EV delta between the camera and what the camera was pointed at), and metering seemed pretty reliably as long as the backlight was off, but at the same time I wasn't on a tripod with fixed focus, and I was using evaluative which in general seems more prone to being "jumpy" when in log light/signal cases when I was tried that.

About the only case where you might have a problem would be shooting someone in a long dark tunnel from outside the tunnel under broad daylight, and even then I'm not sure it'd be a problem (and lack a sufficient tunnel to test with).

If the leak is significant enough to alter meter reading by 1/3 stop or more, then it's unacceptable. And any bandage type of fix (e.g., a black tape) performed outside the factory condition may inadvertently cause more harm to your camera than the leak issue itself (e.g., introduce dusts or alter the position of some precise component by accident).

Well the over the top, "I'm utterly paranoid my images will be wrong" fix, would be to simply put a piece of black gaffer tape over the top LCD and use the rear one for any external meter readings. Won't damage the camera, is easily undo-able, and doesn't involve tinkering in the body. I certainly wouldn't advocate taking a 3-week old camera apart and electrical taping things randomly.

In any case, I think Canon does need to improve the light sealing around the top LCD. The problem I keep coming back to is that so far as I've been able to tell, the meter largely seems unaffected inside the designed range* and under what I'd consider reasonable conditions may prompt a no-action response.


* Again, sample of 1, my camera, which isn't statistically relevant when talking

13

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 14, 2012, 02:25:00 PM »

First, I'd like to understand the basis of the claim that the light leak would cause under exposure. I've heard this many times and it just does not make sense to me. Theoretically, the meter should only measure the light through the lens to give the "correct" exposure for the image in the frame. In reality, the light also "leaks" through the viewfinder and, in the case of 5D III, the top LCD panel as well. My guess is the light leaking through the LCD Is far less than through the viewfinder. I don't think you will get underexposed image if you don't put the viewfinder cover on.

Yes, the light leaking though the LCD can be far smaller than what leaks though the viewfinder. It can also be sufficient to be a source of error if everything is sufficiently dark. For example, the case of a relatively well sealed viewfinder against your eye v. a spotlight shining on you and the camera but not in the lens.

The second part however, largely depends on how bright everything is relatively speaking. If I'm shooting a dimly lit subject from an even dimmer area I don't necessarily have to block the viewfinder, and the backlight will still cause a metering error. Actually, at least according to my testings, so long as the whole environment is dimmer than about EV1 turning on the backlight will alter the meter reading regardless of whether you have lens caps or viewfinder blocked.

A lot of the problem here, IMO, is that there has been lots of "cursory testing", gnashing of teeth, and complaining about how the camera is broken, without understanding either the design limits of the camera or doing any serious controlled testing inside and out of those limits. For example, the original Canon Rumors test with the lens caps on is so far outside the designed limits of the metering system as to be utterly useless in speaking to anything other than to show that there is in fact some light leaking from the LCD/LCD backlight to the meter.

I've conducted more controlled tests, at least to the best of my ability though even I admit that they aren't done to my fullest satisfaction (largely because I don't have sufficient equipment to do so), and they seem to indicate that the meter functions properly inside the designed range (1-20EV) unless you shine considerably brighter light on the top LCD than the lens or viewfinder can observe.

In practice, the situations where you're both operating inside the stated specifications of the meter (1-20EV) and doing something that would put a sufficiently bright light on the top LCD are vanishingly small. Even the assertion that this defect affects astrophotographers and nighttime landscape shooters, runs into problems when in all likelihood what they're metering is already outside the camera's design limits to start with, where they're no guarantee of function anyway. Which is why I keep saying that there is the distinct possibility that Canon will decide that no mitigating action needs to be taken and that the problem only occurs outside the designed limits of the camera. I sincerely hope they don't, since the fix is probably a bit of black tape somewhere, but it's a possibility that can't be ignored.

14

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 14, 2012, 01:57:37 PM »

Yes, I know that, but if the camera KNOWS the backlight is on, then, assuming the defect is relatively uniform in its effect on exposure, it may be possible for the camera to compensate.

EDIT: eg. "When light = on, increase exposure by x."

That's not a workable fix, the problem isn't with the backlight—even though that's what everybody seems to be fixated on. Any sufficiently bright (compared to what the lens sees) light incident on the top LCD will alter the meter reading, and the brighter the light the more the reading is altered. Shine a really bright flashlight on the top LCD and you can alter the meter reading even in relatively bright environments (then again my 1D3 does this only to a much smaller degree).

Only a hardware fix will actually address the problem in any meaningful way.

15

EOS Bodies / Re: Canon EOS 5D Mark III Product Advisory

« on: April 13, 2012, 10:27:17 PM »

I think "dilbert" explained this well enough on the bottom of the first page.  Many nighttime landscape photographers and astrophotographers use tripods with their cameras mounted in extremely bizarre positions.  This can make composition via the viewfinder very difficult, and often times totally impossible with the back display.  Many astrophotographers also implement angle finders to assist with the chore of difficult compositions at night.  That said - once the desired composition is achieved, most people don't want to go back to crawling around on the ground just to meter.

I often times use Av off the top LCD (with backlight on) to get an idea of the available light's impact on the sensor.  Then I calculate out a manual exposure at a lower ISO for a bulb exposure.  But if that initial metering is incorrect, my final manual exposure could be off by an uncorrectable amount.

If you're metering an subject darker than 1 EV with a 5D3, there's no guarantee that the exposure you get will be correct anyway. That's what that little bit in the manual where it says, "EV 1 - 20 (at 23°C/73°F with EF50mm f/1.4 USM lens, ISO 100)," is telling you.  Moreover, if the subject is brighter than 1 EV, my testing at least, indicates that there's no effect on the meter from the backlight. Hence my concern that Canon will come to the conclusion that there is no issue at all and the camera operates as designed, and I still am concerned about this even with the service bulletin having been issued.

As for darker scenes, there's no guarantee that what you're metering is in any way correct at all to start with. The metering sensor is no different than the image sensor with respect to the influence of noise. The influence of dark current, thermal noise, and the LED display in the viewfinder on the metering can be seen simply by the fact that they don't report off scale low (blinking 30" / blinking aperture at all ISOs) when the lens mount and viewfinder are blacked out.

My 40D (1-20EV meter) has a hard lower bound of -1EV (though accuracy pretty much goes to crap below 1EV).
My 1D3 (0-20EV meter) has a hard lower bound of -4-2/3 EV.
My 5D3 (1-20EV meter) has a hard lower bound of -4EV (1EV with the backlight on or I get errors from it).