February 01, 2015, 02:54:57 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - jrista

Pages: 1 ... 97 98 [99] 100 101 ... 328
ISO 3200 as clean as 1DX in 6400 (the most important).

Not gonna happen. Won't even come remotely close. The biggest difference for full-frame images is that the 1D X has a larger FRAME (the larger pixels are irrelevant). Total sensor area is the biggest factor that supports better high ISO performance on F cameras.

The 7D II would need a multitude of significant improvements in multiple areas to come within a literal 1-stop noise performance of the 1D X. The most important of which would be doubling Q.E., and there is just no way that would happen. Even the highest end, high grade CCD sensors for astrophotography, including those from Sony, only reach around 77-82%. There are maybe one or two $10,000 sensors that reach 90% Q.E.

I think ISO 3200 on the 7D II will certainly look better than it does on the 7D, and hopefully better than on the 70D, but it won't ever look as good as the 6D, 5D III, 1D X, or any subsequent FF cameras. In terms of area, an APS-C sensor has 2.6x less than an FF sensor. Throw in increased losses in light-sensitive area to a greater amount of wiring and logic transistors (due to smaller pixels), and the difference is even greater, which means there will always be more than a 1-stop difference in noise, likely more along the lines of a 1 1/2 stop or more difference.

I could see them updating the existing 45p AF system of the earlier 1D's and integrating it here, but I had read an article earlier regarding the future of DPAP that suggested that we would be seeing significant improvements in that technology.  IF that is the case for this rumored camera, it wouldn't be that far fetched to see a camera with high FPS as an optical view finder would not necessarily be needed anymore.   I do not have a 70D, but can someone comment on using live view to track moving people?   I would think it would be a sports photographer's dream to use live view, touch the screen on the player they want to track, then let the camera keep them in focus as they play while clicking away.   

I'm probably speaking crazy talk, but I think that would be awesome.

Live view is NOT conducive to photographing action. It just presents a clunky use case, because your head has to be back from the camera in order to see the live view screen. With the OVF, your face is pressed up against the camera, which gives it a SIGNIFICANT amount of stability. This goes for hand-held or mounted on a tripod.

There is also an intrinsic lag between when action actually occurs, and when it can be presented on a screen. It's only a few tens of milliseconds, but that is enough that you can miss the moment of action your waiting for, because in many cases, especially with higher frame rates, a few tens of milliseconds can mean several frames have been missed.

There are also a lot of things that dedicated PDAF sensors do that DPAF doesn't do, and won't be doing for a while. At the moment, DPAF essentially turns the entire sensor into one giant line sensor. A dedicated PDAF sensor has selectable points, and each of those points can sense in the horizontal, vertical, diagonal, or even a cross or dual cross (horiz/vert + diag in two directions 90° perpendicular). The ability to use cross type or dual cross type AF points gives dedicated PDAF sensors a significant edge in terms of speed, precision, and accuracy. Even with the 7D's jittery 19pt AF, when using the center cross point with my EF 600mm f/4 L II, AF is extremely fast. With the 5D III, it is effectively instantaneous. DPAF, while it is certainly an improvement on previous FPPDAF systems, it is still relatively slow compared to a dedicated PDAF unit that requires a mirror.

As an action shooter myself, I hope Canon has no plans to ditch dedicated AF units for a LONG time. They are tried and true, they have reached their pinnacle with dense reticulated point grids, and they are extremely, extremely effective, especially for situations where your eye is pressed up against the viewfinder. At some point, after several more iterations of refinement and enhancement, DPAF MIGHT be ready to replace a dedicated AF unit, but now is not even remotely close to the time.

It's been rumored before on multiple occasions, so I also expect the 7D II to have a lot of video feature enhancements. The video on the 7D is pretty lackluster. I don't quite know if the new video features will be 7DC level, but they should be of a higher level of quality and capability than any other models except the 5D III, and still maybe better than that.

Yep I suspect it's going to marketed with video features, however still photography wise...I don't see these marginal upgrades such as +1-2 fps (from 8fps) being upgrade worthy though?

It's a prosumer ergonomic design+materials (solid top component over entire plastic) + the AF system that are the sell over the xxD and rebel lines.

What you call "marginal" is actually a 25% improvement (I don't see it being 9fps, it'll probably be 10fps). A 25% improvement in anything is far more than marginal. Besides, the next step up would be 12fps, and I really don't see Canon pushing that kind of frame rate from the 1D X down to the 7D II, regardless of how the two cameras are classified. A 41pt AF system with the same kind of performance/precision/accuracy of the 61pt AF system would be a MASSIVE improvement over the 19pt AF system, so that's certainly not marginal. You also get more custom functions and configurable options with the 7D line than xxD and lower lines, along with C1-3 user configurable dial options. There is also the very strong likelihood it will get dual memory cards (I TRULY hope for dual CF/CFast2, but I suspect the 7D II will be gimped just like the 5D III with a CF and SD slot...in which case the feature is largely useless.)

There is also the high likelihood it will be getting a new sensor (I think it is extremely remote that it would get the 18mp or even the 20mp APS-C sensors...Canon KNOWS they have to really break new ground with the 7D II).

These are all benefits that lower cameras don't get (although the 70D does have one single configurable C user mode dial option). It isn't just one feature or another, it's the complex of features packaged into a single camera. Same deal as with the 5D III...people cherry pick one feature or another to talk about, and no single feature of the 5D III is particularly significant over the 5D II (with the exception of the AF system)...but the camera as a whole, all the features of the 5D III put together, make it a VERY radical upgrade. I think the 7D II will be the same kind of release.

If I recall, the main selling point of the 7D when it was released was it's superior redesigned AF system and FPS over the XXD. Here was a solution to those in the prosumer segment that couldn't afford a 1D series to afford a better AF system and were complaining about the old 9 point AF system. It was definitely a more action/sports/wildlife kinda camera. Right now, I would say Canon's AF offerings are on-par - so really is a 7d mark II even needed?

My question is what "big" photography related improvements could they do to an already fine piece of equipment

I don't want to sound cynical, but I hope the 7DII isn't just a 70D with the 'top end' ergonomics, just as the xxD line had up until the 60 and 70D combined a rebel interface with the larger body.

A little faster, gain a proper rear wheel + joystick, maybe lose the pop up flash.....

I don't know about losing the popup flash. That has always had the ability to remotely control other Canon flashes. You don't actually have to flash the popup, but you can use the IR comm. capabilities to trigger other off-camera flashes. That's a nice, pro-level feature. I would expect the 7D II to still have a flash, but have on capable of communicating with Canon's new radio line of flashes.

I expect the 7D II to also get a higher frame rate than the 5D III, at least 8fps if not 10fps, and I also expect it to get an improved AF system worthy of Canon's current pro line. I'm not sure the 61pt AF system will fit and APS-C frame, and I'm not sure it can be scaled to work with an APS-C frame. I do hope for something along the linesof a 41pt system, though.

It's been rumored before on multiple occasions, so I also expect the 7D II to have a lot of video feature enhancements. The video on the 7D is pretty lackluster. I don't quite know if the new video features will be 7DC level, but they should be of a higher level of quality and capability than any other models except the 5D III, and still maybe better than that.

so are they already in the hands of some sport photographers?

i guess so... canon don´t give them new cameras a few days before the world cup and expect pros to use them for making their living.

but still no specs?
not a single source who has something solid to say?

even the NSA has more leaks...   ::)

Hmm...maybe the NSA should hire some Canon security execs to plug their holes... ;P

Lenses / Re: The Next
« on: May 22, 2014, 12:55:37 AM »
That's the classic rubbish line about the 3rd party. You can just as easily get a dud Canon or Nikon. You could make a fuss with the exact numbers but unless there is something inherently wrong with the design then "in practice" it is not particularly more likely than the other.

It is not just a question of a good or bad design, although any designer of volume products worth his or her salt will try to minimize the sensitivity of the design to manufacturing variations.  The extent to which the manufacturers are able to optimize their process control will play a big part in how likely you are to end up with a dud.

A company which maintains tight control over the materials, assembly equipment, manufacturing processes and externally sourced components will be able to minimize the percentage of out of tolerance products coming off the line.  By controlling their test processes they can also ensure that most of the duds get rejected.  This is what the science of process control is all about, and big companies like Canon take this very seriously.  Not only does it improve the quality of their products, allowing them to charge higher prices, it also saves them money in failures and rework.

Even if two companies share a design, the quality from one may be very different from the other.  An example which was quoted in a marketing class I took many years ago featured a gearbox that was built by both Mazda and Ford, who had (and I think still have) significant design sharing agreements.  According to the class, Mazda's quality metrics were 8 times better than Ford's for the manufacture of an identical product.  (I'm not bashing Ford by the way - this example is several decades out of date, so has little relevance today.)  I don't have any hard data to compare Canon's quality with Tamron's, but I would disagree that the quality of the design trumps the manufacturing methods used to build it.

I recall that once upon a time Leica was kinda trashing Canon, saying yeah they may have great theoretical MTF charts for many designs, but look at the designs, no way they can get a decent enough number of copies come close to the ideal chart build, their designs for a number of lenses require way too fine tolerances, especially for Canon who doesn't test each piece and lens individually.

Only a lens bench test is going to tell you for sure. In that respect, LensRentals tests of Canon lenses indicate that for Canon's more recent lens designs, the quality of each model tends to be tightly clustered towards the highly performing end. There are outliers, but they tend to be pretty rare and far between. That indicates that Canon's manufacturing for lenses DOES keep most copies within tolerance. That goes not only for optical performance, but for AF performance as well (which LensRentals has also tested.)

Leica can *say* all they want. Maybe before the current generation of lenses, it may have been true. Empirically today, however, Canon lenses generally live up to the hype.

Lenses / Re: The Next \
« on: May 20, 2014, 12:01:38 AM »
$3499....same IQ as 200-400mm

There will be a lot of 200-400f/4 Lenses going cheap if this was the case   ;)

I think the 3.5k price Tag is pretty well ballpark though, the Nikon 80-400f/4.5 is selling for around 2.7k so you can safely bet the Canon will be close to 1k more expensive, be worth it as well if they can maintain a constant f/4.

Would work perfectly on the 1DMK IV.

The 70-200F4IS has about the same IQ as the 70-200F2.8IS
The 24-70F4IS has almost the same IQ as the 24-70F2.8

So a 100-400F5.6 (no internal teleconverter) could very well have the same IQ as the 200-400F4....

But however you slice it, it will not be inexpensive.

Your comparing midrange L lenses to each other. The Canon great white superteles are in an entirely different class, there isn't any kind of comparison to be made between any one of the 70-200's and even the 200mm or 300mm great white Ls, let alone the 100-400 L II and the 200-400 L.

It's highly unlikely that a midrange L-series lens that costs anywhere between $2000 and $3500 will have the same IQ as the $10,000 200-400 L. It just ain't going to happen. The longer zoom range alone is going to dictate that it won't happen. The extra 100mm of focal length is going to put additional stress at some other focal length (it's all tradeoffs, either less zoom range but better IQ across the range, or more zoom range with IQ losses somewhere), and for Canon to make it true "supertele" quality would mean it would HAVE to cost at least as much as if not MORE than the 200-400 (even without a built-in TC).

Lenses / Re: Distance-dependent AF behaviour of Canon 35/2 IS
« on: May 17, 2014, 01:24:32 AM »
I typically use two or three samples per AFMA setting on focal, and its usually fine, but with a erratic lens, I find that no number of samples is going to fix the issue.  I might get a average value of many samples, but if the lens varies all over the place, it needs service.  Using a average value when a lens does not work correctly is no help.

This is good advice, too. If the lens is that erratic, then it probably needs servicing.

Lenses / Re: Distance-dependent AF behaviour of Canon 35/2 IS
« on: May 16, 2014, 10:49:12 PM »
With FoCal I use the manual mode and I take 5 shots per AFMA value. The problem is that the variability is so high that the curve is unreliable. I have AFMA'd other lenses with good results. Interestingly, on those lenses FoCal and DotTune measurements don't differ of more than +/- 1. In my experience DotTune is actually quite reliable.

You really need to use at least 10 samples. There is some variability, but with enough samples, it averages out, the outliers are clipped, and the results are much more reliable.

Lenses / Re: Distance-dependent AF behaviour of Canon 35/2 IS
« on: May 16, 2014, 03:53:56 PM »
I have to agree that Dot Tune is pretty unreliable. There is no direct correlation between when AF is confirmed by the firmware, and the AFMA setting. AF confirmation is a bit more arbitrary, which is why there is variability.

When you use FoCal, do you use the maximum samples option? I forget what it is exactly, I think 10 samples are taken per AFMA setting. If you only do the "quick" AFMA tuning with FoCal, which only uses 2 or 3 samples per AFMA setting, it isn't really all that much better than Dot Tune. You really need to use a high number of samples to get accurate results. Small things during the AFMA tuning process, such as a missfocus (which do happen), wins or something else that might temporarily change the focus distance, etc. can all mess with the focus hits at each AFMA setting. By doing at least 10 samples per, FoCal is then able to use some basic statistics to discard outliers and produce a more accurate curve, and thus find the most accurate AFMA setting.

That said, AF IS often distance dependent. This could be due to spherical aberration in a lens, or possibly other aspects of lens construction. Regardless of the why, tuning AFMA for near focus will often result in improper AFMA for far focus. You might want to run FoCal with a high sample count for both near and far focus, and just try to memorize the settings, or write them down and keep the settings in your camera bag, or something like that, so you can reset AFMA if you need to switch periodically between far and near focus.

Animal Kingdom / Re: Show your Bird Portraits
« on: May 15, 2014, 12:34:01 AM »
The Naked-faced Spiderhunter (Arachnothera clarae) is a species of bird in the Nectariniidae family. It is endemic to the Philippines.

Its natural habitat is subtropical or tropical moist lowland forests.

Source: http://en.wikipedia.org/wiki/Naked-faced_Spiderhunter

Location: http://en.wikipedia.org/wiki/La_Mesa_Ecopark

Settings: 1/250 f/8 800mm ISO 800

Interesting bird. Rather exotic.

Animal Kingdom / Re: Show your Bird Portraits
« on: May 15, 2014, 12:33:12 AM »
Hello from Sweden!
After seeing all your great photos of bird portraits may I also add this photo of a mute swan, that was crossing the full moon light gate @ the sea shores of the Baltic Sea, in the coastal area of Sandemar Nature Reserve on the east coast of Sweden at the time of the full moon rise over the sea on the evening of 16th of March 2014. [ Canon EOS 5D Mark II with EF300mm f/2.8 L IS II USM ]

Wonderfully executed! Love the way you put the band of light reflecting off the water right behind the bird's head.

Animal Kingdom / Re: Show your Bird Portraits
« on: May 15, 2014, 12:32:24 AM »

Common Redpoll - Auðnutittlingur
by Rodor54 in Iceland, on Flickr

Great shot! Perfect balance, with those wings head on like that.

EOS Bodies - For Stills / Re: Advice on a upgrade from the Rebel XS
« on: May 14, 2014, 10:01:44 PM »
There is noise reduction circuitry. It's called CDS, or correlated double sampling. There is usually a CDS unit per column, which samples dark current before an exposure is made, and that sampling is subtracted from the pixel charge as each row is read.

Ah.  I assumed that was being done in software rather than hardware.

CDS? CDS has to be done in hardware, since it requires sampling the actual dark current moving through the circuit. The closer the sampling is to the time the dark current is subtracted, the more accurate. This means that for shorter exposures, analog CDS is very accurate.

The first Exmor design, the ones used in still photography sensors, used only digital CDS. The later Exmor designs actually use a dual CDS design, one analog CDS stage and one digital CDS stage. The analog stage takes care of most of the dark current noise, and the digital CDS stage takes care of any residual. As far as I know, the dual-CDS Exmors are only used in video camera sensors at the moment, but I suspect that won't remain that way for long. I actually suspect that the A7s sensor uses a dual CDS approach.

Sony Exmor sensors use column-parallel ADC. They moved the ADC onto the sensor die, and hyperparallelized them. That means each ADC unit in an exmor is only responsible for handling a few thousand pixels, instead of a few million pixels, every fraction of a second. That allows a lower frequency to be used, so the frequency of the clock is lower than the frequency of noise in the circuit itself.

I knew they'd moved it onto the die.  I didn't know about the parallelization.  That's an interesting approach.  I'd be curious whether the use of lots of ADCs causes banding problems like it does for the 5DmkIII.

From what I've read about Sony Exmor, since the ADCs are per-column, that allows the potential to tune each ADC to handle column response differential. The responses of each ADC can be normalized to eliminate vertical column banding.

In the case of both the 7D (to a fairly strong degree) and the 5D III (very slightly), there is noticable vertical banding that correlates with each set of readout channels. In the 7D, you can clearly tell that each vertical band is 8 pixels wide, which corresponds with the 8 readout channels. In the 5D III, the effect is very subtle, so I figure Canon must have figured out a way of tuning or otherwise correcting for the readout differential for each ADC channel.

Anyway, there is potential for vertical banding with parallel ADCs, but it can always be tuned out or otherwise corrected for. With lower frequency per-column ADCs it's easier to fine-tune each ADC.

That might improve sampling accuracy, but at first glance, I would think that you could achieve similar benefits with oversampling.  Maybe not.

It sounds like you understand audio signal processing. While I think some aspects of standard signal processing apply, there are a lot of differences with spatial signal processing. I don't know standard audio signal processing all that well, so I can't say how sampling techniques might apply, but my gut (based on what I do know about spatial signal processing) tells me that there really isn't going to be much in the way of multi- or over-sampling the signal. It generally comes out of the sensor "as is", with the exception of what CDS does.

Now, I do know that Sony, Nikon and a few other manufacturers do some things differently than Canon. It's often called "processing", but in general it's simple things. For example, Canon uses a bias offset in their design to handle the sensor bias signal, where as Sony and Nikon clip the bias signal out entirely (cleaner deep shadow noise, but you lose a good chunk of deep shadow.) For normal photography, clipping seems to be better, however for astrophotography (an arena where Canon cameras are almost synonymous with "modded DSLR") a bias offset is a far better approach as it means with more advanced noise removal techniques, you can recover a hell of a lot more signal from DEEP within the read noise. (Since that signal is clipped in Sony and Nikon sensors, its just gone, discarded, not recoverable.)

(Sony also move the clock and power supply themselves off to a remote corner of the Exmor die, which reduces potential thermal sources and, at least according to Sony's paper on the Exmor design, reduces noise from high frequency components within the ADC units themselves.)

Hmm.  I guess that makes sense.  With my audio hat on, when I hear someone talk about moving an ADC clock away from the ADC, my mind screams "Aaaah!  The jitter!  It burns!", but I suppose that jitter doesn't affect this use case very much, because the value isn't changing....

I don't gather, from the patents and papers, that the Exmor design was easy to achieve. When you look at the sensor layout, you can see in the upper left corner there is a clock, PLL, and a couple other components. Then you have the pixel array, with the photodiode, per-pixel amplifier, and the row/column activate and read wiring. Below that along the bottom you have the CP-ADC units, which contains a ramp ADC, the CDS/Pixel register (CDS readout counts negative, pixel readout counts positive, CDS is effectively "automatic"), and then some more electronics to ship the signal off the die. There are a few other components as well, although it's been long enough that I don't remember all of them.

Anyway, however Sony did it, they seem to think that moving the high frequency components off to an isolated area of the die reduced noise and jitter in the ADC units, which is part of the reason the Exmor readout is so clean. Plus, since each ADC is only responsible for reading out a few thousand pixels they can be clocked slower (whatever the image height is, basically, so in a 6000x4000 pixel sensor, each ADC unit is only responsible for 4000 pixels per read, vs. say Canon's which are responsible for 2.5 million pixels per read).

So I wouldn't say that moving the ADC unit closer to the detectors really has anything to do with reducing noise.

Well, the more important thing is for the first gain stage to be as close as possible to the detectors.  Any noise bleeding into the signal at that point is going to be massively amplified, so you would want to have as little distance there as possible.  I'd expect the distance from there to the ADC to matter, albeit not nearly as much.

The gain is applied by the amplifiers, not the ADC. Maybe you have the two mixed up? While I'll admit I haven't read patents for every possible image sensor design, in the case of CMOS sensors, every pixel always has an amplifier. They are built into the readout logic for each and every "pixel". Now, in some sensor designs use a "shared pixel" design where two or more photodiodes will share some readout logic. Usually, in shared pixel designs, there is one amplifier for every two pixels, connected diagonally. This allows for a larger (longer) amplifier, which I guess improves effectiveness or efficiency (this gets into a realm of CMOS transistor design that is a bit beyond my level of understanding...but I believe it falls into the same category as FinFET and Tri-gate technology...a long thin "fin" of a transistor with multiple source and drain connections allows for cleaner, lower noise, lower head electron transfer).

Anyway, yes, all pixels do have an amplifier right in the pixel, although not all pixels have their own amplifier. Some amplifiers are shared among pixels, however sharing allows for more efficient use of die space, meaning larger amplifier transistors and larger photodiodes, so higher efficiency overall.

One caveat, Canon cameras have two amplifiers. There is of course the per-pixel amplifiers. These kick in AT read time, so they amplify the signal in the pixel directly before anything else happens to it, so it's before any additional noise is added to the signal. However, to achieve the highest ISO settings (usually the top two or three), Canon also uses an off-die, downstream secondary amplifier. This secondary amp is also a source of noise in Canon sensors. I don't know why they do this, however I found a rather old article somewhere a couple of years ago that indicated that Canon somehow determined that the downstream amplifier was actually less noisy. I don't know enough about the specifics to be able to say one way or myself for sure...but I guess I'm willing to trust that Canon knows what they are doing.

Increasing the parallelism of the ADC units, allowing each one to operate at a lower frequency, has a lot to do with reducing noise. Because the ADC units are on-die with Exmor, it also means that the signal is converted from analog to digital immediately...rather than after transit across a bus and through who knows how many additional electronics.

And I suspect you can probably use less signal amplification, because you don't have to send the analog signal a long distance across a bus.

I'm not sure in this case. I'm sure that sending the signal over the bus introduces noise, however for the most part, amplification occurs in the pixels before any transfer across a bus. The one exception would be the top two ISO settings in Canon cameras (not the expanded settings, the top two native ISO settings), which uses a downstream amp.

Regardless, I think digital readout is the way of the future. Digital signals can be transmitted with error correction, and at very high speeds, without having to be concerned about analog noise interfering with the signal. With transistor sizes on sensors dropping to around 65nm now, that leaves a TON of room on the die for complex logic. I really hope Canon moves to a fully on-die system soon. I know they already tested the some of their patents, like their dual-scale CP-ADC and some other enhancements on the 120mp APS-H sensor, where they were able to achieve 9.5fps "low noise" readouts. God only knows when they might actually employ the technology in the actual sensors that go into actual consumer products, though.

Canon also has patents for some other interesting technology. Such as a read-time power disconnect, which decouples pixels being read from the power source, which, at least theoretically as I understand it, could potentially eliminate dark current entirely as a contributor of read noise. That would help shadow noise performance a lot when shooting in higher temperatures...such as outdoors, in the sunlight, for birds, wildlife, landscapes, etc. (I know that my 7D can get pretty hot when I'm out in the sun trying to photograph birds or wildlife...which can take a lot of time to get close, get the right angle, etc.)

Are we talking about ringing on the power supply rails here, or something else?

No, it was a fairly specific patent about a specific transistor setup around the pixels and some other logic in the sensor to disconnect the active power supply during readout (I think there was still some power from capacitors...can't remember). I'll see if I can find the patent again. It's interesting, but it was long ago enough now that I honestly don't remember the specifics.

At one point in time, I'd found a gold mine of patents for Canon. Stuff going back to the early 2000's. I probably still have the bookmark in my old Opera 12 bookmarks file. I'll see if I can dig it up, and hopefully the site is still around. Canon has a lot of cool patents, but they don't seem to employ them. At least, not in their stills cameras (I think they have used some of these patents in their video sensors....but that's nothing unusual, it seems everyone in the CMOS sensor game these days implements all the coolest stuff in video sensors. :P).

Landscape / Re: Waterscapes
« on: May 14, 2014, 02:41:41 PM »
Very nice. Love that long-exposure fogging of coastlines like that. Nice, rich contrast, too!
And a lovely watermark ;)

LOL. That too. :D

Pages: 1 ... 97 98 [99] 100 101 ... 328