« on: December 20, 2013, 06:48:42 PM »
Having seen this setup, now I understand how happy you must be getting the "tiny Canon M" .
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.
The patent looks like a ramp ADC - they don't take the electrons out to count them, but use a voltage comparison. The unknown pile of e- on the right, you measure how long you have to add charge on the left side until both are equal(or the known one grows larger then the unknown). In theory nothing stops you from using multiple heaps that grow at different rates. You just have to keep crosstalk, external influences and such under control.
I wouldn't call it HDR. HDR is a very misused term as it is. In its proper form, a High Dynamic Range image is an image with an EXCESSIVBLY HIGH dynamic range, stored as 32-bit floating point numbers with extremely fine precision and a dynamic range that could potentially equal thousands of stops (i.e. it can represent numbers from a couple billion down to billionths.)
HDR as it is commonly (mis)used simply refers to the mapping of tones into a limited dynamic range from a source file that might have slightly higher dynamic range. What Canon is doing isn't exactly HDR...it is a specialized read process that will allow them to better utilize the dynamic range they already have access to, but which is otherwise being diminished by read noise.
They aren't splitting it. I am not 100% exactly certain what they are doing, but from what I do understand, when a pixel is read, it is amplified twice, and the results of those different amplifications are transferred to the CP-ADC units simultaneously (on different channels). Same source pixel, two separate but full power signals, which are then blended together at conversion time. It is basically the same thing ML did, only with the appropriate dedicated hardware fabricated right into the sensor to do it right.
I keep wondering what is going to happen in the future with dual-pixel technology. They have the ability to read both sides of the pixel seperately, I wonder how much work it would be to set the two sides to different ISO values, read them both, and combine the values for greatly expanded DR.
This would obviously require more computing power than just reading the sensor would, but comments out of Canon about the greater computational needs of future cameras ties in with this... I am really curious to see what happens with the 7D2..... It should be dual-pixel and dual processor (Digic6 or even 6+?) so it will be able to do a lot more computing than a 70D. The next year or so could be interesting.
They wouldn't need to bother with the dual-pixel approach with this patent. They simply read "the pixel" (regardless of whether it is a single photodiode, or two/four binned, whatever) with two different gain levels (different ISO settings, done simultaneously on different signals). This patent offers a much better way to solve the problem without resorting to "hackish" approaches like what ML did, or like what you suggest with reading one half the pixel at one ISO and the other half at another ISO (which wouldn't be nearly as good, since each half pixel is only getting half the light, so the half-reads would already be at a disadvantage large enough to completely eliminate any gains you might make with the dual-read process in the first place.)
Even better than simply reading half pixels at different ISO settings, this patent reads each pixel twice simultanesously at different gain levels, while also bringing the ADC on-die and column-parallelizing them, allowing them to run at a lower frequency, thus reducing their potential to add downstream noise. With column-parallel ADC, they could do what Sony Exmor does...per-column read tuning to eliminate vertical banding. It also brings in the benefit of shipping image data off the sensor in an error-correctable digital form, eliminating the chance that the data picks up even further noise as it travels along a high frequency bus and through a high frequency DIGIC chip. This patent would single-handedly solve a LOT of Canon's noise problems.
The only real difference between Canon's Dual-Scale CP-ADC patent and Exmor's is that Exmor uses digital CDS and digital amplification (basically, it is an entirely digital pipeline)...I see no mention of Canon's patent referring to digital data processing on-die. There are theoretically pros and cons to both digital and analog readout, so only time will tell (assuming Canon actually IMPLEMENTS this design sometime soon) whether Canon's approach produces results that are as good as Exmor or not. Sometimes it is easier, and more accurate/precise, to apply certain kinds of processing and filtering on an analog signal rather than digital bits.
I always enjoy your PP skill TWI by Dustin Abbott .
With 2 kids (2 &5yrs), I wish I can have some spare times and learn how PP digital images.dustin... i'm still waiting for you to write a book on your post processing workflow so i can buy it
nice review BTW much better than my crap attempt when i first got it
Tell you what: in the meantime I will try to find a place to share links to the tutorials I write for various publications. I've got a series of three articles that will go live shortly that I did for Alien Skin.
The downside: when I post those kinds of links I invariably get blasted by some posters here for blatant self promotion. Guess you can't please everyone.
Best thing is to find a shop where both cameras are on display side by side, I am lucky to have found such a shop and took a lot of test shots 6d vs 5d3 and played around with them for hours. Next to the iq, the overall "feel" of the camera is very important, at least to me.
Btw just today I looked at the 70d in the same shop :-p ... seems nice enough and funny thing the lv af suddenly works unlike on 60d, but they did cut back from the 7d in body build and features: af expansion (so the larger amount of points is really only for tracking) and spot af (the af points of the 70d seem to be *very* big).
Crop sensor performance of Canon is a bit beyond Nikon and the 70d's 20mp has't advanced much vs. 18mp, I guess that makes many people bash it in *relative* terms - but in *absolute* terms it's really fine, I've been using the 60d for 2.5 years an 150k shots and the only real "no go" area is shooting motion indoors.
Last not least if people spend a hilarious amount of money on a gadget I'd wager to say it's tempting to rationalize a fun purchase (and the 6d has great iq) as essential even when in many situations crop would deliver the same result for standard print/view sizes.
I'm also not a big fan of the sell & buy game and rather stick to what I have and purchase other things that are also important (esp. lighting gear (flashes, diffusers), but also monitor, color calibration, tripod, filters, printer, software ... repairs!). For crop your 11-16, 17-55, 70-200 should indeed about cover it, the 17-40 & 24-105 are really ff lenses in sharpness & zoom range even if they add weather sealing.
The only way you can justify for yourself if you like the improvement the 6D has over the 70D, is if you use both cameras for yourself, in the situations you shoot in, with the lenses you use. You can't depend on just looking at the work or tests of other people to decide. Plenty of people take great shots with iPhones and compact cameras, especially if it's just content that's displayed at websize. Doesn't mean those are as good as a 6D, but it does mean it depends on WHAT YOU WANT to get out of it, and if you prefer the ergonomics and experience of using a full frame or any specific camera or system.
I used my 50D for 4 years and had over 25,000 shutter cycles. I loved that camera to death, and planned to keep it a bit longer after buying the 6D. After the first couple of days of using the 6D, I had decided to sell the 50D. Eventually a kind gentleman from those internets saw my sale ad, and paid me handsomely for it!
Frankly, if you only shoot birds in very bright daylight with a very high quality telephoto lens (perhaps any of the "big whites"), a 70D very likely makes more sense. The autofocus is no doubt as good or better than the 6D's in bright light, and you get a ton more reach. In the dark, the 6D's center point works where all others in the world do not...and even seems to work better on an f/4 lens in these conditions than an f/2 lens, like my 135L.
For most other stills photography situations, the 6D will excel over the 70D. Perhaps the 70D's image quality is better than the older 7D's, but keep in mind the 7D has generally better AF performance than both the 70D and the 6D...or at least that's what I gather. But the 7D has luminance noise that looks like a gravel driveway overlaying the image starting at about ISO 400. I'll grant you that it isn't as obvious until just above there, but that's not saying much. At ISO 1000 the 7D basically equals the S/N ratio of a Powershot G15 at its own ISO of about half that. That doesn't speak well for the 7D.
Also, one of the main advantages such a high quality image from the 6D is important, is the ability to crop into an image...even one that is shot at high ISO. You can't do that with as much success with the 70D. At the time of shooting, you don't always know or realize, exactly the framing you want...or that a slight or moderate crop winds up looking better when you look at it later on the computer.
For video, the 70D might be better, depending on the situation.
So, if your work is mostly going to be displayed at web sizes, AND YOU HAPPEN TO NEVER EVER CROP INTO AN IMAGE...then you have a lot of affordable choices at your disposal. If you need the flexibility of a Ferrari at Hyundai prices where image quality is concerned, go for the 6D.
It's clear that 6D would produce better IQ than crop sensor if high ISO or shallow DOF is required. I'm curious how much difference there is in other situations. Do you really get significantly better detail, colour, etc at "normal" ISO? I'd appreciate if anybody could post a comparison shots taken with 6D and a crop.
The difference is enormous. I think the closest crop camera is the 40D, which seemed to have a very nice balance of pixels/DR. But as far as the 7D, 60D, 70D, there's no comparison. No noise in the blue channel at ISO 100, no fear off using auto ISO, much sharper image, better color separation, more consistent exposure, etc.
Imho the only correct answer won't make you happy: it depends on the scene.
Some crop shots are indistinguishable from ff or respond very well do noise reduction (not that there are great new algorithms like DxO's PRIME around), and for me some crop macro shots look even superior to ff because the crop "crisp" look goes along with the subject's texture.
Then again, if shooting gradients crop quickly falls apart after some postprocessing because downsizing cannot restore a smooth color transition, or with skin tones and skin texture every bit of nr smudging given an instant plastic look even at low magnification.
If you are not sure about 6d or 70d, my advise definitely would be 70d because it's the better all-around camera, the 6d specializes and excels in some areas but is crippled in others. Just be sure you know what "low light" means (try to meter the LV with your current gear) because even in cloudy daylight crop shooting can become a constant struggle to decide between lower iso or higher shutter speed, resulting in less keepers - the higher iso capability of ff relieves you of that tradeoff and you can concentrate more on the actual shot.
What's your current gear btw? If on a budget it might make sense to go with a 60d and get a better lens, or if you're looking for good iq Canon crop isn't a good choice at all and you should have a look at Nikon...
but is it dramatically better for monitor viewing / moderate size prints, or only fine fur details noticeable at 100%?
Ah, now I though that would be a given - for downsizing to the usual sizes crop is really fine, otherwise they wouldn't sell tons of them, would they?
That's why I was so reluctant to make the ff jump as you can get a stellar lens for €1500, but the sensor iq is just one part, it's the combination with shallower dof and different lens performance that matters as all my lenses are ef and perform better on ff.
It's clear that 6D would produce better IQ than crop sensor if high ISO or shallow DOF is required. I'm curious how much difference there is in other situations. Do you really get significantly better detail, colour, etc at "normal" ISO? I'd appreciate if anybody could post a comparison shots taken with 6D and a crop.Yes.
Well, what exactly do you want to see and what lens do you want the samples made with?
1) If you will try to compare 'camera JPEGs' the huge difference will be the DIGIC brains that do RAW -> JPEG conversion (with lens correction, ALO, etc.). (In case of XTi to 6D comparison, 6D is the Einstein and XTi is the caveman )
2) If you will try to compare 'camera RAWs' you will be at mercy of RAW conversion software camera presets (and number of bits in RAW data -- 6D has more than XTi).
PS: In my experience it's the FOV that makes the main difference. I used to shoot with XTi and 10-22 + 24-105 lens pair for years, and I always considered '24-105' as normal-to-tele lens (and I did not use it very often). The 6D changes the picture, now all my EF lenses make very (and I do mean 'VERY!') different pictures...