JimKasson: Rishi, that's a nice summary. BTW, I've never seen any evidence that any alpha 7 camera in any mode has 14-bit precision. The best I've seen is 13. The camera advertises itself in the EXIF as a 14 bit camera, but when the raw files are decompressed on that basis, every other histogram bucket is unpopulated. One way of looking at this is that the camera deep down inside is 14 bits but that the minimum slope of the tone compression curve is 2, so you lose the 14th bit at that stage. I don't think the Sony engineers care so little about cost that they've designed a 14 bit converter and then later on in the raw pipeline deliberately thrown away the 14th bit.
@photomedium : It is not about the cost of an ADC, but about the ADC mode in use.
Thomas Kachadurian: Seems a bit apologetic, like back in the days when Nikons topped out at 6 megapixels and DPR said it didn't matter until the first release of Nikon 36mpx sensor and then it did.
A lossy compressed file is not, and never can be a raw file. A raw file is a direct sensor dump without alteration.
@Thomas Kachadurian :> A raw file is a direct sensor dumpAnalog memory for such a camera is an interesting challenge.
PVCdroid: There is manipulation of data off the sensor by all the camera makers before a file is written as raw. The question is that of efficiency in the camera's processing of images not what file is the purest in terms of untouched data. You can have a Nikon raw file written as 70+mb or a smaller more processed one in the 30+mb range. The difference is literally garbage that is thrown out which is only used by those engineers and statisticians looking at data, not images. Sony elected to save us all the headache of extra and wasted storage space. Nikon and Canon users will claim that their raw formats are the best and untouched by the manufacturers but it's just not true.
Here is an article from one of the best analyzing what Nikon does to their so called non lossy raw files. Note when reading how similar this process is to the article written about Sony's process by DPR. http://blog.kasson.com/?p=6783
@luigibozi :> Agree, but that's information theory. I'm sure you were aware that we're talking applied information theory.
I'm sure the question is about the amount of information contained in 14 computer bits. Jim suggests 12.5, I agree.
KonstantinosK: Does this issue appear in the A6000 too? Just wondering...
All ILCE, ILCA, SLT, and Cybershots past DSC-R1 original, as well as raw-enabled Handycam NEX-VG cameras are recording lossy delta-compressed raws, leaving no alternative.
Might be the way they are running the ramp on ADC, but it is often programmable.
@luigibozi : Here are two definitions of "bit", in information theory it is not necessary an integer:
PhotoKhan: I can't see what all the excitement is about, regarding this test, specifically.
There are other features in the A7RII that appeal to me but I really expected more from the first use of BSI tech on a full frame camera.
Compared to the 5DSR it features lower overall chroma noise, true, but at clear expense of detail. In addition, the Canon keeps rendering more "contrasty" and pleasant looking colors at high ISOs.
If someone was offering me one of these two cameras, nothing else withstanding and just based on these studio tests, I would have to flip a coin.
@ PhotoKhan:> Why would I use a different converter than the one I prefer?To get better results from a camera.
Again, there is no reason to talk of "SONY colours", or "Canon colours"; or chroma noise with any camera, if you are limiting to a converter. Speak of the converter, than.
> I did try itWell, I specifically pointed at the red patch (CC24 target).
@Tons o Glass 0 Class : with BSI, sensor can use a larger reset transistor, resulting in less noise.
@Rishi Sanyal : yes, it is a calibration issue, but significant part of it is the wrong DCP. What I'm trying to say is - I would not be judging sensor performance based on just a default conversion, especially if looking for minor differences in said sensor performance.
@PhotoKhan : why, they made raw files available. The choice of conversion procedure is totally up to you. For those who convert using ACR defaults, the images are representative, but of the conversion - not of the camera; while you are talking about cameras ("Canon keeps rendering...")
Switch the scene into low light mode and compare red patches between Canon 5DS R and SONY A7R2 renditions, switching between raw and jpeg. What is going here, and why?
Much of what you are saying is converter-dependent.
>it features lower overall chroma noise
Chroma noise is something that strongly depends on how the colours are converted, currently there is no way we can use some standard to define colour noise in raw.
>at clear expense of detail
Well, one first needs to determine the default levels of sharpening and noise reduction in a converter.
>Canon keeps rendering more "contrasty" and pleasant looking colors at high ISOs
Canon, or ACR?
aftab: Few points:1. Looked at 100% all ISO samples are crappy. There is no free lunch yet. 2. As far as the noise and detail goes every ISO is better than lower ISOs pushed for the same brightness. The difference between ISO100 and 6400 is not modest, it is huge. So, your recommendation should be to use the highest ISO (up to ISO6400 for this test) in low light without blowing the highlight and push as less as possible in the post. This is quite opposite to the tone of your article or recommendation. Moreover, higher ISO let one use higher shutter speed in low light handheld situation 3. We don't have a 'true' ISO-invariant camera yet. All modern cameras become ISO invariant at certain ISO. 4. Whenever possible one should aim for proper exposure in the first place. Pushing shadows comes with cost no matter which camera you are using. 5. Best image in this article is the one from D810.
> composition you are shooting needs all 14 stops of dynamic range
But dynamic range one can really achieve and use is no more than 11 stops usually.
Even if the shutter button is pressed twice.
Here is why: http://www.rawdigger.com/Dynamic-range-fair-share-of-flare-and-glare
Chris Noble: Interesting article about a subject that deserves more scrutiny. Thank you! But I am afraid that your analysis is superficial and your conclusion faulty in this instance. There is more than one source of noise, and one of the purposes of analog gain (increasing ISO) is to reduce quantization noise from the A/D converter.
The place where you put the magnification box shows blooming and compression artifacts in the back-lit sign (although the lettering can be recovered up to ISO 3200 in Raw PP); but it is not a good demonstration of shadow noise, as the "dark" area is lit by the streetlight. Move the box to a shadow area (for example, the building top left that is almost in darkness), and you see very significant noise, decreasing steadily as ISO is increased up to 800, with minimal improvement beyond.
Chris, IMHO much depends also on how clean a converter can push, and is it good enough for 9-11 stops of tone mapping whilst preserving full details in highlights. Magic Lantern files with dual ISO are very interesting if one is not going to blow them up unreasonably.
Chris, do you mean this sign?https://s3.amazonaws.com/f.cl.ly/items/3g0I3Q2K223c3B1l0Y2l/Screen%20shot%202015-08-25%20at%202.10.51%20PM.png
kaiser soze: "...a camera with a very low noise floor (high dynamic range) minimizes the need to amplify the sensor's signal in order to keep it above that noise floor (which is what ISO amplification conventionally does)"
This is as wrong as it could possibly be. Amplifying the signal does not have the effect of elevating the signal above the noise floor. The signal is amplified to bring it into the range that the A/D convertor expects. If the signal is too weak, too much of the signal will be below the threshold at which a non-zero quantization value will be recorded. A low noise level simply means that at whatever amount of signal gain is applied, the S/N will be better. That's all. Your entire approach to the subject is based on an understanding that is patently incorrect. Your article is just plain bizarre.
Depends on what is the source of noise.
@ aftab : I think I could use ISO 2000 and careful conversion. An interesting thing however is to take highlights from ISO 200 shot exposed for highlights and shadows from ISO 1600 shot but exposed for shadows (or something along those lines).
buybuybuy: Sony's groundbreaking camera is truly innovative. I believe it's the first camera to manifest more artifacts at lower ISOs!
You can try Canon 5D original for the priority
@ aftab : 3200 is available in a drop-down.
KW Phua: The ISO100 was so bad, unreal. Half-cooked raw?
The question is how to make it possible.
> Weird, the ignore function doesn't work in article comments.
And why did you need to tell me that? "Manual" ignore mode does not work, too?
On all SONY cameras I used the lowest ISO setting was not the best for deep shadows, same as it is with many Canon dSLRs. It changes a little with pixels being smaller and well depths getting smaller as the result, but still it is something to test and consider. On some cameras there was no actual reduction of dynamic range when going 1 to 1 1/3 of a stop higher than the base ISO, just a shift - the loss in highlights was compensated by the gain in shadows.
As to the benefit of "higher analog gain", that is exactly what this "stupid" test is for - to see the results in a torture test and adjust the shooting style accordingly.
I gather quite some of the SONY shooters missed the Jim's and Bill's pages, but may look at this "stupid" test and benefit from it.