Chris Giles
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from what camera is that?I'm happy with it, need to play about some more but initial stuff looks great.
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Canon 5DSr Ken.from what camera is that?
This whole thread Chris has been talking about waiting for his 5DSR to arrive so that he can test it out. Edit: beatenfrom what camera is that?
Yep, +1 by itself is not much.This whole thread Chris has been talking about waiting for his 5DSR to arrive so that he can test it out. Edit: beaten
+100 shadows is nothing though, add +4 exposure as well to really test it out, although even on this web-size jpeg the shadows in the bushes in the background already look fairly crunchy. Canon cameras also have some DR in the highlights, so add some negative setting to the highlights.
Quite, I'm the same with my 645z, expose for the highlights and then push the rest. I tend to expose correctly so don't need the push files so much.I am not really sure I understand the point of underexposing by 4 EV only to push by the same value afterwards.
...although, I do that all the time with my antique Hasselblad MF. It does not have an analogue amplifier, so any ISO above base ISO (which is ISO 50) is digital push. ISO 50 + 4 EV is ISO 400, which I sometimes use. Looks reasonably fine to me. But my Hasselblad is a CCD camera, designed in 2008, 7 years ago.
I am pretty sure you expose correctly! I understand you did that just for the test.Quite, I'm the same with my 645z, expose for the highlights and then push the rest. I tend to expose correctly so don't need the push files so much.
I knowI am pretty sure you expose correctly! I understand you did that just for the test.
What I wanted to point out is that digital pushing by +4 EV was already done as a standard function in digital backs in 2008, since this is the way my antique camera operates when set to ISO 400. If Hasselblad built that as a standard function, I think that they thought it was already good enough at the time.
So, basically, your test shows that your camera can do what a digital back could already do in 2008.
(Note that I am discussing the test, not the particular camera)
I thought with CCDs the signal beyond ISO100 was amped by software anyway and CMOS the amplification was carried out at the point of capture.
Specifically, Sony sensors have on-chip A/D conversion, which is why they have so little read noise compared to other manufacturers. I don't know if there are other companies that have adopted this technology, but you need to have a sufficiently small manufacturing process to put circuitry directly on the sensor, and Canon refuses to budge from their tried and tested methods that are too large to put anything on-sensor except pixels. They recently improved this and now have on-sensor PDAF, but still no A/D conversion, meanwhile Sony is pushing even further by using copper wiring and BSI to maximize the speed at which photons are read off the sensor and converted to data.On CMOS sensors, the ADCs are directly on the chip and the constraints of integration mean that using really fancy ones is difficult.
Chris, I sold my 5DSR two weeks ago, after having tested it against the 645Z (there is a thread on it here).The A7rii is certainly an interesting camera with a high possibility to rip a decent share of the MF market but all the time the sensor is 135 it'll miss a certain look and feel to the image.
Saying that, ask me in two weeks when I've done side by sides of the 5Dsr and the 645z at a few weddings because if I can dump the 645z for the lighter setup and am able to go back to a single line of lenses I will. Just so long as the images don't lose something.
I tested my 5DSR against the Pentax 645Z going from underexposure to overexposure and found that the Canon, even at ISO 100 was unable to pull up the shadows as cleanly. For a fair comparison you will need to have the same scene/lighting set up for both cameras and then see how much the image can be manipulated and what the results are.Yep, +1 by itself is not much.
Canons start to break down at about +3 exposure and at +4 and beyond they get really ugly. Of course the 5DS/R have much more resolution/pixels so one can use noise reduction more aggressively and still retain a lot of detail. But still, color quality in the shadows goes down quickly. The stock Adobe profile for the 5DS/R looks fairly contrasty, I would dial down contrast quite a bit also.
This is a great post. It helps me understand what issues really contribute to and control noise in sensor design. It's really very similar to the relationship of analog s/n to bit depth in audio recording.Not really. The necessity for analogue amps comes from using an ADC with insufficient bit depth.
CCD or CMOS of about 6 µm pitch have a full well of about 50K photons. If you use a 16-bits ADC, you can count from 0 to 65535, so you can count the whole dynamic range of your sensor without needing analogue adjustment.
If you only have a 12-bits ADC, you can count from 0 to 4095, or by analogue amping down by a factor of 2, from 2 to 8191, or from 4 to 16385, or from 16 to 32767, or from 32 to 65535 (full well).
Early DSLRs had only 12-bits ADCs, so they needed an analogue amplifier. Hasselblad chose to use a high-end 16-bits ADC, so did not really need an analogue amplifier. On CMOS sensors, the ADCs are directly on the chip and the constraints of integration mean that using really fancy ones is difficult. Early CMOS ADCs were also only 12-bits.
This is a great post. It helps me understand what issues really contribute to and control noise in sensor design. It's really very similar to the relationship of analog s/n to bit depth in audio recording.
My post was indeed vastly simplified. I was just answering a specific question.There are a couple of points missing.
There is no indication that FWC has increased in a meaningful manner, especially when the pixels have be shrunk. Besides, increased FWC would only be useful if we were able to get more photons, which means either lower ISO or higher quantum efficiency or both. We are already relatively close to the maximum of quantum efficiency on modern cameras.One is that modern CMOS sensors seem to have increased in full well capacity. I don't have actual numbers but I would guess that say Nikon D810 and say Phase One IQ have similar FWC (number of electron charges stored).
Yes and no. Having 4 bits of info on the noise will allow noise reduction to work better.The other point is that the maximum meaningful amount of information from a sensor is FWC / readout noise. Readout noise for a Phase One IQ 180 may be around 12 electron charges. So the amount of information is really around 1:3800, say 1:4000. To represent that range you need 12 bits. So the output from the ADC is 16 bit but 4 bits of that is noise.
That is true and is a Sony Patent.With recent CMOS sensors Sony and other vendors moved the ADCs on the chip. Normally there is an ADC for each column, so a normal 24 MP sensor has 6000 ADCs. Those ADCs are probably simple ramp type devices and can have long conversion times as each ADC only handles 4000 pixels.
Yes and no. Part of that extremely low figure is due to correlated dual sampling, which adds some problem of its own. But discussing this would lead us too far from the title of the thread, which concerns the 645Z and the A7RII. The two cameras use a Sony chip.Noise levels of on sensor ADCs may go down to 2 electron charges.
My post was indeed vastly simplified. I was just answering a specific question.
There is no indication that FWC has increased in a meaningful manner, especially when the pixels have be shrunk. Besides, increased FWC would only be useful if we were able to get more photons, which means either lower ISO or higher quantum efficiency or both. We are already relatively close to the maximum of quantum efficiency on modern cameras.
Yes, but there are indications that minimum ISO is going down. Also, SNR seems to go up a bit. What I see is that the pixels are shrunk but FWC seems to stay around 60000.
For instance: Base ISO on the Sony Alpha is 119 ISO according to DxO and SNR at base ISO is 41.2 dB while the Sony A7rhas a base ISO 73 and SNR 45.2 dB. So SNR (18%), which is only function of full well capacity, has increased 4db. SNR is proportional to SQRT(FWC) so I would suggest that FWC/sensor area has been dubbled between the A900 and the A7r although the A7r has smaller pixels.
Sony Alpha 900 versus Sony A7R - Side by side camera comparison - DxOMark
Yes and no. Having 4 bits of info on the noise will allow noise reduction to work better.
I have not seen article confirming this, you perhaps have a reference?
That is true and is a Sony Patent.
Hi, I don't know if it is a Sony patent, I much doubt it because I think there are older implementations. Leica CMOSIS sensor also has column converters, but with higher base ISO and lower SNR. Toshiba has also column ADCs, so they may be more of a norm than an exception.
Yes and no. Part of that extremely low figure is due to correlated dual sampling, which adds some problem of its own.
Hi, correlated double sampling is simply measuring cell voltage before and after exposure, AFAIK, correct me if I am wrong.
Check this article: https://en.wikipedia.org/wiki/Correlated_double_sampling
But discussing this would lead us too far from the title of the thread, which concerns the 645Z and the A7RII. The two cameras use a Sony chip.
Quite right, both are 14 bit devices.