Dxomark has A700 v4 up now

[caporip]

To an extent i also agree with Don in that kudos to DXomark for revising its results to allow for V4. I think what concerns some people here and elsewhere is how level is the playing field? In other words if producers are altering their raw files, how can you make a valid comparison? I may be way off the mark here but if we accept that Nikon and Sony use the same FF sensor then in theory at least shouldnt the RAW results be the same? As it is, my understanding is that different processing is applied to produce the raw file so how do you allow for that? The answer is, i suspect, that you cant so these results are only ever going to be a guide albeit a pretty good one.

[bfitzgerald]

[quote="Vidgamer"][quote="bfitzgerald"]There are no facts, just charts and numbers!


Are you looking at the same chart I am? I took Don's link, switched the 5d to the A200, and the G10, A200, and A700 all follow the same diagonal line for DR, pretty much -- just with one camera better than the next. But the DR does decrease for the A200.

[quote]

Yes they do decrease, but the DR does not narrow that much on the A200, compared to the 5d. I have both, I use both..I know what's going on by looking and printing the images. My real world experience does not show up on these tests, thus I doubt them very much. That's even before we start on the absurd DR numbers anyway..as if the G10 small sensor has the DR of negative film..yeah right, who are they trying to kid? It's not working I am afraid!

[Dusty]

To an extent i also agree with Don in that kudos to DXomark for revising its results to allow for V4. I think what concerns some people here and elsewhere is how level is the playing field? In other words if producers are altering their raw files, how can you make a valid comparison? I may be way off the mark here but if we accept that Nikon and Sony use the same FF sensor then in theory at least shouldnt the RAW results be the same? As it is, my understanding is that different processing is applied to produce the raw file so how do you allow for that? The answer is, i suspect, that you cant so these results are only ever going to be a guide albeit a pretty good one.

No RAW results shouldn't be the same unless you're processing them with the same engine tuned the same way. We're not talking sensor output, we're talking the RAW file, which is the sensor pixel data interpreted by the firmware's implementation of the Bayer pattern. If one gives more weight to a color channel, or decides that R at +4 and B at +2 and GG at +1 = mauve, while another engine says that = lavender, you have different RAW outputs.

The same way that Racer X and Racer Y both buy racing motors from BMW, however Racer X installs a better exhaust and intake systems, resulting in more horsepower. DXOLabs was saying, in effect, "We only test motors with carburetors, not fuel injection, to determine horsepower."

If I came up with a software engine that totally eliminated noise in RAW files at 64000 ISO, that's RAW file, like it or not. RAW output, indeed all digital photography, is a combination of sensor output and it's interpretation by the software.

Dusty

[bossel]

We're not talking sensor output, we're talking the RAW file, which is the sensor pixel data interpreted by the firmware's implementation of the Bayer pattern.

Hmmm, I'd say the RAW file data is not demosaic-ed (i.e.that Bayer thing). RAW contains sensor information before calculating coloured pixels from sensor data.

[douglasf13]

I can't believe I was actually about to back up Don, and then he checked out of the forum! IMO, DxO Mark, while certainly not perfect, is a very useful reference, and is a step in the right direction for testing. Scientific testing, like Dxo Mark, and more anecdotal testing, like Michael Reichmann's, both have value.

Barry, I think the thing to keep in mind about the Dxo Mark DR tests, like just about every DR test on the web, is that you should ignore the the number applied to the DR, and instead use the DR charts to compare digital cameras to one another.

[Vidgamer]

I can't believe I was actually about to back up Don, and then he checked out of the forum!

Haha, I just re-read his last message and saw that! He probably never had so many here AGREE with him, and NOW he checks out?! OH well....

IMO, DxO Mark, while certainly not perfect, is a very useful reference, and is a step in the right direction for testing. Scientific testing, like Dxo Mark, and more anecdotal testing, like Michael Reichmann's, both have value.

Barry, I think the thing to keep in mind about the Dxo Mark DR tests, like just about every DR test on the web, is that you should ignore the the number applied to the DR, and instead use the DR charts to compare digital cameras to one another.

Yeah, I would think of it as an aid to help get a good idea of the relative difference between cameras. If two cameras are "close", I'm not sure you could draw conclusions about one "wiping the floor" with the other, or some such hyperbole, but it should give you an idea of relative performance.

[bfitzgerald]

Well DxO say the A350 has a better SNR ratio than the A200. So that should mean it's better at high ISO right?

The more you dig around this DxO place, the less believable it becomes.

I notice at the bottom of the ist page it says..
"once upon a time"

[Javelin]

One post on DPR claims that according to DXO the A700 at ISO 100 has lower noise and higher dynamic range and colour than at ISO200 (supposed base ISO) this dissagrees with what DPR and lots of other reviewers have said. Some independant guys posted a while back that it's at it's best at ISO 160 but no lower than that.

[Vidgamer]

Well DxO say the A350 has a better SNR ratio than the A200. So that should mean it's better at high ISO right?

When I look at it with the "screen" setting, it shows the A200 SNR as better than the A350 at all ISOs. That's looking at raw pixels. If you choose "print", it shows them basically the same, with the A350 having a slight edge at a couple of points. All that is doing is letting the higher number of pixels make up for some of the additional noise at the pixel level. They have an article about how more pixels can mitigate the noise problem.

So, based on the DXO charts, I'd say that for high ISO, either camera would be about the same unless you were purely interested in noise at the 100% pixel level and resolution didn't matter.

The more you dig around this DxO place, the less believable it becomes.

I wouldn't say that raw numbers are everything either. But if you can't make some measurements and at least get an idea of performance, well, I don't know what to say. What site do you recommend for camera comparisons? DPR?

I notice at the bottom of the ist page it says..
"once upon a time"

I don't see that...???

One post on DPR claims that according to DXO the A700 at ISO 100 has lower noise and higher dynamic range and colour than at ISO200 (supposed base ISO) this dissagrees with what DPR and lots of other reviewers have said. Some independant guys posted a while back that it's at it's best at ISO 160 but no lower than that.

Why would the A700 have more noise at ISO 100? Less dynamic range, I could understand, but I'd expect less noise. (Although, DxO shows it as having a tad more DR at ISO 100, too!) Maybe if I had an A700 I'd see if I could make my own determination...........

[Javelin]

[quote="Vidgamer]

One post on DPR claims that according to DXO the A700 at ISO 100 has lower noise and higher dynamic range and colour than at ISO200 (supposed base ISO) this dissagrees with what DPR and lots of other reviewers have said. Some independant guys posted a while back that it's at it's best at ISO 160 but no lower than that.


Why would the A700 have more noise at ISO 100? Less dynamic range, I could understand, but I'd expect less noise. (Although, DxO shows it as having a tad more DR at ISO 100, too!) Maybe if I had an A700 I'd see if I could make my own determination...........

Maybe not more noise but the story was that the base ISO at 200 ad better IQ because ISO 100 was derived through processing rather than real.

[Vidgamer]

Maybe not more noise but the story was that the base ISO at 200 ad better IQ because ISO 100 was derived through processing rather than real.

But are they guessing or did they actually see that? I should be able to take any ISO 200 photo, reduce it by a stop of exposure, and get a less noisy photo.
I'll have less DR, but I don't think Sony would add ISO 100 unless it did something. ("Ok, here, you can select it, but it'll just look worse AND be slower, but we'll give it to you anyway.") Well, I suppose you might want a slower mode to help with waterfalls or some such.

[Javelin]

here is part of the DPR review where they talk about ISO sensitivity and DR most review sites said variations of the same thing

http://www.dpreview.com/reviews/sonydslra700/page20.asp" onclick="window.open(this.href);return false;

there was much discussion on this at DPR when the review came out and people settled on ISO 160 at the time as being the best

[Greg Beetham]

I'm no expert on in camera processing and PPP I'll admit, but going on what I've seen written around here in the past, if you were to underexpose an ISO200 photo by one stop too emulate ISO100 and then "lift" it afterwards it's going to generate noise, to my mind it's going too be more noisy than if you actually had a real ISO100 in camera.. it would be like exposing too the left and then dragging detail out of much darker shadows than you would have had otherwise.
Greg

[Greg Beetham]

There is still something I don't "get" with DXO, they claim too measure the sensor generated output before any "in camera" processing takes place...what is not made clear so far is, how do they intercept the output directly from the sensor? before any onboard camera systems get to deal with it, that's a very neat trick, if that is what they are in fact doing, you would have too think that somehow they are able to uncouple the sensor from the system board and take a full channel dump into their own buffers and do their evaluations from there....hmmm might not be good for the camera...I think I read somewhere that they use calibrated light sorces for some tests....maybe that's it, they use a known measured strength of light to expose in, and then evaluate what the camera did in response after an exposure....
Greg

[Greg Beetham]

Well that sort of opens up a new can of worms, a camera and lens combo is a balanced exposure system, the Minolta/Sony system relies on metering through the lens and feedback from the lens to a certain extent...I thought, so now I'm wondering how much the nofocussed light without a lens is affecting the exposure system, as for absolute sure the body would "know" that there is no lens fitted...ie. I would have thought the body would need a lens too establish "on" exposure value for a given ISO at a given ambient light level @ 18% with that particular lens, and from there the +/- exposure compensation table...from that previously established baseline exposure value.
All I'm saying is, how can one be absolutely certain that the behavour of the exposure/sensor/processing system is the same, both with and without a lens.
Greg