It's almost a 1/2 stop difference in SNR. That's rather significant for modern sensors.
Not to mention a 2 stop advantage in general SNR. The GH4 has its place though.
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The difference I see in the SNR is around 1.1-1.2dB, meaning around 1/3 stop. Half a stop would be 1.8 dB. This gap even gets smaller at the highest ISOs. Looking at DR the difference seems even smaller. I don't think that is very significant, although the D610 sensor does seem to perform a little bettering DXOMark, but we don't know why that is. I don't think it has anything to do with on-sensor PDAF pixels, the A6000 does well compared to the D7100, for example.
TrojMacReady
Veteran Member
And arguably, shadow noise is usually the most dominant and limiting factor in low light shots in general.
The SNR graph is just for 18% gray, or middle gray. Not exactly shadows.
If you look at the full SNR graphs below 10% and especially towards 1% gray in the individual reviews or even the DR graph (which reflects shadow noise at high ISO too, since that's the most limiting factor for DR), you'll see the much larger differences.
For example, at a measured ISO 5400 from the A7S, it hits a 10 EV DR, similar to the DR of the A7 and A7R at around ISO 2200-2300. That's well over a stop difference already. Where the A7S touches about 9 stops DR at ISO 21k, the A7 and A7R hit 9 stops around ISO 4700-4900. That's more than 2 stops difference.
Up to a measured ISO 1600, differences in noise will not exceed half a stop, so no, you won't see significant differences there. As expected I would add.
The SNR graph is just for 18% gray, or middle gray. Not exactly shadows.
If you look at the full SNR graphs below 10% and especially towards 1% gray in the individual reviews or even the DR graph (which reflects shadow noise at high ISO too, since that's the most limiting factor for DR), you'll see the much larger differences.
For example, at a measured ISO 5400 from the A7S, it hits a 10 EV DR, similar to the DR of the A7 and A7R at around ISO 2200-2300. That's well over a stop difference already. Where the A7S touches about 9 stops DR at ISO 21k, the A7 and A7R hit 9 stops around ISO 4700-4900. That's more than 2 stops difference.
Up to a measured ISO 1600, differences in noise will not exceed half a stop, so no, you won't see significant differences there. As expected I would add.
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Happy Jones
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If I have this straight all these cameras will perform near the same for shadow noise at ISO6400 and the A6000 will equal the A7 at ISO12800 because shadows noise is the most important factor to consider at higher ISOs?
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TrojMacReady
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Within half a stop for shadow noise based on these graphs, yes. Not accounting for colour shifts and patterns, which these measurements do not represent.If I have this straight all these cameras will perform near the same for shadow noise at ISO6400 and the A6000 will equal the A7 at ISO12800 because shadows noise is the most important factor to consider at higher ISOs?
But my comment was mostly within the context of similar formats and a similar technology age (where shot noise is usually pretty close, shadow noise is more about read noise, which tends to differ more between different sensors covering the same format). Here we're also comparing formats with a difference of up to a factor 4 in size, in which case shot noise differences will be much more apparent too.
In midtones the difference between the E-M1 and A6000 can be up to a stop at a measured ISO 6400 according to their measurements, the difference between the E-M1 and A7 over a stop and a half. That should be quite apparent too. Whether crucial or not, will depend on the circumstances, balance of the visible exposure and your expectations.
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Happy Jones
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This was very helpful.Within half a stop for shadow noise based on these graphs, yes. Not accounting for colour shifts and patterns, which these measurements do not represent.If I have this straight all these cameras will perform near the same for shadow noise at ISO6400 and the A6000 will equal the A7 at ISO12800 because shadows noise is the most important factor to consider at higher ISOs?
But my comment was mostly within the context of similar formats and a similar technology age (where shot noise is usually pretty close, shadow noise is more about read noise, which tends to differ more between different sensors covering the same format). Here we're also comparing formats with a difference of up to a factor 4 in size, in which case shot noise differences will be much more apparent too.
In midtones the difference between the E-M1 and A6000 can be up to a stop at a measured ISO 6400 according to their measurements, the difference between the E-M1 and A7 over a stop and a half. That should be quite apparent too. Whether crucial or not, will depend on the circumstances, balance of the visible exposure and your expectations.
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The difference is 1.7db @ ISO 100 and 1.2db @ ISO 1600. 1.5db is 1/2 stop in DxOMark's scale.
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M
Mike Stratil
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As several members have pointed, all of this analysis of DR is rather meaningless until we have RAW files to work with because most of us work in RAW.
Rather than trying to make precise measurements and debating the meaning of the measurements we make, let's just look at the files and move on.
Rather than trying to make precise measurements and debating the meaning of the measurements we make, let's just look at the files and move on.
rukia
Forum Enthusiast
Probably not due to the OSPDAF. If you compare the Sony vs Nikon implementation, for all the sensors used by both companies, Nikon always comes out slightly cleaner. Even though a sensor, like the one used in the D800, may be fully integrated there are still peripheral components that may influence the quality of the signal. Nikon may have better cooling, less noise on the power rails, less coupling noise, etc. Sony also uses a lossy RAW compression algorithm so their files are not truely RAW. It's important to keep this in mind as DXO compares the A7s to the Df. They are not only comparing different sensors but also different vendors. If Nikon were to drop the A7s sensor into one of their future bodies it would probably come out cleaner.
TrojMacReady
Veteran Member
It probably is (mostly) the OSPDAF. The D800 and A7R were measured within 0.06 EV.
exdeejjjaaaa
Veteran Member
except that for video you have different modes for on die ADCs operation vs how they operate for stills in a single shot mode (that is what DxO is testing)... and that was about video, not about stills, wasn't it ?
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Discussion has been about stills. Sony has s-log2 which tone remaps DR.
I beg to differ. I bought an a7 the day it was released. At iso 6400 I am typically in low light and the a7 af does the following:
- Does not lock focus with static and trying to use continuous AF is just a dream
- Often when it does lock focus the actual focus is blurry. Becuase of EVF gain up you cannot actually perceive it is blurry until you check the photo. Hence this results in me missing unique moments and even for posed shots having to fire off multiple shots
The a7s remedies these but how often do I need to get a good photo at 12800 and above? Sure the camera can capture it but its very limited. instead what would have been ideal is to see a camera that is producing better dynamic range and color in the 3200 iso range. Like if it coudl capture iso 800 equivalent on a7 in a shot two stops higher it would be stellar.
I still think its a boss camera and ultimately necessary in the line up becuase given the abysmal AF system on the a7 it is literally the only camera from this line up that can (hopefully) consistently function in low iso.
exdeejjjaaaa
Veteran Member
but it is useless to compare GH4 vs A7s for stills - people do compare those 2 cameras for video and video is quite different beast.
One more point. I think the a7/a7r have intentionally crippled AF systems so to generate a market for the a7s. I have a feeling they may be remediied via firmware down the road...
And why not a6000 AF system in these cameras? Could be due to difficulty in putting the phase based sensor AF over the full frame (but we see it is possible with the a7.)
But... I actually suspect that Sony is taking a soft entrance approach. Based on their rhetoric they keep claiming to be a company that wants to be 3rd in camera sales. I think this is marketing bull to the other players so they continue to buy sony sensors (thus financially floating sony research and manufacutring) then Sony can put its money into developing the camera bodies. This is a win win because Nikon can focus on cams too and already have massive sales potential so their getting away pretty and Sony basically gets to subsidize their sensor manufacturing and development.
The caveat is that ultimately Sony owns the sensor tech and when their bodies hit the right level of development they can start putting the vice around canikon (canon sensors are not a threat, Nikon has developed dependency on Sony). We are seeing the vestiages of this in the current line up. A sensor that Sony is taking first claim on when usually they let another manufature subsidize them by getting first dibs, an excellent mirrorless AF. It is a slow first move to start trying to acquire the indy video market away from Canon. Not yet a threat to Nikon who really aims at the stills market.
Why not all their tech in the same cam? a6000 focus on fill frame, small body and all three sesnors with a 3mp EVF and stabalization? Well for one it would require 2 processors probably. For two, Niikon would have kittens to the loss of body sales and probably knee jerk reaction to a different sensor manufacturer. With the volume of sales lost, sony would fall behind financially and canikon would keep growing.
I think Sony's strategy is more subtle. Don't appear a threat. Let your consumer base buy intentionally crippled prototypes, do bulk sensor sales via nikon and the MF market and then when you've hit the peak in sensor production (which they already have), the peak in AF system (which they are damn close too) and have a good amount of glass.. Well thats when you synch the noose and drop a camera that meets and exceeds your competitors offerings. At the same time you choke off sensor sales.. Competitors are then left facing an equal or superior body mated to Zeiss glass (which typially exceeds canikon in quality) and without having a sensor that competes.
Then Canikon will die. Sony will bring out a mount that provides superb AF for all the canikon glass to entice all the dinosaur lovers over and I will give a long slow golf clap because those other companies with their dinosaur mirror tech didnt see the writing on the wall.
In the meantime these F&*&*^*(s have me buying the a7s because of the a7 crippled AF. Well played Sony... Well played.
You better firmware update it. You General you.
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There's something seriously wrong here...
I've used my A7 for night time shooting with manual lenses with no problem and I've just tried my only AF lens, the kit lens, for some test shots. The lowest ISO that the camera selected was 8000 and the highest 25600 and at 25600 I repeatedly achieved focus lock and the image was easily seen to be in focus in the VF and the shot was in focus when I loaded it only my pc. Focus was slow and it went forward and backward but it locked.
I obviously don't know what your shooting circumstance was but for static objects my experiences of both MF and AF are different to yours.
Jerry Fusselman
Leading Member
There are many ways to define DR and the absolute number (but not the difference between two cameras) is a function of the arbitrarily chosen print resolution (8 MP with DxO). Choose a lower reference resolution, eg, 2 MP, and you will get higher DR numbers.
dfreerider
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Like you said the absolute number may differ based on resolution. But I find it hard to believe Sony is measuring it based on a 2MP photo.
Also they have pushed hard on the, quote "...unprecedented 15.3 stops of dynamic range.", in their promotional materials. Why would they use the word 'unprecedented' unless they considered it to be quite a bit better than their other cameras.
Makes no sense to market a camera as having unprecedented 15,3 stops dynamic range, if it has less DR than the A7 and A7R.
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