70D Dynamic Range is actually great, despite what DXOMark says

Started Jan 21, 2014 | Discussions
Super486 New Member • Posts: 13
70D Dynamic Range is actually great, despite what DXOMark says
5

I'm considering 70D as a sports, birding and video camera. I know D7100 sensor gets noticeably better ratings on DxoMark, especially in DR. This is repeated on the forums: Canon has poor DR. I don't know about older models, but I was curious to test by myself if the new 70D actually is lacking DR, so downloaded some raw samples with deep shadows, from two reviews I found on the net, and played with them in Raw Therapee. I tried to push them hard, challenging the supossedly lacking DR of the 70D.

Well, the actual results surprised me. I was expecting a ugly mess of blotchy noise, banding, pattern noise, but couldn't see it at all. Sure, the D7100 must be cleaner, and there is some color noise in the shadows, but it cleans up very well and is fine grained. Not a problem at all, at least to me.

Keep in mind these are three +4 EV and one +5 EV liftings, therefore extreme examples:

The overall picture with all exposure adjustments set to 0, a dark 100% crop, then shadow-lifted 100% crop (with some sharpening and color NR).

Overall picture

100% crop, +0 EV

100% crop, +4 EV

Overall picture

100% crop, +0 EV

100% crop, +4 EV

Overall picture

100% crop, +0 EV

100% crop, +5 EV

Overall picture

100% crop, +0 EV

100% crop, +4 EV

What do you think folks? This is great for such a DR-limited sensor, isn't it?

Canon EOS 70D
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Frederik Paul Regular Member • Posts: 105
Re: 70D Dynamic Range is actually great, despite what DXOMark says
8

Who cares what DXO says?

Cane Veteran Member • Posts: 6,900
Re: 70D Dynamic Range is actually great, despite what DXOMark says
5

Dxo only matters if your camera scores well.

(unknown member) Veteran Member • Posts: 4,085
Re: 70D Dynamic Range is actually great, despite what DXOMark says

Thank you for posting your photos.

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Thanks for posting, have a great day.
John

rwbaron Forum Pro • Posts: 14,331
Re: 70D Dynamic Range is actually great, despite what DXOMark says
2

You've demonstrated that for all intents and purposes the 70D is more than good enough.  Sure, the D7100 or other Exmor sensor cameras would provide even more latitude but the question is how often is it needed so of what value is it?  There are far more important parameters in choosing a camera system than just low ISO shadow noise.

Bob

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Sid911 Regular Member • Posts: 290
Re: 70D Dynamic Range is actually great, despite what DXOMark says

Apologies for noobie question, do all the Canon APS-C sensors display the same dynamic range? What I am really trying to find out is, from just the DR perspective, would Canon 70D be similar to say, a T4i or T3i?

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OP Super486 New Member • Posts: 13
Re: 70D Dynamic Range is actually great, despite what DXOMark says

Apologies for noobie question, do all the Canon APS-C sensors display the same dynamic range? What I am really trying to find out is, from just the DR perspective, would Canon 70D be similar to say, a T4i or T3i?

I don't know whether other APS-C get same real-world results as 70D. DxoMark rates all Canons from 500D-70D about the same in DR, but real world testing may be another thing.

TTMartin
TTMartin Veteran Member • Posts: 7,304
Re: 70D Dynamic Range is actually great, despite what DXOMark says
11

Sid911 wrote:

Apologies for noobie question, do all the Canon APS-C sensors display the same dynamic range? What I am really trying to find out is, from just the DR perspective, would Canon 70D be similar to say, a T4i or T3i?

According to DxOMark every Canon dSLR they have tested basically has the same per pixel dynamic range. That includes the original 2003 APS-C Digital Rebel and the full frame 1D X. Any changes in dynamic range scores is because DxOMark uses a formula that changes the print dynamic range score based on the number of megapixels.

So you can choose to believe DxOMark, or you can look at possible flaws that would explain these seemingly erroneous results.

There is a group here that believe the results are accurate and can be explained by noise from the external analog to digital converter, I don't believe this is correct.

First DxOMark attempts to measure sensor noise by looking at the RAW file. This basic concept is inaccurate because manufactures can apply different amounts noise reduction prior to the RAW file being written. Case in point the Nikon D300, Nikon D300s, and the Nikon D90 all use the same sensor. Yet the Nikon D90 scores higher than the Nikon D300 and Nikon D300s, because the D90 applies more noise reduction PRIOR to the RAW file being written.

Camera that use Sony sensors apply noise reduction at the sensor level prior to the RAW file being written.

Canon embeds information in the RAW file to be used by their RAW converter DPP. Third party RAW converters don't take advantage of this information. For example Canon masks portions of the edge of their sensor, to provide information on both row and column sensor noise, 3rd party RAW converters like the one used by DxOMark do not use this information.

Third party RAW converters attempt to directly read portions of the Canon CR2 file and directly convert them to RGB. There are several problems with this, first according to Canon's Chuck Westfall Canon RAW data is recorded in sYCC and not RGB.

So the process of direct conversion to RGB often result in unexpected results, like this CR2 image from my Canon 6D with a 3rd party RAW converter that doesn't know the 6D exists.

Another flaw in this attempted direct conversion to RGB is that it uses the HSB/HSV color space instead of the HSL color space used by Canon.

So what does all this actually mean. In my opinion the Canon CR2 file has been incorrectly reverse engineered by 3rd party RAW converters. This incorrect reverse engineering has only resulted in 12 bits of usable data per pixel and not the full 14 bits. And it is this that actually explains why testing sites that use 3rd party RAW converters show that Canon's per pixel dynamic range has remained unchanged in the last 10 years and not that the 2003 Digital Rebel and the Canon 1D X have the same per pixel dynamic range.

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SystemAgnostic Contributing Member • Posts: 835
Re: 70D Dynamic Range is actually great, despite what DXOMark says

Thanks for your response TTMartin.

This would seem to indicate that one should be able to get better results using Canon's Raw software instead of third party.  Do you agree?

Does anyone have evidence that is the case?

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TTMartin
TTMartin Veteran Member • Posts: 7,304
Re: 70D Dynamic Range is actually great, despite what DXOMark says

SystemAgnostic wrote:

Thanks for your response TTMartin.

This would seem to indicate that one should be able to get better results using Canon's Raw software instead of third party. Do you agree?

Does anyone have evidence that is the case?

Here's a poster who doubted what I was saying and did the comparison himself.

http://www.dpreview.com/forums/post/51955163

The differences are subtle, but, real.

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Tourlou Contributing Member • Posts: 776
Not that impressive.
4

Considering the fact that the pictures were shot at 100ISO, I'm not impressed.  Many cameras on the market can do better than that.  I just can't explain myself the luminance variations on these pictures.  There is lots of red noise one some pictures as well.  Was the temperature very high when you shot these pictures?  Looks like the sensor produces an abnormally high amount of read-out/dark noise to my eye.  High temperature or the excessive use of live view would explain that.  Can you confirm?

Regards

Rene

Tourlou Contributing Member • Posts: 776
Noise reduction before raw file is written??????????????????
1

Where did you take this information?  I want your references.  By definition, a raw file is a map of the electron count of each photosite, not pixel.  What can be applied by the manufacturer, is a correction of the luminance value per pixel to cover for manufacturing variations.  The other map that's applied to a raw file is the defective (dark/hot) pixel correction.  I never read anywhere that a noise reduction is applied at the raw file level.  Anyway, this would not correct the shown images.  The blacks are not black on lifted images.  The image is fulle of read out/ dark noise.  Maybe because of hot weather or a hot sensor (use of live view ).

Regards

Rene

Jonathan Brady
Jonathan Brady Veteran Member • Posts: 6,725
Re: 70D Dynamic Range is actually great, despite what DXOMark says
1

Fantastic post!  Is there any way to prove you're right or are we stuck with theories?

I remember that post you linked to, very eye opening!

bronxbombers4 Veteran Member • Posts: 3,387
Re: 70D Dynamic Range is actually great, despite what DXOMark says

rwbaron wrote:

You've demonstrated that for all intents and purposes the 70D is more than good enough. Sure, the D7100 or other Exmor sensor cameras would provide even more latitude but the question is how often is it needed so of what value is it? There are far more important parameters in choosing a camera system than just low ISO shadow noise.

Bob

All the same I sure hope Canon gets on it soon since I really could make use of those extra three stops often enough. I do like Canon UI and lenses better though (and video, at least once unlocked my ML, without them most of Canon's video advantages would be gone by now, with ML, they are there big time).

bronxbombers4 Veteran Member • Posts: 3,387
Re: 70D Dynamic Range is actually great, despite what DXOMark says
1

SystemAgnostic wrote:

Thanks for your response TTMartin.

This would seem to indicate that one should be able to get better results using Canon's Raw software instead of third party. Do you agree?

no

Does anyone have evidence that is the case?

no

And very few of the major cameras do any of those RAW tricks at the low ISOs under discussion for regular exposure lengths (apparently Nikon start doing some RAW manips if you use really long exposures) so TTMartin is mostly using smoke and mirrors excuses.

bronxbombers4 Veteran Member • Posts: 3,387
Re: 70D Dynamic Range is actually great, despite what DXOMark says

TTMartin wrote:

SystemAgnostic wrote:

Thanks for your response TTMartin.

This would seem to indicate that one should be able to get better results using Canon's Raw software instead of third party. Do you agree?

Does anyone have evidence that is the case?

Here's a poster who doubted what I was saying and did the comparison himself.

http://www.dpreview.com/forums/post/51955163

The differences are subtle, but, real.

Setting both apps sliders to zero does NOT set them on even turns. Even main version to main version of ACR the slider values being the same doesn't apply the same amount of stuff.

birdbrain
birdbrain Veteran Member • Posts: 3,526
Re: 70D Dynamic Range is actually great, despite what DXOMark says
1

Hear, hear!

Which probably explains why I always like using DPP even if it is to do nothing more than to convert CR2 to TIFF.

I find if I do this and then open the TIFF in ACR or LR I can recover highlights and shadows very well.

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JasonED Contributing Member • Posts: 946
Re: 70D Dynamic Range is actually great, despite what DXOMark says

TTMartin wrote:

Sid911 wrote:

Apologies for noobie question, do all the Canon APS-C sensors display the same dynamic range? What I am really trying to find out is, from just the DR perspective, would Canon 70D be similar to say, a T4i or T3i?

According to DxOMark every Canon dSLR they have tested basically has the same per pixel dynamic range. That includes the original 2003 APS-C Digital Rebel and the full frame 1D X. Any changes in dynamic range scores is because DxOMark uses a formula that changes the print dynamic range score based on the number of megapixels.

So you can choose to believe DxOMark, or you can look at possible flaws that would explain these seemingly erroneous results.

There is a group here that believe the results are accurate and can be explained by noise from the external analog to digital converter, I don't believe this is correct.

First DxOMark attempts to measure sensor noise by looking at the RAW file. This basic concept is inaccurate because manufactures can apply different amounts noise reduction prior to the RAW file being written. Case in point the Nikon D300, Nikon D300s, and the Nikon D90 all use the same sensor. Yet the Nikon D90 scores higher than the Nikon D300 and Nikon D300s, because the D90 applies more noise reduction PRIOR to the RAW file being written.

Camera that use Sony sensors apply noise reduction at the sensor level prior to the RAW file being written.

Canon embeds information in the RAW file to be used by their RAW converter DPP. Third party RAW converters don't take advantage of this information. For example Canon masks portions of the edge of their sensor, to provide information on both row and column sensor noise, 3rd party RAW converters like the one used by DxOMark do not use this information.

Third party RAW converters attempt to directly read portions of the Canon CR2 file and directly convert them to RGB. There are several problems with this, first according to Canon's Chuck Westfall Canon RAW data is recorded in sYCC and not RGB.

So the process of direct conversion to RGB often result in unexpected results, like this CR2 image from my Canon 6D with a 3rd party RAW converter that doesn't know the 6D exists.

Another flaw in this attempted direct conversion to RGB is that it uses the HSB/HSV color space instead of the HSL color space used by Canon.

So what does all this actually mean. In my opinion the Canon CR2 file has been incorrectly reverse engineered by 3rd party RAW converters. This incorrect reverse engineering has only resulted in 12 bits of usable data per pixel and not the full 14 bits. And it is this that actually explains why testing sites that use 3rd party RAW converters show that Canon's per pixel dynamic range has remained unchanged in the last 10 years and not that the 2003 Digital Rebel and the Canon 1D X have the same per pixel dynamic range.

It's hard to take any of this seriously given that the D300 and D90 don't use the same sensor.

d90 uses sony imx038

d300 uses sony imx021

This has been well documented.

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fishy wishy
fishy wishy Veteran Member • Posts: 9,358
Re: 70D Dynamic Range is actually great, despite what DXOMark says
4

Super486 wrote:

I'm considering 70D as a sports, birding and video camera. I know D7100 sensor gets noticeably better ratings on DxoMark, especially in DR. This is repeated on the forums: Canon has poor DR. I don't know about older models, but I was curious to test by myself if the new 70D actually is lacking DR, so downloaded some raw samples with deep shadows, from two reviews I found on the net, and played with them in Raw Therapee. I tried to push them hard, challenging the supossedly lacking DR of the 70D.

Well, the actual results surprised me. I was expecting a ugly mess of blotchy noise, banding, pattern noise, but couldn't see it at all. Sure, the D7100 must be cleaner, and there is some color noise in the shadows, but it cleans up very well and is fine grained. Not a problem at all, at least to me.
What do you think folks? This is great for such a DR-limited sensor, isn't it?

You set up your own straw man and knocked the stuffing out of it, so well done. I know dpreview is extremely laissez faire in letting users set up accounts, but I can't see that setting one up for this purpose was worth it. It's clear you already know the ins and outs of posting photos on this site, but to what purpose? People don't say the image quality of the 70D is poor, they just say that the dynamic range of modern Nikons is really remarkable. I don't know that anybody expected banding at low ISO.
The only interesting information has come from TTMartin, that suggests it may pay to use DPP for raw conversion.

Tourlou Contributing Member • Posts: 776
Lifting shadows with 1Dx

Here's a shot taken through a window, facing the sun, with the camera's exposure compensation set to -5ev.

And here is the same photo automatically equalized in lightroom, no noise reduction applied.

Although there's a fair amount of chroma noise, it amazes me every tiime I open these files.

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