Exmor vs DualISO

[zim]

First off, to raptor3x - good article and great comparisons!

Doesn't this show in real world terms just how easy, without changing any sensor tech, it would be for Canon to improve one of the most complained about aspects of their current sensor design?

Complained about by who? Geeks arguing on forums? (No offense intended, I am a geek arguing on a forum.)

Even when you do have to push Canon shadows a little hard...shove the color NR slider over, all the way to the right if you have to, and give it some luminance NR. They're still not as good as Exmor shadows. But the difference is much smaller in a large print or stretched across a large monitor, and completely gone at average print and viewing sizes. The difference is never as large as it is while pixel peeping with minimal or no NR.

Just last night I was revisiting a Canon 7D landscape file with pushed shadows, not quite as hard as this test but hard enough. Pixel peeping on screen I can see the noise and it annoys me a bit. Printed to an Epson Ultra Premium Luster 17x22 sheet for one of my portfolio albums? I can't find any of that noise with my nose on the print.

Speaking of landscapes...high end professional landscape work is not produced by pushing Exmor shadows 4-5 stops. Landscape photographers bracket and HDR. Compare a HDR image to a heavily pushed image, even from Exmor, and the difference in tonality and fine detail will jump off the print at you. With AEB you can easily hand hold a 3 frame bracket.

All that said...I do find it puzzling that Canon went through the effort to make this possible in the sensor hardware but then never exploited it in the firmware. Are they afraid that it might be confusing to users, especially with the HTP mode option? Just add an Extended Dynamic Range (EDR) mode for RAW only and clearly state it's for pro users who are going to manipulate the tone curve in RAW.

It's dumb for Canon not to do this. But it is a much smaller issue, with far less impact on their bottom line, then any of us seem to realize.

Yes I did actually mean this form, no offence taken ;D

 

[bowtiez]

Thanks for your efforts! Interesting comparison.

 

[Marsu42]

The last thing I want to show is that there is another type of artifacting that can occur in situations where you push the secondary ISO very high, for this example 3200, and you have thin lines (i.e. small branches or wires) running almost parallel to the sensor rows.

In theory, this can happen at any iso combination. The way the cr2hdr postprocessing utility works, it tries to interpolate the scanlines and reconstruct missing data in the the shadows and highlights that is only available in one half-picture. Well, if detail happens to be just in one scanline and is clipped, that's that. But Alex (the lead ML programmer) might refine cr2hdr even more to minimize the inherent problems.

But compared to the difference between a vanilla 5D3 and the A7 and this becomes a pretty amazing result.

Thanks for the comparison! Fyi, the 6d works even better with dual iso since the dynamic range is a bit higher and it has less banding noise when pulling the shadows. I use dual_iso more and more at iso 100/800 these days, gaining +2.5ev dynamic range with nearly no iq drawback on the 6d.

Unfortunately, in real life you cannot reduce the comparison to tech aspects. The workflow problems of dual_iso vs. a native high dr sensor are in my experience:

• it's harder to check for focus in camera because the image is interlaced
• it's impossible to check for colors because they are screwed before processing with cr2hdr
• postprocessing hassle, esp. time required for cr2hdr processing
• dual file storage because you want to keep around the original cr2 in case cr2hdr receives further improvements
• results usually needs manual wb (esp. tint) setting even though cr2hdr tries to autodetect it

 

[PureClassA]

As I just brought up this very topic in another chain on here, I wonder would DPAF not be THE perfect sensor to employ a Dual ISO DR extension in the native Canon Firmware. Seems ideal sensor design for that. Has Sony patented the fusion of the ADC onto the sensor? Just wonder Why Canon doesn't alter that aspect of design without having to come up with entirely new pixel/sensor making processes

 

[Marsu42]

As I just brought up this very topic in another chain on here, I wonder would DPAF not be THE perfect sensor to employ a Dual ISO DR extension in the native Canon Firmware. Seems ideal sensor design for that. Has Sony patented the fusion of the ADC onto the sensor? Just wonder Why Canon doesn't alter that aspect of design without having to come up with entirely new pixel/sensor making processes

You're not the first to wonder about that - but it might not work like that, I imagine the phase detect "pixels" cannot be used for bayer rgb readout - and even if, the readout data rate would double which would need another, faster design.

In any case, this would be considered to be a "hack" at low iso simply to catch up to Nikon with their native 14+ev on exmor. It might be interesting at higher iso values, but the effect is weaker as the dr doesn't change that much anymore and values above 6400 are digital anyway.

 

[PureClassA]

@jrista mentioned that Canon has a patent for having the AD converter being on the sensor die, but they haven't yet employed it. Kinda typical for Canon innovation that seemingly never gets used.

 

[tpatana]

Dual-ISO works on every camera that ML supports (nightly builds only) including the 7D. However just note that you cannot push the ISO on the 7D much more than 800, even with Dual-ISO, or it really starts to fall apart.

On of my favorite shot with 7D was at ISO3200. Usually I say don't go beyond 1600, but if you need the 3200 is still usable.

 

[NancyP]

Thanks, raptor, for the very interesting article. I missed it the first time around.