The Sensor of M3

Started May 19, 2016 | Discussions
Gocha Nemsadze
Gocha Nemsadze Junior Member • Posts: 29
The Sensor of M3
1

Hello,

I only tried to make the sky darker in raw converter.

Have you the same Problem?

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Canon EOS M3
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Alan Sh Senior Member • Posts: 2,196
Re: The Sensor of M3

Not me. Are you sure that's not a reflection from a window or something?

Here's a picture from mine with the blue turned up to 10 in DPP.

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Gocha Nemsadze
OP Gocha Nemsadze Junior Member • Posts: 29
Re: The Sensor of M3
1
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iso rivolta Contributing Member • Posts: 550
Re: PDAF pixels
2

Those must be the pixels from rows used for on-sensor phase detection AF. EOS M3 has Hybrid CMOS AF III like the latest Rebels. Unlike dual-pixel AF, this system actually loses light in the pixels used for AF and the processor must correct it, either by interpolating the missing pixels (from neighboring pixels) or by adjusting their output if a signal can still be collected from these pixels (most likely not). If this correction is not perfect, sometimes artefacts like you are seeing can appear.

The original Nikon N1 series cameras had a similar problem under some conditions, you can read here . See below the sensor of Olympus EM-1 showing the AF rows, not dissimilar with the lines you can distinguish in the picture of T6s' sensor from lensrentals. The spots of adhesive have nothing to do with this.

Olympus EM-1 sensor

T6s sensor

Gocha Nemsadze
OP Gocha Nemsadze Junior Member • Posts: 29
Re: The Sensor of M3
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iso rivolta Contributing Member • Posts: 550
Re: The Sensor of M3
1

Gocha Nemsadze wrote:

Here is the original RAW File:

https://www.dropbox.com/s/hi9edgd0ihymupf/IMG_2478.dng?dl=0

In the DNG you uploaded the lines are visible when developing with DC RAW (Irfan view) or ACR. Those are actually double lines. Presumably for AF they use a dual row zig-zag pixel pattern for improving focus precision, like in Canon's AF sensors. You should try using DPP with the CR2 file or other RAW developing software that includes the necessary corrections. Maybe it will work better.

Woodman411 Regular Member • Posts: 410
Re: The Sensor of M3
1

Gocha Nemsadze wrote:

Here is the original RAW File:

https://www.dropbox.com/s/hi9edgd0ihymupf/IMG_2478.dng?dl=0

I was curious if the same thing would happen in DPP4, I guess though that it does not read/open dng files since it does not appear in the open-files window.

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(unknown member) Forum Pro • Posts: 11,521
Re: The Sensor of M3
1

Gocha Nemsadze wrote:

Here is the original RAW File:

https://www.dropbox.com/s/hi9edgd0ihymupf/IMG_2478.dng?dl=0

actually put the original raw file up please. not the dng.

I suspect it's the DNG conversion, and no.. this is not common.

I've seen something similar with an IR converted camera, however the lines were not that wide.

iso rivolta Contributing Member • Posts: 550
Re: PDAF points location
1

Just found this image illustrating the difference between the Hybrid CMOS AF generations. Looks like 7 AF points rows in the current (III) generation, like in the DNG file from the OP. These points are not actually selectable, so there is no direct information from the manufacturer regarding their location.

Also, in the photo of the sensor from lensrentals (above) it can be seen that each line is double, like in the image submitted by the OP.

Alan Sh Senior Member • Posts: 2,196
Re: The Sensor of M3

Alan Sh wrote:

Not me. Are you sure that's not a reflection from a window or something?

Here's a picture from mine with the blue turned up to 10 in DPP.

I processed that image with DPP V4 - so it probably adjusted for the lines (if that is indeed what the issue is).

Alan

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(unknown member) Forum Pro • Posts: 11,521
Re: The Sensor of M3

Alan Sh wrote:

Alan Sh wrote:

Not me. Are you sure that's not a reflection from a window or something?

Here's a picture from mine with the blue turned up to 10 in DPP.

I processed that image with DPP V4 - so it probably adjusted for the lines (if that is indeed what the issue is).

Alan

there's no problem with LR or anything else though that I've tried.

Gocha Nemsadze
OP Gocha Nemsadze Junior Member • Posts: 29
Re: The Sensor of M3
1

Here is the Another RAW Original .CR2 File to simulate:

https://www.dropbox.com/s/arax3l3j88xged9/IMG_2770.CR2?dl=0

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iso rivolta Contributing Member • Posts: 550
Re: The Sensor of M3

Thank you for the CR2 file. I can still see the lines with IrfanView after adjusting Gamma. These are double lines of about 15 pixel in height and separated by about 20 pixels. The lines are greener than the surrounding pixels. In Capture One I had to really look for them to see some traces. After decreasing the exposure and using Clarity and Structure, some sharpening artefacts showed were the lines are. I guess that Capture One corrects the AF pixels. Maybe somebody that has DPP 4.2 installed can contribute. I'm not sure if this behavior is normal, but I believe it is only under extreme circumstances. You should ask Canon.

EDIT: after using the same workflow (IrfanView) on CR2 files from 750D (T6i), I can see a similar, but fainter, pattern of lines in uniform patches of sky. So it's probably normal to see the lines if you're not using DPP or other software having the Canon profiles for handling the CR2 files.

Alan Sh Senior Member • Posts: 2,196
Re: The Sensor of M3
2

I opened it with DPP 4.3, turned the blue up to maximum and saved it as a jpeg. No signs of any lines.

Alan

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iso rivolta Contributing Member • Posts: 550
Re: The Sensor of M3

Alan Sh wrote:

I opened it with DPP 4.3, turned the blue up to maximum and saved it as a jpeg. No signs of any lines.

Hi Alan. Thank you for uploading the DPP converted RAW. The lines are still there, but now you have to look really really carefully to see them. At least I can still see parts of the double lines. I don't know if increasing blue helped to disclose their position.

This is a downsized crop from the green channel of the jpeg you submitted. The histogram was stretched.

bclaff Veteran Member • Posts: 8,391
Re: The Sensor of M3

Gocha Nemsadze wrote:

Hello,

I only tried to make the sky darker in raw converter.

Have you the same Problem?

In my Fixed Pattern Noise (FPN) analysis I have observed bands that are indicative of on sensor Phase Detect Auto Focus (PDAF):

Left: black (Dark Sisnal Non-Uniformity (DSNU)) Right: illuminated (Photo Response Non-Uniformity(PRNU))

-- hide signature --

Bill ( Your trusted source for independent sensor data at http://www.PhotonsToPhotos.net )

iso rivolta Contributing Member • Posts: 550
Re: The Sensor of M3

iso rivolta wrote:

EDIT: after using the same workflow (IrfanView) on CR2 files from 750D (T6i), I can see a similar, but fainter, pattern of lines in uniform patches of sky. So it's probably normal to see the lines if you're not using DPP or other software having the Canon profiles for handling the CR2 files.

Here is a resized crop that I obtained from a CR2 file from T6s (760D).

Gocha Nemsadze
OP Gocha Nemsadze Junior Member • Posts: 29
Re: The Sensor of M3

It’s not a Software problem (ACR, IrfanView or DPP).
This is only a Bad Sensor type (SONY, 24 MP) of these three Cameras: M3, 750D/760D.

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iso rivolta Contributing Member • Posts: 550
Re: The Sensor of M3

Gocha Nemsadze wrote:

It’s not a Software problem (ACR, IrfanView or DPP).
This is only a Bad Sensor type (SONY, 24 MP) of these three Cameras: M3, 750D/760D.

Sorry, you got it wrong. First, this is a Canon sensor, not Sony. And it's not a sensor defect but the normal (though undesired) behavior of a typical sensor having dedicated PDAF pixels. Of course, it's not a software problem, but DPP can hide these pixels through interpolation. Seemingly EOS M3 has some of the thickest AF lines on the sensor compared with other cameras using the technology.

You can read more about other cameras with PDAF having this sort of problems. Nikon J4, Sony A6000, older Canons like 100D, 650D, 700D, EOS M, and possibly all other cameras with dedicated PDAF pixels on the imaging sensor, display some sort of lines or points in strange illumination conditions and/or in uncorrected files. This shows that dual pixel AF is the future and hopefully Canon will generalize it's use in all future EOS cameras. Hybrid CMOS AF is a stop gap.

prime instinct Contributing Member • Posts: 526
Re: The Sensor of M3

Could this be reflection of the sensor onto the rear element of the lens, back onto the sensor again? If so it might not happen with lenses with certain types of coatings?

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