Canon 6D saving at 5496 x 3670 pixels instead of spec'd 5472 x 3648

[dson144]

I am shooting in RAW and have all processing turned off that I can find in the menu. Is there any reason why this might be happening?

Side note - I am doing astrophotography and attempting to process different types of images (calibration and light frames). The calibration frames are taken by me manually and have this non-native size. The light frames are taken with a computer controlled software, and save at the native 5472x3648. The size mismatch is preventing me from performing calibration on the lights. I could crop the calibration frames, but since I would likely be cropping random rows/frames, this would defeat the purpose of the calibration.

TIA!

[shadowsports]

Greetings,

Where is this resolution being reported?

What does Canon DPP report the resolution as?

[Peter · Accepted solution]

The full sensor resolution saved is actually 5568 x 3708px. Optical black area is 72 x 38 px to the left and above. This area is cropped out in post.

After optical black has been cropped, also the borders are trimmed, see https://rawpedia.rawtherapee.com/Demosaicing#Border

From my 6D.

1. The whole sensor area. Take a look at the dimensions bottom left. Bottom right shows no crop.
2. Bottom right the crop is applied removing 72 x 38 px from left and above. At bottom left there are new numbers.
3. The whole sensor area again, but this time zoomed in and before demosaicing. Take a look at the thumbnail top left.

Another thing with 6D that I haven't seen with any other of my Canon cameras is a bright line at the bottom, only visible when shooting in live view. Therefore a 2 px crop from bottom is applied in darktable as default. I tried to extract the Bayer pattern also with dcraw, and the line is there.

[dson144]

Thanks Peter! From your description it looks like my photos are being saved at the cropped 5496 x 3670 resolution from your second photo, and this resolution (outside of spec) is expected from the camera. That's really what I needed to know, I will just have to modify the drivers in my astro software to resolve the discrepancy with the SW-controlled photos vs manually-shot calibration photos.

Thanks again and to all who responded.

[johnrmoyer]

I have been trying to figure out how you get the sensor borders to display in darktable. I have darktable 4.2.1 on Debian Bookworm. I have used darktable very little in recent years and know little about it. Exiftool seems to refuse to change SensorTopBorder and SensorLeftBorder, but I do not know whether darktable uses those.

Thanks in advance.

John

[ebiggs1]

"What does Canon DPP report the resolution as?"

You really do need to d/l DPP4 and use it. All cameras shoot at full resolution all the time. The reduction or compression comes when you save the file. DPP4 is Canon's own editing software and knows Canon cameras better than any other editor you can use. If I was seeing issues I would not use off brand and/or freeware to try and figure it out.

[johnrmoyer]

Good advice on DPP.

In crop mode, the Canon RF cameras appear to me to not read the entire sensor. How do you know that the entire sensor is read?

[Peter]

Three ways:

• In the config file and the method I use https://discuss.pixls.us/t/how-to-learn-image-dimensions-in-darktable/32147/27
• In raw black/white points. In the hamburger menu click passthrough
• In the file cameras.xml you can choose the default crop, colour matrix, black level, white level, optical black to be used to determine the right black level

[johnrmoyer]

Thanks