Does Partial Resolution Limit Camera FOV?

Runsva

I have an ASI178MM monochrome camera that I'm capturing images with, using the ASI SDK in C++.

The maximum resolution by default of the ASI178MM camera is stated as 3096x2080.

However, I can opt to take lower-resolution images from that camera via the SDK functions, instead of the max resolution.
If I opt to take lower resolution images, does that mean that my Field of View on the camera decreases with the smaller capture area? Or does the FOV stay the same, just with lower pixel detail?

Thanks for reading my post, any guidance is appreciated.

w7ay

Runsva does that mean that my Field of View on the camera decreases with the smaller capture area?

Yes, you are using a smaller ROI of the sensor, so you get smaller FOV for the same pixel size. Its just like using a photo editor to crop an image.

Or does the FOV stay the same, just with lower pixel detail?

If you want the FOV to stay the same but with fewer pixels, you need fatter pixels. And you do this by changing the Bin Ratio while keeping the ROI unchanged, instead of changing the ROI.

With CMOS cameras, you also get a 6 dB improvement in camera SNR by doubling both x and y bins (for example, going from 1x1 bin to 2x2 bin). With CCD cameras, you can get a whopping 12 dB improvement going from 1x1 to 2x2 (hardware) binning.

Chen

Runsva

w7ay Thanks for your reply;

So the clarify, the bin of an image taken by the camera determines how many pixels are merged together?
Is that defined linearly, so a bin value of 2 should result in every 2 pixels being merged together? Or is the formula different?

w7ay

Runsva

2x2 bin has 4 pixels, 3x3 bins have 9 pixels. 2 dimension plane.

Chen

Runsva

w7ay Thanks for your reply;

So if I reduce my resolution to 1000x800 as an example (from the original 3096x2080), I would need to set my bin value to at least 3x3 in order to compensate for the lost pixels, correct?

w7ay

Runsva So if I reduce my resolution to 1000x800 as an example (from the original 3096x2080), I would need to set my bin value to at least 3x3 in order to compensate for the lost pixels, correct?

Compensate what?

Changing the ROI simply means the data from a smaller portion of the full sensor is sent to you.

When binning, you simply get fewer super-pixels for the given ROI.

You are never going to get better resolution for the given camera than the native resolution (in µm). Reducing ROI reduces the area of the sensor data (usually used to speed up data transfer, by not wasting time transfering data you don't need). Increasing binning will group the original pixels into super-pixels and reduce resolution (usually used to get better signal-to-noise ratio, and sometimes to get a better plate scale for a long focal length OTA).

Why don't you learn by trying it yourself? It is the best way.

Chen