ZWO ASI 533

[HaleBopp2007]

I am going to get that camera very soon, so I decided to check the manual file. I just cannot understand all of those graphs, the gain, gamma... It's just a mess of words and graphs. This is my first time with a CCD camera, so... could someone please explain these?

Edited December 31, 2021 by HaleBopp2007

[scotty38]

No doubt @vlaiv will give you chapter and verse on what you are asking but I will say by all accounts it's a great camera (I wanted one but at the time they were out of stock so bought a 294). Buy one, stick the gain at 100 and enjoy would be my view 🙂

[ONIKKINEN]

The left-right axis in all graphs here is the Gain value. Gain is like ISO for normal cameras, increasing the value will make the image brighter.

Top graph is full well depth of a pixel in electrons. The 533 has a fullwell of 50 000 electrons at the minimum gain value. Electrons are created when light hits the sensor so the camera measures these in the form of voltage instead of measuring photons directly.

Second graph is the relation of gain to e(lectrons)/ADU. ADU is the pixel value. This one being a 14 bit camera will record values between 0 and 16384. Different gain values change how many electrons does it take to gain ADUs. The marked spot of gain 100 has a 1e/ADU gain so every electron results in 1 ADU increase of a pixel value.

Third graph is dynamic range in stops. Mostly irrelevant for astrophotography, but this camera has a very high DR. Dynamic range is the difference between read noise and full well depth.

Fourth graph is read noise in electrons and is the most important graph to look at in this case. Notice that at gain 100 the read noise drops dramatically, but does not really decrease all that much after. With this particular camera a gain value of 100 is the best for almost all applications. Read noise is noise created by the camera every time an exposure is read from the sensor, so this is the same for a 3s and 300s exposure. Read noise of 1.5e is very low and allows short exposures to be completely sky noise (light pollution etc) limited.

 

Take away from this: Gain 100 is the best for thia model.

[iantaylor2uk]

You're right on the cliff edge at a gain of 100. Just to make sure you are in the low noise region of the camera operation, I would be tempted to use a gain of 150. This still has a good dynamic range and you are definitely in the low noise part of the camera operation.