It all comes down to noise reduction

Your smart telescope’s sensor captures light from celestial objects, which we refer to as the signal. However, it also generates noise, which is an undesirable byproduct. This noise comes from factors like light pollution or the sensor’s electronics.
Since the signal from deep-space objects is so faint, it can easily be overwhelmed by noise, leading to poor image quality.

How to combat noise

This is where stacking comes in. The signal remains consistent across multiple images, but the noise is random. By stacking and averaging multiple images of the same target, the noise decreases while the signal strengthens. The more images you stack, the less noise will affect your final image.

But how long should you acquire images to get the best result?

Understanding "SNR"

SNR, or Signal-to-Noise Ratio, is key to determining image quality. It indicates how much stronger the signal is compared to the noise:

• High SNR: The signal is well above the noise, producing sharp, clear, and detailed images.
• Low SNR: The noise competes with the signal, blurring details and reducing quality.

The relationship between SNR and acquisition time

Here’s the tricky part: the increase in SNR isn’t directly proportional to the number of images you stack or the time you spend acquiring data.
Doubling the acquisition time (or doubling the number of images) results in only about a 40% increase in SNR.

Implications for acquisition time

If you’re looking for a noticeable improvement in image quality, you’ll need to double your acquisition time. Anything less will yield only a modest boost.

Additionally, the effort required to improve image quality grows as acquisition time increases:

• To improve a 1-hour acquisition, add another hour.
• To see a significant improvement over 4 hours, you’ll need to add 4 more hours.

Ultimately, it’s up to you to decide if the extra effort is worth it. A good rule of thumb: Want better results? Double the time.

How significant is the difference?

If you’re mainly doing assisted observations (EAA), extending your acquisition time might not seem worth it, as the real benefits are more noticeable during the image processing phase.

This is why the Multi-Night Observation feature exclusively available on Vaonis smart telescopes is so useful. When combined with the Plan My Night tool, it makes capturing long exposure data incredibly convenient.

Keep in mind that the ideal acquisition time also depends on the sensor of each telescope, the use of filters, and the quality of the sky.

Use the following rule as a general guideline.