![]() This is an oversimplification, and there are additional factors to consider, like whether your camera warms up if it's integrating for too long, which adds extra noise. But for the same total exposure time, the fewer frames the better. Usually the former surpasses the latter, and overall the final image will look less noisy. ![]() ![]() So when you're stacking frames you're doing two things: increasing the total amount of light, which makes the final image look less noisy, and introducing extra noise due to all the additional readouts. When you have a single long exposure, the averaging process you described happens on the fly in the detector: as photons arrive the noise progressively averages out, relative to the underlying signal.Īmong the many sources of detector noise, one is the readout noise, which is introduced when the camera reads the information in the sensor. If you had a perfect detector you would get the same level of noise with a single 20 seconds exposure than with 20 x 1 seconds exposure because the total amount of light is the same in both cases. The first one is called Poisson noise (sometimes also referred to as photon noise or shot noise), and it depends exclusively on the total amount of light that you're getting, regardless of whether you split it among different exposures or not. The other is noise associated with the detector, which in itself has many different contributions. There are two main sources of noise when you take an image: one is the noise intrinsically associated to the behaviour of light. Keep in mind also that if there are foreground objects in your image, you'll have to stack the foreground and background separately. I usually align the frames in Hugin and then continue editing in Photo. If you're imaging a relatively small field of view that should be enough, but for very large areas of the sky Photo won't be able to account for the geometric transformation required to perfectly align the individual frames. The auto-align feature can account for scale, rotation, translation and perspective. Each individual shot should be as long as you can before you start noticing star trails in your image.Īs for whether Affinity Photo can automatically align individual frames, the answer is yes-ish. To shoot the photos in focus bracket mode, you select the start and end focus number, plus the number of photos to take. So taking a series of burst shots it's not going to work. With foreground in focus: With background in focus: After AP's focus merge magic with 6 bracketed photos, all in focus: CameraPixels has a number, 0.0 to 1.0, that specifies the focus distance. That's because in the first case the sensor is read out 20 times as opposed to just once in the second case, and that's an extra source of noise. That is, stacking 20 exposures of 1 second each will yield a noisier result than a single exposure of 20 seconds. Stacking a set of individual frames will always give you a noisier result than a single image with the same total exposure time. ![]()
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