Astronomy: tips & tricks

Maximum Movie Length For Planetary Imaging

All wonderful hi-res planetary images currently taken by many amateur astronomers worldwide are all based on the same technique, i.e. selecting and aligning a lot of single frames from a single movie (typically an AVI file), which are then stacked and processed to yield the final result. The movies are acquired with a camera at average rates of 5 to 15 fps (frames per second) for durations ranging from a few dozen seconds to a few minutes; therefore, they can […]

Calculating the actual f/ ratio of a picture

Every telescope or telephoto lens has its “magic” f/number: that is, the ratio between its focal length and aperture. Although we don’t go deeper into the matter as it’s not within the scope of this article, it’s worth mentioning that the higher the f/ratio, the longer the exposure time required to yield a given picture density (i.e. how much detail we want to record). Each telephoto lens is normally used with the camera body it was built for, so that […]