![]() And since the pixel scale is the same in both setups, so each pixel from first setup will get four times more photons, and the image it will provide will be much better quality – signal to noise ratio (SNR) will be better. 100mm aperture telescope will collect four times more photons than 50mm aperture telescope, because it has four times larger surface that collects light. In astronomy aperture rules, that is why telescopes are first of all large, not fast. But these setups differ with fundamental parameter – with aperture. Do they also provide the same quality images? One could say yes. second camera with 5×5 um pixels with telescope 50 mm aperture and 500 mm focal length – so 50/500īoth setups have the same focal ratio and also provide images with the same 1Mpx resolution and the same pixel scale about 2″/px.first sensor with 10×10 um pixels with telescope 100 mm aperture and 1000 mm focal length – so 100/1000.At both setups we have camera with 1Mpx resolution (1000x1000px): At start let’s consider two setups with the same pixel scale. I also do not deal with optics aberrations here. Two setupsįor this article’s scope, I assume the sensors I describe have the same noises and the same sensitivity (quantum efficiency). As the weather changes, or your location does you’ll need to educate your camera to make sure it has enough light to ‘see’ the scene.Is astrophotography pixel scale and resolution the same? Can we increase resolution just by making pixels smaller? In some cases we can, but quite often we cannot. You’ll spend a lot of time as a photographer switching between F/stops especially if you shoot outdoors a lot. This is what you need to do with the camera when shooting on bright days – make the aperture smaller by choosing a larger F/stop number (i.e F/16). Your eyes will restrict and the pupils get smaller to reduce the amount of light entering otherwise it’ll be too bright. The same goes for when you’re outdoors on a very sunny day. Imagine walking into a dark room, though you can’t see it, your eyes automatically adjust and dilate (just like changing F/stops) to get more light into the retina so we can make the outline of objects. F/1.4) when you’re shooting in low light and need as much light as possible. Given that small F/stop numbers offer the widest aperture, this means more light can get to the sensor creating a brighter exposure.įirstly, use small F/stop numbers (ie. Now we know what F/stops are, let’s look practically at what they do in a photo. When shooting at 55mm the widest will be F/5.6 This means when shooting at 18mm the widest F/stop you can use is F/3.5. You may see zoom lenses advertised as Canon 18-55mm IS EF-S F3.5-F/5.6. ![]() This is because, as we’ve discussed, F/stops are a result of the focal length divided by the aperture diameter – if the focal length changes (like it does on a lens) then you’ll have different F/stops. Zoom lenses will display 2 max apertures. Most lenses all go down to F/22 at least. This means the widest aperture on this lens is F/1.8. You’ll see lenses advertised – Canon 50mm EF-S F/1.8 etc. This is how big the aperture can be set at a certain focal length. These half and third stops will make your shot 30-50% darker or brighter (depending on which way you move).Īll lenses have a maximum aperture size. So for every change in full F/stop to the next one up or down the scale means your image will be twice as bright or dark.Īs technology becomes more sensitive more F/stops have been added so you may see other F/stops appear on your camera screen like below…į/1.4 F/1.8 F/2 F/2.8 F/3.5 F/4 F/5.6 F/6.3 F/7.1 F/8 F/9 F/10 F/11 F/14 F/16 F/20 F/22 F/32 ![]() The difference between moving from one full F/stop to another is a 100% increase (or decrease in the amount of light). ![]() F/32 is the smallest aperture on the scale, meaning it lets the least light in. So the smaller the F/stop number (i.e F/1.4) means it lets in the most light compared to the others. The smaller F/stop number actually represents the larger aperture size.
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