Light is collected through the telescope’s aperture and sent toward the next optical piece inside the scope. The larger the aperture, the more light is collected, which results in a greater image resolution. In a reflecting telescope, the light is then passed on to the secondary mirrors, then to the focal point. In a refracting telescope, the light goes from the main lens (aperture) directly to the eyepiece lens.
Now you might be surprised that your eye pupils have an aperture of 7mm and are doing exactly this exact job as you are reading this article. In comparison with a moderately sized telescope, say 60mm, said telescope harvest 70 times more light than your naked eye!
When you upgrade your telescope for one with a bigger aperture, you may expect the images you see through your scope to be much clearer and sharper. A greater aperture is indeed equal to a greater resolution, and thus a 10-inch telescope will theoretically separate two points in your field of view better. For example, if you are observing Jupiter, you may spot the Galileans moons more easily and see finer details.
Hi Tom, as someone who easily gets confused with technical terms, I’d like to thank you for writing this article. I have chosen to get a starter telescope with an aperture of 6 inches. I can’t wait to receive it and get started 🙂
Hi Marco, thanks for the kind comment. I hope you have plenty of fun with your new telescope. 6 inches is a sweet spot between starter telescope and intermediate. I wish you all the best and clear skies!
I’m curious that since lenses and mirrors are usually circular, does the area of a circle formula determine the amount of light gathering ability? A = π r2. I guess you have to consider the glass quality and coatings like binoculars.
Tom
I appreciate ur article when I moved into a house it had a observatory and 7” refractor. To say the least I was hooked. I then bought a 16 “ dob I can see more but refractor seem like quality was little better
I look forward to next article
On the NASA website, there is shown a considerable difference in Dimensions between the primary mirror diameter and the clear aperture size for the jwst. What is that all about?