![]() Which is better for a first-time telescope buyer? What’s the difference between reflector and refractor telescopes? Isaac Newton in the mid-1600 and so it is often referred to as a Newtonian or Newtonian reflector. The mirror sits in the bottom of a tube and the eyepiece sticks out the side. They start their shopping only to discover that there are also reflector telescopes that are based on mirrors rather than a lens. This is the type that was made popular by Galileo in the early 1600s. If I was to use my 25mm Kellner on her telescope, the magnifcation would be 12x - which is less than HALF the amount of magnification I would get on my own telescope! The moon would be only half the size in her telescope's field of view as it would be in mine if it was useing the same eyepiece! Similarly, if I was plug in my 10mm Kellner, the mangification would be 30x - almost what it was in my telescope with the 25mm eyepiece! Thus, the 70mm Refractor with a short 300mm focal length gives a far wider field of view compared to my reflector when useing the same eyepieces.Most people, looking for their first telescope, will have an image in their mind of a long tube with a lens on one end and an eyepiece in the other. My friend Jenny's 70mm Refractor she build has a focal ratio of only 300mm. ![]() Thus, I am looking through a narrower field of view than I was when I was looking through the 25mm Kellner. But, I am now looking at a smaller area of the sky as I was before. Craters and ejecta from the craters are now really visible. At 70x, I can see much of the moon in my eyepiece, but I cannot see all of it at one time. With this eyepiece, the magnification is now 70x. Let's say I now replaced my 25mm Kellner with my 10mm Kellner. At 28x, I could see the entire moon in my eyepiece. If I was to use my 25mm Kellner eyepiece with it, I would get a magnification of 28x. My 3" Spaceprobe telescope has a focal length of 700mm. The mathmatical formula for magnificaiton is as follows:įocal Length (divided by) the eyepiece mm = the magnification of the image. The less your magnification is, the more of the sky you can see in your field of view. In other words, the more magnification you have, the narrower the field of view. The focal length of a telescope determines how much magnification it gives a certain eyepiece, and thus, how wide the field of view is on the telescope. that is, a proportion between two things. I hope they help!Įverything in Astronomy is based on ratios. These are a reprint of my notes on the subject when I used to tutor Astronomy. In urban settings, refractors afford better contrast because the light-polluted night sky looks blacker than when seen through a reflector (through which the background sky looks bright gray). To me, globular clusters were a visual toss up - resolution versus visible numbers - and, of course, galaxies where way cooler in the 36. The view of Saturn, for instance, through the guide scope was better than through the 36", although not nearly as bright. In years passed, I used, among others, a 36" reflector with a 6" refractor as a guide scope. On the other hand, reflectors typically gather much more light than refractors and can see many more things - dim things far outnumber visually bright things - than refractors can see. Refractors are typically of greater focal ratio - ratio of the diameter of the imaging lens/mirror to the focal length - than reflectors and require less magnification to produce an image scale where details can become obvious (iow, refractors at low magnification can see things that reflectors can see only with greater magnification). ![]() Refractor's are better suited to observing the sun, moon and planets - bright objects with detail. Of course in liquids the reflected light from an object will make the object seem distorted. Refraction usually occurs in clear (or near clear) liquids and prisms (crystals etc) light is reflected but only partially and depending on the substances depends again on how the spectrum is reflected throughout the object or liquid. (This is depended on taking an angle of the lights path with a perpendicular point and then mirroring this angle to work out the lights trajectory.) Reflection is also dependant on the composite of the surface in it's shineyness and what spectrum it reflects. Reflection is light being rebound with the exact same degree as it hit and object. Of course just looking at what each entails gives you an idea (I can only put that forwards because I'm not sure if this is even the correct type of response.) I guess you mean some form of telescopic lense for either of these methods, Reflection or refraction.
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