"How powerful is it?"
You check to see what eyepiece is in the drawtube, and reply. In one recent instance, the answer was 37x when using a low power Plössl to observe the Perseus Double Cluster with my 8" dobsonian. The visitor seemed almost upset about this. "That's IT? With a telescope THIS BIG?" Unfortunately, his reaction isn't at all surprising, and we have low-end telescope manufacturers and cognitive biases to thank for that.
For most of the general public, the word "telescope" calls to mind the image of small refractors on spindly tripods that are seen in malls and department stores around Christmas time, usually advertising a magnification in the range of 575x.
What people fail to understand is that this is unscrupulous advertising at its worst. On the surface of the deception is that 575x magnification is shockingly unrealistic in all but the highest-end, large aperture telescopes under the most pristine of observing conditions. Probing deeper, this fancy packaging plants in people's minds the most common misconception that exists about telescopes; that the purpose of a telescope is to magnify distant objects.
This is, of course, a natural assumption because telescopes always magnify the image being observed, but the truth is that magnification is essentially a byproduct of the telescope's primary purpose; to collect and focus light.
This seems counterintuitive to many until you compare a telescope collecting photons to a bucket collecting rain. If you have a bigger, wider bucket, you'll collect more rain. Telescopes work the same way, and it is, in fact, their primary purpose. With larger aperture optics, you will see brighter images with greater resolution. In fact, many amateur astronomers refer to large reflecting telescopes as "light buckets."
What surprises many people is that magnification isn't intrinsically defined by the telescope itself. The telescope's size and quality will dictate an upper limit of useful magnification under perfect seeing conditions, and the telescope's focal length will indicate what magnification you'll get with a specific eyepiece, but swapping eyepieces is what gives you different magnifications. The trick is to learn how to use the right magnification based on observing conditions and the object being observed.
Here we get to another misconception the public has about telescopes; that higher magnification gives a better view. In 95% of targets, the opposite is the case. Typically, astronomers reserve higher magnification for planets and double stars. The vast majority of observable objects in the sky are so large and so dim that high magnification can render them invisible, or only show you a small portion of the object. Take the Andromeda galaxy for example. The angular size of the object in our sky is so huge that most large telescopes can't frame the entire object in the field of view even when using the lowest practical magnification. Increasing the magnification also dims the view, which can be counterproductive when looking at "faint fuzzies."
It's always surprises people when you tell them that most serious deep sky observers actually go out of their way to be able to use the lowest magnification realistically possible with their telescopes. That is, at least. until you explain the bucket metaphor to them. Using a high power eyepiece with a big light bucket on a dim, diffuse object is like trying to bail out a large bucket full of rain water using a plastic coffee stirrer as a straw, while using a low power eyepiece is like bailing it out with a high-capacity pump.
Beyond being a shining example of how hype-filled marketing can give people a poor understanding of science (and make the job of science outreach more difficult), the magnification myth also serves as an illustration of how scientific fact is often at odds with what most people see as common sense. The truth is that our cognitive biases serve a purpose to us from an evolutionary standpoint. They help us organize the world into what makes sense and what doesn't based on the limited information provided by our senses and perception. This allows us to go about our daily lives without getting bogged down by sensory overload. Reality, however, is much more subtle and complex than the seemingly simple simulacrum filtered through our sensory restrictions and cognitive limitations. When our common sense breaks down under new contradictory data, the scientific method gives us a way of expanding the reach of our knowledge beyond what our senses and biases limit us to.
The real universe is far grander than the one our perception limits us to. To get the big picture, we must learn to use the right magnification.
This is, of course, a natural assumption because telescopes always magnify the image being observed, but the truth is that magnification is essentially a byproduct of the telescope's primary purpose; to collect and focus light.
This seems counterintuitive to many until you compare a telescope collecting photons to a bucket collecting rain. If you have a bigger, wider bucket, you'll collect more rain. Telescopes work the same way, and it is, in fact, their primary purpose. With larger aperture optics, you will see brighter images with greater resolution. In fact, many amateur astronomers refer to large reflecting telescopes as "light buckets."
What surprises many people is that magnification isn't intrinsically defined by the telescope itself. The telescope's size and quality will dictate an upper limit of useful magnification under perfect seeing conditions, and the telescope's focal length will indicate what magnification you'll get with a specific eyepiece, but swapping eyepieces is what gives you different magnifications. The trick is to learn how to use the right magnification based on observing conditions and the object being observed.
Here we get to another misconception the public has about telescopes; that higher magnification gives a better view. In 95% of targets, the opposite is the case. Typically, astronomers reserve higher magnification for planets and double stars. The vast majority of observable objects in the sky are so large and so dim that high magnification can render them invisible, or only show you a small portion of the object. Take the Andromeda galaxy for example. The angular size of the object in our sky is so huge that most large telescopes can't frame the entire object in the field of view even when using the lowest practical magnification. Increasing the magnification also dims the view, which can be counterproductive when looking at "faint fuzzies."
It's always surprises people when you tell them that most serious deep sky observers actually go out of their way to be able to use the lowest magnification realistically possible with their telescopes. That is, at least. until you explain the bucket metaphor to them. Using a high power eyepiece with a big light bucket on a dim, diffuse object is like trying to bail out a large bucket full of rain water using a plastic coffee stirrer as a straw, while using a low power eyepiece is like bailing it out with a high-capacity pump.
Beyond being a shining example of how hype-filled marketing can give people a poor understanding of science (and make the job of science outreach more difficult), the magnification myth also serves as an illustration of how scientific fact is often at odds with what most people see as common sense. The truth is that our cognitive biases serve a purpose to us from an evolutionary standpoint. They help us organize the world into what makes sense and what doesn't based on the limited information provided by our senses and perception. This allows us to go about our daily lives without getting bogged down by sensory overload. Reality, however, is much more subtle and complex than the seemingly simple simulacrum filtered through our sensory restrictions and cognitive limitations. When our common sense breaks down under new contradictory data, the scientific method gives us a way of expanding the reach of our knowledge beyond what our senses and biases limit us to.
The real universe is far grander than the one our perception limits us to. To get the big picture, we must learn to use the right magnification.
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