How does diffraction affect telescope magnification?

[Emilyjoint]

"my eye is a small telecope"...thank you for your help.

 

[micromass]

OK, a final attempt, expanding on Jimmy's hint:

If I stand in a bright room and I turn off the light, then I can't see anything. However, a little while after, I can see quite well in the dark. What happened??

 

[micromass]

Let's say I'm in a dry african country and I want water. Suddenly it starts raining. What is the best strategy to catch a lot of water??

1) Standing outside, with your mouth open and pointed up to the sky.
2) Putting a bucket outside.
3) Building a large pool to catch water.

 

[Emilyjoint]

How does that help me in this problem/ discussion.
33 responses and I am no better off...not your fault...if you cannot help/give an answer just accept it and say so.
It is only a discussion question...at least I have some things to talk about.

 

[Jimmy Snyder]

Q: Stars are points and a telescope does not magnify them. How then can more stars be seen with a telescope?
A: It magnifies them.

This doesn't pass the giggle test. Are you absolutely certain that's what you want to go into the classroom with? I recommend you reread micromass's post #32 and tell us what you think about it.

 

[Jimmy Snyder]

if you cannot help/give an answer just accept it and say so.

It has already been said that we cannot give an answer and it's starting to appear that in your case, that means we cannot help.

 

[Emilyjoint]

I have read post 32 and am no wiser.
Where else can help be found for physics problems?
How Is it that more stars can be seen though a telescope?
I am afraid that the contributions here have been of little help.
It must be my fault

 

[turbo]

Emily, this is my last post here. You can find the relevant qualities that allow telescopes to see more stars with perhaps a 30-second Google search. Maybe a minute or so if your search criteria are looser. We have helped, hinted, and tried to steer you as much as possible. I have been an amateur astronomer for ~50 years now and have more books on astronomy than your local library does, probably. We cannot give out answers. You have to dig and show your work. When you have made progress, then we can help more, but not before.

 

[Fredrik]

Where else can help be found for physics problems?

There's no better place than here.

How Is it that more stars can be seen though a telescope?
I am afraid that the contributions here have been of little help.
It must be my fault

It is your fault actually. People have been giving you hints that are very close to a complete answer, and you just get irritated and ignore them every time. Things would have been different if you had tried to answer their questions instead of just suggesting that they shouldn't have asked them.

The reason why more stars can be seen through a telescope than through your eyes, is the same as the reason why more stars can be seen through a "good" telescope than through a "bad" telescope. This is why a web page that helps people choose what telescope to buy can tell you something that answers your question.

Suppose that you and a friend are looking at stars through your own two telescopes, and you discover that there's a star that can be seen clearly through your friend's telescope, but not yours. What do you think is the difference between the light that reaches your location from that star, and the light that reaches your location from a star that can be seen clearly in both telescopes? If you could change one property of your telescope (i.e. if you could replace it with one that's very similar, but different in one important way), then what property would you choose to change if you really want to be able to see that star without having to borrow your friend's telescope?

By the way, I don't know anything about telescopes. I just read this thread and saw what people are trying to tell you. It has nothing to do with diffraction. It's much simpler than that.

Edit: Just to clarify, I'm not saying that telescopes have nothing to do with diffraction. I just meant that that the specific detail that people have been trying to tell you about in this thread has nothing to do with diffraction.

 

[vela]

I am lost ! I think that the telescope does make the image of the star larger...isn't that what the diffraction pattern is.
That is the only thing that I can think of that makes it possible to see more stars.

Diffraction does make the image larger but not in a useful way. If the telescope could focus perfectly, the image of a point source would be a point; however, because of diffraction, actual telescopes smear the light from a point source into a smudge. In other words, because of diffraction, the image from a telescope will always be slightly out of focus. You've probably seen a movie or a picture that was out of focus. The image of an object is larger in an out-of-focus picture than when the picture is in focus, but the larger size doesn't help you see the object more clearly. In fact, an object is often harder to see because its image overlaps with the image of other things in the picture.

Another reason diffraction doesn't help is that it takes the light from a source entering the telescope and spreads it out, so the smudge will be fainter than the (unattainable) single point. So again, diffraction works to make an object harder to see.

What you want to find out is what's so important about a telescope's aperture. Try reading up about that.

 

[Emilyjoint]

Thanks Vela...I got it now.
I was confused about size of lens (aperture) and diffraction and brightness...thank you again

 

[davenn]

and in her last post she answers the question without realising it !

Emily, if you read this thread again, look at what you wrote and take out the one word -- diffraction
what are the other 2 words left ? and how does one affect the other ?

cheers

Dave