Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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4 votes
1 answer
960 views

Trying to use Canon 60D DSLR with Skywatcher 130P. Can't focus image

I have a Skywatcher Heritage 130P FlexTube Dobsonian Telescope. It works well, I can see lovely stars, planets, moons of Jupiter etc. It came with two eye pieces (1.25 inch): 10 mm and 25 mm. I also ...
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1 vote
1 answer
140 views

50mm f1.8 for Astrophotography

I am considering using a 50mm f1.8 maybe even try aN 85mm f1.8 on my Astro FI 102MM Telescope have you any thoughts or suggestions? I have never taken images via a telescope so this is a whole new ...
7 votes
2 answers
2k views

Jupiter with a mobile phone and Celestron Astro FI 102mm Maksutov

My name is John, I am new here and now that I am retired I decided to get myself my first ever telescope, why I never got one before I have no idea...probably too busy. So I thought I would try and ...
2 votes
1 answer
3k views

Black dot visible when looking into the telescope

A few weeks a go I bought a telescope. The problem is I am a total beginner. I was able to setup the telescope correctly and I already saw the moon very clearly. Then I moved on to jupiter. When I ...
1 vote
0 answers
195 views

Is there a good replacement finder scope for the Celestron 127EQ?

I've had a Celestron 127EQ for a couple years now and have only used it a couple times. One of the reasons I haven't gotten much use out of it is that when I do use it I spend all of my time aligning ...
2 votes
0 answers
53 views

Can telescopes determine whether Hygiea is in hydrostatic equilibrium?

10 Hygiea is a spherical body in the main asteroid belt. With future telescopes like the Vera Rubin LSST or the James Webb Space Telescope, can we determine whether Hygiea is actually in hydrostatic ...
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3 votes
1 answer
234 views

Help stabilizing telescope

First time astronomer here... (pardon any less than accurate terminology) My son received a secondhand telescope, a Celestron Powerseeker 114AZ. Last night I calibrated the Starpointer, and was able ...
2 votes
1 answer
95 views

What are these three black cap-like pieces?

My son received a secondhand telescope for his birthday. It is a Celestron Powerseeker 114AZ. I found these three black cap-like pieces separate from other parts. I can’t find what they are or what ...
6 votes
4 answers
1k views

Is there a website that shows equivalent views through different telescopes?

I'm trying to buy a beginners telescope. I have a Celestron TravelScope, but would like something better. When I look at other models, many users have posted images from their viewfinders. Is there a ...
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7 votes
1 answer
285 views

Lucky imaging with Celestron 14 - is this result reasonable?

I attempted to do some lucky imaging of Jupiter using a permanent installation (Celestron $14$" SCT + Paramount ME II) and Nikon D5600 attached directly to a Baader Hyperion 8-24mm eyepiece (...
1 vote
1 answer
82 views

Can the electromagnetic counterpart of a gravitational be seen by 'small' telescopes?

As follow-up question for my previous question I'm thinking about the search for the electromagnetic (EM) counterpart of a gravitational wave (GW). Is it possible to search for those events with '...
7 votes
2 answers
529 views

My local night sky is so bright that I can only see the Moon, so would a low-cost telescope be any use?

Light pollution is so bad near our home that we can't see anything other the Moon in the night sky. For instance there is a street light on all night right in our lane and there are many other housing ...
3 votes
1 answer
366 views

How can I improve the Field of View of my home-made telescope?

I made my telescope, with two convex lens of focal length 1000mm and eyepiece (plano-convex) with 25mm focal length. But I can see only a very small field of view, with inverted image. Do I need to ...
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1 vote
1 answer
484 views

Distance between objective lens and eyepiece

I am trying to make home telescope, I have a convex lens of focal length 1000mm and eyepiece (plano-convex) with 25mm focal length. What is the ideal distance between objective and eyepiece to see ...
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3 votes
1 answer
484 views

Effect of black coating on the inside of a hobby telescope's tube?

I was watching this (rather old) episode of The Making, where they show how a telescope is built in a factory. At 7:34, the cylindrical body of the telescope is shown to have a dark coating on the ...
1 vote
1 answer
123 views

What to expect to see

I have telescope with a diameter of 60 mm and a focal length of 900 mm. I have a 2x Barlow lens and eyepieces with focal lengths of 10 mm. Can I see any details of any galaxies? Andromeda for an ...
1 vote
2 answers
619 views

How to install the Barlow lens on this telescope?

I've brought a 4.5inch astronomical telescope recently which has an aperture of 114mm and a focal length of 1000mm, and two eyepieces. The two eyepieces were of 25mm and 10mm. I enjoyed stargazing ...
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2 votes
1 answer
196 views

What is the magnification of my new telescope?

I just bought a Skywatcher telescope with a diameter of 60 mm and a focal length of 900 mm. I have a 2x Barlow lens and two eyepieces with focal lengths of 10 mm and 20 mm. How can I calculate the ...
2 votes
0 answers
49 views

Telescope focal length, reducer and/or Barlow

Say I have a scope with a given diameter $D$, a given focal length $f$, and a given exit barrel diameter $B$. It has a maximum true FoV of $B/f$ (supposing $B<<f$). Would adding a 0.5x focal ...
2 votes
0 answers
373 views

Which Barlow lens should I choose, 2x or 3x?

I recently bought a 6-inch reflector, 750 mm focal length and I want to get a Barlow lens to get better observations. I have 2 eyepieces, one 9mm and one 25mm. My question is: Should I go for a ...
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3 votes
1 answer
92 views

How to plot curvilinear coordinates in the frame of a Cartesian telescope field of view

I am wondering what projection is used to produce plots like this: (Image taken from here, author: NASA/Ames/JPL-Caltech, Image credit: Software Bisque) More generally, I am trying to figure out the ...
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1 vote
3 answers
143 views

Frames per second capabilities cameras currently installed in Modern Telescopes?

What are the present real-time capabilities of various modern telescopes as video cameras? How do these compare with the capabilities various of space telescopes? For example, if it was known that ...
2 votes
2 answers
1k views

I can't see any detail through my telescope

I have a AILINK 114mm diameter, 900mm focal length, reflector telescope. I'm able to see the moon very well however, I can't see Planets very clearly The first two images are what I can see and the ...
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3 votes
1 answer
105 views

Which telescope would be better with a DSLR?

I'm interested in astrophotography and since I haven't left my home in six weeks, my interest in photographing the skies has been growing. I'm on a tight budget and I've found these two options: A ...
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10 votes
3 answers
435 views

Why are telescopes positioned in Lagrange points?

In this Wikipedia article about the list of space telescopes to be launched (which I assume is exhaustive), of the 11 telescopes yet to be launched, 6 will be positioned at the Sun-Earth L2 Lagrange ...
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0 votes
1 answer
298 views

How does diffraction occur in a reflecting telescope?

It's understandable how diffraction occurs in refracting telescopes, because the lens itself is a small aperture for light to pass through. But what about reflecting telescopes? Since light is ...
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4 votes
4 answers
549 views

How do focal length, angular magnification and field of view relate?

The larger the focal length the larger the angular magnification The smaller the focal length the larger the field of view. I don't understand why this applies. I'm talking specifically about ...
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3 votes
2 answers
448 views

Why are Cassegrain telescopes shorter than Newtonian reflecting telescopes?

Many websites say this is because the effective focal length of the objective is increased by making the secondary mirror convex. This allows a Cassegrain telescope to be shorter than a similarly ...
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1 vote
2 answers
177 views

Why are larger hex mirrors round and the smaller aren't?

Per this diagram why are the larger (30 meter and European) mirrors filled out to nearly a full circle, while the smaller mirrors composed of hexagons retain a hexagonal border limit instead of ...
3 votes
2 answers
127 views

Is looking through a telescope to do astronomy a thing of the past?

Do astronomers actually look through a telescope with the naked eye or do they mostly look the the data generated by telescopes on computers? Are they mostly working behind the computer and pencil ...
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5 votes
1 answer
126 views

lousy mirror corrected by software

Would it be possible to get a terribly shaped mirror, like a large sheet of something reflective, give it a general shape like a telescope mirror, but not anywhere near as precisely shaped as in a ...
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14 votes
2 answers
2k views

Space telescope located in outer solar system

I want to pose a question from someone who's astronomy knowledge would fit neatly onto a single piece of paper so please bear this in mind with any comments or answers. I am interested and want to ...
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3 votes
1 answer
84 views

What could I resolve with my Telescope

I recently won a Common 50mm refracting telescope with Solar Filter too.. I'm trying to Understand things I can skygaze with it. It's pretty basic and I should have known. Unfortunately, I don't ...
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4 votes
0 answers
45 views

How was astronomical data meant to be handled on HST precursors?

The first drafts for a large space telescope such as Hubble were made in the 60's, and the idea of a space observatory originated long before that. From Wikipedia: In 1968, NASA developed firm ...
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1 vote
1 answer
206 views

Verifying refractor lens about scratches

I found an used Skywatcher 70mm telescope for buying, but its lenses are a little suspect about harming. In one photo, it looks clearly a scratch, but in the another, it is not visible. Could it be an ...
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2 votes
1 answer
604 views

DSO in a 60mm telescope

I am thinking about buying a telescope, but here in Brazil they are very expensive and hard to find where to buy. So, the better telescope I can pay for is a Celestron Powerseeker 60AZ. My main ...
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1 vote
1 answer
386 views

Is moisture harmful to a Newtonian Reflector?

It is often cold outside, especially in the evening. So when I take my Newtonian Reflector back in my house, it starts condense. Can the water destroy my telescope? or the mirrors? Do I have to clean ...
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0 votes
1 answer
55 views

mirror image of the earth in the past [duplicate]

For example, if there was an object somewhere in the room, say 100 light years away, which would have to be very large and have the surface of a mirror, you could theoretically point the telescope at ...
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2 votes
3 answers
219 views

What's the cheapest lens to buy for showing ISS to a flat earther?

Recently I entered a discussion with someone that has a relatively popular YouTube channel which says among other things that the earth is flat. I said that earth isn't flat because you can see the ...
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2 votes
0 answers
69 views

How to pick a telescope? [closed]

I am trying to find a started telescope for my high school sister and my goals are to have awesome pictures and to let her explore her interest in the stars! They live in a clear night sky area so Im ...
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1 vote
0 answers
126 views

Methods for testing a refracting telescope lens

I have an old (nearly 50 years old)alt-azimuth three-inch (7.6cm) refracting telescope that someone else made. They ground the lens, created the cylindrical body and added a rack and pinion style ...
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0 votes
1 answer
76 views

How can I determine if a typical low-end telescope is a refractor or reflector?

Is there a way to distinguish (with no manual, product info etc)?
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2 votes
1 answer
131 views

Number of actuators in adaptive optics

It is well known that diffraction resolution of a telescope depends on the exterior radius of aperture: One can, for instance, use just a narrow outer ring of a parabolic mirror and the resolution ...
6 votes
1 answer
417 views

What are the benefits of a large refracting telescope?

Currently, refractor telescopes are limited in aperture because gravity will deform the main lens over time. According to Wikipedia the largest practical refracting telescope is 1m. If we were to ...
3 votes
0 answers
65 views

Is it possible to build a ground-based telescope that can directly image Earth-like planets orbiting in the habitable zone of sunlike stars?

In the following discussion I will refer to Earth-like exoplanets planets orbiting in the habitable zone of sunlike stars simply as “Earth-like exoplanets." NASA is currently developing or ...
1 vote
0 answers
42 views

How to determine Az-El pointing of a telescope spiral scan?

I am writing a simulation of an automated telescope observation program. One part of this is to run a spiral scan pattern on and around objects of interest. I would like to tile this scan pattern so ...
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4 votes
1 answer
137 views

If we've only observed Oumuamua as a single pixel, how can we know its shape?

On a separate Oumuamua question (Oumuamua alien space junk?), I was confused how shape could be inferred from a single pixel, per another user's (@Uwe) comment. It was suggested I ask this question ...
3 votes
1 answer
83 views

Beneficial astronomical uses of satellite constellations like Starlink?

Has any thought been given to software that would use predictable occultations by Earth-orbiting satellites to improve (rather than degrade) astronomical observations? Potential challenges I could ...
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3 votes
1 answer
178 views

Would a 1000 km telescope be able to resolve microscopic detail?

I have calculated that a 100m telescope can resolve 16m on the moon. Does that mean a 1000km telescope is 10000x better and can resolve 1.6 mm objects on the moon and even smaller closer? Or is there ...
10 votes
4 answers
1k views

Why are telescope mirrors made of glass?

Optical telescope mirrors are typically made from endlessly polished glass surfaces that have been aluminised to provide a very smooth surface of reflective aluminium. But why the need for glass at ...
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