Questions tagged [dobsonian-telescope]

A Dobsonian telescope is a relatively inexpensive Newtonian telescope, in which the tube assembly slips freely in the lower base.

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Improving portability of truss Newtonian

I'm designing a 10in f/6 truss Newtonian as a sort of big travel scope; something that I can break down into parts to fit in a backpack or similar but will still give me decent angular resolution. In ...
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Hoping to do some viewing and astrophotography with a large-ish Dobsonian and a DLSR, is this scheme workable?

I haven't put a camera behind a telescope since the lunar eclipse of 1975 except for a few experiments with a cell phone held behind a pair of binoculars. I want the occasional thrill of using a ...
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Could someone explain what is wrong with my telescope, and what should I be able to see with it?

In January of 2016, I received my first telescope, through Astronomers Without Borders. It was and is my first telescope: an AWB 130 Newtonian tabletop telescope with a 650mm focal length and a 130mm ...
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Dobsonian telescopes: do collapsible scopes have any drawbacks?

When choosing between a collapsible and a non collapsible 12” dobsonian scope what drawbacks if any do collapsible dobsonian scopes have? If I transport any scope it will need collimating. Obviously a ...
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Which is a better way to increase magnification - by choosing an eyepiece of lesser focal length or by choosing a telescope with higher focal length? [duplicate]

Magnification of a telescope = (focal length of telescope / focal length of the eyepiece being used) $$M=\frac{f_{objective}}{f_{eyepiece}}$$ If I want 75 X magnification and the following are the two ...
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Practicality of Dobsonian telescopes

I've been using binocular for more than a decade for visual observation. I'm thinking of upgrading to a telescope. The Dob caught my attention due to its simplicity in setup and also cost ...
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1 answer
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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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How to chose a comfortable 2 inch eyepiece for a Skywatcher Dobsonian 150 mm f/8 reflector?

Totally newbie here. I got the Skywatcher Dobsonian 6 inch (150 mm) f/8 Newtonian reflector. I had a brief chance to test it yesterday when the skies here in Melbourne cleared a little bit. I was able ...
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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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What are criteria to compare and evaluate different 12 inch truss Dobsonian telescopes?

What are criteria to compare and evaluate different 12 inch truss Dobsonian telescopes? I'm primarily interested in comparing mirror quality and weight (price I can do myself of course). Two examples ...
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How to adapt small Dobsonian to use with a tripod?

I am the owner of a small 4", f/6.3 tabletop Dobsonian telescope with a 102mm aperture and 640mm focal length. It is based on a Dobsonian mount but I would like to use a tripod instead because of ...
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Eyepiece diameter for small focal length planetary viewing on a large dobsonian?

I have a 12" dobsonian with a 1500mm focal length and want to do some higher magnification planetary viewing. Currently my highest magnification is ~80x via my 19mm eyepiece (calculated here), but I ...
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2 votes
2 answers
151 views

"Ideal" primary thickness in a Dobson

I plan to buy a 12" or 14" dobson, the choice depending on my final budget and on the total weight of the instrument. I have several options for the primary mirror. I tried to find a formula that ...
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Laser Collimator For Dobsonian vs Newtonian

Will a laser collimator like the Gosky 1.25 Metal Laser Collimator, https://www.amazon.com/gp/product/B01M4IVUYG/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AHQ6VCR020F8X, work for a dobsonian ...
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Problem with Dobsonian reflector telescope

I'm not sure whether I should ask this question here but I'll give it a shot. I have a XT8 Dobsonian Reflector telescope and it works fine. But recently when I use the focuser to focus the image when ...
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12 votes
2 answers
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Cancelling out earth rotation speed, Altazimuth mount

I have a Dobsonian telescope. It is using Altazimuth mount. Basic idea of using it is to target the object by moving telescope vertical axis perpendicular to the ground, and an elevation axis that is ...
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Appropriate battery for overnight viewing to drive telescope and GOTO?

I have a Plettstone 18" Dobsonian telescope with GOTO and clock drive that runs off a 12 volt cigarette lighter adapter. What is an appropriate battery to use to run this overnight while viewing all ...
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8 votes
1 answer
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How can I accurately find & apply the white donut to the center of my mirror?

I have a Plettstone 18" Dobsonian telescope and use a Howie Glatter tuBlug, laser collimator, and Square Grid Projection Attachment to adjust the mirrors. Proper collimation requires an accurate ...
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33 votes
1 answer
2k views

How could a hobbyist astronomer determine apparent magnitude of a star?

Apparent magnitude is a rather complex way to determine the brightness of a star. Quoting the introduction text from the linked to Wikipedia page: The apparent magnitude (m) of a celestial body is ...
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15 votes
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How do I build a stargazing aficionado's Sun funnel to observe our nearest star safely?

How do I observe the Sun safely, with tools I could build myself and without breaking the bank? If I wanted to build a Sun funnel on my own and use it on my enthusiast grade telescope, how would I do ...
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22 votes
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How can I collimate a dobsonian telescope with a laser collimator?

I've had a dobsonian telescope for a while now, but I've never been able to collimate it. I thought I had it collimated once, but when I looked through it the star didn't look right, it looked kind ...
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