49
The Agony of Buying Your The Agony of Buying Your First Telescope First Telescope Sorin SoggyAstronomer.com
The Agony of Buying Your First The Agony of Buying Your First TelescopeTelescope
SorinSoggyAstronomer.com
Too Many ChoicesToo Many Choices
Red Tasco
Cheap options with bad optics Cheap options with bad optics can be tempting…can be tempting…
until you see the view.until you see the view.
Spending a bit more delivers a Spending a bit more delivers a world of difference!world of difference!
Three Fours
• 4 Key Terms• 4 Questions• 4 Types of Telescopes
4 Key Terms
Magnification
400x200x
100x
= Disappointment
Aperture
50mm50mm100mm100mm
200mm200mm
20 cm2 78 cm2 314 cm2
< 9mm
Aperture = Clarity
50mm50mm100mm100mm
200mm200mm
20 cm2
33x78 cm2
130x314 cm2
514x
< 9mm
1x
Focal LengthThe distance over which an optical system converges light
Field of View
Longer Focal Length = Narrower FOV
Shorter Focal Length = Wider FOV
3˚
30’M51 Jupiter
110’
11’
7’
<1’
Field of View
4 Questions
1. How much do you want to 1. How much do you want to spend?spend?
2. How far will you need to 2. How far will you need to move your telescope to use it?move your telescope to use it?
3. What do you 3. What do you reallyreally want to want to see?see?
4. Visual observing, or astrophotography?
4. Visual Observing or 4. Visual Observing or Astrophotography?Astrophotography?
Image Credit: NASA
4 Types of Telescopes
Schmidt-CassegrainsSchmidt-CassegrainsDobsoniansDobsonians
RefractorsRefractors NewtoniansNewtonians
RefractorsRefractors
Best For:•Wide Field of View•Terrestrial Observing•Fast Cool Down•Double Stars
Be Aware Of:•Cheap Mounts•Chromatic Aberration•High cost per inch at larger apertures
NewtoniansNewtonians
Good For:•Planetary and Deep Sky Observing•Astrophotography
Be Aware Of:•Complicated or Shaky Mounts•Occasional Collimation•Not as good for splitting double-stars•Long Cool Down
DobsoniansDobsonians
Best For:Best For:•Cost per Aperture Cost per Aperture •Ease of UseEase of Use•Planetary and Planetary and Deep Sky Deep Sky ObservingObserving
Schmidt-CassegrainsSchmidt-Cassegrains
Be Aware Of:•More Expensive Than Newtonians & Dobs•Narrowest FOV•Long Cool Down
Best For:•Astrophotography•Planetary and Deep Sky Objects•Small Size for Large Aperture
GoTo vs. Manual
• Forces you to learn the sky
• No Alignment Process
• Cheaper
• Can point you to hard to find DSOs
• Tracks objects while observing
Astrophotography
Image Credit: flurryofsmoke on Flickr
You Don’t Need Crazy KitYou Don’t Need Crazy Kit
A DSLR Camera is a great A DSLR Camera is a great way to get startedway to get started
Astrophotography is Astrophotography is where GEMs Shinewhere GEMs Shine
Jupiter M42 Orion Nebula
AP does take patience…AP does take patience…
and a lot of practice.and a lot of practice.
AstrophotographyAstrophotographyAstrophotography
is only as hard as you make it.
Yeah, ok, that’s great…Yeah, ok, that’s great…
Now which telescope do I Now which telescope do I buy?buy?
Four Key Terms
• Avoid Telescopes Advertising Avoid Telescopes Advertising MagnificationMagnification
• Larger Larger ApertureAperture = Better Clarity = Better Clarity
• short short Focal LengthFocal Length = Wide = Wide Field of ViewField of View
• LONG LONG Focal LengthFocal Length = Narrow = Narrow Field of Field of ViewView
Four Questions
1.1. How much do you want to spend?How much do you want to spend?
2.2. How far will you need to move your How far will you need to move your telescope to use it?telescope to use it?
3.3. What do you really want to see?What do you really want to see?
4.4. Visual observing or Visual observing or Astrophotography?Astrophotography?
Schmidt-CassegrainsSchmidt-CassegrainsDobsoniansDobsonians
RefractorsRefractors NewtoniansNewtonians
Star Parties
Attend a public Star PartyAttend a public Star Party
Join a ClubJoin a Club
Email: Email: Twitter: Twitter: Website:Website:
[email protected]@soggyastronomer.com@[email protected]
Thank You!Thank You!
Appendix
Chromatic AberrationChromatic Aberration
Newtonian
Schmidt Cassegrain
