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:

sorin@soggyastronomer.comsorin@soggyastronomer.com@SoggyAstro@SoggyAstroSoggyAstronomer.comSoggyAstronomer.com

Thank You!Thank You!

Appendix

Chromatic AberrationChromatic Aberration

Newtonian

Schmidt Cassegrain