1 Beginners Night Choosing a telescope Eric Grieve FAS Instrument Custodian.

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Beginners Night

Choosing a telescope

Eric GrieveFAS Instrument Custodian.

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Beginners Night

Choosing a telescope

Why leave out the binocular option?

So I won’t

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Choosing a telescope

What should a beginner do?What should a beginner do?

I hope to cover:I hope to cover:

•Ask yourself the right questions.•The choices to be made.•First beg, borrow or steal?•What and where to buy.

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Options

FIRST OPTICAL AID.

Practical advice.

Importance to beginners.

Getting it wrong now can put people off this hobby for life.

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Ask the right questions

Start with: 

What do you think you would most like to observe?

Solar System: The Moon and Planets:

OR

Deep Sky objects:

Galaxies, Nebulas and Star clusters?

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Ask these questions

How do you wish to observe?

As nature intended, with the mark 1 eyeball

Or

Mostly taking pictures 

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Ask these questions

How long would you observe for?

Quick half an hour but up to two hours on a good clear evening.

Or

The early hours of the morning!

I have no job, no partner or I always have cold feet in bed. 

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Ask these questions

How often will you have time to go and observe?

Weekends only or when family time permits.

Or

Most clear nights  

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Ask these questions

How patient are you.

Think about setting up time?

Getting it into position.

Scope alignment.

Optics cooled down.

All take time.

Can be up to an hour..

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Ask these questions

 Observe at home or a site elsewhere?

Home: Is your observing site - rural or is sky polluted?

OR

If elsewhere: Mobility – movement in and out of the car?

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Ask these questions

 Where would you be able to store it?

Consider the size and weight.

May need alignment each time its moved?

Remember : it will be at night and in the cold. Health and safety?

Telescopes are delicate instruments.

Some types of scope are not happy being in a garage.

I’ve seen many a scope residing in the dining room, or in a blanket box in the spare room.

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WHAT are the options?

Having tried to answer the questions what are the options suitable for the beginner?

What about a pair of Binoculars!

Going for a Telescope at first not always best .

Not as glamorous as a telescope, but an excellent way to start observing.

FAS members: John Rees and John and Roberta Smyth, their first serious purchase.

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Binoculars Advantages Versatile, light weight, simple, convenient to hand.

A good quality pair (£35) 10X50 general use.

Will show: 10’s of thousands of stars.

Brighter galaxies.

Star clusters and some Lunar & planetary detail.

Age sight lose. So 8X40 appears the same to me! And cheaper.

DisadvantagesOnly lower magnification available.Only lower magnification available.

Not suitable for tracking the stars.Not suitable for tracking the stars.

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Refractors Advantages

Excellent definition and image contrast.

Optics system holds alignment well.

No reflecting surfaces needing maintenance.

Simple eyepieces all work well.

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Refractors

Disadvantages

Optical Tube : - Bulky and long for given aperture.

Costly for given aperture -especially the modern short focal length variety!

Not suited for Deep sky objects.

BUT

Recently advances in the affordability of high quality .

Modern exotic glass, means reduced focal lengths available.

Now more practical and usable for Deep sky.

All this, with digital cameras.

Make them the scope for a wider choice of objects, for even advanced amateurs.

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Refractors

Disadvantages

Optical Tube : - Bulky and long for given aperture.

Costly for given aperture -especially the modern short focal length variety!

Not suited for Deep sky objects.

If detail definition is critical for fine planetary or Lunar detail.

Refractors are better. You need about double the size of reflector to meet the detail seen in a refractor.

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Reflectors Advantage

Per unit aperture cheaper.

Eyepiece usually conveniently positioned,

Fairly compact.

Larger aperture readily available.

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Reflectors Disadvantage.Disadvantage.

Collimation requiredCollimation required

Alignment easily altered when movedAlignment easily altered when moved

Diagonal and central obstruction .Diagonal and central obstruction .

If aperture, light grabbing is critical for variable stars and faint deep sky objects.

Then a reflector is better

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Catadioptics

Advantages

Extremely compact- folded optics.

Good quality for price.

Reflective coatings are protected.

Many models, all the sizes.

Combines a front lens and a mirror surface

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Catadioptics

Disadvantages

Collimation and alignment required.

Has a lower image contrast, central obstruction causes more light to be scattered.

Can be heavy for a given Aperture.

If its portability and convenience with the larger sizes. Then it’s a Catadioptic you need

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Mounting systems.

Kevin spoke about them last month.

What should the beginner look for.

You must consider:To spend the same amount of money on the mounting, as you do on the optics.Optical bits are sexy, and a tripod is boring.

In the majority of cases, a cheap telescope a let down to the novice, by the shaky mount, not the optical system. Its all about steady seeing.

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Azimuth Mounting

Advantages

Easy to manoeuvre

Simple solid construction. Simple solid construction.

Low Cost.Low Cost.

Disadvantages.

Single axis star tracking not possible.Single axis star tracking not possible.

Field rotation if tracking is applied.Field rotation if tracking is applied.

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Equatorial Mounting

Advantages

When aligned, allows easy star tracking.

Setting circles allow straight forward object identification.

One hand turn will follow the star or add electric drive.

Disadvantages

More complex and more costly than Azimuth.

Greater weight, uses a counter weights.

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The GOTO Mount

Advantages

Modern computer driven systems.

Will GOTO any object you command.

Will automatically track objects.

Some will even follow satellites!

Many offer a guided tour of the interesting objects visible in the particular nights sky.

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The GOTO Mount

Disadvantages

It’s a computer! Batteries included!

Lack of overall control! (To me)

Scope drives are often slow motion.

It requires alignment procedures.

Added cost and complexity.

I don’t think a novice can learn their way around the night sky with one of these!

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Finally and most important.

How much money do you wish to spend at this time?

Second hand sources .

Car boot sales just £7 last year for the FAS 60mm equatorial in its box.

New prices

Binoculars from £35

Refractor from £100

Reflector from £150

Cat from £400

Simple Goto Systems £200

Details of offers always in the magazines

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The advantage of FAS membership

Don’t despair – help is at hand.Being a member you can learn from FAS meetings and talking to members of their experiences:

Committee members are contractually obliged answer to all questions raised, other than their star sign!

You will get to know:• What to look for in the night sky.• What to expect it to actually looks like.

This can only increase the pleasure from any instrument you own.

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Choices - Choices

Buy Now!

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Choices - Choices

Buy Now! – Don't.

Loss of health, wealth and family life can result!

FAS has over time seen many people with problems, as a result of buying the wrong instrument.

Get yourself some more information.

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Further Information:

Magazines: Astronomy Now

Sky @ Night

Astronomy

Sky and Telescope

 Last month’s copy is often free - at the back on the Hall.

The FAS library contains many books that cover the subject.

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Beg, borrow or steal

  Then why not try before you buy!

Make full use of the FAS equipment loan items. You can try something out AT HOME and AT NIGHT with the real sky, before you buy.

If only this was the case in my day!

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FAS LOAN ITEMS

Available:PST.Reflectors: 110mmRefractors: 60mm – 90mmAzimuth, Equatorial and GOTO Mounts to try.

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FAS LOAN ITEMS

Plus Peter West has his 7 inch Newtonian also available.

Please just speak to me!

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Useful Websites:

When you wish to buy your first bit of kit.Look in the magazines and then try these sites.

www.telescopehouse.com (Fullerscopes - as was)

www.opticalvision.co.uk (Good general supplier)

www.celestron.uk.com (David Hinds)

www.astronomia.co.uk (A local shop in Dorking)

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Choosing a telescope

We have covered:We have covered:

•Asking yourself the right questions.•Making the right choices.•Sources of further information.•Try to beg, borrow and the FAS stock.•Buying? - Then where from.•What next...

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Finally

If you just won the lottery.

Then you will be looking to buy a complete observatory.

Come to:

FAS Meeting Tuesday August 14th 2012

I’ll be talking about a chap

who did exactly that!

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Meeting Tuesday August 14th 2012

Patrick Y Alexander and his Aldershot Observatory

By FAS member - Eric Grieve