Simple Telescope Tester

ballaratdragons (Ken) · #1 24-01-2005, 11:24 PM

I thought I would take this chance to tell you how to make a simple tester for the planetary optical performance of your Telescope by using actual scale distance.

1. Cut paper circles (sizes below).

2. Lightly colour the planets to match the real object.

3. Glue them onto a piece of dark cardboard.

Sizes of Planets: (at closest distance to Earth)

Mars - 21mm diameter
Jupiter - 40mm diameter
Saturn - 18mm diameter
Saturns Rings - 40mm oval
Uranus - 3mm diameter
Neptune - 2mm diameter
50km Lunar Crater - 25mm diameter

Now you are ready to test your scope.

Place the cardboard tester 165 metres from the telescope (or binocs) and see how clear an image you can get.

Let us know your results and which scope you used.

MintSauce (Gordon) · #2 25-01-2005, 12:11 AM

gee 165 meters away? might have some trouble doing that :|

can we not make even smaller circles?

ballaratdragons (Ken) · #3 25-01-2005, 12:31 AM

Good astronomical telescopes won't focus at a distance less than that.

Place the Card on a power pole 165m up the road or go to a sports ground.

NOTE: Be sure to do this test in daylight hours!

iceman (Mike) · #4 25-01-2005, 06:12 AM

Make an even smaller one for a star, and it can be your artificial star to do star tests to check for collimation

I don't really understand the reason for this test really either.. I suppose it could be used to check optics in a small way, or an eyepiece when comparing eyepieces.. but any target during the daytime could do that.

I might try it though, and take an avi.. it might be the best saturn image I get when I don't have to peer through bad seeing

Vermin (Tom) · #5 25-01-2005, 10:10 AM

Quote:

Originally posted by ballaratdragons
Good astronomical telescopes won't focus at a distance less than that.
...

I beg to differ.

My TV101 can focus at about 10 - 15m.

Striker (Tony) · #6 25-01-2005, 12:33 PM

WTF........165 meters away......I dont walk that far in a marathon.

ving (David) · #7 25-01-2005, 12:43 PM

just a case of whos property i put it on!
eek!
interesting tho...

ballaratdragons (Ken) · #8 25-01-2005, 04:19 PM

Quote:

Originally posted by iceman

I don't really understand the reason for this test really either.. I suppose it could be used to check optics in a small way, or an eyepiece when comparing eyepieces.. but any target during the daytime could do that.

It's just a fun way for beginners to check their scope and to see what objects should sort of look like when observing at night.

[QUOTE] Originally posted by Vermin

I beg to differ.

My TV101 can focus at about 10 - 15m.

[QUOTE]

Lucky Bugger. I bet the neighbours hate you.

I meant that MOST telescopes don't like close focusing.
Sorry bout dat!

rumples riot · #9 25-01-2005, 05:04 PM

Yeah, I think it depends upon the focal ratio of the scope. my f10 can focus easily 25m. But I get the point. That being, the further the distance the better the test for resolution. But this will depend upon collimation also. Collimation would need to be near perfect for this test to work.

ballaratdragons (Ken) · #10 25-01-2005, 05:52 PM

Yep!

That's the point.

Wow! I can't believe the amount of controversy over a simple test which could help some people or just be fun to others. Might have to keep any future suggestions to myself.

Vermin (Tom) · #11 25-01-2005, 06:01 PM

Hehe, call me Mr pedantic.

I have an amateur astronomy book (too hot to get up and go find the actual details) that has a page specifically for this test. It has pictures of Mars at opposition and [the opposite?] as well as Jupiter Saturn and sections of the moon.

I've never tried it.

ballaratdragons (Ken) · #12 25-01-2005, 08:52 PM

Hey Tom,

I got the dimensions from an Astronomy book about 15 years ago. Can't remember its name.

We used to teach this method to kids and beginners at our society and they had a bit of fun with it and you can show non-astronomical people in the day time.

Everyone I ever showed was pretty amazed and most said things like "I'm gonna buy a telescope and have a look" and 'can you really see them that good for real?"

Vermin (Tom) · #13 25-01-2005, 09:07 PM

I think it must be the same book! I just went and looked, the distance is listed as 165m too. Same objects and sizes.

FYI, it's "The Amateur Astronomer" by Anton Rukl, Octopus Books Ltd 1979.

Cool! I didn't realise it was by Rukl, I've got his excellent "Moon Mars and Venus" maps book as well.

If you like I can scan the scope test page when I go back to work on Thursday.

ballaratdragons (Ken) · #14 25-01-2005, 09:12 PM

I wouldn't bother.

This lot will only pick the crap out of it again. I really don't know why I bother.

Thanks for the offer though Tom, at least YOU are interested.

Vermin (Tom) · #15 25-01-2005, 10:37 PM

LOL, chill Winstun

I'll do it anyway, if one person uses it - it'll be worth it.

ballaratdragons (Ken) · #16 25-01-2005, 10:48 PM

hehehe

I can just picture it now, a bunch of growd-ups sitting in their loungerooms with their kids coloured pencils, scissors and glue right now as we speak, hoping no-one finds out that they are really making a planet test chart!

hehehehehe.

Vermin (Tom) · #17 25-01-2005, 11:09 PM

The Papercraft ones are for the experts and take forever (but look incredible):
http://www.yamaha-motor.co.jp/global...aft/index.html

This has to be built to be believed:
http://www.scitoys.com/scitoys/scito...aper_ring.html

It took me ten years, an old origami book and the help of this site to build the Jackstone:
http://anools-origami.tripod.com/jackston.htm

Last one, maps should be folded like this (Miura-Ori folding):
http://www.u3p.net/fold/pliage_a.htm
http://www.britishorigami.org.uk/theory/miura.htm

ballaratdragons (Ken) · #18 25-01-2005, 11:33 PM

Wow! The Sci-toys paper ring is amazing. The missus wants to make it.

Vermin (Tom) · #19 26-01-2005, 01:08 AM

Hehe tell her to go for it. For someone with eyes good enough to spot a flash of aurora that you miss it should be a sinch.

Also, it'll keep rug rats fascinated (and quiet) for about, oooh, I dunno, possibly...

a minute.

Vermin (Tom) · #20 27-01-2005, 05:50 PM

http://www.webclot.com/scope/scope_test.pdf