Hi bros and sis
I intend to buy a telescope but have absolutely no idea which one to buy.
my requirements:
- where we will be viewing: from the 39th floor of a hdb flat.
- what we will be viewing: golf course, greenary, buildings in the vincinity. The nearest object is around 150m away, the golf course is approx. 700-800m from us. Last but not least, is it possible to see the squirrel on a tree 15km away?
- portability: not important. intend to mount the scope on a tripod and place it in the living room.
- user-friendly and easy to maintain for a newbie like me: no need frequent adjustments or special setups or configurations.
- budget: $1k. if not realistic, pls advise the amount required.
- any shops to recommend where i can buy this equipment
thanks for reading and thanks in advance for your kind advice.
cheers!
Jessie
Advice needed - Which telescope to buy
- weixing
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Re: Advice needed - Which telescope to buy
Hi,
Anyway, are you going to use it for astro use? If no, what you need is a spotting scope (a type of telescope design for terrestrial use). I don't have experience in them, but many photographic shop do sell them and their price vary a lot depend on brand, name and model. May be some of us here will be able to help you.
As the question "is it possible to see the squirrel on a tree 15km away", need to do some calculation ( just wonder what is the typical length of a squirrel? :-P ) before can answer this... but most likely you won't be able to see it clearly even with very high magnification(power)... this is due to the air turbulence (cause by the heat on the ground) which will blur the image.
Have a nice day.
Not many people come to an astronomy forum to ask for advice on telescope for terrestrial use, but since it's telescope related some of us might be able to help...jessquek wrote:Hi bros and sis
I intend to buy a telescope but have absolutely no idea which one to buy.
my requirements:
- where we will be viewing: from the 39th floor of a hdb flat.
- what we will be viewing: golf course, greenary, buildings in the vincinity. The nearest object is around 150m away, the golf course is approx. 700-800m from us. Last but not least, is it possible to see the squirrel on a tree 15km away?
- portability: not important. intend to mount the scope on a tripod and place it in the living room.
- budget: $1k. if not realistic, pls advise the amount required.
- any shops to recommend where i can buy this equipment
thanks for reading and thanks in advance for your kind advice.
cheers!
Jessie
Anyway, are you going to use it for astro use? If no, what you need is a spotting scope (a type of telescope design for terrestrial use). I don't have experience in them, but many photographic shop do sell them and their price vary a lot depend on brand, name and model. May be some of us here will be able to help you.
As the question "is it possible to see the squirrel on a tree 15km away", need to do some calculation ( just wonder what is the typical length of a squirrel? :-P ) before can answer this... but most likely you won't be able to see it clearly even with very high magnification(power)... this is due to the air turbulence (cause by the heat on the ground) which will blur the image.
Have a nice day.
Yang Weixing
"The universe is composed mainly of hydrogen and ignorance."
"The universe is composed mainly of hydrogen and ignorance."
Re: Advice needed - Which telescope to buy
hmm..
assuming height of squirrel = 15cm
taking 1/2 of height of squirrel as opposite, 7.5cm
adjacent is the distance, which is 15km
let S be half the angular size of squirrel
tan S = 7.5cm/15km
given a 8" telescope, maximum magnification of 400x
angular size of squirrel at 400x magnification = 400 x S x 2
i don't have a calculator with me, anyone can help with the math?
~MooEy~
assuming height of squirrel = 15cm
taking 1/2 of height of squirrel as opposite, 7.5cm
adjacent is the distance, which is 15km
let S be half the angular size of squirrel
tan S = 7.5cm/15km
given a 8" telescope, maximum magnification of 400x
angular size of squirrel at 400x magnification = 400 x S x 2
i don't have a calculator with me, anyone can help with the math?
~MooEy~
Last edited by MooEy on Wed May 23, 2012 9:41 pm, edited 1 time in total.
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Re: Advice needed - Which telescope to buy
I think you can use this calculator.
http://www.1728.org/angsize.htm
When I used this calculator assuming the squirrel is standing on its rear legs , all of 15 cm tall, it will appear 2 seconds in angularb size. Remember moon'a angular size is 1800 sec . So you will know how the squirrel will look like 15 km away.
Kochu
http://www.1728.org/angsize.htm
When I used this calculator assuming the squirrel is standing on its rear legs , all of 15 cm tall, it will appear 2 seconds in angularb size. Remember moon'a angular size is 1800 sec . So you will know how the squirrel will look like 15 km away.
Kochu
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Re: Advice needed - Which telescope to buy
i think u can also consider a bino. with 20 or 25 times u can see km away lol
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Re: Advice needed - Which telescope to buy
good morn!
thanks to all seniors for your replies, i had a good laugh!
initially i thot of getting a good bino. but if i can haf a good scope, i may venture into stargazing in future ;p
am looking at this scope currently, need to do more research and find more info
Orion StarMax 127mm Equatorial Maksutov-Cassegrain Telescope
http://www.telescope.com/Telescopes/Cas ... p/9826.uts
thanks to all seniors for your replies, i had a good laugh!
initially i thot of getting a good bino. but if i can haf a good scope, i may venture into stargazing in future ;p
am looking at this scope currently, need to do more research and find more info
Orion StarMax 127mm Equatorial Maksutov-Cassegrain Telescope
http://www.telescope.com/Telescopes/Cas ... p/9826.uts
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Re: Advice needed - Which telescope to buy
Just a side note. Do Check out the design of a telescope first before using it for terrestrial. Some of it might cause invented images.
Re: Advice needed - Which telescope to buy
Hi bro Davegn
can teach me wats invented image? and what are the things i should look out for?
thanks
can teach me wats invented image? and what are the things i should look out for?
thanks
Davegn wrote:Just a side note. Do Check out the design of a telescope first before using it for terrestrial. Some of it might cause invented images.
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Re: Advice needed - Which telescope to buy
Hi Jessquek,
Sorry for the typo, was chatting with my boss at my work place when I made the post online.
What I mean is inverted image (Maybe right becomes left Or Up becomes down Or maybe both). It have to depends on the telescope design or how many mirrors the scope is using.
Basically there are 3 types of Telescope designs,
- Refractor
- Reflector
- Maksutov–Cassegrains
Reflector on the other hand, can’t be used for terrestrial as they may cause inverted or mirror image due to the fact that it uses mirrors to catch the light.
For Maksutov–Cassegrains, I am not quite sure. Did not own one of this before. But basically the design uses both mirrors and lens. So is like a mix in between Refractor and Reflector.
For terrestrial use, Refractors are the commonly used with a 45 degree diagonal for easier seeing.
For terrestrial wise, if I am not wrong you would not need a really big telescope.
Sorry for the typo, was chatting with my boss at my work place when I made the post online.
What I mean is inverted image (Maybe right becomes left Or Up becomes down Or maybe both). It have to depends on the telescope design or how many mirrors the scope is using.
Basically there are 3 types of Telescope designs,
- Refractor
- Reflector
- Maksutov–Cassegrains
Reflector on the other hand, can’t be used for terrestrial as they may cause inverted or mirror image due to the fact that it uses mirrors to catch the light.
For Maksutov–Cassegrains, I am not quite sure. Did not own one of this before. But basically the design uses both mirrors and lens. So is like a mix in between Refractor and Reflector.
For terrestrial use, Refractors are the commonly used with a 45 degree diagonal for easier seeing.
For terrestrial wise, if I am not wrong you would not need a really big telescope.
Re: Advice needed - Which telescope to buy
Inverted image. Meaning upside-down image.
Most telescopes do not give an upright image. All spotting scopes and binos give upright or erect image. To see an upright image in a telescope, you need to use an erect-image diagonal, not the standard star diagonal. For both terrestial and astronomical use, i would suggest you get a 80mm ED doublet refractor which can cost under $1000.
I dont think it is practical or realistic to observe a squirrel at 15km away
Most telescopes do not give an upright image. All spotting scopes and binos give upright or erect image. To see an upright image in a telescope, you need to use an erect-image diagonal, not the standard star diagonal. For both terrestial and astronomical use, i would suggest you get a 80mm ED doublet refractor which can cost under $1000.
I dont think it is practical or realistic to observe a squirrel at 15km away
Richard Low