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View Full Version : Episode 33: Choosing and Using a Telescope



Fraser
2007-Apr-25, 04:11 PM
Buying your first telescope can be a nerve-wracking experience filled with buyer's remorse. This week we discuss the basics of purchasing your first binoculars and telescope. What to look for, how to clean older equipment, and how to use it for the first time. Let's make sure your first investment in this wonderful hobby is money well-spent.

Read the full blog entry (http://www.astronomycast.com/observing/episode-33-coosing-and-using-a-telescope/)

EvilEye
2007-Apr-26, 12:22 AM
I loved this show even though it was similar to a previous episode.

You explained a lot more, and it was very helpful.

I have an added question about using Binocs (until I can afford a Dobsonian tele)

I have an astigmatism (Horizontal Nystagmus) in my right eye.

When viewing close up objects (trees, the house down the street etc...) I have good vision with binoculars. But when trying to view something as far away as the moon, I can't get my eyes to converge and make one object. I either see two moons (one still and one wiggling back and forth trying to converge) or I see two moons distincly and I have to close one eye.

Is this my eyes, or is it just that the binocs I'm using are too wide for my face?

(they are 10x50) but they only "swing" so far one way or the other.

Anyway... thanks for the great and helpful episode. As soon as I can, I will be investing in a "real" telescope.

wavey63
2007-Apr-26, 11:57 AM
I still have not seen the new episode populate in ITunes. Is there a problem with my store or is everyone just getting the cast from the site? Thanks guys.

jwkabbes
2007-Apr-26, 05:56 PM
I can very much relate to your tales of bad experiences with poor telescopes. The scope I bought as a kid had a horrible mount, bad optics, and drove me away from astronomy for years. The clearance 8" SCT I picked up 8 years ago was much better, but finding objects took so long that showing folks anything other than a bright object was impossible, especially with the light pollution in the Chicago suburbs.

When I broke down and got the GO-TO scope, it was wonderful. It pointed to Neptune in the orange haze that had no stars for star-hopping. I can show folks as many objects as I want, with almost no delay in between.

Galaxy
2007-Apr-26, 09:05 PM
I still have not seen the new episode populate in ITunes. Is there a problem with my store or is everyone just getting the cast from the site? Thanks guys.

I'm getting it in my iTunes, and Pamela's got it in hers. Do you have it now? If not, try unsubscribing and re-subscribing.

Email us at info@astronomycast.com if you still can't get it to work and we'll do our best to help.

-Rebecca
Astronomy Cast student worker

clint
2007-Apr-27, 05:25 PM
Does anyone have an advice for star-watching close to a big city?

I mean, the obvious thing to do is to get as far away form all that light contamination as you can, sure.
But since I cannot do that every night, is there any trick to improve the sight?

ArrowJ
2007-Apr-28, 01:40 AM
7 or 10 x 50 - Check
$80 - Check
Brands To Avoid?
Brands To Prefer?

wavey63
2007-Apr-30, 12:09 PM
Thanks Rebecca, I did get... just a littl late. But I do have another question to pose, what is the overall impression of the larger scope dealers? I am on my second dealer trying to get my scope that I had ordered originally over a month ago. I won't mention any names, but the first one told me it would be"7-10 day" to be shipped. After waiting over 3 weeks, I emailed them and they said it was backordered but sure to ship in another week.Finally cancelled with them after waiting for info for 2 more weeks then being told"a few more weeks". Went to another store online and they said "have it in stock and it will be there by Friday"...2 weeks later, no scope, order , or ven a courtesy email stating status of order. I know I should shop local but there are no scope dealers near me and I also have two very youg children so $$$ is tight. Any thoughts?

Don't Panic
2007-Apr-30, 02:35 PM
I just want to say thank you to Pamela and Fraser for this episode. I am just jumping into the world of Astronomy, and this helped me out alot. After this episode I knew exaclty what I wanted for my Birthday and I ended up getting Nightwatch, and a pair of 10x50 binocs. It's been overcast here for a while but I can't wait to head outside and start identifying some constellations, and other goodies. I have been investigating what to start with and what books to buy, etc, etc, and this episode helped me to decide what to start with. Can't wait to learn the sky so I can go out and buy that telescope. Thanx again!!

jlutzcc
2007-Apr-30, 03:09 PM
I have night blindness and can't see many stars. Looking at some of the telescope manuals I would have to line up to the north star, which I can't see. Also I can't see the milkyway. To see more stars, is there anything like 2X50 binoculars?
In general, is there a product for a person with night blindness.

Nebulous
2007-May-02, 05:39 AM
I had to laugh when Pamela said that that bit about spending as much for a telescope as one would spend on a car. In my case, I didn't exactly spend that much on the telescope but I did buy myself a 12 inch dob and then went out and bought a new SUV to haul it around in. I just couldn't fit in in my Civic. One thing you didn't touch on is the hidden danger of getting addicted to high end eyepieces. I borrowed a 31mm Tele Vue Nagler one night and was stunned by the view. I now own 3 Naglers and have more money invested in the eyepieces than I do in the scope. Is there a support group out there to help me kick this habit?

Mrs B
2007-May-09, 11:29 AM
Thanks for the great podcast. I've been trying to get my boyfriend to listen to your podcast for ages. I forced this episode on him during a long car drive. He's been listening to some older casts out of his own accord and he's already skimming through some magazines and stores to purcase his first stargazing equipment! So thanks again for getting someone interested in astronomy just by sharing some clear information. Love certainly didn't work...

Fraser
2007-May-09, 09:26 PM
Nicely done. :-) You do what you need to do to get the word out. Anyway, there's nothing more romantic than an evening of stargazing.

AliCDKey
2007-May-14, 07:43 AM
Thanks Fraser for the advice on picking up the book called "Nightwatch" by Terence Dickinson. :clap:

I've tried several attempts at astronomy with various texts and books, however, after listening to the podcast I decided I could stop by Chapters here in Mississauga, ON and see what it's like.

So far, it's a great book excellent for amateurs such as myself.

Thanks for the great tip. I'm definitely looking into purchasing a pair of binoculars since I don't have room in my apartment to hold one.

yojimbo-san
2007-May-16, 09:11 AM
Thanks for another great topic. I heard the first pass through this subject way back, but it didn't get me moving. Now it's getting dark early down here (New Zealand) so the timing was right ... 4 hours ago I bought a set of Tasco 10x50 binoculars, got home and it was overcast for the first night in ages! But Jupiter was soon out, and now I'm a happy three-moons-visible-kinda-guy! If I'd spent a few more minutes figuring out how to keep stable perhaps I'd have spotted Io too ... I may try again soon :-)

clint
2007-May-18, 12:11 AM
I was talking to a friend the other day, who said he almost sympathises with the
'conspiration' theory that NASA never actually made it to the moon.
(considering the extremely primitive IT equipment at the time of the Apollo missions)

In that context, I was wondering:
When will we be able to see the Apollo stuff on the moon?
(and thus have the ultimate proof that those images were NOT tricked or shot in the Nevada desert, etc.)

Are the latest telescopes getting close to that?
How much better resolution will we need to get there?

kokosnood
2007-Nov-11, 10:36 PM
I loved this show even though it was similar to a previous episode.

You explained a lot more, and it was very helpful.

I have an added question about using Binocs (until I can afford a Dobsonian tele)

I have an astigmatism (Horizontal Nystagmus) in my right eye.

When viewing close up objects (trees, the house down the street etc...) I have good vision with binoculars. But when trying to view something as far away as the moon, I can't get my eyes to converge and make one object. I either see two moons (one still and one wiggling back and forth trying to converge) or I see two moons distincly and I have to close one eye.

Is this my eyes, or is it just that the binocs I'm using are too wide for my face?

(they are 10x50) but they only "swing" so far one way or the other.

Anyway... thanks for the great and helpful episode. As soon as I can, I will be investing in a "real" telescope.

I'm on my second pair of binocs. They start out ok, but eventually they get dropped or something and then I get 2 images when I look through them. I wrote to the manufacturer of the first pair and they sent me an article on how to adjust the collimation via a small screw under the rubber eye guard. This might help you EvilEye.

However; I can never quite get the 2 images to line up perfectly once they have been knocked off alignment. My questions are two:

1. Would more expensive binocs be less likely to have this double image problem?

2. Is there any trick to making the adjustment and getting it back to a single image?

Kind regards,
s

Here is the reply I got from the binoc manufacturer:
Dear Consumer,

This is the collimation procedure it does state for Bear 15x70 but, this is also for all Binoculars.

Thanks and good lucků..



Binocular Minor Collimation Procedures

by Pete Rasmussen

The typical (and usually very simple) collimation procedure for the 15x70 BEAR binoculars is often as an easy operation. One notable exception to this is when the binoculars are in gross misalignment. Gross misalignment is easily determined when the large circle of light beamed through the eyepiece end, as viewed _from_ the objective end, is noted as significantly off center of the binoculars internals. In other words, this large disc of light (which is the same exact thing as the aperture opening of the eyepiece itself) will not be seen as circularly centered against the circles that are the prism hole in the middle of the binos, and the objective lens circumference. These three areas mentioned are viewed in series from the front (objective) end of the binoculars. Choose the optical tube that looks the most misaligned when ready to make the needed collimation adjustment.

If the binoculars were already misaligned, or had become that way from a drop, etc., most often only a slight tweaking of one or both of the tiny set screws, that tilt the rear porro prisms (the ones nearest the eyepieces), is all that should be required. This procedure will true up the parallel nature of the two binocular tubes that make up the binocular vision.

To accomplish this truing of alignment, one should set the binos on a solid surface pointing them horizontally. Center in the field of view a focused image of a prominent, distant (about 1/2 mile or more away) fixed object. Tripod mounting the binoculars is also optionally good for stabilizing for this procedure and may be preferred to the solid surface mounting approach. The reason is you might can more readily position yourself behind the binos to work on them.

Take a very small 1mm size jeweler's flat bladed screwdriver and stick it into the gap at the edge of the rubber covering next to the prism covers (see image showing the location). These prism covers are the ones with the name and specifications on them and are located just under the eyepieces. The location to do the "prying" is right above the word "BEAR" on the left tube assembly, and also above the numbering "15x70" on the right tube assembly.

Work the screwdriver tip back and forth to scrape and pry loose the attachment of the rubber from the body itself. Separate the rubber just far enough back away from the body so you are able to grasp the edge of the rubber covering with thumb and forefinger. That will be enough so that the alignment screw can be easily accessed. Place a small acorn nut or similar object under the rubber covering to keep it well raised enough for accessing the adjustment screw. Place the screwdriver tip into the screw in the set screw hole. Next, place your eyes about 6" away from the eyepieces while looking at the chosen distant fixed object. View through both bino tubes together (at this 6" distance from the bino eyepieces) as you normally would do with regular viewing.

Turn the tiny screw back and forth slowly (less than 1/4 of a turn each way) while watching the images shift apart from one another or merge together. Find and stop turning it at the point where it seems to be best for a well joined (fused) image as viewed through both bino tubes. Note: Instead of being 6" away, you may have better results trying this procedure with the eyes right up to the binoculars as they would normally be used. See which works better for your eyes.

If the image still seems to remain a bit out of alignment no matter how close you can get the image to fuse, turn the tiny screw on the other tube in the same fashion to *walk* the images together better. The images will walk at a 90 degree angle to that of the first tubes adjustment screw motion. Once you get a feel for the motions involved with this, that should be all it takes to get good alignment with both optical tubes. The rubber covering most normally springs right back into place so there is not a need to glue it down. You can always go back and adjust things again if ever needed.

Good luck ... and may the images happily merge together for you!

Sincerely,

Tara Rodriguez

Barska Optics

Tara Rodriguez

Account Executive