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Thinking about buying my first telescope.(r/Astronomy)
EDIT: This post has been edited many times. I may continue to do so. Or not.
> What kind of things would I be able to see with this scope?
Almost anything that your sky could show you. Saturn’s rings, including the Cassini division. Jupiter’s equatorial belts. Lots of tiny details on Moon’s face. Sunspots (with an appropriate solar filter, which must always be used when watching the Sun; the finderscope must be capped or removed from the scope). Double and multiple stars like Albireo and Mizar. Globular clusters like M13. Galaxies, nebulae and so on. Tons of stuff, the words fail.
> Any suggestions for a first timer?
I’m going to give you a lot of info. Don’t let it overwhelm you, it’s a lot but you don’t have to do all that stuff at once. Just bookmark it and tackle each issue separately as you gain more experience. Easy does it.
I wish someone told me all these things at once when I was a beginner.
Here we go.
What type of telescope should I get? There’s dobsonians, then there’s refractors, SCTs, Maksutovs, etc. etc.
Which ones are better for planetary observations? Which ones are better for deep space stuff?
Which ones are more portable? And how about maintenance?
Some answers to this type of questions:
Some extra theory to read.
Magnification, seeing, resolving power:
Did you know that any telescope has a limited range of useful magnification? A few cool facts about telescopes and what they can, or cannot, do. (Warning: some math included, avoid if allergic) from Astronomy
How bright is an object seen in a scope:
Keep your scope collimated, if it’s a newtonian OTA (like a dobsonian). This is the most common mistake that many people do – they don’t collimate their newtonian and then performance takes a dive. There are many techniques and procedures, it can be bewildering. Google how to collimate a telescope and apply that knowledge. Start doing this right from the beginning, and keep learning.
If you use a laser collimator, make sure the laser itself is collimated:
You could use the star test to check collimation, some say it’s the ultimate performance test for a scope. Plug in a strong eyepiece, point it at Polaris, and investigate the diffraction rings:
Once the scope is collimated, you’ll get an additional performance boost by using a mirror fan – but don’t worry about that at first:
Reflectors 4″ or smaller usually don’t need a fan. 6″, fan is kind of optional. 8″ or bigger, definitely use a fan.
Before making an observation, turn the fan on full blast and take the scope outside, let it reach thermal equilibrium for 15…20 minutes or so; more is okay, less is not. Then reduce the fan speed to a mere trickle, and start observing; keep the fan on for the entire duration, at low speed, as long as it doesn’t create vibrations (if you turn the fan off and stars are suddenly not fuzzy anymore, then it was creating vibrations). A PC fan speed controller (cheap gizmo you could find at the computer store) is very useful.
Vibrations are usually reduced if the fan is on an elastic suspension, as opposed to rigidly attached.
If you don’t have a fan, at least take the scope outside about an hour before starting the observation, let it “breathe out” all the heat.
Eyepieces need maintenance too. The eye-facing lens gets dirty within seconds of using it. It’s the oil on your eyelashes that sticks to the glass and blurs the image. It’s unavoidable.
The best procedure for cleaning them up is explained by Tele Vue, the makers of top performance eyepieces in the US:
TLDR: Blow off the dust, then use Q-tips and a little reagent acetone or alcohol. Careful with acetone on cheap eyepieces, better use alcohol there.
Get a book called “Turn left at Orion”, it’s full of suggestions for interesting things to watch. Very useful when you’re new to this hobby and have no idea what the scope can do.
You’ll need some sky maps. A planisphere is the most basic one, not a lot of detail, but it gives you a snapshot of the whole sky at once.
A pocketbook atlas has lots more detail:
The ultimate resource would be something like Wil Tirion’s “Uranometria 2000.0” and “Sky Atlas 2000.0”, huge books with lots of details, but don’t worry about that now.
On a computer or smartphone you could install Stellarium or SkySafari, which are electronic maps.
Subscribe to Sky & Telescope, they have lots of up to date info.
A few words about finderscopes, since they are a very important tool in the process of finding objects on the sky:
When you observe “faint fuzzies” like galaxies and nebulae, it’s important that your vision is dark-adapted. Complete dark adaptation occurs after spending 30 minutes in perfect darkness – you may not want to do this every single time, or even often, but it’s required on those rare occasions when you do a particularly difficult observation of some faint nebula. Most cases when looking at faint fuzzies, just stay in a dark place.
For reading the maps, changing eyepieces, etc., use a variable red flashlight. Red light does the least damage to your dark adaptation, and if it’s variable you should keep it on the minimum useful level of light.
When observing the Moon or the big planets, don’t worry about dark adaptation, it’s not needed if your scope is not too big. In fact, the Moon is painful to look at if you’re dark adapted, so don’t. Some folks use “moon filters”, but those are not needed if you don’t let your pupils dilate too much and you observe at a small exit pupil in your scope (1 mm or less). Just stay under plenty of ambient light for the Moon-observing sessions. I look at the Moon from a place right under the street light.
Dark adaptation is not dogma. Use it wisely.
Speaking about filters. There’s colored filters, “moon filters”, light pollution filters, OIII filters, Hydrogen beta, UHC, and so on. Which one to get? Short answer – no filter, at first. Use the scope as-is for a while. After you get some experience at the eyepiece, read this and make a decision:
For planets, the Moon, and double stars, you’ll need high magnification – from 100x…150x to as much as the scope and seeing would allow. These are high resolution objects, and are affected by air turbulence – “seeing” as we call it. They are NOT affected by light pollution; in fact, the Moon and Saturn’s rings could be observed even at sunset, before full darkness.
You could predict seeing if you go to this site, choose a location nearest you, and watch the third row in the diagram – if it’s dark blue then seeing is good:
For nebulae, galaxies and so on, low and medium magnifications may be used, sometimes high. These are faint objects which are affected by light pollution; if light pollution is strong, you’ll have a hard time observing them; seeing doesn’t matter for these objects. Here’s a light pollution map:
> If anyone has pictures of images they’ve captured with their scope, if they could post them so I could get an idea that’d be great.
Nobody should start directly with astrophotography. It’s tricky, it requires experience, dark sky, and good (expen$ive) gear – that is, if you want to do it right. Do some purely visual astronomy for a while, gather some experience, then you’ll make far better choices.
Join the local astronomy club and go to star parties. That’s a good way to learn a lot quickly.
An 8″ dob is a great way to start with astronomy, since it has a very high performance / price ratio. It is not a great scope for photography (but at less than a few thousand dollars, there is no great astrophotography stack that you could purchase anywhere).
If you do want to get started on an 8″ dob, the Zhumell Z8 is a better deal than the XT8.
Don’t go on an eyepiece shopping spree. Most newbies think that they would automatically get better results if they buy more glass, which is not always the case. The Z8 comes with a 30 mm and a 9 mm, which are a good start. A 2x barlow combined with the 9 mm would give you a “virtual” 4.5 mm eyepiece, which is good for high magnification.
Later on, after you gather some experience, if you’re looking to buy better eyepieces, look into the Explore Scientific 82^o series, they provide 90…95% of the performance of Tele Vue at 1/4 or 1/3 the price.
One issue with dobsonians is that the eyepiece height is not fixed. Sometimes it’s high, other times it’s low. An adjustable chair would be great. There are some nice commercial solutions, like the Catsperch chair, but they can be expensive. A cheap alternative is the Denver observer’s chair. You can either purchase it, or make one in a week-end from a 2×4 and various bits of hardware. Here are some plans:
Here is a slightly modified plan: