So You Wanna Buy a Telescope: Advice for Beginners (2015) • Hacker News Board

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#21

Post by mrob » Mon, May 23, 2016, 6:23 AM UTC

_ph_ wrote: post #19

skybrian wrote: post #11

Why is astrophotography hard?

Astrophotography requires more experience with the telescope handling, a more stable platform and usually the best beginners telescope for observing isn't ideal for photography. For photography you should plan at least $500 for a tracking mount, you might start even with the cameras lenses or a small refractor telescope. "Barndoor" mounts are a good alternative for not too long focal lengths. Photographic mounts for…

Couldn't you use manual tracking at first? The steadiness of the tracking isn't so important if every individual exposure is short, and most cameras have a continuous mode so you can take many thousands of photographs. I've successfully stacked hand-held photos using Hugin:

http://hugin.sourceforge.net/

You will probably need a camera with raw support for this to work, because each individual exposure will be extremely noisy, and any in-camera noise reduction will destroy too much detail. You will probably also need at least two bright stars in frame for alignment to work.

And if you have a huge number of images you can also keep only those with low atmospheric distortion:

https://en.wikipedia.org/wiki/Lucky_imaging

The same principle could be used to keep only those images with little tracking-induced motion blur.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#22

Post by _ph_ » Mon, May 23, 2016, 6:39 AM UTC

mrob wrote: post #21

_ph_ wrote: post #19

Earlier quoted context omitted.

Astrophotography requires more experience with the telescope handling, a more stable platform and usually the best beginners telescope for observing isn't ideal for photography. For photography you should plan at least $500 for a tracking mount, you might start even with the cameras lenses or a small refractor telescope. "Barndoor" mounts are a good alternative for not too long focal lengths. Photographic mounts for…

Couldn't you use manual tracking at first? The steadiness of the tracking isn't so important if every individual exposure is short, and most cameras have a continuous mode so you can take many thousands of photographs. I've successfully stacked hand-held photos using Hugin: http://hugin.sourceforge.net/ You will probably need a camera with raw support for this to work, because each individual exposure will be extreme…

That could work - and I am a strong believer to try everything, even if the equipment at hand is not "officially capable" of doing the task. If one does that in the proper spirit of experimentation, this is great and you learn a lot and can have tons of fun. People who have no astronomy experience might though think that you can just take photos as you see them in the web or in magazines.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#23

Post by sankoz » Mon, May 23, 2016, 6:40 AM UTC

I wish I had come across this article earlier. Recently bought my first telescope: a 6" reflector with EQ mount (Celestron Astromaster 130 EQ). While the images are superb, I find it very hard to find my desired objects in the night sky. The finderscope on the unit is either useless, or I don't know how to use it correctly.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#24

Post by mangamadaiyan » Mon, May 23, 2016, 6:41 AM UTC

tilt_error wrote: post #17

joshumax wrote: post #9

Earlier quoted context omitted.

Another thing I commonly get is (after explaining that decent telescopes have the ability to swap eyepieces (If you're lucky it'll take 2" ones without vignetting)) is which eyepieces will "get the most zoom." People seem to be under the impression that because most objects in the sky are far away, they are also really "small." So if misguided they'll go buy 4mm Kellners with huge coma, have a painful time trying to…

In english? You seem to be giving good advice to newbees, but the language is incomprehensible to that audience.

There's a little context involved:

- The magnification you get from a telescope/eyepiece combination is F_t/F_ep, where F_t is the telescope's focal length, and F_ep is the eyepiece's focal length.

- There are different kinds of eyepieces, and not all of them perform equally well on all targets. Broadly, you have "Planetary" targets, which are the planets, and DSOs, or "Deep-Sky Objects". The latter category includes galaxies, nebulae, and the like.

---

Essentially, what GP is saying is, "Don't rush into buying equipment, look around and pick the right tool for the job".

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#25

Post by max_ » Mon, May 23, 2016, 6:42 AM UTC

I was expecting one that you could connect to a computer.

Can someone give me any recommendations?

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#26

Post by nikdaheratik » Mon, May 23, 2016, 6:46 AM UTC

tilt_error wrote: post #17

joshumax wrote: post #9

Earlier quoted context omitted.

Another thing I commonly get is (after explaining that decent telescopes have the ability to swap eyepieces (If you're lucky it'll take 2" ones without vignetting)) is which eyepieces will "get the most zoom." People seem to be under the impression that because most objects in the sky are far away, they are also really "small." So if misguided they'll go buy 4mm Kellners with huge coma, have a painful time trying to…

In english? You seem to be giving good advice to newbees, but the language is incomprehensible to that audience.

There are two problems in Astronomy:

1. Objects are distant so you only have so many photons from them that reach your current location. This means they appear "faint". The solution to that is a large aperture scope which collects more light.

2. Objects still appear relatively small even after collecting more photons. This can be improved somewhat by using an eyepiece to "zoom up" the image.

But just like magnifying a lower resolution image on a computer, the image through your scope gets fuzzy as you blow it up since you are still only collecting so many photons. So a good eyepiece doesn't help as much as beginners think it will.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#27

Post by kevinpet » Mon, May 23, 2016, 6:51 AM UTC

tilt_error wrote: post #17

joshumax wrote: post #9

Earlier quoted context omitted.

Another thing I commonly get is (after explaining that decent telescopes have the ability to swap eyepieces (If you're lucky it'll take 2" ones without vignetting)) is which eyepieces will "get the most zoom." People seem to be under the impression that because most objects in the sky are far away, they are also really "small." So if misguided they'll go buy 4mm Kellners with huge coma, have a painful time trying to…

In english? You seem to be giving good advice to newbees, but the language is incomprehensible to that audience.

The equipment that is sold for "this lets you do amazing things" is the worst equipment for general purpose use. In this particular comment, the magnification of a telescope is the ratio of the primary (mirror or lens) focal length divided by the secondary (eyepiece). An entry level scope might include a low magnification 25mm lens and a high magnification 10mm lens, but going down to 4mm will mean that the field of view is tiny making it hard to track objects. Also, higher magnification requires more light, so it will be dim on a small scope, and usually has a more limited range of eye relief, in other words, how carefully you have to move your head to just the right spot to see through it.

Kellner, EP: I think these are kinds of eyepieces, defined by the stacking of convex and concave lenses. DSO: Deep space object. FOV: field of view 2": the larger of two standard eyepiece form factors

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#28

Post by lake99 » Mon, May 23, 2016, 6:56 AM UTC

The advice here seems dated, even for 2015. Here's my advice:

1. Install an astronomy app on your mobile phone. Start with free ones, and see where it leads you. I recommend Skeye. This is good for going out by yourself and looking up things you see in the sky. For a PC, Stellarium is the best I have seen.

2. Get a camera capable of taking long exposure RAW photos, and get a tripod. There is so much hidden within the range of our FOV, that a telescope or binoculars are overkill. You'll use the camera for other things, so that won't be a special-nights-only investment. A basic DSLR should be fine, though I am curious about how well generic travel-zoom cameras do. If you have such a camera already, and played around with it, let me know.

Telescopes come after this stage.

> What about Astrophotography?

> Don't.

Sorry, this is shitty advice. His friend blew thousands of dollars on the hobby. I didn't.

> and untold thousands of rejected images

In the days of DSLRs? That's like saying I'm no good at computer games because of all the "bullets" that didn't hit my intended target. Lame. To put it bluntly.

> 8) Avoid any thoughts of astrophotography.

Fuck off.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#29

Post by aortega » Mon, May 23, 2016, 7:13 AM UTC

I disagree with the astrophotography thing.

Even with a telescope your human eyes are limited to planets and the moon, that's it. Forget about seeing galaxies with the naked eye, unless you have a 1-meter diameter telescope. All other objects are basically points of light. Artificial satellites are really fun to see, but also points of light.

But a 2006 DSLR (EOS400) that I found in the garbage, connected to a cheap newtonian telescope can capture 1000X the detail your own eyes can see. Is your telescope too small? no problem. Just increase the exposure or ISO, you cannot do that with your eyes.

I've seen comets moving in real time. Tracking satellites, resolving detail on the ISS, the moons of Jupiter and Mars, incredibly detailed nebula, and a freaking quasar, all this from my window in the middle of the city, with the highest light-pollution.

One advice I have is, try to get a scope that's no more than 15 kg. More than that, and it's a hassle to move.

And get a computerized robotic mount. They are expensive (~800 us$), but awesome. No point of getting a 15-century instrument today.

Re: So You Wanna Buy a Telescope: Advice for Beginners (2015)

#30

Post by starik36 » Mon, May 23, 2016, 7:21 AM UTC

wmblaettler wrote: post #3

Bought the recommended Orion XT8 Dobsonian a year ago for my 10 year old daughter (ok, and for myself!). It is super easy to setup (minutes), captures plenty of light and has been a joy to view through. I have observed the moon, Saturn, Jupiter and its moons and several Messier objects - even tracked a few satellites as they transited overhead.

Were you able to see the rings of Saturn with this telescope? How about the red spot of Jupiter? Any of its moons? And finally, do you observe these objects in a place with a lot of light pollution?