Comment by Prey4Jesus | Hacker News Reader

Comment by Prey4Jesus | Hacker News Reader

The most important thing to look for is the diameter of the aperture. Your resolution is proportional to the diameter of the telescope (absent atmospheric conditions). I would recommend a minimum of 6" in diameter. 8-12" is preferred.

With this in mind, the best telescope you can get for the price is a Dobsonian. Dobsonians are extremely mechanically and optically simple. This makes them long, and bulky. It also makes them cheap. It also makes them rather easy to point. They have a lot of mass and inertia, and a large moment of inertia. This makes them easy to move and point slowly and carefully.

Dobsonians are ideal beginner telescopes. Easy to point, cheap, good resolution.

This is the model I have (8" aperture, $450): https://www.amazon.com/Orion-8945-SkyQuest-Dobsonian-Telesco...

They're also rather easy to construct, if you are of a DIY mind. Here's a 90 minute youtube video on how to build one, with John Dobson himself: https://www.youtube.com/watch?v=snz7JJlSZvw

I'll glom on this only to add that while building your own reflecting telescope is valuable as a fun project or an educational exercise, you are unlikely to save much (if any) money doing it. A lot of John Dobson's "Sidewalk Astronomer" guidance comes from a time in Southern California where it was easy to find discarded porthole glass for free to grind into a mirror blank and when hardware shops would hand out teflon samples for free. Even finding the correct cardboard "sonotubes" can be a little tricky these days, and you're likely to blow out the price of an Orion or Apertura procuring a mirror (or sourcing the glass and getting it silvered.)

I hope that doesn't deter the "makers" among you from building a Dobsonian for the experience of it all, but if you want to get from zero to observing as cheaply as possible these days, you're probably better off just buying a Dobsonian similar to the one the parent comment linked.

Great advice! Start with good binoculars for $100-200. I would get a used telescope. Many of them are as good as new and here in Germany you get them for 50-70% of the regular price.

I bought an 8" SC myself used for 550€ including a mount with tracking.

binoculars cant go too far, the diameter is too small to allow enough light to be concentrated into your eye. With binoculars, u can look at the moon. boring. with a telescope, well u can see the planets live and take amazing photos

Orion has considered this problem... :)

https://www.amazon.com/Orion-2x54-Ultra-Angle-Binoculars/dp/...

That's a wider FoV, not a larger diameter objective. I was thinking more along the lines of...

http://www.jerryoltion.com/binoscope.htm

Or on a more serious note, binoculars do come with pretty large objectives, but they get to be expensive when you get past 100mm. Here's one with 150mm objectives. And since binoculars have two objectives, that has the light-gathering capability of an 8-inch telescope.

https://www.apm-telescopes.de/en/telescopes/bino-telescopes/...

With a nice pair of coated binocs you can see some of the closer star clusters. Of course Andromeda is always a good view. And the occasional bright comet too.

The nice thing about binocs is they are easier to bring out than the scope. Plus they give the wife something to look at while I find cool stuff with the scope.

You can see a lot even with a pair of pocket binoculars. Easy targets are the moons of Jupiter, the Pleiades, and the Orion nebula. A good pair of binoculars will resolve the naked-eye planets to small disks and the stars to points.

With pretty much all binoculars you can see Jupiter's moon, which is a real eye-opener.

I have a 4.5" Dobson. It is quite cheap even with an additional set of eyepiece that is almost mandatory. Our use case is occasional observation while on holidays and weekends, when space in the car is counted. You can leave kids touch it and on good nights reach magnification levels where pursuit starts being painful. Around 11-12PM kids are asleep, cold, bored and you have observed every visible planets. You can stay later searching for deep sky objects: it is difficult and not very impressive but you'll be quite happy when you find one for sure (often you'll doubt). I would say: perfect instrument for the setting I describe. Maybe binoculars would be great too, have not tried.

Agree on the Dobsonian on being a great entry level option unless you need to be mobile. You can still be mobile with a smaller dobsonian, but the bigger you get, the harder mobility becomes.

I think 6" is still pretty manageable for most people--you can probably fit it in the trunk of a sporty two-seater car. It's really only when you get to 10" and beyond--telescopes that are probably not a good "first scope" purchase for a variety of reasons--that the Dobsonian becomes a beast.

Yes, you absolutely hit what I was thinking! I was thinking the 6" Dobs would be portable, the 8" still ok, but past that ... probably not so much!

Unless you want to image things, either for EAA or full blown astrophotography, in which case the question is more about the mount than the telescope.

If you want to get into astrophotography, the phrase "entry-level" should probably not be in your vocabulary any more, though.

This is pretty universal advice, yes, in most (all?) skywatching tutorials. The astrophotography rabbit hole is deep, infinitely expensive and the learning curve is steep. It's a lot more sensible to start with visual observation.

(That said, I ignored the advice because really wanted to do photography more than anything else.)

Your parenthetical is why I commented - astrophotography isn’t just more advanced visual astronomy, it’s really a separate hobby.

That might be true in general, but this is a forum full of highly technical people. At the end of the day, doing basic Astro is not rocket science, and if OP is into photography they might be more interested in buying a small tracking mount for their DSLR than a telescope.

The hobbies are more parallel than sequential.

Did some Googling — apparently you can use Dobsonian for astrophotography.

Seems to me the field is wide open for someone to come in and solve it using off-the-shelf hardware. Maybe tapping the CCD and detecting the minuscule changes ... servo to rotate the CCD, servos to adjust pitch, yaw ... a feedback loop that blips the servos and decides if the image error is increased or diminished....

I'm not surprised one can do it but it seems kind of silly, like using a motorcycle to pull a plow, or using a microwave oven to bake a cake. By the time you get it working halfway well, you could have just bought the right piece of equipment in the first place.

> Seems to me the field is wide open for someone to come in and solve it using off-the-shelf hardware.

Solve what?

You certainly wouldn't be the first to build a motorized tracking mount for astrophotography. There are plenty of existing products for manually-aligned star-trackers, and several still for "autoguiding" trackers that use the position of fiducials in the image plane. (These can use either a mirrored split in the optical path of the main imager "on-axis", or use a piggy-backed guidescope imaging system on the same mount.)

Check out high-gain, high-sensitivity imagers like the ZWO ASI290MM Mini, controller like the ZWO ASIAIR Pro, and tracking mounts like the iOptron CEM25P or Sky-Watcher EQ6-R Pro.

These are expensive, carefully engineered solutions, though. They don't really exist in the same market space as Dobsonian telescopes, and it wouldn't make any sense to make those tracking solutions twice as complicated and twice as expensive using by non-equatorial mounts.

I was unable to find a tracking solution for Dobsonian mounts. If they exist, awesome. I doubt a home-brew solution though would cost as much as the ones you identified.

This is already a thing (tracking + derotator+ ccd in alt-az), but it’s super expensive and doesn’t work as well as just using an equatorial mount in the first place.

More basic tracking dobs are used for planetary and lunar astronomy though due to the shorter exposure times.

Would these be of any use in the bay area or places with high population and hence light pollution? I have clear view of my sky from my backyard except for the ambient light pollution in the sky.

I'm stunned how much I can see even with a bit of cloud cover in my front yard (and we have streetlights close by). But of course, you should probably get a case and go camping with one of these (in a secluded area) for best results)

This is the sort of thing where darker is always better, but John Dobson started a movement around "Sidewalk Astronomy" in the 60s and 70s in San Francisco with this very telescope design. I'm sure the light pollution has gotten worse since then, but the moon, the planets, and perhaps a few brighter Messier objects will still be within reach. It's a big sky and there's a lot to see.

> I'm sure the light pollution has gotten worse since then

Perhaps. In the South Bay they still have many of the sodium street lights because of Lick Observatory in the hills. I'm always amazed at how well you can see the stars from my driveway. I don't recall it being as clear in the midwest when I lived there.

There was a guy who regularly brought out his Dob (11" I think) in the Sunset district of San Francisco near Parkside Square as part of Sidewalk Astronomers public outreach. Good views of the moon, saturn, jupiter some nebulae, etc. and the San Francisco Amateur Astronomers often held star parties near at Land's End and Crissy Field pre-pandemic though their main viewing spot is usually Mt. Tam I think. Quite a few of Dobs show up I think.

just make sure the diameter is as large as you can afford. Watching Saturn with its ring and moons is something i still remember 20 years later. Definitely a good investment

Saturn is quite bright — you don't need much diameter (aperture) to see the rings. A smallish refractor with the right eyepiece (50x magnification) is enough.

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