The Amateur Astronomy thread

AntennaMan said:
Only able to go at the end of the month. And I'm guessing the first visit not much will happen. I'm going to see what everyone else does and how well it turns out.
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I spent some time there about 5-6 years ago. Always lots of interesting projects on the go.
 
Item: Celestron 1.25" eyepiece kit

Age: 2 years
Price: R4,500 neg
Warranty: none
Packaging: Yes complete
Condition: as new 10/10.
Location: JHB / Fourways
Reason: Don't own telescope anymore, can't use
Shipping: On buyer
Collection: Yes
 

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theratman said:
Nothing extensive, some mountain and ocean viewing. Something more powerful than binoculars for casual viewing. Budget around 2k. I'm looking at a Celestron 70AZ as an option but honestly have no clue.
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So, some things to consider when you are looking for a terrestrial scope.

  • Astronomical telescopes often give you an image that is upside down or inverted left/right. For viewing stars and planets, this matters little, and the extra reflection or two that you need to correct the image's orientation wastes contrast! ;) So if you want to buy a telescope for terrestrial viewing (i.e. stuff that's on earth) look for the keywords "erecting" (or "erect image") diagonal. The diagonal is the bit that goes between the tube and the eyepiece (on a refractor scope anyway)
  • Cheap telescopes can be frustrating. The OTAs (Optical Tube Assemblies) are usually not actually that bad, so if you gave me a Celestron 70AZ, but I could use my mount and eyepieces, then I'd get good-ish images out of it. The eyepieces that come with them are typically crappy, and the mounts (and tripods in fact) are so wobbly that you won't be able to see anything if there's even the slightest wind (or if someone touches the telescope).
So. Some recommendations, bearing in mind your budget.

I'd recommend the following: how much more powerful than binoculars do you want? Would you consider more powerful binoculars?
I have some of these for instance:

Celestron SkyMaster 15 x 70 Binocular - R2,095.00 : Eridanus Optics CC, Affordable telescopes available in South Africa

Eridanus Optics CC Celestron SkyMaster 15 x 70 Binocular - Celestron SkyMaster 15 x 70 Binoculars.Celestron's SkyMaster series of large aperture binoculars are a phenomenal value for high performance binoculars ideal for astronomical viewing or for terrestrial (land) use, especially over long...
eridanusoptics.com
They work quite well in the daytime and at night, but the limitation is that they're quite heavy and it's difficult to hold them steady. I have always meant to build myself something like this, but never quite gotten around to it.

Another alternative which is specifically a terrestrial scope, not even pretending to be an astronomical one, is something like this:

Celestron 60mm LandScout Spotting Scope - R1,845.00 : Eridanus Optics CC, Affordable telescopes available in South Africa

Eridanus Optics CC Celestron 60mm LandScout Spotting Scope - Celestron 60mm LandScout Spotting ScopeWinter special while stock lastQuick OverviewThis Celestron 60mm LandScout Spotting Scope is an affordable, entry-level spotting scope.Eyepiece angled at 45º allows tripods to sit at lower...
eridanusoptics.com
(They're called Spotting Scopes, I think they are originally designed for use in hunting, but will work just as well for watching birds or whales.)

I only know of the above seller, feel free to shop around though. It's best if you can find someone that has something like this and try it out first, to see if it meets your requirements. Cheaper certainly than spending the money and deciding that you don't really like what you're experiencing.
 
^^Thanks for the time you out into that response.

The telescope is a gift for my father, I considered getting a ok set of binocs but I know he already has a good pair. A spotting scope would have been ok, but not as versatile as a set telescope.

I ended up picking up the 70az as it ticked a few boxes wrt to size and function, also simple for him to use. It says it does terrestrial viewing and was within budget.

I'll give some feed back early December once it's been gifted.
 
surface said:
Assuming one has interest and money, do we (in SA) have all the parts available to build something like this ?

https://www.reddit.com/r/space/comments/k83ujw
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The hardest thing to get would be a piece of glass big enough. Bigger than about 10" they become rather unwieldy.

The rest is just what anyone with a few power tools can put together in a weekend. It's not that hard. The crowd in Joburg that hosts Scopex will likely be able to provide input on that.
 
surface said:
And? No pressure. :p
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I went there a couple of weeks ago. One of the gents was kind enough to spend some time chatting to me, discussing everything.

His recommendation is to start with a 6 inch f8, and to maybe order the first set of mirrors, just to test the waters. They can then help with the tube assembly.
Their rule of thumb is that grinding takes around 1 hour/square-inch and another 1 hour/square inch for the polishing. So a 6-inch mirror will take around 30 hours to grind and another 30 to polish. 8 inch will be 50/50.

He showed me a 16-inch glass blank that a newby started, but never finished. For reference, using their rule of thumb, that will be 200 hours of grinding and another 200 of polishing!

Currently, I'm waiting for Agena Astro to get stock of their mirror sets, as that might be the best for me, as I can't commit the full 60-80 hours of grinding and polishing at this time.
 
AntennaMan said:
I went there a couple of weeks ago. One of the gents was kind enough to spend some time chatting to me, discussing everything.

His recommendation is to start with a 6 inch f8, and to maybe order the first set of mirrors, just to test the waters. They can then help with the tube assembly.
Their rule of thumb is that grinding takes around 1 hour/square-inch and another 1 hour/square inch for the polishing. So a 6-inch mirror will take around 30 hours to grind and another 30 to polish. 8 inch will be 50/50.

He showed me a 16-inch glass blank that a newby started, but never finished. For reference, using their rule of thumb, that will be 200 hours of grinding and another 200 of polishing!

Currently, I'm waiting for Agena Astro to get stock of their mirror sets, as that might be the best for me, as I can't commit the full 60-80 hours of grinding and polishing at this time.
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I never finished mine. I got it ground, but not polished. Those rules-of-thumb sound about right.

I'd do it while watching TV in the evenings with the fam. But then I graduated, got a job, moved to Cape Town, and never actually finished. I wish I had :-(
 
AntennaMan said:
I went there a couple of weeks ago. One of the gents was kind enough to spend some time chatting to me, discussing everything.

His recommendation is to start with a 6 inch f8, and to maybe order the first set of mirrors, just to test the waters. They can then help with the tube assembly.
Their rule of thumb is that grinding takes around 1 hour/square-inch and another 1 hour/square inch for the polishing. So a 6-inch mirror will take around 30 hours to grind and another 30 to polish. 8 inch will be 50/50.

He showed me a 16-inch glass blank that a newby started, but never finished. For reference, using their rule of thumb, that will be 200 hours of grinding and another 200 of polishing!

Currently, I'm waiting for Agena Astro to get stock of their mirror sets, as that might be the best for me, as I can't commit the full 60-80 hours of grinding and polishing at this time.
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Thanks for feedback. Starting small sounds a good plan. 60 hours is fine I think but I suppose one needs to spend this time at the centre as they will have all the power tools?. Will look at Agena astro - not sure how long it takes though. Did they tell you what exactly to order? and if you could share it here? Thanks.

p.s. looked at 8-inch mirror - will cost 5K including shipping.
 
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surface said:
Thanks for feedback. Starting small sounds a good plan. 60 hours is fine I think but I suppose one needs to spend this time at the centre as they will have all the power tools?. Will look at Agena astro - not sure how long it takes though. Did they tell you what exactly to order? and if you could share it here? Thanks.
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The general feeling at the ATM club is to avoid power tools. You get a better surface if you do it by hand because you can make it more random. Some of them have experimented with power tools as far as I remember but most do it by hand.

You use two pieces of glass, and then progressively finer grit, and rub them against each other. I made a little wooden jig to hold my bottom one in place. Like I said, most of my hours took place in front of the TV with the family in the evenings.
 
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