newby_investor
Executive Member
Eridanus or Telescope Shop. Have bought decent eyepieces from both of them.
I got a camera adapter from Amazon last year. I'll try and find a link. I'll describe more when I get back to a computer.
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The Amateur Astronomy thread
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I got a camera adapter from Amazon last year. I'll try and find a link. I'll describe more when I get back to a computer.
Sideshow Bob
Honorary Master
LOL - yeah.. my 2nd day as amateur - give me a break on my silly usage of terms randomly. I meant finderscope fit actually but once I did that I was going to align finderscope cross-hair to that of eye-piece so that I don't get 2 totally different views. That is what I meant.I think you meant aligning the finderscope and not collimation as that is something you only do when the mirrors inside the telescope is out of alignment.
So the o-ring goes into the narrower of the two grooves on the finderscope. The finderscope bracket then attaches to the telescope with the end of the finderscope bracket where the two adjustment screws are being closer the primary mirror end of the telescope. You then slide the larger groove end of the finderscope into the finderscope bracket from the secondary mirror end of the main telescope. The finderscope should slide into the finderscope bracket up to the point where the o-ring is out of sight (this can be a rather tight fit). The two adjustment screws on the finderscope bracket will tighten into the larger groove of the finderscope when you turn them. This will allow the front end of the finderscope to be somewhat fixed with the o-ring pressure and the back end of the finderscope adjustable via the two adjustment screws for alignment of the finderscope with the telescope.
Thank you very much. I think below bold part that you said is what no one seems to mention (or I missed it spectacularly). I will try this now.
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newby_investor
Executive Member
I bought the following for an astrophotography attempt:
I see shipping to SA at the moment is prohibitively expensive, but I was in the US a couple of years ago so I grabbed these on impulse. There may be something similar available here...
One thing that I found with my particular telescope / focuser, was that the range of motion of the focuser wasn't large enough that if I attached the camera directly (i.e. "prime") I couldn't get it in focus. I had to use the eyepiece adapter and I forget now but I may even have needed a Barlow.
My little telescope is a bit weeny, so attaching all this with a camera body on the side made it... impractical shall we say. The best that I've been able to produce so far, I announced in another thread (gosh nearly a year ago, how time flies!): https://mybroadband.co.za/forum/threads/astrophotography-orion.1039339/post-24010553
You've got a much bigger focuser on that 10", and the thing is a lot heavier so you may have more success than I did. Big Dobbies are more for visual observing though, for astrophotography you really want a refractor. You can get away with smaller aperture since you're typically going to do longer exposures, some people even pay big money for apochromatic lens setups to make sure there's no aberration. But now you're talking a much more expensive hobby than your R11k Takealot purchase ;-)
In terms of eyepieces:
In general, your magnification is the focal length of your telescope divided by the focal length of the eyepiece. Your Dob probably came with a 10mm and a 25mm Plossl eyepiece? (That's fairly common IIRC.) The focal length is 1200mm, so you'll get 120x and 48x magnification respectively. That's a fairly decent range.
For planets you may want a slightly higher power, because they're small. A 6mm will give you 200x, or a 4mm will give you 300x. Much past 200x unless atmospheric conditions are pretty much perfect isn't really useful, and past 300x is definitely not useful in my experience. You can in theory put a Barlow on a 4mm lens to get 600x magnification, but if you can aim your telescope at all with such high power, it'll just be so grainy and wobbly that it wouldn't be worth it.
For DSOs (deep-sky objects), depending on how extended they are, lower magnifications actually work better. Things like open clusters and nebulas benefit from lower magnifications. You're making use of the large aperture of the telescope then to gather more light to get it in your eye, rather than magnifying the heck out of things. (Hence why they often call big Dobbies "light buckets".)
There's a certain minimum for a telescope beyond which it's not worth going. To figure this out, take your aperture diameter (i.e. 250mm for the 10") and divide by 7mm. This is because - the largest that your pupil can dilate is about 7mm (a bit less, 6 or 5 even if you're older), so if you use less magnification than 250/7 then the light isn't even all going in your eye anymore. So the minimum magnification you should use is around 35x, which translates to a ~34mm eyepiece. Such long ones aren't common, but just bear this in mind when you do your shopping.
Quick tip: If any of your eyepieces say H (for Huygens) or K (for Kellner) then toss them in the bin. They'll make the experience horrible. Plossls are fine, I prefer something with a wider field of view and a bit more eye relief.
I have the full set of these: https://www.telescope.com/Orion-Expanse-Wide-Field-125-Eyepieces/e/55.uts
They are not the greatest, but they're good enough in all aspects that I quite enjoy using them. I wouldn't let them go unless I had much more expensive ones.
Other aspects to consider when choosing an eyepiece:
Eye relief - this is the amount of distance that your eyeball needs to be away from the glass. Longer is better - some cheap eyepieces, it's in the range of 1-4mm, this is uncomfortable. Mine are about 10-12 IIRC, and this is quite comfortable.
Apparent field of view (AFOV) - how big the circle is when you look in. Wider is better. Anything below 50 degrees - not worth it. 60 plus is nice, well beyond is available but then you get crazy expensive.
Amazon.com : Celestron 93402 T-Ring for Nikon Camera Attachment : Celestron Adapter : Camera & Photo
Amazon.com : Celestron 93402 T-Ring for Nikon Camera Attachment : Celestron Adapter : Camera & Photo
www.amazon.com
I see shipping to SA at the moment is prohibitively expensive, but I was in the US a couple of years ago so I grabbed these on impulse. There may be something similar available here...
One thing that I found with my particular telescope / focuser, was that the range of motion of the focuser wasn't large enough that if I attached the camera directly (i.e. "prime") I couldn't get it in focus. I had to use the eyepiece adapter and I forget now but I may even have needed a Barlow.
My little telescope is a bit weeny, so attaching all this with a camera body on the side made it... impractical shall we say. The best that I've been able to produce so far, I announced in another thread (gosh nearly a year ago, how time flies!): https://mybroadband.co.za/forum/threads/astrophotography-orion.1039339/post-24010553
You've got a much bigger focuser on that 10", and the thing is a lot heavier so you may have more success than I did. Big Dobbies are more for visual observing though, for astrophotography you really want a refractor. You can get away with smaller aperture since you're typically going to do longer exposures, some people even pay big money for apochromatic lens setups to make sure there's no aberration. But now you're talking a much more expensive hobby than your R11k Takealot purchase ;-)
In terms of eyepieces:
In general, your magnification is the focal length of your telescope divided by the focal length of the eyepiece. Your Dob probably came with a 10mm and a 25mm Plossl eyepiece? (That's fairly common IIRC.) The focal length is 1200mm, so you'll get 120x and 48x magnification respectively. That's a fairly decent range.
For planets you may want a slightly higher power, because they're small. A 6mm will give you 200x, or a 4mm will give you 300x. Much past 200x unless atmospheric conditions are pretty much perfect isn't really useful, and past 300x is definitely not useful in my experience. You can in theory put a Barlow on a 4mm lens to get 600x magnification, but if you can aim your telescope at all with such high power, it'll just be so grainy and wobbly that it wouldn't be worth it.
For DSOs (deep-sky objects), depending on how extended they are, lower magnifications actually work better. Things like open clusters and nebulas benefit from lower magnifications. You're making use of the large aperture of the telescope then to gather more light to get it in your eye, rather than magnifying the heck out of things. (Hence why they often call big Dobbies "light buckets".)
There's a certain minimum for a telescope beyond which it's not worth going. To figure this out, take your aperture diameter (i.e. 250mm for the 10") and divide by 7mm. This is because - the largest that your pupil can dilate is about 7mm (a bit less, 6 or 5 even if you're older), so if you use less magnification than 250/7 then the light isn't even all going in your eye anymore. So the minimum magnification you should use is around 35x, which translates to a ~34mm eyepiece. Such long ones aren't common, but just bear this in mind when you do your shopping.
Quick tip: If any of your eyepieces say H (for Huygens) or K (for Kellner) then toss them in the bin. They'll make the experience horrible. Plossls are fine, I prefer something with a wider field of view and a bit more eye relief.
I have the full set of these: https://www.telescope.com/Orion-Expanse-Wide-Field-125-Eyepieces/e/55.uts
They are not the greatest, but they're good enough in all aspects that I quite enjoy using them. I wouldn't let them go unless I had much more expensive ones.
Other aspects to consider when choosing an eyepiece:
Eye relief - this is the amount of distance that your eyeball needs to be away from the glass. Longer is better - some cheap eyepieces, it's in the range of 1-4mm, this is uncomfortable. Mine are about 10-12 IIRC, and this is quite comfortable.
Apparent field of view (AFOV) - how big the circle is when you look in. Wider is better. Anything below 50 degrees - not worth it. 60 plus is nice, well beyond is available but then you get crazy expensive.
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Sideshow Bob
Honorary Master
I have heard that DOB is not great for AP but going to try it once I figure few things out. Planning to buy this
Telescope Camera Lens Adapter Metal Bracket 1.25inch T-Ring for Nikon Mount
Telescope Camera Lens Adapter Metal Bracket 1.25inch T-Ring for Nikon Mount Features: It offers 1.25 inch mounting sizes on telescope side. Attach for Nikon DSLR camera to the telescope with standard 1.25 inch It is compatible for Nikon camera Color: Black Material: Aluminum Size: 5.5cm x...reliablestore.co.za
Come to think of this - I will give this site a miss.
I think these guys have moved off bidorbuy and set up their own site as they don't have a single item for sale on bob. Last 10 feedback received on bob site are negative. Please beware of this if you want to deal.
Items for sale from ReliableStore on bobshop.co.za
View all the items offered for sale by ReliableStore on bobshop.co.za
I have bought astronomy items from these guys before: https://shop.technopro.co.za/. Been a while but perhaps check them out as well.
Sideshow Bob
Honorary Master
Thanks. Looking for barlow lens and T-ring for nikon, will have a look there.
All skywatcher items are out of stock on technopro. Found this one. I hope it fits the skywatcher one - at least size is same - 2". Going to enquire and find out.
TechnoPro - Alpen HSS Super Drill Bit 2mm Bulk
HSS JOBBER DRILLS DIN 338 RN HSS SUPER - Ø 2,0 mm precision jobber drill bit Bulk packaging: Qty 10 drill bits - priced per individual bit Range of application: HSS twist drill ground from solid, bright finish: toughness and precision combined with excellent cutting efficiency for drilling...
shop.technopro.co.za
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newby_investor
Executive Member
They are the guys that operate Skywatcher.co.za it seems.
newby_investor
Executive Member
The Skywatcher stuff is out of stock on that site because (it seems) that they now sell on skywatcher.co.za. Was it you that posted that link initially? If you look at the "contact us" pages, you'll see it's the Technopro guys.Thanks. Looking for barlow lens and T-ring for nikon, will have a look there.
All skywatcher items are out of stock on technopro. Found this one. I hope it fits the skywatcher one - at least size is same - 2". Going to enquire and find out.
TechnoPro - Alpen HSS Super Drill Bit 2mm Bulk
HSS JOBBER DRILLS DIN 338 RN HSS SUPER - Ø 2,0 mm precision jobber drill bit Bulk packaging: Qty 10 drill bits - priced per individual bit Range of application: HSS twist drill ground from solid, bright finish: toughness and precision combined with excellent cutting efficiency for drilling...
Why do you want a Barlow exactly? Depending on what you want to look at, I'd have thought a wider-field eyepiece would be more useful.
Sideshow Bob
Honorary Master
So, I got 10mm and 25mm eyepiece that comes standard with traditional dob. With Barlow 2x, I would effectively get 5mm and 12.5mm if I read your earlier post correctly. I just want to experiment now that I got the tele. And using barlow would increase eye relief as well, right? I need it as I wear spectacles.
Sideshow Bob
Honorary Master
They do. I called them last week for telescope enquiry and lady said go to technopro site.
newby_investor
Executive Member
Your maths regarding the effective focal lengths is correct. Magnification isn't everything though. The Barlow will double your effective magnification but it comes at a cost of some image quality. If you get the opportunity at some stage to compare a 5mm eyepiece to your 10mm plus a Barlow, you'll likely see less distortion especially at the edges. Granted, with astronomical objects this is seldom of much importance, especially if you're not photographing.
I don't think a Barlow will help with eye relief. At least that hasn't been my experience. The Barlow goes into your focuser first, then the eyepiece into the Barlow. So the eye relief is really just a function of the optics of your eyepiece. Unless I'm much mistaken, as it's not something I've experimented with personally.
Depending on Why you need specs, you may even be able to get away without using them at all. If you're near- or far-sighted, you can remove your specs and just adjust the focuser slightly further forward or back compared with where a person without glasses would put it. If you're astigmatic though, this probably won't work.
Two points that I just want to make. The first is that there's no wrong way to do amateur astronomy. Whatever brings you the most pleasure is fine.
The second is that it's tempting when you're in the heat of the moment to rush off and get loads of toys. If you can afford this, great, but I suspect you'll want to spend your pocket money judiciously so that you can get the most pleasure for your hard earned rands. I had the advantage that I got to play with other people's toys for a while before buying my own. Credit to the guys at the Pretoria centre for that.
I have a Barlow but I don't remember it costing that much. I also don't use it a lot unless I'm trying to observe planets. Probably the accessories that I've gotten most use out of (apart from my eyepieces) are the red dot finder, and a dual-polarised filter for observing the moon. (The moon is really bright! It can hurt your eyes without some kind of a dimming filter in the way.)
Sideshow Bob
Honorary Master
Lol - been there when I got my Nikon DSLR - not gonna buy just because I can. Thankfully, I bought moon filter along with telescope - it came strongly recommended in couple of forums.
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newby_investor
Executive Member
Indeed! So it's best to take time to see what's best to spend the funds on. But invariably you will need to experiment a bit to see what works best for you.
On the topic of moon filters, not all are created equal.
The basic kind is like this:
Celestron Moon filter - R425.00 : Eridanus Optics CC, Affordable telescopes available in South Africa
Eridanus Optics CC Celestron Moon filter - Celestron 1.25" Moon Filter.Celestron's Moon filter is an economical eyepiece filter for reducing the brightness of the moon and improving contrast, so greater detail can be observed on the lunar surface. The clear aperture is 21mm and the transmission...
eridanusoptics.com
I subsequently got myself one of these:
Amazon.com : ICE 1.25" Variable Polarizing Eyepiece Moon Filter for Telescope Polarizer : Camera & Photo
Amazon.com : ICE 1.25" Variable Polarizing Eyepiece Moon Filter for Telescope Polarizer : Camera & Photo
www.amazon.com
Filters in general are actually a whole 'nother rabbit hole that I haven't ventured too deep down. I've heard that for visual observers, a light-pollution filter (something like this: http://eridanusoptics.com//store/index.php?main_page=index&cPath=167_20_76_45) can help if you're observing from your suburban back yard, but I've never actually tried one. You get all sorts of individual colour filters which are really more useful if you're photographing.
LlamaParty
Well-Known Member
- Joined
- Oct 17, 2018
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It depends on how much you want to spend, you can go crazy with Televue and other expensive brands but I don't think that's quite necessary for someone starting out.
I bought a set of these "red line" and "gold line" eyepieces from Amazon, they get decent reviews on some astronomy forums:
They're obviously not top of the line but they're better than the Plossls you get with the scope. They have a wider field of view and more eye relief at the shorter focal lengths.
Just don't get that Celestron accessory kit on Takelot, it has more crappy Plossls and filters you don't need, not worth the money.
newby_investor
Executive Member
These look exactly like my "Orion Expanse" eyepieces. Same 66 degree AFOV as well. Probably made in the same factory, just with a different sticker.
Like you said - not top of the line exactly, but you have to spend a lot of money before you get significantly better.
LlamaParty
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Two bits of gear that made a big difference for us was a RACI (Right Angle Correct Image) finder scope, and one of those strong green lasers.
The RACI finderscope makes it a lot easier to star hop, because everything isn't upside down, and the right angle makes it just so much easier to look through. We got one like this:
https://shop.technopro.co.za/skywatcher-9x50-rightangled-erecting-finder scope-p-801.html?cPath=336_194_5_125_149
What I found tricky sometimes was just getting the scope to point at the right spot in the sky, this is where the green laser comes in. You shine it right through the eyepiece or finder scope and it projects a beam out of the scope into the sky where its pointing. Then you can easily move it around to point in the right general direction and fine tune with the finder scope from there.
The RACI finderscope makes it a lot easier to star hop, because everything isn't upside down, and the right angle makes it just so much easier to look through. We got one like this:
https://shop.technopro.co.za/skywatcher-9x50-rightangled-erecting-finder scope-p-801.html?cPath=336_194_5_125_149
What I found tricky sometimes was just getting the scope to point at the right spot in the sky, this is where the green laser comes in. You shine it right through the eyepiece or finder scope and it projects a beam out of the scope into the sky where its pointing. Then you can easily move it around to point in the right general direction and fine tune with the finder scope from there.
Sideshow Bob
Honorary Master
LlamaParty
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Aww damn, looks like these guys do, but the prices have gone craaaaazy. I bought mine on special for $10 each.
It might be worth it to try again in a month or two when things have calmed down.
Amazon.com : Astromania 1.25" 15mm 66-Degree Ultra Wide Angle Eyepiece for Telescope : Camera & Photo
Amazon.com : Astromania 1.25" 15mm 66-Degree Ultra Wide Angle Eyepiece for Telescope : Camera & Photo
www.amazon.com
It might be worth it to try again in a month or two when things have calmed down.
newby_investor
Executive Member
This is a cool trick. Totally non-obvious until you've seen someone do it. It blew my mind. I use it all the time now.
When I get my telescope out that is
I'd forgotten about the laser actually.It *looks* to me as though this is basically the same thing but with a different sticker:
Orion Expanse eyepiece set - R2,595.00 : Eridanus Optics CC, Affordable telescopes available in South Africa
Eridanus Optics CC Orion Expanse eyepiece set - Orion Expanse eyepiece setFor 1.25" focusers; 6mm, 9mm, 15mm and 20mm; Fully coated; 66° field of view; Threaded for filters.Money-saving set of all four Orion Expanse telescope eyepiecesSet includes 6mm, 9mm, 15mm, and 20mm focal length eyepieces...
eridanusoptics.com
Might be worth doing some more research though.
LlamaParty
Well-Known Member
- Joined
- Oct 17, 2018
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- 156
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I know! The first time someone showed me that laser trick I felt so dumb that I hadn't tried it before.This is a cool trick. Totally non-obvious until you've seen someone do it. It blew my mind. I use it all the time now.
When I get my telescope out that is
It *looks* to me as though this is basically the same thing but with a different sticker:
Orion Expanse eyepiece set - R2,595.00 : Eridanus Optics CC, Affordable telescopes available in South Africa
Eridanus Optics CC Orion Expanse eyepiece set - Orion Expanse eyepiece setFor 1.25" focusers; 6mm, 9mm, 15mm and 20mm; Fully coated; 66° field of view; Threaded for filters.Money-saving set of all four Orion Expanse telescope eyepiecesSet includes 6mm, 9mm, 15mm, and 20mm focal length eyepieces...eridanusoptics.com
Might be worth doing some more research though.
You're right, they do look veeeery similar. Most of Orions stuff is made by Synta I guess, which is Chinese, so I wouldn't be surprised. One would just need to decide if you need all four of those focal lengths.