Barlow lens
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By thepainpastor
Greetings All!
Very Short Explanation: I'm disabled (43) and desperately trying to find ways to still bond/spend time with my youngest son (13).
My son expressed an interest, about two months ago, in Astronomy after watching a few YouTube videos on the subject (specifically, the moon and our neighboring planets). He asked if one day we could get a telescope. I was somewhat surprised when, over the course of the following days/weeks, he didn't forget about his request or shift his attention to other, "more 13 year old pressing matters." In fact, he became increasingly MORE excited, despite our lack of progress on the subject (except for many hours of questions and research regarding all things space).
So, I decided that somehow, someway, I would discover the means in which to make this dream of his a reality. However, due to our financial situation, I wasn't sure it would ever happen. Well, lo and behold, I stumbled across a Vivitar 76700 Reflecting Telescope, while killing time before a drs appt, at the local Goodwill, for only $14.99. I immediately withdrew my "Emergency $20" from my wallet, and I purchased it!
When I finally arrived home, I began the process of putting it together. Unfortunately, I soon discovered that it lacked everything which is placed in the "lens hole/slot" on the top, back of the telescope (just a hole, no lens, barrel, or anything originally included to fill said hole.
!!!EDIT/CORRECTION!!!: It DOES have the piece which screws onto the side of the telescope that has "adjustor knobs" below it for, I'm assuming, extending/retracting the lens(?). There is just nothing INSIDE this piece except a hole/space. Sorry!
This is our youngest son (13), who is a "loner." He is very quiet/shy/lacks self-confidence, and suffers from mental/learning disabilities, but truly is "sharp as a tack" in many, many ways. So, when we discover something, anything, educationally speaking, that peaks his interest, we try our hardest to encourage him!
Now, I don't really have any/much money to spend on getting this telescope in complete working order (I am NOT asking or soliciting for ANYTHING!!) , but I refuse to pass up this chance to bond with him, encourage this budding passion for Astronomy, and help get him OFF that blasted PlayBoxCube more frequently, and into something more beneficial for his young, developing mind!
Now to my question(s)...
What further (inexpensive) equipment would suffice in completing his new-to-us telescope, and increase his allure to the wonders awaiting his discovery in the heavens above? Quality vs Price? Trade-offs? On-topic/slightly off-specific-topic advice?
Links, articles, groups, periodicals, videos...ANY suggestions gratefully welcomed!
Thank you, in advance, for indulging my attempted-to-be-brief background/relevant personal info, and for taking the time to help this guy be a (better) dad again. I feel blessed to have found this particular site/group.
Live Long & Prosper,
-Larry
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By Rchurt
Hello,
I recently purchased my first telescope and camera, and now I want to make sure I have the correct Barlow or reducer to couple them together to achieve Nyquist sampling on the camera (or slight over-sampling). In case it’s important, I’m interested in planetary imaging—in theory that shouldn’t matter for this sampling question, but maybe there are other considerations to take into account.
I used this calculator (https://astronomy.tools/calculators/ccd_suitability) and plugged in my info:
Telescope: Celestron 8 SE
Camera: ZWO ASI462MC
Seeing: experimented with this one, but would like to get optics that allow for poor or very poor
Binning: prefer 1x1 to preserve spatial resolution, but could consider higher if SNR is a problem
I’ve seen on several forum posts that people often use a 2x Barlow to couple the two. However, according to this calculator, that will always lead to over-sampling. If anything, it says I should use no intermediate optics or even a reducer.
So my questions are:
Binning: Will I be able to see anything with 1x1 binning, or should I expect to need to bin to collect enough light?
Is there some other consideration that’s more important here than achieving correct sampling? It seems like most others are over-sampling, and perhaps there’s a good reason for this. If so, is there another formula that would let me determine the appropriate optics to buy?
Thanks in advance for any help!
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By Corpze
Hi, i have made a video where i show a coople of eyepieces that i use and like, and also show how a barlow works, compared to the "Powermate" from Televue. And how is the FOV affected when changing the magnification with different eyepieces?
Feel free to comment and give me feedback - I hope you like the video!
/Daniel
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By Zermelo
I picked up a Celestron Omni last year quite cheaply and had originally been using that with stock eyepieces, which was fine.
Since then I've bought a couple of BST Starguiders and a Hyperflex zoom, and I'm now wondering if I'd notice any difference with a better barlow (this is now being used on an F/5 150mm Newtonian). Otherwise, the pennies can be directed elsewhere.
I'd not considered it before as the next rung up seemed to be around the £90-£100 mark, which seemed out of line with the rest of the spend. But I've seen some positive reviews of 3-element models in the region of £35-£40.
In particular, I've read good things about the Revelation/GSO Astro 2.5x (though apparently closer to 2.2x) and the Baader Classic Q 2.25x.
- does anyone have experience with both of these, and have a preference?
- would I notice any significant difference with either, compared with the Omni?
- I read somewhere that the Baader in particular required focussing the tube into the OTA to an extent that caused some image degradation. Obviously I'd want to avoid this if true, so is this a feature of the Baader, or of both, or of all (shorter?) barlows? (to be honest, I'd not thought to see whether this was happening with the Omni, I'll try to remember to check, if this weather ever breaks).
Thanks in advance.
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By LondonSi72
Hi SGL,
My lovely wife bought me a SW Explorer 130 with the basic RA drive for my 40th birthday 8 years ago, and I've enjoyed using it on and off ever since. I've started getting more into it - it's a great beginner scope, but I'm - like lots of others on this forum - looking at upgrading. One of the things I found tricky with the scope was getting the focus just right at high magnification (I'm sure that's kind of obvious!). It does wobble quite a bit on the EQ2 mount when focusing. I get pretty good - if small - views of Jupiter, Saturn, (the Moon, of course) and have had hints of seeing some DSOs.
I bought a 8mm BST Starguider, and it's a great improvement on the standard 10mm that comes with the scope, but if I push the scope by adding the 2x Barlow and the 8mm it's a blur and the focus seems to keep missing the sweet spot. I saw a post elsewhere on this forum by MakTheNight, (looks like they've left now - last post was 2 years ago) who added a Baader Helical Focuser that attached directly to the T-thread on the focusing apparatus on the SW. Link to that post is below. I got one and it is indeed a great improvement on fine tuning - the problem is I can't use it with the Barlow as the helical focuser is about an inch long and the focuser can't move far enough into the scope to focus with the Barlow and any of my eyepieces (the 8mm BST, or the 10 or 25mm standard eyepieces)
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Clearly MakTheNight managed to get their setup to work with some specific eyepieces (a Luminos 10mm and 32mm Plossl) and a specific Barlow, so I tried looking up how I could work out what combination of eyepieces and Barlow would work, rather than randomly buying kit and having to return it because it won't work with my scope, but I haven't found anything useful yet. So I thought I'd take the plunge and ask here
Can anyone help me figure out how I can calculate what combinations of eyepiece and Barlow would work with this setup? I'm also looking at upgrading the OTA and mount to a 200P and EQ5 at some point, so ideally would have a combination that could work with that too - the focal length and mirror is quite different - 1000mm on the 200P parabolic vs 900mm spherical on the 130.
Many thanks!
Simon
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