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Old 31-05-2018, 10:49 AM
brent130
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Included eye piece question

Hi all,

I'll start by saying I am totally new to the world of telescopes. I was given a skywatcher 130/1000 as a birthday present which I've only used 2 times due to Melbourne weather

It came with a 10mm and a 20mm eye piece although it is meant to be a 25mm instead of 20mm.

Is it worthwhile to swap the 20mm for the 25mm at the shop? So far I've only looked at the moon and still have lots to learn about using the telescope.

The only problem I see is if I were to get a 2x barlow, then I wouldn't gain anything from the 20mm.

What are people thoughts?
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Old 31-05-2018, 07:59 PM
gaseous (Patrick)
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I'd definitely be swapping for the 25mm, for the barlow issue you mention.
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Old 31-05-2018, 08:13 PM
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Or 40mm.. plus 2x barlow.
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Old 31-05-2018, 10:02 PM
Wavytone (Nick)
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Hi Brent,

Think of the max possible range of eyepieces that suit this scope, and divide that into 4 or 5 roughly equal magnification steps and lets see from that what makes sense.

At the short end 7 or 8 mm. At the long end a budget 25mm eyepiece should give the maximum field of view in the 1.25” barrel.

Using 10 and 20: a set could be 7, 10, 14, 20 or the 25.

Personally I’d say skip the Barlow and buy 7 and 14. Not a lot of difference between 20 or 25, keep what you have.

Or the Barlow and a 14mm or thereabouts.

There are also 1.4X and 2.5X Barlow’s, which open up more possibilities
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Old 01-06-2018, 05:38 AM
astro744
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What 20mm is it? If a widefield then your true field will be similar to the 25. I'd say keep the 20 and get a 32mm Plossl for maximum true field in 1.25" and nice bright images. There is a good 25mm Plossl for sale in the used section if you really want that focal length.

Note maximum true field is determined by the eyepiece field stop diameter. Max for 1.25" is 27mm and this is available in 40mm Plossl, 32mm Plossl and 24mm Widefield with 44 deg, 50 deg, 65 deg apparent field respectfully.
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Old 01-06-2018, 01:04 PM
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, to IIS Brent thats a good starter scope by the way so enjoy it , as it is for now and if you can afford it keep the 20mm and grab that good 25mm in the classifieds , if its still there but if not keep an eye there as they do show up often .

Then as said by Wavytone a 14-15mm ( the 15mm Plossl in the classifieds would be a good buy ) later on is good advice , as in my opinion unless you want to spend $100 plus ( TelVue ) on a quality barlow you might be dissapointed as some of the cheaper barlows out there are not the best in shorter focal length Newtonion reflectors like yours , that is are designed for long focal length refractors where they work ok .

Yes a 10 , 15 , 20 and 25mm plossl set would be a great starter set that will last you for a long time ,,,, until you need that 6-7mm and 32mm and ,,,,,, it will happen so be careful .

Good luck .

Brian.
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Old 01-06-2018, 02:25 PM
m11 (Mel)
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Hi Brent,

I think I have a couple of bintel plossls - need to check but i think i have the 15mm and 25mm to Brian's recommendations.

Give me a yell if you want them for free.

Regards,

M11
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Old 01-06-2018, 04:07 PM
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Hi Brent, I agree with Brian and Wavy, when you can, get a 15mm. I have a 14mm and this range has been highly used across three telescopes (4", 6" & 10"). Great for viewing star clusters and in my 10" is my go-to eyepiece for comet hunting. 7mm hits the spot nicely for planets and the seeing conditions often allow pleasant views; if not, just throw on the 10mm. I've never needed to use my 25mm since I got my 22mm.

My most used ones are: 7, 10, 14 and 22.

Seems I pretty much did in order what Brian suggested :
Quote:
Yes a 10 , 15 , 20 and 25mm plossl set would be a great starter set that will last you for a long time ,,,, until you need that 6-7mm and 32mm and ,,,,,, it will happen so be careful .
I got fed up with mucking around in the dark barlowing different eyepieces so I replaced and bought more eyepieces, I went for all wideviews.

That's what happens once you get into this hobby... you will always want more .
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Old 01-06-2018, 05:59 PM
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3 thumbs up Mel ! what an awesome gesture .

Brian.
Quote:
Originally Posted by m11 View Post
Hi Brent,

I think I have a couple of bintel plossls - need to check but i think i have the 15mm and 25mm to Brian's recommendations.

Give me a yell if you want them for free.

Regards,

M11
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Old 02-06-2018, 08:31 AM
brent130
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Quote:
Originally Posted by m11 View Post
Hi Brent,

I think I have a couple of bintel plossls - need to check but i think i have the 15mm and 25mm to Brian's recommendations.

Give me a yell if you want them for free.

Regards,

M11

Wow thanks for such a kind offer. I will PM you
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Old 02-06-2018, 08:43 AM
brent130
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Thanks for all the replies. Really appreciate it. I'm still getting my head around some terminology and calculations but it's nice to get some help from you all.



I am not sure what eyepieces they are. They just say "super 10mm". Can't find any brand names. Assume it's SkyWatchers plossls generic ones. I'll keep the 20mm either way.



Will keep an eye on the classifieds and add some more pieces to my collection over time.



On a side note, I was able to see the ring around saturn with the 10mm last night and also make out some lines on jupiter and see some of its moons. It was an amazing experience, I felt like a little kid full of excitement. What an interesting hobby



Thanks again everyone
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Old 02-06-2018, 10:00 AM
m11 (Mel)
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Re: eyepieces

Hi Brent,

All good buddy.

Just replied back to your pm. Forgot to add I have a 26mm or 30mm if you are interested in taking - these eyepieces are 2 inches.

M11
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Old 15-06-2018, 05:04 AM
AEAJR (Ed)
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Cool

I would not swap the 20mm for a 25. I would keep the 20 and add a 32. I will explain why.

I am going to outline a strategy for you. This approach applies to any telescope. The only change is whether you have a 1.25" or 2" diagonal/focuser.

Watch the Video - First, some background on selecting an eyepiece -
This is a very general video discussion of eyepieces and why there are a variety of designs
https://www.youtube.com/watch?v=m7u9Q5hV7yc


EYEPIECE STRATEGY SUMMARY


* One or two low power wide view eyepieces
* One or two midrange eyepieces
* Two to four high power eyepieces
* Or, Zoom plus barlow to cover mid range and high power
* Planning to use a barlow can save you money

You have a 130 mm / 1000 mm FL scope.

A general guideline is that you double the aperture in mm to get the maximum usable magnification you can expect under excellent conditions.

130 X 2 = 260X - not a limit or a guarantee, just a target.

FL scope / target power = FL eyepiece =

1000 / 260 = 3.84 mm. Call it 4 mm for convenience.

Assuming your scope has a 1.25" focuser, the best low power/widest view eyepiece would be a 32 mm Plossl. That will give you 31.25X and a 1.6 degree field of view, FOV. That is a good low power and wide view for this scope. It will help you when star hopping and when you want the widest view possible.

So we have established the low power, 32 mm, and the high power, 4 mm. Now we fill in between.

Focal length scope ( FLS) / Focal Length eyepiece ( FLE) = Magnification


31.25x = 32 mm Plossl - Add this one

50X = 20 mm ( you have)

100X = 10 mm ( you have)

143X = 7 mm

The above mags should work almost any night.
The below mags will be usable under good conditions. You may choose to barlow for these rather than buying more eyepieces.

180X = 5.5 mm

220X = 4.5 mm

250x = 4 mm ( top mag for this example)

Nothing rigid about these mag targets, I am just using them as an illustration of a spread of options. You might choose different focal lengths/ magnifications based on the line of eyepieces you like or the magnifications you want to hit. The point is that you want to work toward a spread of magnifications, as budget allows. This lets you use the right mag for any given target to get the best view.

Nothing to stop you from trying to go higher than 250X, and on certain targets, like the Moon, you may be able to go higher on exceptional nights. A lot depends on transparency and "seeing".


What is SEEING and why it can be bad. How it will limit how high you can go. This is not a problem with your telescope or your eyepiece.

http://www.skyandtelescope.com/astro...ng-the-seeing/
http://www.damianpeach.com/seeing1.htm
http://www.damianpeach.com/pickering.htm


The alternative method to multiple eyepieces is to use a zoom eyepiece. This is my primary approach. An 8-24 mm zoom will give you 41X to 125X and everything in between.

You could put the zoom in a 2X barlow for 82X to 250X. Going over 250x for that scope will be a very rare night, BUT it might be fun to try it on the moon on an exceptional night using a 3X barlow.


The 32 mm Plossl +zoom + barlow is typically the lowest cost approach to covering the entire range of your scope. It has become my primary approach for all of my scopes.

* I never expected the zoom eyepiece to become my primary eyepiece, but it has.
* With a zoom, the eyepiece seems to disappear as you just move in and out at will, no swapping, no thinking about eyepiece changes
* Watching double stars split as I rotate the barrel is wonderful
* One filter serves over a wide range of magnifications, no screwing and unscrewing to try other eyepieces
* Moving smoothly from and between small changes in magnification helps when seeing is not the best
* I am always working at the optimum magnification for this target.
* Sharing the view with others is easier, especially in my manual tracking Dob - I hand it over at low mag so it stays in the view longer. They zoom back in to whatever magnification works best for them.
* My eyepiece case has been greatly simplified
* Kids love the zoom

So, eyepieces are a tool that you will want to add over time. Like having a spread of wrenches/spanners in your toolbox. Above is just a strategy for where and how to add them.

If you were in the USA I would provide a list of sources and eyepiece lines but I am not certain what is available locally.

I hope you find this helpful.

Ed
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Old 17-06-2018, 10:54 AM
brent130
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Quote:
Originally Posted by AEAJR View Post
I would not swap the 20mm for a 25. I would keep the 20 and add a 32. I will explain why.
Hi Ed,

Thanks for the write up. Those calculations helped me understand things better. I appreciate you taking the time to do that.

I kept the 20mm and was given a 15mm,25mm and 26mm by the generous Mel above. I also have a 6mm on its way. So I feel that gives me a good range for now. Now just waiting for clear nights

How is the Celestron zoom? I have read mixed reports about the zoom pieces but you have got my interest. The Baader zoom is out of my price limit but may be interested in the Celestron .

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Old 17-06-2018, 02:40 PM
AEAJR (Ed)
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I like the Celestron. The BH Zoom is better but 4X the price.

I tend to use the Celestron in my ETX 80. The BHZ in my 8" Dob. But before I had the BHZ I used the Celestron in both.

I understand that Meade also has a good quality low cost 8-24 zoom though I have never tried one.
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