Lens location??

[Sumac]

Hello,

I'm new to this forum and I would really appreciate some help from those who are far more knowledgable than me!

I have just bought a used Celestron Powerseeker 114eq to get my son and I started in amateur astronomy.

On opening the box and unpacking the contents I found a lens was rattling around inside the scope tube. Should it be attached somewhere inside the tube or is it a lens from an eyepiece?

Does anyone know what it is and where it should be please?

I'd be upset if it turns out I have bought a broken scope.

Thanks to anyone who can assist in helping me find where it should be. 

[ronin]

Well the Celestron Powerseeker 114eq does not appear to be a Bird-Jones design so it cannot be the barlow that fits in the focuser as there is not one in it.

The lens appears to be a positive as well so again not a Bird-Jones item.

What diameter is it? Just appears a reasonable size, guess 30-40mm diameter ?? In which case doubt it is fram an eyepiece, but check the eyepieces in case.

Basically not a clue where it is from or where it should go, but cannot think of any part of your scope that would incorporate that item. Scope should be small mirror angled at 45 degrees at the top, main mirror of 114mm dia at the bottom and lots of air until the eyepiece.

Can only suggest you put an eyepiece in the focuser and aim the scope at something and you will hopefully see the object. Without the presence of that lens.

[JOC]

I'm not expert, but others here might comment on my idea.  Could it be from the finderscope if it came with one?.  OP - have you tried the telescope, does it appear to work as it stands?

[Sumac]

Thanks for your suggestions ronin and JOC. NO, I haven't yet assembled the telescope as I've had to go out to pick up my daughter from work. I will measure the lens and let you know the size. 

I need to sit down and read the instructions and the list of what comes with the telescope (eyepieces etc) then try to work out where it's fell out of. 

Im just relieved that it wasn't part of the internal fixtures inside the tube of the scope. 

 

Thanks again. 

[Sumac]

Ok, it's 2cm diameter. 

Here is some photos of an eyepiece in the box. Has it come from one end of that maybe?? 

Thanks. 

[Charic]

Thats the erecting eyepiece and looks normal, nothing missing!

http://www.celestron.com/support/knowledgebase/articles/i-“accidentally”-took-apart-my-celestron-20-mm-erect-image-eyepiece-how-do-i-put-it-back-together

Compare your erecting EP with the one here........https://stargazerslounge.com/topic/259232-celestron-20mm-eyepiece/

Are we sure its not a Jones-Bird construction, my 127EQ was?  To check, look at the base of the focuser assembly. If the bore of the focuser is clean, and no fitting to accept a lens, then as above, its not a Jones-Bird, but if there is some sort of fitting, that's where the loose lens belongs!

[Sumac]

Hi Charic,

mystery is solved! The lens was from step 5 on the instructions you posted. Thank you everyone for your swift replies and the worry you have saved me from. 

I'm sure I will have many more questions as time goes on as totally new to astronomy. 

I'll try to set it all up now and see how I get on. 

 

[Charic]

.....so I got it wrong about "nothing missing" but at least your sorted now.

Welcome to the SGL.

[Sumac]

Hey Charic,

No worries! 

If you would be kind enough to tell me what this lens is I would be most grateful. It appears that the 'Barlow' lens is missing from the box but I presume I could pick one up online or in a shop?

sumac

[JOC]

That looks like it could be an eyepiece (EP) giving a high amount if apparent magnification.  The smaller the number in mm the more magification you will get.  It may require you to put your eye very close it to see properly though.  My higher magnification EPs require me to do this.  it should fit into your focusser unit probably with a grub screw.

[Charic]

I wasn't sure what the third image was, did not appear to be any depth to the image, but now realise its the top of the eyepiece?

The Celestron 4mm eyepiece would have been supplied with the telescope. If you look at the data plate on the scope and look for the F-????? focal length number, and divide that into the size of the eyepiece 4, the result is the power or magnification of that eyepiece in that scope, as power/magnification will differ between telescopes dependent on the focal length of the telescope.

[JOC]

I can't get the link to come through but a Google image search shows a Meade 4mm plossl eyepiece with a raised eyecup that looks identical.

[Alan64]

That's the 4mm Huyghenian, Ramsden or Kellner that comes with the kit.  You won't be using that one much, if at all.  

At that price-point, Synta(Celestron) is going to give you a good telescope, else they wouldn't sell very many of them, but the eyepieces and accessories that are included with the kit are generally not so good.  The 20mm, however, should be useful. 

This is the telescope... http://www.celestron.com/browse-shop/astronomy/telescopes/powerseeker-telescopes/powerseeker-114eq-telescope  

It's a 114mm f/8 classical Newtonian, with a focal-length of 900mm, and thankfully not a Jones-Bird.  The included 20mm will give a power of...

900mm ÷ 20mm = (45x)

You may want a 32mm or 40mm Plossl straightaway, and in order to get your bearings there in the sky...

http://www.365astronomy.com/32mm-GSO-Plossl-Eyepiece.html (28x)

http://www.365astronomy.com/40mm-GSO-Plossl-Eyepiece.html (23x)

A 12mm... http://www.365astronomy.com/12mm-GSO-Plossl-Eyepiece.html (75x)

A 9mm... http://www.365astronomy.com/9mm-GSO-Plossl-Eyepiece.html (100x)

You can 2x-barlow that 12mm for an effective 6mm(150x), which would be at or near the highest power practical for most nights.  With the Moon being so close to Earth, you might possibly bump the power up to 200x.  The EQ-1 equatorial mount may make that a bit easier to accomplish, as opposed to an alt-azimuth mount.

A 2x barlow... http://www.rothervalleyoptics.co.uk/antares-x2-achro-barlow-lens-125.html

In any event, you may want a low-profile barlow, like that one, so as not to have a tower of items jutting out from the focusser.

 

This is the Jones-Bird of which mention was made earlier...

http://www.celestron.com/browse-shop/astronomy/telescopes/powerseeker-telescopes/powerseeker-127eq-telescope

Kits with a Jones-Bird catadioptric telescope should be avoided, always.

[Sumac]

Thanks Alan64 for your advice. 

This is the telescope I bought:

http://www.celestron.com/browse-shop/astronomy/telescopes/powerseeker-telescopes/powerseeker-114eq-telescope

Looks like I should purchase a 12mm lens and a x2 Barlow lens. 

That should give me plenty magnification to see a few objects. Once I gain experience I can add more if required. 

Mince again thanks everyone for your replies. Good to know help is here when needed. 

Sumac

[Alan64]

Incidentally, you can motorise the RA-axis of the EQ-1, and for automatic hands-free tracking of any object.  This is the motor-drive unit...

http://www.rothervalleyoptics.co.uk/celestron-astromaster-motor-drive-unit.html

It's optional, of course, as the RA-axis' slow-motion control is quite easy enough with which to track.  In order to track an object, you will need to aim the RA-axis at the NCP, or north celestial pole.  The star that's very near to said pole is Polaris, the north star...

First, the latitude-scale is set to your location's latitude.  This needs to be done only once per location.  For example, I live at 34° N...

Therefore, I know that Polaris, and the NCP, is 34° above the northern horizon when I walk outside...

There in central Scotland, the latitude is at about 56° N, depending, so you would set the indicator at that position.  The NCP, or Polaris for that matter, does not move, but everything else in the sky does, and revolves around the NCP and Polaris, like the spokes of a wheel around a hub.  For visual use, with eyepieces, getting the RA-axis aimed at the NCP is not that critical.  Just set the latitude, then eyeball along the side of the RA-axis and aim it at Polaris.  It also helps to level the mount.

Then, you unlock the clutches of the two axes(RA and DEC) so that the telescope can move freely, and start the hunt.  Once you find an object that you'd like to observe for a spell, you then lock the clutches and switch to the slow-motion controls to track it.

[Alan64]

Incidentally, search for this title on YouTube: "Eq1 to Alt-azimuth set up".  It will show you exactly how to transform an EQ-1 into a simpler alt-azimuth.  I do not want post a link to the video here, as it contains a couple of colourful words, but it's the only video available of its kind.

[Charic]

9 hours ago, Sumac said:

Looks like I should purchase a 12mm lens and a x2 Barlow lens.

Your telescopes focal ratio of f/7.89 (rounded up to f/8) suggests for a 8mm eyepiece to provide you with 112x power. If you were to find (don't look) a 7.89mm eyepiece it would provide you with 114x power, which considering you have a 114mm objective/mirror is a good match. Passing this theoretical limit of your scope, by using a smaller focal length eyepiece will reduce the image detail very quickly, due to the higher magnification, and the limits afforded from the small 114 mirror. Some folk are still dubious about how much power is required, thinking more is better, whereas many of the targets up there are better/most viewed at lower magnifications, providing in many cases, clearer, brighter and more detailed images, but the target image of interest may be quite small.l

Your 12mm is a good choice, but 2x Barlowed  would provide 150x power/magnification, and this I would expect from say a 150mm 6" scope, the 114 will struggle at this magnification on nearly all astronomical targets except the Moon, and your terrestrial targets!

Alan64's information is spot on for your type of telescope, but its the reason I upgraded to my present scope, the 200P, I don't have any of the issues with unlocking clamps, re-setting slow-mo controls, ensuring latitude setting is correct ( a one off) and correct polar alignment every session! Not only that the images are better, due to the larger mirror.

My first scope was the  Celestron 127EQ and for some folk it was a pain,  some even went to the extreme of removing the internal Barlow to try and laser collimate their scope. JUST DON'T DO IT, the scope had a spherical mirror and was easy to collimate by eye, as instructed by the user manual.

I also stripped my 127 to bits, centre spotted the mirror, had the perfect set-up ( to my knowledge ) even tried better eyepieces, the 127EQ is what it is........avoidable?
The 114 appears to not have the internal Barlow, but you will still have the benefit of learning about set-up and polar alignment, but for visual use only, nothing fancy is required in the eyepiece department, but whatever you buy will be transferrable to a newer scope, if/when that day arrives.

If you need any guidance for an eyepiece, then the BST Starguiders ( my favourite ) which were purchased from e-bay are now available from our site sponsor, First Light Optics, just click their banner at page top.  My  GSO's, branded Revelation Astro are Plössl's  and were individually purchased from Astroboot,  very cheap, all A1 new!

Lastly, eyepieces are  a personal item, what fits us may not suit you. A better eyepiece can in some cases, offer a better field of view, longer eye-relief, and apparent brightness, and just an overall sense of comfort that feels better than the original.

Ultimately, the telescope provides a real image at the focal plane, which is visible to the naked eye, but its just too small to illicit the details, so an eyepiece is a must to magnify that image. All  this happens in front of the eyepiece, therefore its of my opinion that no matter what eyepiece you choose, be it a £9 Plössl or a £300+ Delos, the eyepiece alone only makes for a more comfortable viewing experience, inasmuch that you can now see the image, as clear as the original, it can't add anything that the telescope has not produced, so if the focal plane image is poor due to mis-collimation or bad seeing, the eyepiece will show the same.
That said, I experienced exactly the same with my 127EQ, better quality eyepieces than those supplied, made no difference or improvement to the original image, it was the messing around and constant adjustments to the various controls and locks that put me off the scope.

Its not all doom and gloom, I was blown away the first time I viewed the Moon with the 127EQ and the terrestrial images were ok, when using the erector eyepiece, but a high fence limits the angle over my terrain, so had to view from a bedroom window, but thats limited now due to the forrest? but the scope I have now is a keeper, until something breaks, and  I was hoping to upgrade to the 12" possibly a 10" even purchasing some premium optics for the newer scope, but its sensible for me to keep this scope.

Whatever you buy, its a learning curve, until one day you sit back and think, that was good, or this one seems more suited, It just takes time and patience, and finally when you think everything is set up correctly and your ready to go, the clouds remain?

 

 

[Sumac]

Charic,

I very much appreciate you going to such great lengths giving me valuable advice but I must say it's way over my head now. 

Mall I have is a 20mm and 4mm lens that was in the box. I don't want to put out too much money in case this whole amateur astronomy venture doesn't work out. 

Am I right in understanding that you feel I shouldn't bother purchasing a Barlow lens at all? 

You advise an 8mm lens. Anything else or should the 20, 8 and 4 mm suffice? 

What about moon and planet filters ?

The more websites I look at the more confused I am! 

Sumac

[Ricochet]

3 hours ago, Sumac said:

Anything else or should the 20, 8 and 4 mm suffice? 

What about moon and planet filters ?

I would say that actually the 20 and 8mm would suffice to find out if astronomy is for you. The 4mm is about half of your scope's focal ratio and thus only really suitable for splitting close double stars. At this magnification you will clearly see stars being diffracted into airy disk patterns and on planets this same effect will blur the details. For planets you want an eyepiece that is 0.85-1x your scope's focal ratio, so a 7 or 8mm. For deep space objects you will usually want an eyepiece with an exit pupil of 2-3mm, so a focal length of 2-3x the focal ratio which is about 16-24mm. Here your existing 20mm will do for now although as you progress you might decide to replace it with something of better quality. The other eyepiece that may be of interest to you at this stage is one that maximises the true field of view. For 1.25" eyepieces that can be achieved by a 24mm 68° or 32mm 50° (i.e. a Plossl). 

At this stage I would not bother with filters. Many people don't find much benefit from the coloured filters and you might not need a moon filter either. If you do decide a moon filter is required then a variable polarising filter is the best one to get in my opinion. 

[Sumac]

Ricochet,

Very informative and helpful info, many thanks. 

Lots to think about and I can't wait to try the telescope out on a clear evening. I'll be starting with the moon and hopefully Jupiter, getting used to different lenses and moving the scope around etc. 

As with all things the more practice the better I'll be at understanding all the information I've been kindly given. 

Sumac

 

 

[Charic]

6 hours ago, Sumac said:

I very much appreciate you going to such great lengths giving me valuable advice but I must say it's way over my head now.

It won't take long before it all makes sense, and there's really no rush, just take your time, we've all been in the same situation as yours.

That 4mm Celestron could be the reason that the scope was sold in the first place, you'd be best just sticking it in a drawer, and passing it on when you sell the scope! It will bring no joy or satisfaction. This is the reason we often say that the longest focal length supplied will be ok, but consider changing the shortest focal length.
You would think that the manufacturers would supply something half decent with their scopes, but alas, not the case?

An 8mm or a 12mm would be fine, and you could still sell them on if astronomy is not for you, or just the 8mm and use the 20mm as suggested by Ricochet.  A  Barlow doubles the use of the eyepiece set, so having an 8mm 12mm and a 2x Barlow  would be the equivalent of having a 4mm, 6mm, 8mm & 12mm, so not a bad situation to be in.  With just an 8mm and your 20mm you'll effectively have a 4mm  8mm 10mm and 20mm at your disposal. But you already have a 4mm, from the celestron, but as this is too powerful and degrades the image, even using another branded eyepiece,  so a 12mm or even a 15mm would  do well in this situation, but don't expect Hubble type images, not even my scope can achieve that quality.

[Alan64]

3 hours ago, Sumac said:

Ricochet,

Very informative and helpful info, many thanks. 

Lots to think about and I can't wait to try the telescope out on a clear evening. I'll be starting with the moon and hopefully Jupiter, getting used to different lenses and moving the scope around etc. 

As with all things the more practice the better I'll be at understanding all the information I've been kindly given. 

Sumac

The telescope that you purchased is a Newtonian.  The light from the object enters the through the front of the tube and strikes the large mirror at the bottom of the tube.  The large mirror then takes that collected light and makes a cone-shaped beam out of it, then sends it to the small, angled mirror near the front of the tube.  The small mirror then directs the tip of the light-cone into the eyepiece, and into the eye and mind of the observer...

 

Simple enough, but if you look closely at the small mirror assembly at the front, and at the back of the telescope, you'll see screws and bolts...

The mirrors move, out of alignment, and back into alignment, and in respect to each other.  There's a third component that also plays a part in the alignment(collimation), and that would be the focusser.  All three must be aligned in a near-perfect L-shaped path, as illustrated above.  Fortunately, the focusser is in a fixed position there onto the tube, and does not move.

The alignment is not that critical when observing at low powers.  You want it close, but it doesn't have to be near-perfect.  But for the moderate powers, and especially the higher powers, the more precise the alignment is, the sharper the images will be at those powers. 

Collimation instructions...

http://www.forumskylive.it/Public/data/serastrof/201281510358_Astro Babys Guide to Collimation.pdf

Take your time.  Just look it over.  There's no need to take it too seriously at the moment.

When you're ready to at least check the collimation, a collimation-cap will be required...

https://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html

The cap is inserted in place of the eyepiece, and the telescope aimed at a bright, blank surface.  You will then be presented with a view of the complete optical system...

...with that being a view of a well-aligned 114mm f/8 Newtonian.  Your own may already be collimated, and to near-perfection even.  On nights of good seeing conditions, the appearances of the objects themselves will let you know, especially at the moderate-to-high powers.

A barlow will keep you from having to view through the tiny pinhole of the 4mm that came with the kit.  The eye-relief would also be greatly improved, and where you wouldn't have to press your eye up to the 4mm's tiny eye-lens to see something.

The GSO Plossls are among the best of the low-cost eyepieces, yet ones that will offer pleasing views.  You don't need the whole set, just one or two, and a barlow if you want to max out the power of which a 114mm aperture is capable.

The oculars suggested elsewhere have barlows built into them.  For example...

This is my 4mm orthoscopic, and similar to your 4mm...

But instead of using that, I combine a 12mm eyepiece with a 3x barlow...

...for greater eye-relief and a wider view, and for an effective 4mm.

Notice how this eyepiece looks very similar to my combination...

https://www.firstlightoptics.com/skywatcher-eyepieces/skywatcher-uwa-planetary-eyepieces.html

http://www.365astronomy.com/Planetary-Eyepieces/

Those are merely examples of the type.

They also provide a somewhat wider view over the Plossls.  Plossls do provide a respectably-wide view, but the eye-lenses through which to view are smaller, and the eye-relief tighter, and again, where one would need to almost touch their eyeball to the lens to see the full view.  This is particularly true with Plossls shorter than 10mm(8mm, 6mm).

A telescope is only one half of itself.  The other half are the eyepieces.  You can't use one without the other, for either one by itself would be as a brick, useless, therefore the two are as one.   

The nice thing about your long-focus Newtonian is that it's easier to collimate, to align, and in retaining the alignment over time.  In addition, corrective and therefore costly eyepieces are not needed for pleasing views.  The shorter and faster the Newtonian, the more finicky it tends to be in those two instances.