Question about C-Star Optics TT-150 Telescope

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Lens SR6 We are having trouble focusing and seeing objects using the SR6 lens. the H20 works well. Why can't the SR6 be focused as clearly as the H20? Kim

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That's because it is TOO MUCH magnification for that small aperture telescope. This is one of the most common problems for beginners. They believe that you need a lot of magnification to see objects in the night sky. In my 8 inch telescope I rarely go over 120 power -- magnification is the least important property of a telescope. Aperture and good optics are much more important.

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Posted on Jul 09, 2011

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Unable to get lenses to work on ioptron twinstar telescope have the 36mm af 40• can't see anything the picture shows how it is set up

Take the lens cap off-- put the eyepiece with the largest number written on it into the focuser. DO NOT use the 2x barlow if you have one. Take it out during the daytime and practice focusing on a distant object. The moon should be your first target at night.

Clear skies

Jul 29, 2015 | iOptron Telescopes

1 Answer

When I use a Barlow lens do I insert it before focusing on an object through the eyepiece or do I insert the lens after I've focused on an object (eg: Jupiter)

You will have to refocus after inserting the barlow. The barlow will change the focal point of the eyepiece

Apr 06, 2013 | Telescopes

1 Answer

Just bought a starnavigator 114. Purchased a Barlow lens to use with my 26mm lens, but with the barlow I can't see anything. Do I need to make changes in the lens config. in the Autostar?

The barlow may be too much magnification for that aperture telescope. The higher the magnification the SMALLER the sweet spot is in focus.

Turn the knob slower and also practice focusing during the day time on a distant object.

Mar 30, 2011 | Meade DS-2114 ATS (325 x 114mm) Telescope

1 Answer

I am inexperienced at this, attempting to enjoy this with my grandsons...When using the diagonal mirror, what is the difference in using the H20 eyepiece and the SR6 eyepiece? When using the 1.5x Erecting...

The numbers on the eyepieces are the focal length in millimetres. You can calculate the magnification of the telescope by dividing the focal length of the main objective by the focal length of the eyepiece in use, so if the main focal length is 700mmm and you use the H20 (Huygens 20mm) eyepiece, you will get a magnification of 35. The SR6 ( Symmetric Ramsden 6mm) would give about 117 magnification. You will find that the LOWEST magnification is about the only one that is usable. I wouldn't use the Barlow at all.

There is a good website full of info about this HERE

Dec 31, 2010 | C-Star Optics TT-150 Telescope

1 Answer

I am having trouble seeing through the 60mm Objective Lens. I'm able to see clearly through the Finderscope. Also how do attach the Barlow and Erecting Lens?

You put the prism into the focuser and then the eyepiece with the largest number written on it. DO NOT USE the 2x barlow until you learn how to focus properly.

Dec 27, 2010 | Bushnell Deep Space 78-9512 (120 x 60mm)...

1 Answer

It's not clear. Like it's kinda foggy, Kathy

Is the eyepiece lens clear or dirty? Are any of the other lens dirty?

If not practice focusing on a distant object during the day time. Clean the lens and eyepiece with regular eyeglass cleaning solution and a clean soft towel or pure white kleenex.

May 13, 2010 | Telescopes

1 Answer

Trouble focusing Vivtar telescope

The telescope is designed to use the diagonal - it adds the necessary length to reach a focus point.

Mar 21, 2010 | Vivitar (1607225) Telescope

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I've completed the set-up, but the eyepiece still is black. I looked in the trouble shooting guide and it says to check to see if the objective lens cover has been removed. Where is the objective lens...

What I believe you did was mount the scope UPSIDE DOWN. If it looks like the picture in your question the eyepiece and focuser end is pointed UP the mirror is on the bottom.

Turn it around and take the lens cap off.... this end is pointed toward the sky.

Jan 22, 2010 | Bushnell 78-9669 Telescope

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Cannot see an image through the lens

I bought one of these telescopes, and had trouble at first, but finally got some decent results. If you dont have any experience with telescopes, I suggest trying it first in daytime, since daytime objects are much better for getting experience. Also, start with the lowest power eyepiece, the 12mm 50x, the one with the largest lens. Start by looking towards something pretty big, like a car or a house, and it needs to be some distance away to even have a chance to get a focus. If your target is closer than about 1/4 mile, you should add the right angle eyepiece attachment to allow you to focus in on closer objects.

When you are finally set up with the low power eyepiece, and have a good big target in the daytime, start looking thru the telescope while turning the knob thru the entire range. At some point of knob turning, you should see some image appear in the eyepiece..Turn the knob slowly to focus it clearly.

And this is for the shaky tripod. If you can hang a book under the middle of the tripod, the added weight will help stabilize the telescope, and you should be able to see a little better, without so much motion at the slightest touch.

After you look at the first car or house, you can start to see how careful you have to be to use the telescope, and you can start to look at other objects. When you move to the higher power 100x eyepiece, it will be even more critical in getting it both aimed and focused. If its off by just a few degrees, you wont see what you are looking for.

When you start nightime viewing, start with the largest object in the sky, the moon. Its the same process as daytime, except the eyepiece mechanism will have to be adjusted a little closer to the main body of the telescope.

Viewing planets and stars will be the ultimate test. Stars and planets are harder to see, since they are small, and hard to see unless they are in focus. When you can see those views, you have passed the telescope test. Its a matter of careful aim, and having the telescope focus set close to the point where you can see objects that are VERY FAR AWAY. If you are able to focus on the moon, you will be fairly close to being able to focus on the planets. The hardest part is actually getting the planet in the view of the telescope, in other words, aiming it.

The last item that can really mess up the view is a fogged up lens. Usually this happens in the summer when the scope has been in the air-conditioned room, and then it fogs up when taken outside. The solution for this is to let the telescope sit outside for 20 minutes, so the fogged lenses can clear. By the way, the same fogging may happen when you bring the telescope inside during the winter.

I hope this helps you eventually get a clear view of some amazing views in the sky. Your final exam is to take a look at the moon, the rings of Saturn, and the moons of Jupiter, some time in the near future. Have Fun!

Nov 14, 2007 | Vivitar (1607225) Telescope

3 Answers

Bushnell 18-1560 Telescope

What you have is called a refractor-type telescope with the primary lenses (the Objective) at the top of the tube and the only other lenses in the system are your selection of eyepieces, probably a barlow lens (2X magnification of any eyepiece used), and a diagonal (in line mirror so that you cand see into the telescope from the side.). As the focal lenth of the eyepiece decreases, so does the distance away from the Objective Lens. I believe that you are using the telescope with a diagonal mirror which makes the optical path longer. The fact that your longer focal lenght eyepiece can focus and not your short one would be only if you didn't have the diagonal or the eyepiece all the way in tight to allow the focus mechanism (rack and pinioin) to get compressed enough to focus. Look at the Moon, if the image gets smaller then bigger as you focus, but not sharp, then I would have to tell you that your eyepeice lenses are not in the right order. Someoner may have taken it apart and didn.t put them back in the correct order. The lenese could just be very dirty also. Barrow a short focal lenght eyepice from a friend and see if it works in your system. Then you will know for sure.

May 15, 2007 | Bushnell Deep Space 18-1560 (150 x 53mm)...

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