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  #1  
Old 07-03-2017, 07:58 PM
gotduss (Gauthier)
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Advice on how to use my telescope

Here is the telescope I have had for 3 weeks "Astronomical Telescope 114mm Aperture 675x Zoom TL114A". I have been trying to observe trees in the daylight as well as the moon during night time using the 20mm eyepiece but I have only been able to see some sort of brightness and haven't been able to see objects. It seems to work as it gets totally dark when I place my hand in front of the telescope. Is there anything wrong with the telescope or am I doing anything wrong? . I have also attached a picture of my telescope.
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  #2  
Old 07-03-2017, 08:44 PM
gaseous (Patrick)
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Quote:
Originally Posted by gotduss View Post
Here is the telescope I have had for 3 weeks "Astronomical Telescope 114mm Aperture 675x Zoom TL114A". I have been trying to observe trees in the daylight as well as the moon during night time using the 20mm eyepiece but I have only been able to see some sort of brightness and haven't been able to see objects. It seems to work as it gets totally dark when I place my hand in front of the telescope. Is there anything wrong with the telescope or am I doing anything wrong? . I have also attached a picture of my telescope.
Hi mate, and welcome. Silly question maybe, (and I'm not trying to take the p!ss), but are you removing the large dust cap at the end of the tube? I see in the photo it's still on the end, with just the smaller cap removed.
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  #3  
Old 07-03-2017, 10:52 PM
gotduss (Gauthier)
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Hi and thank you so much for your reply. As you can see I have just started being interested in space and I have a lot to learn; thanks to my son. I had no idea this large cap could be removed; is that all I was forgetting? I will try again and let you know how I go. Hopefully this will work. Thank you again.
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  #4  
Old 07-03-2017, 11:12 PM
gotduss (Gauthier)
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I just saw the moon. You were very helpful, thank you so much. Is it possible to see the moon's craters with a 20mm or should I use a different eyepiece (12.5mm)?
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  #5  
Old 08-03-2017, 07:13 AM
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Allan_L (Allan)
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Quote:
Originally Posted by gotduss View Post
I just saw the moon. You were very helpful, thank you so much. Is it possible to see the moon's craters with a 20mm or should I use a different eyepiece (12.5mm)?
Hi Gauthier,
From what I can gather, your telescope is
114 aperture
900 focal length
f/8
and you have eyepieces H20 H12.5 and SR4

Short answer to you question is Yes. You should be able to make out craters on the moon with the H20. And this is usually the best eyepiece to start with. Once centred in the eyepiece you can switch to higher magnification if required.

Magnification is calculated by focal length (900 in your case) divided by eyepiece number.

So without the barlow or erecting tube (both which increase magnification -3 times and 1.5 times respectively) your eyepieces should give you magnifications of:
H20 = 45x
H12.5 = 72x
SR4 = 225x

The theoretical best usable magnification is twice your aperture.
So 114x2 = 228x
But you will need good conditions to be able to focus clearly even for that.
So the reported 675 zoom claimed is advertising BS. and will provide nothing more than a BIG, but fuzzy blob.

Also, the higher the magnification, the quicker the target will appear to move through the eyepiece field of view. So another reason to start with the smaller magnification.

Enjoy your scope, you may find the limitations prompting you towards a bigger and better scope and (more especially) better mount, quite quickly once you get hooked.

Tip. Moon is better viewed when smaller. ie not Full moon. More detail of craters can be found along "The Terminator" the line between bright and dark part of the moon.

Next: Point at the middle "star" in the sword of orion. (some people call the handle of the teapot) for a nice bright Nebula.

Feel free to ask more questions
Welcome to IcenSpace
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  #6  
Old 08-03-2017, 07:45 AM
glend (Glen)
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That Self-Erecting tube is actually a 1.5x barlow lens, i would remove that for testing. Just start with your lowest powered eye piece in the focuser and get that to focus first. The alignment ( or collimation) of the primary and secondary mirrors may be an issue, but i hestitate to recommend looking at it just yet.
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  #7  
Old 08-03-2017, 07:47 AM
miker
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Quote:
Originally Posted by gotduss View Post
I just saw the moon. You were very helpful, thank you so much. Is it possible to see the moon's craters with a 20mm or should I use a different eyepiece (12.5mm)?
Hi Gauthier,

As you have asked about craters, I am wondering if you have been able to achieve focus.
In your photos, there is an "erecting prism" adaptor shown between the eyepiece and the focuser. This device is used to show objects right way up when using the telescope for terestrial objects (trees, mountains etc).

Remove the adaptor and and just put the 20mm eyepiece into the focuser.
Adjust focus for a clear sharp image by turning either one of the black round knobs below the eyepiece on the focuser. You should be able to go from blurry image to crisp sharp image and back to blurry again. If you can not get it to focus as described then we need to discuss further.
You will be able to see plenty of craters with the 20mm eyepiece if you are getting it to focus correctly.
The shorter focal length eyepiecs will just increase the magnification.

Let us know if you can get a nice clear image of the moon with the 20mm.

Michael
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  #8  
Old 08-03-2017, 07:52 AM
gaseous (Patrick)
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Quote:
Originally Posted by gotduss View Post
I just saw the moon. You were very helpful, thank you so much. Is it possible to see the moon's craters with a 20mm or should I use a different eyepiece (12.5mm)?
No worries - whatever questions you may have, I'm sure you won't be the first (or last) to have them. I know you're just getting started, and for one reason or another you may not feel the need to do so just yet, but if you persist with astronomy your viewing may be assisted to some degree by some better eyepieces. I've lifted this from the rocketroberts.com website:

"Beware of telescopes that have eyepieces with any or all of the following markings: H25, H20, H12.5, and SR4. If the scope has one or more of these eyepieces, it is likely that the images will be marginal to poor. The "H" stands for "Huygens", one of the poorest performing optical designs available (they are inexpensive to manufacture however). "SR" stands for Symmetric Ramsden. Trust me on this: no small telescope will benefit from an SR4 eyepiece. The manufacturer simply includes this so that the high end magnification of the telescope sounds very impressive (it is a marketing ploy). Most people will find using an SR4mm eyepiece extremely frustrating. The SR4mm eyepiece has what is known as very poor eye relief. If you wear glasses, the SR4mm eyepiece will be impossible to look through."
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  #9  
Old 22-04-2017, 02:23 AM
AEAJR (Ed)
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Cool

Quote:
Originally Posted by gotduss View Post
Here is the telescope I have had for 3 weeks "Astronomical Telescope 114mm Aperture 675x Zoom TL114A". I have been trying to observe trees in the daylight as well as the moon during night time using the 20mm eyepiece but I have only been able to see some sort of brightness and haven't been able to see objects. It seems to work as it gets totally dark when I place my hand in front of the telescope. Is there anything wrong with the telescope or am I doing anything wrong? . I have also attached a picture of my telescope.
Quote:
Originally Posted by gotduss View Post
Hi and thank you so much for your reply. As you can see I have just started being interested in space and I have a lot to learn; thanks to my son. I had no idea this large cap could be removed; is that all I was forgetting? I will try again and let you know how I go. Hopefully this will work. Thank you again.
Quote:
Originally Posted by gotduss View Post
I just saw the moon. You were very helpful, thank you so much. Is it possible to see the moon's craters with a 20mm or should I use a different eyepiece (12.5mm)?
In a short time you have made progress. Congratulations.


How about an update? We love to hear of your successes and glad to answer questions.


I will add a note about eyepiece to build on what Allan_L said earlier.

It appears you have 3 eyepieces. The higher the number the lower the magnification. Simple math as Alan described.

The long tube, the barlow, will give each eyepiece a second magnification. So you will have the equivalent of 6 eyepieces.

The normal way a Newtonian telescope displays images is inverted. Kinda weird on the ground but in space there is no up an down so it doesn't matter. you just have to get used to it so you know how to move it when you are following something.

Assuming Alan is right and that is a correcting image barlow than it is intended primarily for daytime use so the images display correctly. You can use it to get that added magnification at night but realize that things will display one way with eyepiece alone, the way we would normally use the telescope, then they will flip when you use the correcting image tube.


Let me offer this as a way to become more comfortable with your telescope.


Daytime Activity

Spend time during the day getting the finder aligned with the scope. Read the manual. Use a distant target. 100 feet is way too close. 1/4 mile away minimum. I like to use phone or power poles and target in on the cross arm.

(How to align a finder scope https://www.youtube.com/watch?v=r3zGgrY7sK8 )


Test the scope with each eyepiece. Focus on distant things. Get used to the fact that the image is inverted. Figure out how to move around with that reversed image. Do this during the day.

Find a branch or a bird or something that has lots of detail. Use low power then high power to see how much detail you can get. If you have a barlow, use it to get closer.

Notice how well the image is in the center vs. the edge. There may be some loss of sharpness at the edge. A little, or only the outer 10% is fine. If you start to lose significant sharpness during the day any more than that then there might be a collimation issue or some other issue. A lot depends on the type of eyepieces you are using.

(Eyepiece Designs - http://www.chuckhawks.com/common_eyepiece_designs.htm )

Take note of the difference in field of view between your eyepieces.

Move from one target to another and get used to refocusing.



Finding and tracking during the day

A very very high jet is perfect. A bird will be too fast.

Use your finder scope to get that Jet in the FOV. Now, using the longer FL, higher number, eyepiece try to pick it up in the eyepiece. You might have to lead it a bit to account for moving from the finder to the eyepiece. Let it fly into the FOV. This will also test how well your finder and your eyepiece are aligned.

Now track that jet with the low power eyepiece. How much detail can you see? How long does it stay in view?

Now do the same with the high power, shorter FL eyepiece. Note it will be a little harder to keep it centered as the FOV is now much smaller. Stars and planets move slower than that jet so they will be easier to track.


All of this will be valuable training for the night time. These are the same skills you will need but they will feel easier during the day. When it is dark you will already be used to doing these things.
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  #10  
Old 24-04-2017, 07:19 AM
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sil
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tons of great advice above. With telescopes as with camera lenses the numbers dont mean too much and its the quality of the optics that you are really paying for and with cheaper beginners scopes the eyepieces and barlows/erecting tubes often use plastic optics instead of glass which can effect the quality of what you see greatly. Plus every layer of optics the light has to travel reduces the potential quality at the eye or camera sensor. So for now I'd forget bothering with the erecting tube as its likely doing you more harm than good. its handy for when you are able to train the scope on a target and want a bit more close up on it.

Also the front end caps (one inside the other) can be useful for really bright targets like a full moon (the moon is much better observed when NOT 100% full though) to make it easier on the eye. Just pop in the larger cap without the smaller one in its center
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