Celestron PowerSeeker 127EQ focusing problem

[AstroSandy]

Hi,

Recently I purchased PowerSeeker 127EQ , I'm having difficulty in focusing and collimation when I try to focus on Jupiter. any help highly appreciated

I'm a beginner to astronomy just few weeks into this hobby

Here are some pictures I tried to get

[Ricochet]

How were you trying to take photos? Just by holding a mobile phone up to the eyepiece? That is probably the only way I would use with that telescope as it is really only intended for visual use. If you do that then the focus point for your eye and for the phone camera should be pretty similar.

The images you have posted really just look like they are out of focus so that you are seeing the inside of the telescope, not Jupiter or whatever target you have the telescope pointed at. Remember that the focuser is not a zoom function. The point of best focus is when the planet is at its smallest. With the telescope pointed at your object turn the focuser wheel so that the size of the circle becomes smaller, not larger. 

With regards to collimating this telescope, the best that you can do is to look down the focuser through a collimation cap, not an eyepiece, and make adjustments so that the mirrors and their reflections all appear centred and concentric.

[lenscap]

Hi AstroSandy & welcome to SGL.

If this is your first telescope it can be a good idea to practice focusing in daylight to start with.

In daylight place your 20mm eyepiece in the focuser and aim the scope at a distant target such as an electricity pylon or TV antenna (keeping well away from the Sun of course) and bring the target into sharp focus. Leave the  eyepiece in place.

Take the opportunity to check/adjust the Finder scope so it points at exactly the same spot as the main scope.

Now when you point the scope at a nighttime target it should be in focus, or maybe need a very slight adjustment.

Hope you enjoy this great hobby.

[AstroSandy]

I tried to use is in daytime to focus on distant hills & buildings approx. 5 km away it was able to focus correctly. Now while adjusting main reflecting mirror at bottom of telescope not able to align it properly or focus.

Also tried another approach at dark night time from the Eyepiece put up torch light from eyepiece to check normal alignment and was able to see good beam of light coming out from open end of the Telescope

[AstroSandy]

On 23/09/2018 at 17:47, Ricochet said:

How were you trying to take photos? Just by holding a mobile phone up to the eyepiece? That is probably the only way I would use with that telescope as it is really only intended for visual use. If you do that then the focus point for your eye and for the phone camera should be pretty similar.

The images you have posted really just look like they are out of focus so that you are seeing the inside of the telescope, not Jupiter or whatever target you have the telescope pointed at. Remember that the focuser is not a zoom function. The point of best focus is when the planet is at its smallest. With the telescope pointed at your object turn the focuser wheel so that the size of the circle becomes smaller, not larger. 

With regards to collimating this telescope, the best that you can do is to look down the focuser through a collimation cap, not an eyepiece, and make adjustments so that the mirrors and their reflections all appear centred and concentric.

 

re: Collimation technique on the main mirror I don't see marking for center of the mirror as shown in youtube video of collimation

[happy-kat]

Hi, I think you need to read up on how to collimate a telescope that is a jones bird design as it is harder then on a telescope that doesn't have a barlow built into the focuser assembly.

Your telescope tube is roughly 500mm long but the telescope focal length is 1000mm which suggests there is a built in barlow in the focuser assembly.

[Charic]

You shouldn't really need to collimate this scope?

The scope if new should have been factory collimated,  and a spherical mirror  like the one installed is almost always collimated by design, and as long as the spherical mirror has not moved during transit ( their pretty secure, unless the scope has been dropped from a great height ? ) all you need to do is look down the focuser and check that you can see the three primary mirror clips ( their 120° apart around the circumference of the main mirror, and the secondary mirror is central/concentric to the inner wall of the focuser tube. As long as you can see these, then the mirror is aligned, it doesn't get much better.

There are collimation instructions on page 27 of the user manual should you wish to tamper /learn what the settings do, but just get out and setup during the day, then try with the longer focal length eyepiece  at night.

[Ricochet]

1 hour ago, AstroSandy said:

 

re: Collimation technique on the main mirror I don't see marking for center of the mirror as shown in youtube video of collimation

These scopes don't have the centre marked, I guess it's a cost saving measure. If you want it marked you will have to remove the mirror and mark it yourself, however, so long as you get everything concentric you should be ok. 

[Alan64]

On 30/12/2018 at 08:44, AstroSandy said:

re: Collimation technique on the main mirror I don't see marking for center of the mirror as shown in youtube video of collimation

You can mark the mirror yourself...

You need a drawing-compass w/pencil, clear double-sided tape, white paper, scissors, a ruler, a permanent marker, and a single polyvinyl(plastic, not paper) notebook-paper reinforcement...

Measure the diameter of the mirror with a ruler, and at its widest point.  Take care not to touch the mirror's surface with the ruler, or any other object; only the paper may come in contact with the mirror.  Make a paper pattern using the compass, and slightly smaller than the mirror.  You want to see only a sliver of the mirror, the outside edge all around, when you place the pattern on to the mirror.  That will aid you in centering the pattern over the mirror...

Eye the edge over all round, and center it.

Here, the paper pattern in centered on to the mirror...

Take the permanent marker and press its tip into the hole made by the compass.  The smaller the mark, the better.  Here, the pattern has been removed, leaving only the mark made by the marker...

Take the pattern and cut out a hole in the center.  It doesn't have to be precise.  Lay a strip of the clear, double-sided tape over the pattern's hole.  Peel off a polyvinyl reinforcement from the pack, and stick the reinforcement to the underside of the tape, with the adhesive side of the reinforcement facing downward.  Place the pattern back on to the mirror, center the reinforcement over the marker's mark, as shown, then press the reinforcement firmly into place...

Carefully(!) lift the pattern off of the mirror and the reinforcement, and you're done...

What, easier said, or shown, than done...

https://www.youtube.com/watch?v=QWlB2rD-sPY

 

[Charic]

Marking the central mirror can be done, as shown above, but I found there was no benefit or any improvement over the basic method described for collimation  in their instruction manual. What it did do was to give me an insight of how the scope was assembled and worked, nothing more.

Looking at page 12 in the instruction manual #21049, they show a diagram that depicts a simple image of what you should see whilst looking down the focuser tube without eyepiece inserted.

Unless you want to learn disassembly / re-assembly,  having already been down this route,  I would not  reccommend marking the 127EQ's mirror. In my opinion, it bought no improvement benefit. You will not improve the configuration/collimation on a spherical mirror !!

Live with the image on page 12, and if you need a tool to aid your eyesight whilst collimating, just punch a 1mm hole in the focuser's dust cap.