<blockquote>
  <p>I have made sure that the laser is straight by 1. spinning it in the
  eyepiece holder and the laser stayed in the same spot 2. zooming in
  and out and again the laser stayed in the same place. the laser seems
  to be centered so I put it in the middle of the doughnut on the mirror
  and the laser bounces back into the middle of the colimating lens</p>
</blockquote>

<p>Very good. You're doing all the right things. Kudos for taking care of your telescope.</p>

<p>Now, about Mars looking like a fuzzball.</p>

<p>The angular size of Mars right now is 6.5 arcsec. The maximum theoretical resolving power of your scope is 0.4 arcsec. In ideal conditions (assuming everything was perfect, which it never is), you'd get something like 16 "pixels" diameter for the image of Mars in your scope. That, I'm sure you realize, is a very low resolution. No wonder it looks like a fuzzball.</p>

<p>Mars is a tricky target. The best times to observe it is around oppositions, which happen once every two years (plus a few months). Mars is nice and big a few weeks before and after opposition, and otherwise it's pretty small. The last opposition was in July 2018, when it measured 24 arcsec. The next one is in October 2020, and it will measure 22 arcsec.</p>

<p><a href="http://www.nakedeyeplanets.com/mars-oppositions.htm" rel="noreferrer">http://www.nakedeyeplanets.com/mars-oppositions.htm</a></p>

<p>Stick to a few weeks before and after opposition. In the rest of the time, Mars is just too small.</p>

<p>Another source of problems is seeing - or atmospheric turbulence. When seeing is bad, all the high resolution targets (like all planets and the Moon) look bad. Nothing you can do about it. When seeing is good, your scope can work closer to its theoretical resolving power.</p>

<p><a href="https://en.wikipedia.org/wiki/Astronomical_seeing" rel="noreferrer">https://en.wikipedia.org/wiki/Astronomical_seeing</a></p>

<p>To predict seeing, go on the Clear Dark Sky site, choose a location closest to where you live, and check the forecast they give you for that location.</p>

<p><a href="https://www.cleardarksky.com/csk/" rel="noreferrer">https://www.cleardarksky.com/csk/</a></p>

<p>The row called Seeing is a seeing forecast. When it's dark blue, seeing is good. When it's white or light blue, seeing is bad. No point in looking at Mars when seeing is bad.</p>

<p>Finally, make sure collimation is actually good. You seem to be doing all the good stuff with the laser collimator. That's great. Now, when seeing is good, point the scope at the North Star, defocus a bit (move the focuser in or out of perfect focus a tiny bit) and look at the star image. It looks like a shooting target, a bunch of concentric rings. If those rings are perfectly round and concentric, your collimation is probably good.</p>

<p><a href="http://www.astrophoto.fr/collim.html" rel="noreferrer">http://www.astrophoto.fr/collim.html</a></p>

<p>This is called a star test, and it's the most accurate test of collimation. It's also the most difficult. So use your laser collimator on a daily basis, which is much easier, and maybe do the star test once or twice, just to keep your laser honest. Once you're convinced your laser technique works well, there's no need for the star test.</p>

<p>Oh, one more thing. Make sure your scope is at thermal equilibrium with the environment. If you're storing your scope indoors, it's probably way hotter than the cold night air. That will create internal turbulence within the scope. It's basically like bad seeing, except it's all inside your scope.</p>

<p><a href="https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-1/" rel="noreferrer">https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-1/</a></p>

<p><a href="https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-2/" rel="noreferrer">https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-2/</a></p>

<p>No need to install a fan on the primary (although that would definitely work if you're willing to make the extra effort). Just take the scope outside 1 hour before you begin using it. It will "breathe out" all the heat and it will be close to equilibrium.</p>

<p>Good luck and clear sky!</p>

CC BY-SA 4.0
2019-01-22T12:40:59.057Z
really helpful answer, it's so nice when someone takes the time to write such a thorough discussion.
uhoh
CC BY-SA 4.0
2019-01-22T16:30:23.137Z
wow, that was really in-depth and very informative thank you for all the links and responding so quickly. I will try these tonight if cleardarksky says it will be good!
Cameron Austin
CC BY-SA 4.0
2019-01-23T18:34:06.933Z
What do craters on moon look like at high magnification?
Wayfaring Stranger
CC BY-SA 4.0
2019-01-22T11:53:34.653Z
2019-01-22T11:59:43.920Z
2019-01-22T11:59:43.920Z
Florin Andrei
<p>I am having a lot of trouble getting a sharp image in my telescope. It is a skywatcher with a focal length of 1200mm and a diameter of 254mm. I have a laser colimater that I got for Christmas, so I have been using that but when I try to look at mars I see three mars in an overlapping triangle. I am not sure what to do. I have made sure that the laser is straight by 1. spinning it in the eyepiece holder and the laser stayed in the same spot 2. zooming in and out and again the laser stayed in the same place. the laser seems to be centered so I put it in the middle of the doughnut on the mirror and the laser bounces back into the middle of the colimating lens, but when I look at mars there is still three and there is no detail its just a red fuzz ball. I also checked the collimation of the telescope by zooming all the  way out to see where the shadow was and it seemed to be right in the middle.hopefully this makes sense, but let me know if I should say something in a different way. thank you In advance.</p>

CC BY-SA 4.0
2019-01-22T03:33:48.227Z
Hi. What is a Skywatcher? Is that a Newtonian reflector? Something else? Perhaps you can link to the sellers website in case there are other question about the optical design. And Mars is not good choice for testing the optics because it is currently far away appears very small. Few scopes will show much on it. A better test is a bright star, high in the sky, and at high magnification. When taken slightly out of focus, are the diffraction rings round? Are they triangular? If so, the mirror may be held too tightly and is being flexed.
JohnHoltz
CC BY-SA 4.0
2019-01-22T08:33:39.770Z
Have you tried looking at a distant object during the day?  See where your eyepiece needs to be for the image to be sharp, and use that as a starting point for looking at night.  Use low power (longer focal length) eyepiece at first.
Dr Chuck
CC BY-SA 4.0
2019-01-22T16:41:17.990Z
John: the sky watcher brand that I have is a reflector and thank you for the advice. I think when looking for the rings I went too out of focus, so I will look tonight if the sky is clear.
Cameron Austin
CC BY-SA 4.0
2019-01-22T16:43:30.773Z
Chuck: I have not thought of looking during the day.
Cameron Austin
<planet><solar-system><mars><newtonian-telescope>
I need help getting mars to look like a circle
Cameron Austin
# I need help getting mars to look like a circle

(Asked by: username_0 on 2019-01-22)

I am having a lot of trouble getting a sharp image in my telescope. It is a skywatcher with a focal length of 1200mm and a diameter of 254mm. I have a laser colimater that I got for Christmas, so I have been using that but when I try to look at mars I see three mars in an overlapping triangle. I am not sure what to do. I have made sure that the laser is straight by 1. spinning it in the eyepiece holder and the laser stayed in the same spot 2. zooming in and out and again the laser stayed in the same place. the laser seems to be centered so I put it in the middle of the doughnut on the mirror and the laser bounces back into the middle of the colimating lens, but when I look at mars there is still three and there is no detail its just a red fuzz ball. I also checked the collimation of the telescope by zooming all the way out to see where the shadow was and it seemed to be right in the middle.hopefully this makes sense, but let me know if I should say something in a different way. thank you In advance.

**Tags:** planet, solar-system, mars, newtonian-telescope

> **Comments:**
> **username_1**: Hi. What is a Skywatcher? Is that a Newtonian reflector? Something else? Perhaps you can link to the sellers website in case there are other question about the optical design. And Mars is not good choice for testing the optics because it is currently far away appears very small. Few scopes will show much on it. A better test is a bright star, high in the sky, and at high magnification. When taken slightly out of focus, are the diffraction rings round? Are they triangular? If so, the mirror may be held too tightly and is being flexed.  
> **username_2**: Have you tried looking at a distant object during the day?  See where your eyepiece needs to be for the image to be sharp, and use that as a starting point for looking at night.  Use low power (longer focal length) eyepiece at first.  
> **username_0**: John: the sky watcher brand that I have is a reflector and thank you for the advice. I think when looking for the rings I went too out of focus, so I will look tonight if the sky is clear.  
> **username_0**: username_2: I have not thought of looking during the day.  

---

## 1 answers

### Answer by username_3 on 2019-01-22. Score: 5 | Accepted answer

> I have made sure that the laser is straight by 1. spinning it in the
> eyepiece holder and the laser stayed in the same spot 2. zooming in
> and out and again the laser stayed in the same place. the laser seems
> to be centered so I put it in the middle of the doughnut on the mirror
> and the laser bounces back into the middle of the colimating lens

Very good. You're doing all the right things. Kudos for taking care of your telescope.

Now, about Mars looking like a fuzzball.

The angular size of Mars right now is 6.5 arcsec. The maximum theoretical resolving power of your scope is 0.4 arcsec. In ideal conditions (assuming everything was perfect, which it never is), you'd get something like 16 "pixels" diameter for the image of Mars in your scope. That, I'm sure you realize, is a very low resolution. No wonder it looks like a fuzzball.

Mars is a tricky target. The best times to observe it is around oppositions, which happen once every two years (plus a few months). Mars is nice and big a few weeks before and after opposition, and otherwise it's pretty small. The last opposition was in July 2018, when it measured 24 arcsec. The next one is in October 2020, and it will measure 22 arcsec.

<http://www.nakedeyeplanets.com/mars-oppositions.htm>

Stick to a few weeks before and after opposition. In the rest of the time, Mars is just too small.

Another source of problems is seeing - or atmospheric turbulence. When seeing is bad, all the high resolution targets (like all planets and the Moon) look bad. Nothing you can do about it. When seeing is good, your scope can work closer to its theoretical resolving power.

<https://en.wikipedia.org/wiki/Astronomical_seeing>

To predict seeing, go on the Clear Dark Sky site, choose a location closest to where you live, and check the forecast they give you for that location.

<https://www.cleardarksky.com/csk/>

The row called Seeing is a seeing forecast. When it's dark blue, seeing is good. When it's white or light blue, seeing is bad. No point in looking at Mars when seeing is bad.

Finally, make sure collimation is actually good. You seem to be doing all the good stuff with the laser collimator. That's great. Now, when seeing is good, point the scope at the North Star, defocus a bit (move the focuser in or out of perfect focus a tiny bit) and look at the star image. It looks like a shooting target, a bunch of concentric rings. If those rings are perfectly round and concentric, your collimation is probably good.

<http://www.astrophoto.fr/collim.html>

This is called a star test, and it's the most accurate test of collimation. It's also the most difficult. So use your laser collimator on a daily basis, which is much easier, and maybe do the star test once or twice, just to keep your laser honest. Once you're convinced your laser technique works well, there's no need for the star test.

Oh, one more thing. Make sure your scope is at thermal equilibrium with the environment. If you're storing your scope indoors, it's probably way hotter than the cold night air. That will create internal turbulence within the scope. It's basically like bad seeing, except it's all inside your scope.

<https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-1/>

<https://garyseronik.com/beat-the-heat-conquering-newtonian-reflector-thermals-part-2/>

No need to install a fan on the primary (although that would definitely work if you're willing to make the extra effort). Just take the scope outside 1 hour before you begin using it. It will "breathe out" all the heat and it will be close to equilibrium.

Good luck and clear sky!

> **Comments:**
> **username_4**: really helpful answer, it's so nice when someone takes the time to write such a thorough discussion.  
> **username_0**: wow, that was really in-depth and very informative thank you for all the links and responding so quickly. I will try these tonight if cleardarksky says it will be good!  
> **username_5**: What do craters on moon look like at high magnification?  

---

