I have a AILINK 114mm diameter, 900mm focal length, reflector telescope. I'm able to see the moon very well however, I can't see Planets very clearly

The first two images are what I can see and the second two is what I want to see Is that possible for my telescope also, how can I take better pictures like those examples.

Note* it was pre windy and the image was a little better then in the picture

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  • $\begingroup$ Your first i,age of Jupiter is just overexposed. Generally, if you have enough exposure to see Jupiter's moons, Jupiter itself will be overexposed. If you want a picture of both, take one properly exposed of Jupiter, one exposed to get the Moons, and make a composite image. That image also looks slightly out of focus, or taken in poor 'seeing' conditions. The other pictures look pretty much like what you'd expect from a 114m Newtonian scope with a 900mm focal length. You could try a barlow lens, but depending on your optics and collimation it might not help. $\endgroup$
    – Dan Hanson
    May 11, 2020 at 22:35
  • 1
    $\begingroup$ An F/8 Newtonian is likely to be a Bird-Jones design, with a spherical rather than parabolic mirror, and a corrector built into the focuser. Usually the mirror and corrector are poor quality and don't give good results. Can you / have you collimated this telescope? $\endgroup$
    – Aaron F
    May 12, 2020 at 9:24
  • $\begingroup$ If the optical tube length is about the same as the focal length, it's more likely a proper Newtonian. $\endgroup$
    – Mike G
    May 13, 2020 at 14:54

2 Answers 2


The planets appears to be smaller than the Moon, so it is more difficult to see the details on them. These are some of the factors that determine how good the image will be.

Steadiness of the scope. You mentioned that it was windy, so I assume that the scope was vibrating a lot. To get a good view, you need a scope that does not vibrate when you do not touch it. (A rule of thumb is that the vibration should dampen out in 1 or 2 seconds when you are done focusing or moving the scope to track an object.)

Steadiness of the air. If you look over a paved road on a hot day, you can see how the air is shimmering. Now imagine magnifying that shimmering air by 50x or 100x, and that is what you are dealing with when using an astronomical telescope. The steadiness of the air will limit the size of details that can be seen. (Astronomers refer to this as the "seeing". The shimmering of the air is generally not as bad as my example of the road, but looking through 20 miles of atmosphere and magnifying it make it seem as bad.) The telescope can also create air currents if the scope is warmer than the air. Waiting 15 to 60 minutes (depending on the design and size of the scope) to let the telescope cool down to the air temperature can help with the air currents inside the tube.

Viewing an object when it is high in the sky will help with the seeing because you are looking through less atmosphere (and less distortion). Viewing an object when low in the sky will usually be disappointing. (Move to a location where the object is higher in the sky! :-)

Quality of the mirror A telescope mirror needs to be ground and polished to a high degree of accuracy. Without someone performing a test on your scope, it is hard to know if the figure is excellent, acceptable, or poor. (I have not ground a mirror myself, but I have read that it is not hard to make a good mirror. Or course, it is even easier to make a poor mirror!)

Quality of the eyepieces The eyepieces are just as important as everything else. Some eyepieces provided with small telescopes are of low quality. If the diameter of the eyepiece barrel is about 1 inch (25 mm) or has the letter "H" in front of the eyepiece size (like H20mm), the quality is likely to be poor. 1.25 inch (32 mm) diameter eyepieces are generally better quality.

Magnification A rule of thumb is that the maximum useful magnification is 50 times the diameter of the optics in inches (or 2 times the diameter of the optics in mm). For 114 mm, that gives a useful magnification of 220x. You will find that lower magnifications are used more often because the image gets worse at higher magnification, especially when the seeing is poor. 50x to 150x should be enough to give good views of Jupiter and Saturn.

Collimation A Newtonian reflector has two mirrors. If the mirrors are not aligned properly, the image quality will deteriorate. (The alignment is known as collimation.) The way to check the collimation is to look at a bright star high in the sky. When in focus, the star should be a sharp point surrounded closely by a faint ring. When you un-focus the image slightly, the star will be a larger dot, and the faint rings (diffraction rings) will be a little larger and easier to see. The rings should look like a bulls eye around the dot of the star. The image should be the same on either side of the focus.

If the image is not round, or if the image changes from inside focus to outside focus, either the quality of the mirrors is poor, or the mirror is warped in the mount (too much force in the holding mechanism is bending the mirror!) or the collimation is off. The warping of the mirror can be corrected by not applying as much force on the clips that hold it in the cell. The collimation can be adjusted to correct for problems with the alignment. See How to Align Your Newtonian Reflector Telescope on the Sky & Telescope website for example. A poor quality mirror cannot be easily corrected unless you know someone with the skill to re-polish it.


The images you took may just be affected by bad seeing. Some nights are better than others, as shown in this article about an observing run at the Subaru Telescope. Clear Sky Chart provides seeing forecasts for numerous locations in North America. Clear Outside offers a seeing forecast as an "experimental" feature worldwide.

Even on a night of good seeing, the image quality will fluctuate. The finest details are visible maybe 2 out of 30 seconds. Lucky imaging works around this by recording video, discarding the blurry frames, and stacking the sharp ones in software. The Gemini Observatory used this technique for the infrared image of Jupiter in the news recently. Amateurs can buy video cameras built to fit into a standard eyepiece holder.


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