Take binoculars and a telescope with the same aperture and magnification and try to compare their ability to observe objects in the night sky. Phil Harrington, in his book Touring the Universe Through Binoculars, says that observing with two eyes greatly increases one’s ability to detect and recognize faint objects. In addition, the perception of color and contrast is improved. As a result, according to Harrington and many other experts, there is a 10-40% improvement in color perception and contrast.
Telescopes or Binoculars
I myself have long been a fan of binoculars. I see their advantages quite clearly. It is also true that for the same aperture, a quality refractor telescope is better than a refractor telescope when observing planets and double stars. That said, I haven’t seen any data anywhere about the results of comparing refractors and binoculars. In the late 80’s I bought a wonderful binoculars with excellent lenses and image quality – Fujinon 14X70Ts. Complete with a Bino-Mount binoculars and a stable tripod, these binoculars are delightful. A few years later I realized that to shoot the total solar eclipse in Aruba in February 1998 I needed a telephoto lens with a focal length of about 500mm. A TeleView Ranger reflector telescope with a pair of ED lenses was just what I needed. It has a 70 mm objective lens diameter, a focal length of 480 mm and I could easily take it with me on trips. It was a good match for my binoculars. With the improved diagonal mirror and the 32mm Meade Super Plossl eyepiece it gained a fifteenfold magnification and became a true champion in its weight. And because it had fewer lenses in the system, it had a slight advantage over binoculars in light transmission. It also had a slightly higher magnification. Except that its real field of view of 3.5 degrees was less than the binoculars’ 4 degrees. These small differences were the reason for serious comparison of the two optical instruments.
Anyway, one night in February, I decided to have a competition between the telescope and the binoculars. The day was windy, cloudy, and hot, and toward evening there was not a single cloud in the sky. At about 10 p.m. I set the telescope and binoculars down and let them cool off for about thirty minutes. The night was just perfect for observing. Although the atmosphere was turbulent, the sky was perfectly clear, the light pollution was moderate, and six of the seven stars of the Little Bear were visible to the naked eye.
The first target of the comparison was the object M42, the great Orion Nebula, high in the sky to the southwest. Through the telescope, the grayish nebula was seen clearly and distinctly, measuring almost half a degree. The trapezoid was partially visible, three stars out of four. The binoculars allowed me to see the same three stars of Trapezia, but the nebula was definitely larger, twenty percent larger. The advantage of the binoculars seemed clear. Now let’s test the optics on star clusters, galaxies, and other wonders of deep space. Could the binoculars take out the telescope in one wicket?
I turned both instruments toward M1, the Crab Nebula in the constellation of Taurus. Through the binoculars, the nebula seemed larger, but not by much. More magnification was needed to see this nebula better, but it would be unfair to turn the telescope magnification to maximum.
Next, I moved on to the open star clusters in the constellation of Ascendant, one of my favorite objects to observe. M36 and M38 in both binoculars and telescope were the same size. I looked for stars visible in one, but invisible in the other instrument. Nothing like that was visible. Then I realized that I could adjust the field of view to see NGC 1893 as well. This is a much dimmer cluster, with a total stellar magnitude of 7.5 and a diameter of 12 angular minutes, according to Harrington’s book, Observing the Universe with Binoculars. In the Barnham Star Guide, this cluster includes about 20 clusters with star magnitudes ranging from 9 to 12. Again, no definite difference in the image. The view was amazing in both instruments. I slowly examined the visible area and noticed through the binoculars a small faint patch of light, about midway between M36 and NGC 1893. This object was not in the Barnham Gazetteer, but Uranometria 2000 had a faint cluster, Do20, with a star of magnitude 6 in the foreground on the western side. The star could be easily seen with a telescope, but the cluster was no longer visible even by the “side-view” method. Similar situation occurred with a nearby NGC 1907, an open cluster of 40 stars of about 10 magnitudes. I was able to see it by “side view” with a telescope. But with binoculars its view was definitely clearer.
Two nights later I pulled out my optics again for comparison. The weather was clear and not as cold as that time. I went back to the familiar objects and checked the previous observations. This time, incidentally, I found two faint stars in the constellation of Ascendant, which were barely visible with the telescope and not at all visible with binoculars. Could this have been due to the slight magnification advantage the telescope had this time? Quite possibly. M31 in the constellation Andromeda was perfectly visible with both instruments, but, again, with binoculars the nebula was visible by 20% more. A certain pattern was beginning to emerge.
Here we came to the answer to the question of what is better for looking at dim objects in space. My conclusions are as follows. A quality telescope, by virtue of having fewer lenses and better light transmission, can show objects slightly dimmer than those seen through binoculars. Binoculars, which use two eyes for observation, show dim objects twenty percent more, because of the way our brains work. But is this a scientific explanation? Yes, of course, the advantage remains with the telescope when you want to use more magnification or screw in a filter or two. And I understand that there are certain models of binoculars that have interchangeable eyepieces and allow you to mount filters. You can also put a binocular device on a telescope, if funds allow you to buy one and extra eyepieces. I have seen some amazing photos taken with a six-inch telescope paired with this device. I only doubt that this design is better suited for observing nebulae and faint clusters. My main goal was to compare a telescope and binoculars of very similar size and quality and to understand what is better to use for faint star objects. All things being equal (magnification, aperture, quality of optics, etc.) binoculars are superior to telescopes. That’s why many amateur astronomers use giant binoculars to observe comets. And my recommendation: use binoculars to find an object and put it in perspective at maximum field of view. Then point a telescope at it, increase the magnification, and look at the object in detail. Use both instruments whenever possible!