Why Are Telescope Images Black And White?

Why Are Telescope Images Black And White

Whenever we see an image of galaxy or nebula, the color strikes us the most. The pink patch of color in stars, vibrant red and green hues of nebulas and a blue hint of the cosmic dust is sure to leave us at awe! However, when you are observing any object with your telescope, you’ll be pretty disappointed. You’ll see the objects mostly in a black/white or dark greyish color, far from what you are accustomed to seeing in the internet or magazine.

Why does this happen? We are going to learn exactly that in this article.

Telescope images seem black and white because at night, when there is low light, our eyes use rod cells to see objects. Rod cells can’t reveal a lot of color or details. that’s why when we see something with a telescope at night, it seems black and white.

A Bit Details

Why Are Telescope Images Black And White
Credit: Nathan Smith, University of Minnesota/NOAO/AURA/NSF and NOAO/AURA/NSF

Human eyes have two types of cells for sensing colors: rod cells and cone cells. The cone cells help us to see brighter, colorful objects. They need thousands of photons to activate and can reveal a lot of details.

On the other hand, rod cells are activated in low-light situations. Rod cells can work in a low-light situation where there is very little photon, however, it can’t reveal a lot of details and colors.

That’s why, when we try to observe anything with our telescope at night, because of the low light situation, our rod cells get activated and present us with a dull black and white image.

So, How the Internet Gets Colorful Images?

There are 2 reasons: long exposure shot and computer enhancement. When NASA takes pictures of the celestial objects, it uses long exposure shots. Long exposure shots mean the camera took a lot of time to gather all the light coming from the celestial object. As the camera gathers more light in long exposure shots, the images come more vibrant and colorful. We don’t have that advantage in a telescope.

Also, most of these images are further enhanced by computers. Generally, the images are taken in grayscale mode and then colored depending on the level of the gray. Some advanced computers use spectral analysis for further detailed enhancement of each of these photos.

That’s why the Internet, NASA, and other magazines have colorful images.

To see the basic difference here are two images of the same nebula:

What Can We Do?

Since we don’t have any way to gather more light like a camera, there are basically 2 things we can do to improve the color: use a Barlow lens or a filter. Also, getting a larger telescope will help, but it is not an economical or feasible solution for most beginners.

Using Barlow Lens

In simple words, a Barlow lens is a type of lens that is used to increase the magnification power of a telescope. It is a concave type lens placed between the mirror or objective lens and the eyepiece in a telescope.

Barlow lens comes with many magnification settings, but the most common one is the 2x Barlow lens. The thing Barlow lens does is it effectively increases the focal length of a telescope. Thus using one can improve the viewing quality of an object.

Using Filters

Using color filters is the cheapest, effective and recommended way to observe the night sky with a telescope. Color filters are simply a type of material that works as a gate for colors. The filter passes a specific range of colors while blocking the rest. By adding a color filter to our telescope, we can enhance the color we want to see and reject the unwanted ones. Thus it can offer us a more detailed view of the object we are trying to see.

How Color Filters Can Improve Image Quality?

The light we see from the objects through our telescope consists of a range of lights. These lights are generated from a range of wavelengths. The different wavelengths can interfere with each other resulting in a poor image quality.

What we can do is, enhance only those light wavelengths that we want to see and discard the rest. The way to do that is by using a color filter. When we use a color filter, it isolates only a small portion of the huge light spectrum and enhances that portion. As a result, we can see a more vibrant image with further more details.

There are many types of color filters. The one you need to use depends on the object you are trying to observe.

Here are some of the most popular color filters:

Light yellow

This filter adds a yellowish hue to the image and cuts down the deep blue and violet portion of the spectrum. This filter is mainly used to observe the Moon. The filter can enhance the details of the mountains, craters and the rilles of the Moon.

The light yellow filter is also used to observe some other planets, like Mars, Saturn and Jupiter. It makes the Mars easier to see and identify. Also, the cloud belt of Jupiter and Saturn gets easier to observe with this filter.

Even when observing comets, you can use this filter to see the dust tail clearly.

Orange

This filter blocks the violet, blue and green color of the spectrum and adds an orange hue to the images. The orange filter is particularly useful for increasing the contrast of fine details of celestial objects, like Moon. It also helps to observe the Mars like the previous filter

With the orange filter, the blueish atmosphere of Jupiter’s atmosphere will get more prominent. You can also observe Mercury or Venus with this filter.

Blue

By blocking the green and red portion, this filer adds a blue hue to the image. Craters on the moon, specifically the Maria can be observed further in details with this filter. Also, the cloud belts, Jupiter’s Great Red Spot, polar ice caps of the Mars, and shadings in Venus can be observed with this filter.

Which One Should You Get?

Instead of buying separate color filters, I’ll always urge you to get a kit of color filter lenses. These kits are available on Amazon at a very cheap price. Here you can check out my recommended color filter kit for telescope on Amazon.

This kit includes 3 types of filters: CPL filters, Moon & Skyglow filter and lastly color filters with 5 different colors: yellow, orange, red, blue and green. This is surely the most feasible color filter kit right now in the market.

There Is Another Solution

Although this is the most effective solution, it is not economically feasible for everybody. The solution is using a camera with your telescope to take long exposure shots. Of course, the camera needs to be of good quality, preferably a DSLR or a mirrorless camera.

Some people have got good result using a good quality smartphone camera too. But for this, you’ll need additional gadgets such as cell phone adapter for the telescope, a motorized right ascension, and an app that can allow long exposure shots. This is not suitable for absolute beginners and you need to have a good grasp on your telescope.

Final Words

So this is why telescope images seem black and white to our eyes. If you are new to using a telescope, don’t let this demotivate you. Try out the solutions mentioned in the article and you’ll start to get better quality images within no time!

 

 

Muntaseer

I have wondered how the Stars and Moons look like for many years. I’ve fallen in love with Cosmology since I was a boy. I am writing these articles to share my love for astronomy with you.

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