Microscope + Telescope =?

At first glance, the headline says some kind of nonsense. These optical devices are completely opposite in purpose, why put them together? Nevertheless, I decided to try to combine the microscope and telescope in a single design. My goal will be to take photographs of the moon through a DigiMicro Mobile digital microscope . Consider this an interesting experiment with optics like macro photography through a drop of water , and not a serious guide to astrophotography.

Bit of theory

The principle of operation of all telescopes for visual observations (reflectors and refractors, regardless of their optical design) is based on the following. The lens (mirror or lens), forms in its focal plane the image of the object of observation. The dimensions of this image are usually in millimeters or even fractions of a millimeter. Therefore, the observer sees it through the eyepiece, as through a magnifying glass. So, for example, the optical scheme of the Newton reflector looks like.



What if we remove the eyepiece and examine the image “hanging in the air” through a microscope? For the image to be in focus, you need to combine the focal plane of the telescope and the subject plane of the microscope. Simply put, you need to fix the microscope in the eyepiece of the telescope. I expressed



this idea back in June last year., but reached its embodiment only now. Many thanks to Yuri from Dadget for supporting my idea and sending me a device for experiments.

I have a simple Celestron Astoromaster EQ 130 telescope, which I used a year ago to observe a solar eclipse live. If you read last year’s article, then you already know that you can easily get a picture through a telescope simply by placing the cellphone’s camera on the eyepiece. When replacing a mobile phone with a digital microscope, the eyepiece becomes unnecessary, it can be removed (almost all amateur telescopes have interchangeable eyepieces). Therefore, better results can be obtained by simplifying the optical design. Ideally, of course, you can put a bare matrix in the focus of the telescope. It is on this principle that digital astrocameras for telescopes work, for example this:



In the same way, you can use the “carcass” from the DSLR by connecting it through the T-adapter . However, using a turnkey solution would be completely unsportsmanlike. The purpose of this article is to conduct an interesting optical experiment, and not to get perfect photos.

Some design features of DigiMicro

A digital microscope is about the same as a digital camera. The difference is only in the optical characteristics of the objective, which allow to obtain a sharp image of objects at a distance of only a couple of centimeters. The DigiMicro focusing wheel allows you to move the lens in very large limits, as a result of which there is one interesting feature about which nothing is written in the instructions. The microscope has two lens positions at which the image is sharp, and, therefore, two real optical magnifications. One of them turns out when the lens is closer to the subject than to the matrix, the other when the opposite is true.



Original pictures: first , second .

In the first case, the image on the matrix is ​​larger than the subject itself. In the second, the projection is reduced in relation to the original, as in a conventional camera.

We train on cats nA waxwork Moon

First of all, I wanted to figure out whether the moon would fit into the field of view of the microscope. The focal length of my telescope is 650 millimeters, and the average angular diameter of the moon in the sky is about half a degree. Consequently, the diameter of the image of the moon in focus will be approximately 5.6 millimeters. I printed a small circle of the same diameter on a laser printer and pointed a microscope at it, exposing a smaller magnification.



What a luck! The circle fits perfectly in sight! When shooting a real moon, the area of ​​the microscope matrix will be used almost to the maximum.

Manufacturing adapter telescope microscope

The landing diameter of the eyepieces of most amateur telescopes, including mine, is 1.25 inches. It would be chic if that were the diameter of the round part of the microscope case.



As you can see, luck left me here - the diameter was a millimeter larger, and the microscope did not physically fit into the eyepiece.



If the diameter was a little smaller, you could just rewind the blue electrical tape ... And so, you have to craft a more complex adapter. You can glue it from cardboard tubes, order a metal part from an engineer Brunsat a familiar turner, or print on a 3D printer. The cardboard construction will be flimsy and short-lived. The metal may be too heavy and upset the telescope mount. Therefore, I chose to print on a 3D printer. To get started, a sketch on paper:



Transferring to SketchUp :



Printing on 3D MC7 Prime mini . This is a very cheap designer for self-assembly of a 3D printer, masterkit now sells them for 15,500 r.











The surface of the finished part under the microscope:



The inner diameter was a fraction of a millimeter less than necessary. Apparently, this happened due to the fact that SketchUp draws surfaces of revolution with polyhedra, and the radius of the circumscribed circle is taken as the radius. Therefore, the outer diameter came up perfectly, but you have to tinker with the inner one. It doesn’t matter, polylactide is easily processed. I took just such a short Phillips screwdriver: I



wrapped the handle first with masking tape, then with double-sided tape, and then with a strip of sandpaper. The result was an impromptu mill.



Ten minutes with the drill and you're done. The microscope is inserted tight and does not hang.



Left - Barlow Lens. Its frame has a standard diameter of 1.25 ″, I used it to check the adapter, so as not to carry the entire telescope with me. And this is how the whole assembly looks: The



mount fell deep into the loose spring snow :-)

Telescope test

Due to cloudy weather, I decided to conduct the first tests on a ground object taken from a long distance (more than a kilometer). Such an object was a television tower with a height of 350 meters. Here it is, peeking out from behind the cloud: The



smoke has dissipated a bit, we are pointing the telescope:



It turned out that the combined use of the focusing wheels of the telescope and the microscope allows you to smoothly change the magnification, it turns out something like a zoom lens. It’s just that the microscope’s screen fades in bright daylight, and focusing on it is problematic. Here's what happened at medium magnification:



The fact that I missed a little with focus became clear only after I threw the picture on the computer. In addition, atmospheric conditions left much to be desired. I had to shoot against the light, the sun was ten degrees higher. Due to the fluctuations in the heating air, the image trembled, and the tower sometimes took the most bizarre forms ( one example , two example ). Nevertheless, the telescope-microscope bundle is working; at dusk or at night a better result can be obtained. Taking pictures with a smartphone through a telescope is much easier, autofocus helps out.

To understand the scale:



You can also look at the photo taken from the same point last fall at the time of the “eclipse” of the Sun by the top of the tower. Let me remind you that the angular diameters of the solar and lunar disc are approximately the same - about thirty angular minutes (half a degree). For shooting, the same set of equipment was used as for observing a real solar eclipse a year ago. Unfortunately, cloudy weather still has not allowed me to photograph the moon. I honestly waited almost a month, but there was no clear weather in combination with a convenient phase of the moon. I decided to break off at the most interesting place and break the story into two parts. In the second part of the article, I plan to talk about shooting the moon through a microscope and achieve a quality close to that obtained by a bunch of the same telescope with an iPhone camera (see





example 1 , example 2 , example 3 ). I will also touch on the topic of stacking and try to implement manual exposure control (the microscope camera does not have a manual mode). Therefore,

to be continued...

Update: ... a continuation: The moon under the microscope .

PS: You can buy the same microscope in the online store Dadget .