Since the invention of the telescope and its use for astronomical purposes, the exploration of the universe has progressed at first slowly, and then much faster. That also included advancement in the performance of telescopes themselves. The two main types of telescopes, refractors and reflectors have been around for about 350 years.
Among both types of telescopes, I own one that is my particular favourite. It's a 75mm refractor, purchased used in 1964; its true age I don't know. Here is a picture:
This 75mm, f16 refractor came with a solid wooden equatorial mount tripod (hand-driven tracking).
The telescope is now mounted on an used EQ5 tripod, purchased about three years ago.
Right-ascension-tracking and declination motors are powered by a D-battery power pack (not shown).
The telescope has the brand name "Polaris", and someone told me that it is the European version of the "Unitron" brand which was very popular here in North America in the middle of the last century. It has an achromatic objective - chromatic aberration is almost unnoticeable because of the large f-ratio. The telescope produces beautiful views of the major planets, the moon, and open star clusters, but is just on the borderline of dissolving globular clusters into individual stars (i.e. M 13). It's also pretty good at showing the brighter nebulae (Orion nebula, Dumbbell, etc.) and double stars (Mizar, Alcor, the "double double" Epsilon Lyra when pushed to 130 times magnification power, and much more). It's my preferred telescope for Public Astronomy Nights.
In previous centuries, instruments of this size and performance (3", 4", and somewhat larger telescopes) were used to do serious scientific work. For instance, Johann Heinrich von Mädler and Wilhelm Beer produced a highly accurate atlas of the Moon (in four volumes fro 1834 to 1836). It was used by astronomers for over a century. Mädler and Beer also produced the first reliable Mars maps and were instrumental (pun intended) in assigning Sinus Meridiani as the Prime Meridian on Mars. Photography was not yet available, so all maps were hand-drawn. Here's an example:
A part of the "Mappa Selenographica" by Mädler and Beer.
(from planetologia.elte.hu)
Mädler and Beer were also able to determine the rotation period of Mars to within 1.1 seconds. It is highly admirable that astronomers made such demanding observations with telescopes of really moderate size. Even today, refractors built many years ago are still in use for scientific research.
Photography through my 75mm (3") telescope is also possible. With today's digital cameras and technology it's much easier to take some good pictures. Below is an image of the southern part of the Moon, taken with a handheld Samsung smartphone.
Handheld smartphone photography through a telescope held against the telescope's eyepiece is difficult, because precisely aligning the optical axes of the smartphone with that of the telescope is mostly a matter of luck. Smartphone holders which attach to a telescope and position the camera lens of a smartphone precisely in line with the telescope eyepiece are available.
You can see that even old and relatively small telescopes are really useful for getting involved with Astronomy. One additional requirement is a sturdy tripod on which to mount the telescope. It should be included in any telescope purchasing budget. Nothing spoils the performance of telescopes more than a wobbly tripod.
Old workhorses indeed.
