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From Scope F70076
* Telescope F70076 * Price * How is it useful * Comparison with other cheap telescopes * Newton reflector * What was inside the box * Huygens eyepieces * Moon filter * Finder scope * The mount * Star hopping * The size and weight * Cleaning mirrors * Collimating * What can I see through it o First light o Ring Nebula o The Great Cluster in Hercules o Saturn o Mars o Praesepe cluster o The Pleiades o Andromeda Galaxy o Orion Nebula * Astrophotography
76mm reflector telescope F70076
Contents |
I'm a complete beginner what concerns telescopes and astronomy, so I thought that my experience about telescopes might be useful for other beginners. Therefore also, a lot what I write here is about what I think, I just discover all these things for myself, only for entertainment.
What can I see through it
I don't really have much idea what can I see through that telescope, but Charles Messier who made the catalog of 110 deep sky objects (galaxies, nebulae and star clusters) in 1780, had a telescope which may be equivalent to today's 3 inch telescope, so I should see all these objects at least somewhat. But of course the skies of Paris were not so light polluted at that time, when there were no electric lights yet, than the skies of the cities today. Indeed I have found that I cannot see as much as Messier did, in addition having by far not such experience of observing as Messier had. Hodierna [1] found 19 deep sky objects already in 1654, using only a Galileo telescope with 1 inch aperture, of which 12 were Messier objects and 7 of these (M31, M36, M37, M38, M42, M44 and M45) were in the northern constellations.
There is a review in Cloudy Nights of the Orion SpaceProbe 3 EQ [2] which has an equatorial mount, but is otherwise optically similar to this telescope. At least it shows that one is able to see with this telescope the colors of the Orion nebula. I though didn't succeed the see colors of the Orion Nebula in my conditions, but considering how bright the nebulosity is, it seems believable that one can see some colors even with the visibility one magnitude better than mine, which is even not so good visibility, and you don't even have to be in a rural area. So don't be discouraged, your visibility is most probably better than mine.
The Great Cluster in Hercules
April 26, 2008. Tonight I found another deep sky object, the Great Cluster in Hercules, or M13. The visibility was bad, there were even some small clouds in the sky. So I had to move ahead from Vega again, because this was the only star nearby which I saw, no stars in Hercules were visible. The star hopping guides often instruct to "move in the direction" of some star. This means that you should know in what direction from your starting point is the star towards which you should move, you should find out what this direction is in your location at the time when you do your observation. I use Linux Stellarium to find that out, it can also be derived from the star maps, though it is a bit more difficult. You though have to move only approximately into some direction, because you always have to move until you reach something very distinguished, mostly a bright star, which you easily see when it would appear into your field of view. So, using the finder scope, I moved ahead from Vega in the direction of Theta Herculis, which is the closest star to Vega in the constellation Hercules, until I reached Theta Herculis, or more exactly, the first bright star which I saw. From Theta Herculis I moved in the direction of Pi Herculis, which is almost the same direction as before. Pi Herculis is one of the stars of the keystone of Hercules, four stars of almost equal brightness which form a well distinguished tetragon in the sky. I moved into that direction until I saw three bright stars quite close together, these stars are Rho Herculis, e Herculis and Pi Herculis. I moved the first of these stars in my direction, Rho Herculis, into the center of the crosshair, and looked at it through the eyepiece (I always use the 20mm eyepiece with 35x magnification when I search the objects). This star should have a double star close to it, and indeed there was a double star, made of two stars whith equal brightness, near that star. From that I knew, that these three stars which I saw, were really Rho, e and Pi Herculis. From these three stars I moved towards Eta Herculis, another star of the Hercules keystone, until I reached Eta Herculis. This direction was again almost the same as before. But from that star I couldn't move ahead with the finder scope, as finder scope did show a complete darkness, no stars whatsoever, between Eta Herculis and Zeta Herculis, where the Great Cluster in Hercules is located. So I looked at Eta Herculis through the eyepiece. Close to that star there should be an almost equilateral triangle made of small stars of equal brightness, but with the conditions of bad visibility I were not able to see even these stars. But in the same direction a little further from that equilateral triangle there should be an isosceles triangle of brighter stars with equal brightness, with its shortest side towards the Eta Herculis. I indeed saw that triangle. The shortest side of that isosceles triangle is a part of seven stars in a row in almost a straight line. I saw this line of stars, and from that I knew that the bright star which I looked at was indeed Eta Herculis. Then I moved in the direction of that line of stars, until I reached three stars of almost equal brightness in almost a straight line. Look at the brightest star nearby, which you should see in the same field of view together with these three stars. These three stars together with that brighter star form an almost isosceles triangle, the base of which is formed from these three stars, and in the center of that isosceles triangle is the Great Cluster in Hercules. Though if you followed that track, you most likely did notice that object already earlier. I observed the Great Cluster in Hercules through the 12.5mm eyepiece (56x magnification). I saw a dim hazy patch, which was cleary round, and was brighter in the center. The patch which I saw was quite big, some 1/8 of the field of view of my 12.5mm eyepiece. I saw though no stars in it or anything brighter. Several times during my jouney to that object, looking through the eyepiece, I saw satellites, and once I saw a meteorite. The Great Cluster in Hercules is quite far from Vega, so I proved with that, that with star hopping using only a finder scope, and sometimes eyepiece of course, it is possible to find most of the deep sky objects, proceeding from a visible bright star which is closest to them, even when only a few stars are visible in the whole sky. I should say that I did like the process of finding that object, sitting near the telescope in the darkness of the night sky, and all the observation during that, seeing so many stars during all that time. It is somehow relaxing, just to see the stars, and once you saw them through the telescope, you need to see them again. That the objects which I saw looked bad, is not the fault of the telescope, but it was because of visibility -- when you see only a few brighter stars in the sky, then the visibility is likely below the magnitude 2. The Great Cluster in Hercules was discovered by Edmond Halley in 1714.
Saturn
May 3, 2008. The night was cloudless, but I still didn't see more than ten stars in the sky. This time I looked to the other side, to the west, and I saw there two bright stars close to each other. From the Stellarium map I later found out that these were Saturn and Regulus in the constellation Leo. Regulus is another bright star, which is though usually not very high in the sky. I looked at these two objects through the finder scope and one, which appeared to be Saturn, had an elongated shape even through the finder scope, so that a small 1 inch finder scope appears to be as efficient as the Galileo telescope in spite that it has only 5x magnification. I looked at Saturn through the 20mm and 12.5mm eyepieces. Through the 20mm eyepiece I first saw that this object is clearly something bigger than a star. But after more focusing I clearly saw the disk and the ring of Saturn, and saw that the ring is separated from the planet, but couldn't see any belts. Through the 12.5mm eyepiece I saw the same, only somewhat bigger, it was quite small object there. I also looked at it through the 20mm eyepiece and through the 2x Barlow lens, it was bigger but I did not see any more details. With great difficulties I was able to see it through the 4mm eyepiece. Centering it in the 20mm eyepiece and then changing the eyepieces, was at that not a successful method at all. I saw no more detail, it was only just a bit more hazy. The finder scope is not exact enough for using the 4mm eyepiece, and the telescope cannot be moved exactly enough to use the 4mm eyepiece without much trouble. I'm sorry but, in spite of all respect towards the PowerSeeker 76 AZ, in many ways such telescope is not good enough for the 4mm eyepiece, and the 12.5mm eypiece is good enough for almost anything. The function of the telescope is light gathering, and therefore the magnification doesn't matter that much.
Mars
May 4, 2008. The visibility was almost as in the previous night. Mars was in the constellation Gemini, to the left of the two brightest stars in Gemini, which were the only stars which I saw in Gemini. Mars and these two stars formed almost a straight line with equal intervals. Mars was very small through the 12.5mm eyepiece, I saw that it was a disk and I saw its reddish yellow color, but that was all, it was much too small to see any surface details or icecaps. Mars is a beautiful object though, and its color is really nice and impressive. BTW, what concerns a color, one can see the color of some brightest red and yellow stars. The only star which I so far have seen to have some color, is Gamma Sagittae, the brightest star in the constellation Sagitta, which supposed to be a red giant, its color was clearly yellow. I don't know what the color of this star supposed to be, but the color of some red giants can also be yellow orange. So it is not completely true that one cannot see colors at all with this telescope, but in the light polluted skies only a few objects have a clear color.
Praesepe cluster
May 10, 2008. There were only some slights clouds in the sky near the horizon, but still I think that not more than twenty stars were visible in the whole sky. In fact I found the Praesepe cluster (the Messier object M44) easily because the Moon was near it, but it should also be possible to find it by moving from Pollux, one of the two brightest stars in Gemini, towards Delta Cancri. Praesepe cluster is in the constellation Cancer near the stars Delta and Gamma Cancri. It filled all the field of view of the 20mm eyepiece, but what I saw was really nothing than maybe twenty stars, not closer together than the stars usually are for example in the constellation Cygnus on the milky way. I didn't really see anything more through the 12.5mm eyepiece, except that it seemed to me that I saw some very faint nebulosity near some groups of three and more stars, but I couldn't be sure in that. The Praesepe cluster was first mentioned by Aratos in 260 B.C.
The Pleiades
Sep 20, 2008 This was the first night this year when the sky was dark and clear enough after the light nights in summer. There were still some clouds in the sky. Again it was quite easy to find the Pleiades (the Messier object M45) because the Moon was quite near it, and because the Pleiades is a quite big object so that when moving from Moon in the approximately right angle, it was easy to see that object in the finder scope. To find it otherwise, the Pleiades is in the constellation Taurus, and Aldebaran (Alpha Tauri) is the brightest star in Taurus. Aldebaran is a very bright, less than magnitude 1 yellow star, so one most likely can find it, but the Pleiades itself is also quite bright, so with clearer skies one may also see it with the naked eye. The Pleiades filled all the field of view of my 20mm eyepiece. There were the seven bright stars, and many smaller ones. I saw something which resembled nebulosity, but it was likely rather a large number of small stars which my telescope couldn't resolve. Later I also saw Pleiades with the naked eye. It was a glow in the sky bigger than the Moon, but it was very faint so that it was barely visible, it is possible to see it though when you know where to look. The Pleiades cluster was mentioned by Homer in 750 B.C.
Andromeda Galaxy
Sep 23, 2008 There was some slight cloud cover in the lower part of the sky, maybe 20 stars were visible in the eastern part of the sky. I saw Cassiopeia, except a star in the one end of it. The five brightest stars in Cassiopeia form a W shape in the sky. In fact, four of them are brighter, and of almost equal brightness, thus what I actually saw was not the W shape but a triangle with the fourth star as an extension of its base, something like a triangular-shape dipper. The bigger triangle in that W points to Mirach, one of the brightest stars in the constellation Andromeda. Mirach or Beta Andromedae is the first bright (magnitude 2) star in that direction. Mirach is a red giant, which looks like a bright yellow star. Near it (some 0.1 degrees from it) is a magnitute 8 star. As there are not many stars in that area, it was possible to identify Mirach by that nearby star, which located at almost the same distance from Mirach at almost the same angle as on the Stellarium map. Stellarium caused some confusion though, as it showed some red 5.6 magnitude star near Mirach, which I didn't see through the telescope. I found that this star is also missing in Your Sky map. Your Sky is a public domain star map, which is good to use when you would doubt in something in Stellarium, also it can be used to print star maps for different times of observation, when you would use telescope somewhere where you cannot use a computer. Using the finder scope, I moved from Mirach to Mu Andromedae, and from there in the same direction to the next bright star, Nu Andromedae. These stars form what is called the girdle of Andromeda. Nu Andromedae has two brigter yellow stars near it, of equal brightness, I saw these two yellow stars and thus verified the location. Andromeda Galaxy (the Messier object M31) is quite near to that star, so I moved in the direction of Andromeda Galaxy and indeed saw it. It was the best to observe the Andromeda Galaxy with the 12.5mm eyepiece. I saw a faint glow, this glow covered almost 1/4 of the field of view. There seemed to be a bright spot in the center, and the glow became fainter smoothly further from the center. The glow didn't seem to have a completely round shape, it was brighter in some directions. It had no color, the most it seemed to be white. It looked like something deep, and left a feeling that this object is something special. It seems that such telescope in my conditions doesn't show colors of the Messier objects, it may be that it would show some colors in Orion Nebula, which is the brightest nebula, but in my conditions of light pollution there most likely would not be much colors. Andromeda Galaxy was likely the most interesting deep sky object which I have ever seen with my telescope. It was the first deep sky object which I have seen that was not just many stars or a gray batch, but was indeed a nebulous glow of light, and of course this was the first galaxy which I have seen through the telescope. The Andromeda Galaxy was first mentioned by Al-Sufi in 905, who described it as a "little cloud".
Orion Nebula
Oct 4, 2008 There were some clouds on the horizon. It was not very difficult to find the Orion Nebula (the Messier object M42). I saw the Orion belt that was quite low on the horizon, but not so low that I couldn't reach it with my telescope. The Orion belt consists of three stars of equal brightness in a row with equal intervals, a pattern in the sky which is very easy to recognize. I saw all the three stars of the Orion belt in the finder scope. Then I moved from the central star of the Orion belt, Epsilon Orionis, also called Alnilam, in the direction of the Orion Nebula, until I saw some bright objects in the finder scope. Then I looked through the 12.5mm eyepiece, and with some slight moving around I saw the Orion Nebula. What I saw was a bright star and a double star near it, surrounded by nebulosity. The bright star was likely Theta1 Orionis and the double star was Theta2 Orionis. It seems that what I saw was almost exactly what Hodierna saw [3], thus it seems that in my conditions I can see through my 3 inch telescope exactly the same what Hodierna saw through his 1 inch telescope. The nebulosity seemed to be more on one side of these stars. The nebulosity was very clear and became fainter further from these stars, it covered almost 1/4 of the field of view (when I say field of view, I mean the diameter of the field of view). But I didn't see any color, the color was not blue though, the most it seemed to be white. I couldn't observe the Orion Nebula for a long time, because the clouds covered it soon. This was the second object on which I have seen a clear nebulosity. I also saw the Orion Nebula through a 2 inch spotting scope, but this was only a good luck that I happened to spot it. The spotting scope could barely resolve Theta2 Orionis, but I saw some nebulosity around these stars, somewhat less though than with this telescope. The Orion Nebula was discovered by Johann Baptist Cysatus in 1619.
Astrophotography
Astrophotography can be done using an ordinary digital camera which almost everyone has in their pocket, I for example use Canon Powershot A430. I use the normal exposure, though all these cameras enable to increase the exposure. This method of astrophotography is called afocal astrophotography, which simply means putting the camera objective against the eyepiece of the telescope, tuning it until the picture looks nice on the LCD display, and then taking the picture. First of all, the physical zoom of the camera must be increased a bit, until all the field you see in the eyepiece covers the LCD screen. Then you have to focus the telescope, so that the image is the sharpest. In general, it is very difficult to take photos that way, because you have to adjust many things at the same time. I found that it is the best to hold the camera with the left hand in the correct position against the eyepiece, and focus with the right hand. It is completely possible to take photos that way, though not easy, and certainly needs to get used to.
April 16, 2008. I tried to photograph the Moon first, to test the astrophotography with my telescope. You see though, that the image is out of focus. It took some time to focus the image properly, and when I then tried to take the next photo, the batteries became empty, and as a result I have nothing better to present as the result of my first night of testing the astrophotography, than this image.
May 4, 2008. I tried to photograph Saturn, but all I got was just a hazy patch. It seems that focusing for your eye is also good enough for focusing for the camera. I even once saw a clear shape of Saturn on the LCD screen, but with hand I was not able to hold the camera stable enough. I think though that it can be done with a little more practice.
