Gonariu

I read some time ago that a 12-13 cm long focus achromatic refractor is equivalent to an 8" SCT on the Moon & planets; clearly in the deep sky and on double stars it is superior (1" versus 0.6"). In general, a reflector of diameter d and obstruction α is equivalent to a long focus achromatic refractor whose doublet diameter is D = d - α

A few days ago I bought a used Celestron Newton 76/700 complete with tripod, altazimuth mount, optics and two 20 mm and 10 mm eyepieces (I don't really know which optical scheme, they seem the same as those of the Travelscope 70). I got it because I needed a new photography tripod for the Konus Vista 80 and the one for this telescope seemed like it would work. Last night I tried it on the moon and I must say that the optics are beautiful, I also put a 2.3 mm Celestron Xcell eyepiece in it and, despite the 304X which gave a dark image, it was still quite well defined with my great amazement. The problem, as in all small telescopes, was the tripod which was not exactly ideal for this optics; I'll try it with the Sckywatcher Maksutov 90/1250 sight and neck to see if it can work with them.

I also observe the sun and, even if the climate of Sardinia is less rainy than that of the British Isles, due to the cloudy skies I am unable to have the consistency I would like. I have been thinking for some time about joining the Italian Amateur Astronomers' Union to participate in the "Sun Section" to which I can send my observations of our star. On the day that I cannot observe it, someone else will do it and things are carried out with the collaboration of everyone. In the UK you have the British Astronomical Association which I had heard about while reading James Murden's legendary book "Astronomy with binoculars" (in Italian translation).

I agree, I have a Newton Starfinder 8" (203/1200) which I am not currently using (I would have to redo the collimation properly); the magnification I use on the Moon and planets is X150-X200. I very rarely use X300 with good results, at this enlargement I once saw Gassendi's internal rhymes well, but it was the only one. I don't think the skies over England are the limit, here in Sardinia I am at 40 N and with many fewer rainy days than the UK. my Vixen 102 M 333X can be used profitably much more often.

I agree; almost 10 years ago I bought a full aperture glass solar filter for 70/80 mm telescopes, discounted by 50% which in total I paid 35 euros, I use it very profitably on the Konus Vista 80 and on the Celestron Travelscope 70.

All of us amateur astronomers in the world are in fact one big family, thanks to the internet and also to SGL, we can hear each other all over the planet in the language that is now that of the whole world: English! Eternal memory to your friend!!!

I wasn't aware of this, so far I've used the hairdryer on cold air. I was thinking of making a cardboard lens hood covered on the inside with black cloth.

Old thread but still relevant! I had bought a CPC 8 in 2010 sold on promotion for 1700 euros, which was stolen in the summer of 2012 while I was at the seaside. In 2021 I bought a used Nexstar 8 SE from a friend for 1500 euros which I am currently using with pleasure on the Moon. Why buy a C8: it certainly combines its portability well with universal use and the convenience of computerization. I would really like the Maksutov Skywatcher 180/2700 but it is a very specialized optic (Moon & planets) even if divine in its field. The big limitation of the C8, as of all SCTs, is the condensation that forms on the correcting plate!

Currently I find myself having: Konus Vista-80 (achromatic 80/400); Skywatcher Maksutov 90/1250; Celestron Nexstar 8 SE; Vixen 102 M (achromatic 102/1000); Ziel GEM 60 (achromatic 120/600); Bresser 60/900 (achromatic); Starfinder 8 (Newton 203/1200); Konusuper 120 (120/1000 achromatic which I use diaphragmed at 90 mm due to a lateral splinter in the achromatic doublet); Galileoscope (50/500 achromatic, given to me by an amateur astronomer friend); Celestron Travelscope 70 (achromatic 70/400); Stein optik 60/800 (achromatic sold to me used that I should fix, they sold me a bin!). The ones I use the most are the Vista and the Maksutov 90/1250, the Nexstar mount supports them very well; I use the Vista for the sun (I bought a 50% discounted full-aperture glass solar filter years ago) and the Maksutov for the moon. I forgot: I decided to calm down, I'll try not to expose myself to temptation (gulp!!!).

The 180 mm Maksutov is certainly a nice optic for the Moon & planets, when I got the Nexstar 8 SE I also thought about this telescope, then in the end I preferred the SCT as it is more universal in use. I must say, however, that every now and then the temptation comes back to me also because I have seen how beautiful the smaller "brother", the Skywatcher 90/1250, is in terms of optical rendering of the Moon, Venus and panoramas.

In 2021 I bought back the SCT 8" (the Nexstar 8 SE) but I'm using it little, on the Moon & planets I prefer the Konusuper 120 diaphragmed at 90 mm or the Vixen 102-M which on the Moon I sent to good X300s on the nights a which the air was calm. In winter the correcting plate of the Nexstar fogs up, I have to make a lens hood covered inside with black cloth, I haven't done it yet..... Good on the Moon the Maksutov Skywatcher 90/1250 , a few days after the first quarter of this month I received a beautiful photograph of the moon with my smartphone. On short focus achromats: it is certainly true that they are not telescopes designed for the planetarium but for the deep sky, however I happened to use them on the Moon and Mars with some profit (I have a Konus Vista-80 and a Ziel Gem 60 ), on Jupiter I did very little with them but for me Jupiter is not an easy subject even with other lenses.

I think that a 100/1000 refractor is of almost universal use because it allows both good views of the Moon, planets and double stars and of deep sky objects, even large ones like the Pleiades (with a 40 mm eyepiece that gives ). For residual chromaticity, a light yellow W8 filter can be used. The Maksutovs are very beautiful but they are very specialized optics for the planetarium, double stars and DSO objects such as planetary nebulae, for more extensive deep-sky objects they are not good. As a mount, I prefer the equatorial one as it allows you to better follow the object observed at magnifications over X200. Furthermore, setting it up for visual use is not difficult if you can see the Polaris. For high magnifications an azimuthal mount is less comfortable although more intuitive to use.

Yesterday afternoon I took a shot of the sun with my smartphone, placed next to my little 80/400 achromat that I'm sharing here. The photography is acceptable but nothing exceptional, with an iPhone placed at the eyepiece of a Tak you get much better shots. What I aim for with photographs of this type is to calculate, at least approximately, the size of the sunspots. This is done very simply, you see how many pixels the solar diameter corresponds to and how many pixels the size of the spot corresponds to (I took the vertical length); since the diameter of the sun is known, with a proportion the desired dimensions are obtained. The dimensions I came up with are approximately 119,000 km (i.e. 74,400 miles). I'm sharing the image after retouching it. Observation: There were some clouds at the time of shooting.

Waw!!!!

It looks like a 60/900 achromatic to me too; , I think it must be from the 70s (I'm not an expert), it certainly gives some nice images of the sun, moon and double stars. I bought a vintage Bresser one which gives beautiful views of the moon at 225X (a few days before the first quarter of this month, with a 4mm SR eyepiece I had a splendid view of our satellite which surprised me).

Last night at 11pm I tried to take a shot of the Moon by connecting my smartphone to the eyepiece of a Maksutov Skywatcher 90/1250. The other day I received the Celestron adapter for the Nexyz smartphone, using which I hoped to get better shots than when I held it in my hand. The image was processed a bit later.

Nice, here in Sardinia we really like going to Spain with which we Sardinians have a historical bond.

I'm spoiled for choice, living in Sardinia I was thinking about the August 2026 eclipse in Spain or the August 2027 eclipse in Tunisia, both are quite close. Certainly for the language Spain is better for me as Spanish can be understood by those who speak Italian and Sardinian, for the duration of the whole Tunisia is better.

Good idea, my first ever optic was a Russian-made 10X30 monocle of excellent workmanship, given to me at 14 years old way back at Christmas 1981.

A few years ago I bought a vintage 60/900 Bresser refractor (complete telescope); the reason for this purchase is that I wanted an old-fashioned classic 60mm; I bought it when I was 16 in 1983, then 14 years ago I gave it as a gift. Yesterday I put it on the terrace taking advantage of the good weather and the very mild temperature of this umpteenth "winter without a winter", my intention was to see some abseils, even narrow ones. So I tried to split Rigel: nothing, I try with ζ Orionis: worse still, Mintaka and σ Orionis "save" me a bit (all three components are visible at X41) and M42 doesn't mind either, at the Trapeze is small. What really surprised me, however, was the 6X30 finder which has adjustable focus by moving the eyepiece back and forth: a sea of stars that made the vision poetic, I couldn't have imagined it at all! I must say that, being short-sighted and lacking 5 diopters, to use the finders now supplied with telescopes, I have to wear glasses and this is deeply uncomfortable for me, but yesterday the music was totally different!

I feel comfortable in my neighborhood, then here in the village where I live we have around 1800 inhabitants and we are all relatives. It must be said that a bit of sensitivity towards others is also needed; 20 years ago I got a dog, Lupine, who the first year I let sleep outside and at night sometimes he didn't let the neighbors sleep, so the second year I let him sleep inside, me in my bed and him on the sofa. Some nights he would bark and make me jump on the bed (behind my house it's all countryside and at night you can hear a whole series of noises due to the movement of nocturnal animals). As for the astronomical aspect, when I was a boy and I came here for the holidays in August (I lived in Cagliari at the time), the alley where my house is was without street lighting which they later put in; in my case it wasn't the fault of electrical waste neighbors.

I have a C8 SE, I think the mount is compatible but the problem is another: while the SE mount is fine for the C6, with the C8 it is barely sufficient for visual use and when focusing the optics it vibrates a lot.

Yesterday I took this shot with a smartphone next to a small 80/400 achromat. The smartphone was held by hand.

Yes, it is!!!

Good team!!!