Rob Sellent

Been here for about 8 weeks and to be honest SGL seems like a huge family from all over the world. There are lots of specific sections to dip into, many helpful, knowledgeable and very talented folk to bounce questions off, the mods are welcoming, sort without a fuss any problems and activily participate in the discussions themselves without a hint of pretension or affectation . The site is extremely generous in its bandwidth, as also with the type of threads that can be set up (just take a peek at the lounge!) and categories in general . In short, SGL is probably the best astronomy site in the world and until Fermi's paradox is significantly addressed, no doubt the best in the known universe. I'm thoroughly enjoying my stay and glad I came aboard. I just have a couple of questions/suggestions: the profile page has a category called "day's won". What does this mean? How does one win more days? And can one lose days? would visual observers be interested in something similar to the imagers challenges and competitions? Not to clutter or make more sections, but within the observer's sections, say? (tricky double stars of the month challenge, awkward lunar feature or sketch challenge of the month etc) would a section on reviews be amiss (books, films, docus, shows, star parties, software, podcasts etc), related, of course, to astronomy & science? Not something like, 'this is worth seeing/reading' but actually a short review. Again, thanks for everything . Rob - - - - - Welcome to SGL @Theoldboy You're very fortunate to have no light pollution and neighbours to boot . Can't go wrong with a 10". I thnk a 10" or 12" are kind of the goldilocks of Dobs. I look forward to meeting you on the boards.

Sure, but the stars will be above them

Dan, I wrote as much the other day, but a similar idea will also suffice here. If possible take your time. Try to appraise your gear first and then you'll have a better idea of where you want to go and how you want to get there. I feel you ought not to upgrade or buy anything until you know you are missing something that is essential to your astro-sessions. If you're a relative beginner, slow down, for it's going to be tricky to make a sensible and informed decision. Regardless of the excellent advice you'll get here at SGL. Moving on...for general observing, that is pretty much everything but planets, moon and double stars - I tend to just stick to 3 quality eyepieces and from time to time a decent x2 Barlow. With something like an 8" f6, I'd like to work with a low power wide field between 20mm to 24mm (depending how dark my skies are), a middle power wide field around 13mm to 14mm and a tad higher power wide field around 10mm. That way - including the Barlow - I've got about 50x, 90x, 120x, 180x and 240x. The lower focal length eyepiece is nice for general hunting and framing largish objects, the middle grounds for globs, galaxies, nebulae, the higher powers for Saturn, Jupiter and Lunar work and the 240x for those exceptional nights with the planets, Moon or tighter double stars. If you got yourself a Baader solar filter from FLO, your 50x would also double up nicely for white light solar observations. In general, in this hobby you get what you pay for. Like scopes and mounts, some eyepieces are considered to be better than others. Needless to say, my general percept when it comes to buying stuff is to buy once and make it count. Although initially expensive, premium eyepieces such as TeleVue, Pentax XW etc will turn out to be the cheaper option in the long run and are never going to be a waste of money. When buying premium you only cry once. Or again, paradoxically speaking, "a poor person cannot afford not to buy premium." Let me explain. Generally speaking, premium eyepieces - unlike scopes - become lifers, you never have to upgrade again or you can always re-sell them without losing much money, especially if you have bought them already secondhand. Premium eyepieces hold their value more than cheaper ones. They also offer an important psychological benefit. After a session, you are not left with any nagging feeling of 'what if...', for you know that this end of your optical system is about as good as it is going to get. If the view was poor, if you didn't get the expected detail, it will not be due to the eyepiece itself. This ties in with what was said at the beginning. All you really need for your 8" f6 are 3 decent eyepieces and a decent Barlow. And there is no hurry in accumulating them. Spend your time scanning the secondhand market, for if you start out buying cheap, you'll either lose a significant percentage of money when trying to resell, or you'll eventually end up upgrading and again lose money, for in this case, not only are you buying the upgraded eyepiece, but you've already spent a load of money on the cheaper eyepiece. So, for the moment don't spend your hard earnt cash. Get to know your kit a little more. Oh, and welcome to SGL and I look forward to meeting you on the boards

Dan, just a quicky, what is it that you want to upgrade on? Field of view, eye-relief, field stop, possible sharpness and contrast across the field, dodgy aberrations that you've noted in your aforementioned eyepieces, brand name? What do you think you are missing that is essential to your astro-sessions?

Can't add to what others have already said but just to add voice to the discussion. If field of view and eye relief isn't a big concern, then for good quality planetary eyepieces, I've found Baader Genuine Orthos a good move. Indeed, the quality of image is as good as something like a Delos. I have also used Tele Vue's Plossls and have found the quality of image as good as Tele Vue's more expensive glass. However, I find eye-relief with them more uncomfortable than with the Orthos and personally wouldn't recommend going less than 11mm. Like @alan potts, I have a couple of TV plossls in a box but haven't used them a great deal.

First of all, I'd like to congratulate you on your new telescope . The 8" Dob should last you many many years, if not a lifetime. Now, I appreciate that nights can get cold ⛄ and on those occassions there's no harm done viewing from open windows but whenever possible try to avoid this option. As @John has already explained, looking from inside the house through open windows causes drafts 💨 and general air disturbance 🌪️ which will seriously compromise seeing. You may think, 'well, I'll just close the window.' And although a reasonable conclusion, again, it's not really going to help. The window's optical quality cannot match those of your mirror or eyepieces, so you're degrading the image once again. I'm going to put on my lectuer's cap on for a moment . If possible take your time. Try to appraise your gear first and then you'll have a better idea of where you want to go and how you want to get there. I feel you ought not to upgrade or buy anything until you know you are missing something that is essential to your astro-sessions. If you've hardly used your scope, it's going to be tricky to make a sensible and informed decision. For general observing, that is pretty much everything but planets, moon and double stars - I tend to just stick to 3 quality eyepieces and from time to time a decent x2 Barlow. There are as many tastes and budgets as there are colours, so it's tricky to say, x, y and z are the eyepieces you need, but for me, with something like an 8" f6, I'd like to work with a low power wide field between 20mm to 24mm (depending how dark my skies are), a middle power wide field around 13mm to 14mm and a tad higher power wide field around 10mm. That way - including the Barlow - I've got about 50x, 90x, 120x, 180x and 240x. The lower focal length eyepiece is nice for general hunting and framing largish objects , the middle grounds for globs, galaxies, nebulae 🤩, the higher powers for Saturn, Jupiter and Lunar work and the 240x for those exceptional nights with the planets, Moon or tighter double stars. If you got yourself a Baader solar filter from FLO, your 50x would also double up nicely for white light solar observations. As it stands, then, I wouldn't recommend 6mm for your scope 😕. Maybe when you've got to know your kit and skies a tad better, you may feel the need for a dedicated high power but understand that 200x will probably be your maximum mean power during a given year, is not particularly suited for things like galaxies or nebulae or open clusters and seeing conditions will not always allow such magnification. It's a bit of dilemma to advise what's best because some prefer no filter, some prefer an ND filter, some prefer a variable polarising filter, some prefer Moon & Sky Glow filter, some prefer using colour filters, some prefer a neodymium filter, and so on. However, there is some good news 🤗. I find the intensity of light isn't so much based on the scope itself, but rather what phase the Moon is in. So, again, lecturer's cap on, before going any further, it might be a good idea to observe the crescent Moon 🌜and see how you get along. If you still don't like the light's intensity, you'll probably need to experiment a little. Borrowing filters from an astro-mate is a possibility not many of us can enjoy, so failing that purchasing and trying out the filters is realistically the only way you will be able to find out what works best for your eyes. Personally, I wouldn't bother with a Moon filter but if you did find the need, try to double its work 😅. For example, purchase a polarising filter for the Moon and Sun (with the solar filter, of course!), or purchase the neodymium filter with an eye also on Jupiter and Mars as well as the Moon, and so on. I find that in general in this hobby you get what you pay for 🤑. Like eyepieces, like scopes and mounts, some Barlows are considered to be better than others. Needless to say, my general percept when it comes to buying stuff is to buy once and make it count. Although initially expensive, premium eyepieces or Barlows will turn out to be the cheaper option in the long run and are never going to be a waste of money. When buying premium you only cry once 😫. Or again, paradoxically speaking, "a poor person cannot afford not to buy premium." Generally speaking, premium eyepieces/Barlows - unlike scopes - become lifers, you never have to upgrade again or you can always re-sell them without losing much money, especially if you have bought them already secondhand. Premium Barlows or eyepieces hold their value more than cheaper ones. They also offer an important psychological benefit. After a session, you are not left with any nagging feeling of 'what if...', for you know that this end of your optical system is about as good as it is going to get. If the view was poor, if you didn't get the expected detail, it will not be due to the eyepiece or Barlow in itself. This ties in with what was said at the beginning. All you really need for your 8" are 3 decent eyepieces and a decent Barlow. And there is no hurry in accumulating them. If you start out buying cheap, you'll either lose a significant percentage of money when trying to resell, or you'll end up upgrading and again lose money, for in this case, not only are you buying the upgraded eyepiece, but you've already spent a load of money on the cheaper eyepiece. Again, this ties in with what has already been mentioned. Get to know your kit. Get to know what you are missing that is becoming essential to your astro-sessions. Then you can set up threads here on SGL and get some tip-top advice 🤪. This is the type of collimator I used for more than a decade before getting into Howie Glatter's dream collimator for a faster dob. The former is a good tool and as @Trikeflyerhas already stated, will do its job just fine. I'm not sure of the exact science involved but it seems that most astronomy gear, especially when it's new, emit Moiston molecules. Moistons group together to form huge clouds. The full Moon is capable of absorbing Moistons and thus giving us relatively clear nights on full Moon nights but reemits them as it ebbs towards becoming new again 🌚. Moistons also collect inside unopened telescope boxes and are released into the atmosphere whenever a newly purchased telescope (secondhand or not) is opened. This is the reason why companies such as FLO supply their telescopes with the warning, 'may contain clouds'. Here are a couple of pics which better describe the situation:

Cracking image @astroavani and glad to see you had time to put together such a gorgeous image

Outstanding image, @MartinFransson. Thank you for sharing your photography with us

@Rodd I apologise if I don't visit the imaging section that much - do imagers check out the sketchers section etc? - but I just wanted to say I find your photography outstanding and a joy to see. The two images supplied in this thread are absolutely gorgeous

Welcome to SGL, Cary . Great idea about the bins to get a grounding on the night sky. Look forward to seeing your sketches and artwork

Can't beat @Ruudexcellent suggestion. The Dob will offer you 8" of aperture and so in terms of resolution will resolve detail more than any other scope within this price range. It will give you low-power rich field viewing and with reasonable dark skies you'll be able to view galaxies, nebulae, globulars, and so on. It will also train you in the relatively simple art of collimation which will stand you in good stead as a general astronomer or if you ever fancied a Mak or SCT in the future. You will get more than sufficient magnification on objects (limited like all the other scopes on atmospheric conditions and aperture), it comes with a good solid mount so you don't need to buy one. Like a refractor it isn't susceptible to dew formation, so techniques such as dew shields and heater strips become unnecessary as they would necessaily be for Maks and SCTS, but unlike an achromatic refractor, you won't get chromatic aberation. Furthemore, it won't take as long to cooldown as a Mak or SCT and on good seeing nights should give really nice contrasty views on planets. If this weren't enough inch for inch, it's also the cheapest option and fits right into your budget 😀. There are a couple of downsides to the Dob. Some folk find collimation annoying but to be honest, it's really no more than a little tweak of the mirror every session. Some folk don't like diffraction spikes when viewing bright objects and with a focal ratio of f5 these scopes are more demanding on eyepieces, so you will probably have to spend a little bit more on quality eyepieces than you would if you had a longer +f10 scope. Inch for inch, then, Dobs are a lot cheaper than Refractors, Maks or SCTS and because you can afford more aperture for less, you're getting more resolution, brighter images, and the possibility of going deeper and seeing more. For a first time, all round, general purpose scope to help you enjoy the wonders of the night sky, I really don't think you can go wrong with an 8" or if expenses allow, a 10" Dob. Hope that helps a little

Excellent posts I think one of the issues is that as a hobby visual astronomy is unforgiving. It starts to collapse not due to the faults of the individual but simply to factors completely outside their control. Frustration would be a normal response to this kind of opposition, but drag it out for a good number of years and the visual observer might start to feel disappointment, and sentiments of being let down...again. Under such conditions, I can imagine countless visual observers start out with great enthusiasm but a decade or so down the line, their spirits have dampened, they have dwindled in their number or drifted into imaging. I also think that like Dickens, we are in the best of times but also in the worst of times. There's more kit on sale today and at acceptable prices than ever before but light pollution continues its arrogant stride across the 'developed' and 'developing' world. Perhaps, then, the wane in visual observing is also due to the dying night sky. Our way of life will more than likely be condemned by future generations and perhaps, therein, lies hope for the visual astronomer of tomorrow.

I belong to a cracking astro-society. It's made up of friendly, extremely informative and kindly folk from all over the world and its free Here's a link for those interested: Stargazers Lounge

I think there are a couple of places in the skies where it's difficult for telescopes to navigate. Scopes on EQ mounts maneuvering around the Celestial Poles and AZ mounts negotiating the Zenith are often recipes for frustration. In this particular case, when you are near the zenith the manual observer doesn't have much authority in AZ and needs to move a lot on ground in order to move a little in the sky. Indeed, so vexing is the situation, grappling with the scope to observe the Zenith, that it has actually created its very own dance movement called the Azimuth Dance Movement - ADM. In the image below, we can see an ADM performer offering a particularly graceful Azimuth movement with an AZ mounted frac: Not to be out down, the Dob mob have not only created their very own progressive version of the Azimuth Dance - commentators often point out the similarity between grappling and twirling grizzly bears and the Dobber's ADM - but have gone a stage further and have actually coined their own terminology to desribe the place where very few Dobsonians will ever care to venture. Dobo-foraminis in Latin, commonly referred to as the Dobsonian Hole or Dobson's Hole, casually abbreviated to the Dob Hole. 😄

I enjoy using the AZ4 with the small 76 but get a little nervous when mounting the 4". A few years back I bought this Skywatcher(?) mount (see below) from a fellow astronomer in Alicante. It's excellent for mounting the 76 and 60 Lunt for dual solar viewing and I've also been using it with the Vixen. So far so good, and a lot more sturdier than the AZ4. Nevertheless, I'm also very intrigued by what FLO has in store. Playing around with the two AZ mounts, I also think much stability comes from the tripod as well. For high power viewing for anything over f7, perhaps a decent 2" tripod is also necessary? @jock1958Don't quote me on this but I don't think Skywatcher make the Skytee 2. As such, the TS mount and the Skytee 2 are probably from the same manufacturers with pretty much identical specs.

😁 but what joy to be a beginner all over again, to start the great adventure anew, returning to the stars from whence we all belong 😀

I studied the BA Hons in Politics, Philosophy and Economics at the Open University (OU) more than a decade ago. A degree is made up of 360 points. The first 240 points was relatively easy going but I found the last 120 a bit of a slog. In my case, each 60 points contained 6 units. You swot up, write an essay from a set question and repeat this for each unit during the year until around May when you have to supply a final essay which carries more weight and is marked accordingly and in June you sit a final exam. Part-time is 60 points a year, so if you kept at it, you'd get a degree in 6 years. Because I don't live in the UK, I had to pay about £1,000 per 60 points. Thankfully, I studied this stuff purely for pleasure, there was no necessity for qualifications, employment or what have you. And therein lies a problem. Comparing my experience at OU to a more traditional 'brick and mortar' university the OU's grading system is ruthless. The OU is a bit like the special forces, you're only as strong as your weakest link and as such, it is your worst score which determines your overall course grade. It is extremely difficult, then, to achieve more than an acceptable pass. To sum, if you're looking for a bit of 'fun', something new to learn and direction in which to pursue that learning at a distance, then OU is good. If you're looking for a degree or qualifications per se, there are probably easier options.

I use Baader's MK IV zoom in a Lunt 60 for ease of use. With my general seeing conditions I find it a lovely eyepiece for h-alpha.

@davheiToothpick! Genius 😀 Inspirattion comes from all corners but you have found it and applied it to your own art and it has come off a treat 👍

Rather than being solely a function of aperture, seeing colour in DSOs is predominantly a function of the eyes' sensitivity which differs in each individual. While some observers may see hints of colour in brighter emission nebulae, for example, others won't see any colour regardless of how big their telescope. My advice, then, is to use fairly low powers in your 8" and to observe the brighter regions of nebulae per se and see if you see any colour. Clear skies 😀

Lovely work, Davhei and a joy to see some stars on these rainy days in Spain ⛈️🌧️⛈️ Think you've worked your technique with the diffraction spikes to a tee 👍

What's your budget, Bungle ? At a guess with an f7 apo-triplet, you can't go wrong with looking at a little Green and Black as @Philip Rsuggests 😋

@MysticReverieis there any chance you could pop along to a local astronomy club and try out some of their scopes? It's not always feasible, but if the opportunity were there.....

Aye, 254 would be the mirror size: 254mm or around 10". The 1200 number is the scopes focal length: 1200mm. Clearly lacking the skills of Davhei, I think I'd struggle to find Mayall II with a 10" under dark skies With an apparent magnitude of around 14, even under dark skies, I reckon Mayall II is a tad beyond what a 90mm could pick out Not wanting to speak for Davhei but I imagine it is a pencil sketch of Mayall II (not M31) and the smudge could have been produced with a blending stump.

Amazing observation, Davhei Not only blessed by good skies but excellent observation skills. So glad you made a sketch of this. Not only as a nice record of evens but also a tip-top reference for future observers. Thank you