Rob Sellent

9 minutes ago, Mick H said:

which would be best suited to my setup

At f10, I don't think you need any fancy eyepieces. Along with your 32mm and 25mm eyepieces, you might want to consider something in the 12-15mm (1.2-1.5mm exit pupil) range for medium power viewing and an eyepiece in the 8-11mm (0.8-1.1mm) range for planetary and very small DSOs. On most nights that's probably all the atmosphere/seeing will allow.

Adding a x2 Barlow might be an idea if either a) you lived in an area of good stability, or b) to expand your eyepiece range (the 24 to 12mm, the 32 to 16mm). If the latter route, you may not even need to purchase anything other than a higher power eyepiece, say something around 8-10mm, or so.

With your 8", a few reasonably priced eyepieces, a dew shield, observing hood (& pirate's eyepatch), an adjustable chair, decent power source and a simple pocket sky atlas and you'll all done. Other than that, for visual work training your eyes to 'observe' is probably more important than any accessory no matter how popular or pricey.

36 minutes ago, Mike JW said:

Once you start drawing, that is the beginning of a new adventure

Aye, I think this is true. I started simple sketches, branched out into using soft chalks for H-alpha observations and from there really got into painting tiny scale models and miniatures. Never know where or when one thing leads to another

Lovely video @Jim Smith. I think no matter how many years one had been observing and regardless of telescope type this area of the sky just keeps on giving.

@mark81 the Moon can take some pretty high magnifications but - with a nod to aperture - to what degree will more often depend on your seeing conditions. When the conditions are good, one can easily go over the typical x200 frontline but during the last few months, for example, I can only count the number of times I've done that on one hand.

Personally, I'm not really a fan of pushing magnifications to extremes (+0.6mm exit pupil). With the Moon I tend to find myself increasing the magnification until I feel that either I'm not gaining anything more from the image or upsetting the pretty 'eyepiece-landscape' I have in view. These magnifications are different from night to night.

Again, although not essential, I've also found binoviewers on the Moon are a nice addition. If 'tuned' correctly they can be very relaxing to use and do offer a lovely, almost 3D visual experience.  

15 hours ago, markse68 said:

just splashed out on a pair of Sorels on Amazon but they were pricey, are ridiculously huge and I don’t think I’ll be wearing them in daylight

@markse68 wheeling out his brand new boots for another chilly astro-session 😃

14 hours ago, Littleguy80 said:

Any suggestions to keep my toes warm

Holiday in Spain? 😋

  A lovely little guide (Dob AP Tutorial.pdf) to get you in the ball park for Dob imaging.

I wonder whether H-alpha observing would change anything? On average, irrespective of day time or night time observing, a stargazer in southern UK can expect to:

• not being able to observe about 50% of the year.
• maybe being able to observe around 20% of the year.
• and can almost definitely be able to observe about 30% of the year.

Interestingly, costs factors would still indicate that within reason UK stargazing/imaging could be as much as twice as expensive as it is in Spain. Observing in white light and using one's scope for both daytime and night-time would significantly reduce these costs but I feel the general ratio would remain, for those in Spain would do likewise.

 As such the arguments above remains the same:

• to avoid sentiments of frustration or annoyance it might be a good idea to understand UK stargazing whether done in the daytime or at night as a peculiar type of 'seasonal hobby'
• within reason, one cannot expect to observe celestial objects per se more than about 50% of one's free time and in consequence, it makes sense to have other hobbies or pursuits on the go
• this 'seasonality' is in fact a boon for it opens up the possibility of being able to do so much more (building, tinkering, swotting up or whatever).

3 hours ago, Rusted said:

Perhaps we should cost the hobby in Pounds/Dollars/Euros invested per hour of observation/imaging per year?

Personally, this is how I tend to work out the cost of something. To this, I try whenever possible to also consider Thoreau's idea that the cost of a thing is the amount of life which is required to be exchanged for it. Curiously, somethings which are considered expensive end up being relatively cheap, whilst cheaper options can sometimes end up being costly 

Going over the thread 'Hobby Killers' and sleeping on the idea, I wonder whether UK stargazing could to be treated as a rather peculiar and frustrating 'seasonal hobby'. Unlike fruit foraging, mushroom picking or skiiing, for example, you can potentially do it all year round but just like these pursuits, you can only do it for about a third of any given average year.

Using Meteoblue's diagrams and working through the average number of cloudy days in a handful of cities in the south of England and those cities around where I live in Spain reveals some interesting data.

Cloudy Days

According to my sums, Southern UK on average annually experiences:

• 35 clear days a year where cloud cover is below 20%                                                                                                 
• 180 partly clear days a year where cloud cover is between 20-80%
• 150 overcast days a year where cloud cover is over 80%

Whilst accordingly, this area of Spain on average annually experiences:

• 122 clear days a year where cloud cover is below 20%
• 195 partly clear days where cloud cover is between 20-80%
• 48 overcast days a year where cloud cover is over 80%

Partly Cloudy Days

Evidently, the partly clear day category is too comprehensive. Within it would include relatively clear days and rather dull overcast days. If we accept that the percentage difference of 20 to 80 is 25%, we can taper this category into four smaller divisions:

• 25% of partly clear days where cloud cover is between 20-35%
• 25% of partly clear days where cloud cover is between 35-50%
• 25% of partly clear days where cloud cover is between 50-65%
• 25% of partly clear days where cloud cover is between 65-80%

We can now adjust our tables and speculate that:

Southern UK on average annually experiences:

• 35 clear days a year where cloud cover is below 20%                                                                                                 
• 45 days a year where cloud cover is between 20-35%
• 45 days a year where cloud cover is between 35-50%
• 45 days a year where cloud cover is between 50-65%
• 45 days a year where cloud cover is between 65-80%
• 150 overcast days a year where cloud cover is over 80%

While this area of Spain on average annually experiences:

• 122 clear days a year where cloud cover is below 20%
• 49 days a year where cloud cover is between 20-35%
• 49 days a year where cloud cover is between 35-50%
• 48 days a year where cloud cover is between 50-65%
• 49 days a year where cloud cover is between 65-80%
• 48 overcast days a year where cloud cover is over 80%

Observable Nights

Now, for the sake of argument, let's assume that those days are in fact nights and that as individuals we have two possible states to be in: either potentially we are able to observe, or not. With that in mind we could argue that:

In southern UK about

• 125 nights a year - about 34% of the time - it is potentially possible to observe where cloud cover is 50% or less.
• 90 nights a year - about 25% of the time - it is going to be tricky to observe where cloud cover is between 50-80%.
• 150 nights a year - about 41% of the time - it's pretty much impossible where cloud cover is over 80%.

On the other hand, in this area of Spain:

• 220 nights a year - about 60% of the time - it is potentially possible to observe where cloud cover is 50% or less.
• 97 nights a year - about 27% of the time - it is going to be tricky to observe where cloud cover is between 50-80%.
• 48 nights a year - about 13% of the time - are pretty much impossible where cloud cover is over 80%.

Speculative Sum

Needless to say, these possibilities are not solely dependent on cloudless or partly cloudless nights but ought to also take into account fatigue, compromises, commitments, family and work, studies, holidays, astronomical summer twilight hours, full moon, coldness, sky visibility from observing site, visiting in-laws, anniversaries, birthdays, illness and dodgy gear, and so on. Again, for the sake of argument, could we thus assume that on average between 5-10% of one's free time during the year is also taken up by other factors which make observing extremely difficult?

If that were so, we could now try to round up our figures above to get just a general gist or inclination of what could be averagely expected during a given year.

In the UK - on average a stargazer can expect to

• not being able to observe about 50% of the year.
• maybe being able to observe around 20% of the year.
• and can almost definitely be able to observe about 30% of the year.

On the other hand, in this area of Spain, on average a stargazer can expect to

• not being able to observe about 25% of the year.
• maybe being able to observe around 15% of the year.
• and can almost definitely be able to observe about 60% of the year.

Concluding Remarks

It would be interesting to see if the figures above do justice to the situation. Are they misleading? Are there just too many speculative statistics and averages being bandied around? That this is just not what happens in reality?

However, if any of this is feasible, perhaps to avoid sentiments of frustration or annoyance it might be a good idea to understand UK stargazing as a peculiar 'seasonal hobby'. It is something one can expect to do each season but only on about a third of that given year. If one gets more observable nights under one's belt, then that's good news. If not, no worries, for on average this is to be expected.

Often we point out to beginners what sort of telescope they ought to purchase. Other times, we indicate sketches or pictures of what is possible to observe visually or by imaging. But what might also be helpful within those threads is to point out that in the UK one cannot realistically expect to observe more than about 50% of their free time and in consequence, it makes sense to have other hobbies or pursuits on the go.

To this we could also factor in costs. In a very real sense, it becomes cheaper more quickly to observe/image in Spain than it does in the UK. Just taking 'definitely observable nights' into consideration, UK stargazing/imaging is twice as expensive as Spain. Or again, an astro session in Spain is potentially half as much as it is in the UK. By drawing this to our attention, it might make sense - according to one's means - to take this into account when working out an astro related budget. By doing this, one needn't feel they have spent too much or tied up too much money in unused gear.

Finally, it's rarely a good idea to put all one's eggs in the proverbial basket. As a 'seasonal hobby', any extreme sense of dedication/specialisation will only lead to being disheartened and frustrated, or perhaps worse, a kind of laziness where one does relatively 'nothing' in their free time unless observing/imaging. This should not be the cherished lot for a UK stargazer. Instead, this seasonality opens up the possibility of being able to do so much more, being able to dedicate oneself to other fulfilling hobbies or avenues of astronomy.

This little lot should keep you busy

2 hours ago, Alfster said:

I want to know some good deep sky objects suitable with this scope

Under reasonably dark skies you should be able to see all of Messier's objects. The catalogue includes some of the most spectacular wonders of nature that can be observed from Earth's Northern Hemisphere. 

Welcome to SGL, @Jenova.

I think you've done your son a massive deed simply by joining this forum before purchasing a scope. It makes my heart sink when I see someone with a tatty but equally-as-expensive telescope that will inevitably frustrate one to the point of never wanting to use it again. To be honest, I'd be wary of buying secondhand if I wasn't sure what exactly I was looking for and how I could distinguish between the good from not so good. If you or someone you know is confident in their knowledge, it would also make sense to check the gear before committing to buy.

As such, I'd strongly suggest that you buy your first set up from a specialist telescope shop that can provide advice and an ongoing service – not from ebay, not from Amazon and not from some department store or photographic shop where the staff will generally have no knowledge of what they are selling. If you haven't already had a look, First Light Optics comes highly recommended as one of Great Britain's best astronomy shops and, of course, SGL can help out a lot.

When looking around at your new potential purchase the general precept is that aperture rules and so you'll find that if a beginner asks 'what should I buy?' 99% of those answers are going to suggest the biggest Newtonian (reflector) you can afford and carry about, and more than likely a Newtonian which is Dobsonian mounted rather than GEM (EQ) or AZ mounted, simply because Dobsonian mounts (the rocker box) are easier to use and set up and are cheaper, so in effect you're putting more money into the optics and less into the mount.

Like a refractor the Dobsonian telescope 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'll get more aperture and 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 views on planets.

I think FLO's beginner recommendations make a lot of sense to which I'd also add the Skyliner 150p. Any one of the Skyliners or Heritages by Skywatcher would make a lovely present for your son. The scopes come pretty much assembled and generally only need the finder attaching. They're well made, very sturdy on their wooden Dobsonian mount and look very attractive. There are a couple of downsides to the Dob. For any type of Newtonian scope you will need a collimation tool to collimate the mirror. 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 you'll probably need a seat to sit on so as to avoid bending down to view objetcs with the Skyliners and a table to support the Heritages when in use. 

To get a relative comparison of sizes this picture is useful. Note, the tiny Dob 76 to which the Heritage scopes are family; that the 200 Dob's footprint is a tad smaller than it is for a mount necessary for a Mak 127 or 102 refractor, for example, and weight wise is probably a bit heavier but can be split into two manageable parts:

As is evident, inch for inch, Dobsonian scopes 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.

With all that said, it might now be helpful to run through a number of questions with your son to help hone both of your pursuits and just as importantly, expectations:

• where will I be viewing from?
• where will I store the gear?
• what kind of weight and size would I be comfortable with?
• what are the sky conditions like in terms of light pollution?
• if I need to carry the scope/mount etc is this easily done from the storage area?
• what do I expect to see? (Nasa images vs Visual astronomy)
• have I budgeted for all the other bits and pieces which maybe necessary (collimation tool, star atlas, red torch, warm clothing, case, extra eyepiece, etc)?

It shouldn't take too long to get a rough gist of what is involved. Then, with these ideas in hand, come back and the wizards of SGL will be able to help tenfold.

Hope that helps a little

Been quite a year. In terms of benefits to my astronomy :

Gear-wise

• finally bought a house in a village in Spain with a darkish garden with clear views running from east to south.
• finally found a dream scope: a Vixen FL102S f9 Fluorite Apo. I really don't think another scope will be needed.
• changed the Vixen's 30 odd year old focuser to a more modern Moonlite
• experimented with binoviewers and although not necessary, feel they're a nice addition.
• upgraded the Skytee 1 (now used solely for Ha and white light solar work) to TS's AZ5
• purchased another Mark IV to go with the BVs, a small Tak 1.25" diagonal to counter balancing issues and a few other bits and pieces.

Brain-wise

• joined SGL around end of August after many months of oohing and aahing
• re-read Cosmic Clouds by Kaler and Stardust by Gribben which has sparked a deeper reading into star evolution, chemsitry and astrobiology.

Creative-wise

• finished buidling a scale model of Voyager space probe and a Mars Rover
• sadly in the house move my entire collection of scale model rockets (soyuz, vostok etc) was destroyed. Oh well.
• slowly working on Bandai's Perfect Grade Millennium Falcon

Observing-wise

• one would have to be hypo-obsessive to observe on every cloudless day and night here. Needless to say, I don't suffer the same cloud/rain frustrations as my SGL colleagues further up north.
• enjoying this year's (and last year's) anti-aperture fever: superior convenience, frequent use and exquisite views.
• partial lunar eclipse in July, Mercury's solar transit in November were nice events to catch.

Disappointment-wise

• in terms of white light and H-alpha surface features (not prominences) it's probably been my worst year in solar viewing in over a decade
• very little observing of Mars and Jupiter and Saturn were a tad too low
• garden is fine but local council refuse to remove unnecessary street light

I dislike observing in low single digit celcius figures.

It's not just about the cold or about the extra weight of clothing needed or the very real expense of finding clothing which deals with colder temperatures sufficiently, but the fact that unless heading out to the mountains there just aren't that many cold days here. Today, for example, is a typical autumn day. It's a sunny blue sky 25ºc outdoors and tonight will be around 15ºc. It'll remain like that until the heart of winter kicks in when I guess everything will drop by about 10ºc for a week or two.

On the other hand, I don't mind the heat and only begin to suffer when temperatures outdoors pick up to around +50ºc.

53 minutes ago, joe aguiar said:

I'm not really sure what the bottle zone...is

This link gives an indication of what the Bortle scale refers to.

Along with @Ben the Ignorant informative post, it is worth recalling that point light sources are easier to observe. These include the moon, stars, planets, open clusters and double stars. Targets which are more sensitive to light pollution and aperture are galaxies, nebulae, planetary nebulae, globulars and comets. These objects have a tendency to spread their light over a larger area, lowering their contrast, so they're more difficult to resolve.

 If it helps with planning a DSO session a very general rule of thumb could be useful:

• Take the limiting magnitude of your scope, subtract at least 2 or 3 from that number to begin with and choose objects accordingly, making a list from brighter magnitudes to fainter. If after working through the list the faintest objects were observable, work on a magnitude less, and so on.
• For DSO objects of any given magnitude the smaller it is in size, brighter is the object as opposed to a larger object with similar magnitude.
• Edge on galaxies are easier to observe than face-on elliptical galaxies.
• Estimate how big the object will be in the eyepiece. If your field of view (FOV) is a degree and the object is 10 arcmin in diameter then it should occupy about one-sixth of the FOV. Knowing this will help you know what to be looking out for. 

Bearing this in mind, with your scope under reasonable skies you should be able to observe all of Messier's objects, a thousand or more NGCs, countless double stars, all the solar system's planets, the moon, orbiting satellites, comets, large asteroids and with appropriate filters the sun in white light. All you have to do is dodge the clouds and rain and go out and observe. At the end of the day/night there is no magic formula. It must be you who experiences your own successes and failures and come to appreciate what works and what doesn't .

27 minutes ago, Neil H said:

didn't want to spend loads out just yet

I think that's exactly the right approach, @Neil H.

Apart from a necessary collimation tool such as a Cheshire eyepiece to collimate your scope, my advice is not to buy anything for your scope or mount until you and your wife have put them through their paces. In that way, you'll have a much better idea of where you want to go and how you want to get there. In other words, if you haven't used your scope that much you're unlikely to make a sensible and informed decision.

While out in the field, I'd be paying attention to the supplied eyepieces, the x3 Barlow, finderscope and mount.

For example, is the mount stable? Does it hold magnification well or does it start to shake/wobble when you step beyond a reasonable 80x? How aboout that x3 Barlow? Regardless of Celestron's department-toy-store marketing tactic of the scope being able to reach x675, in conjunction with the 4mm it's effectively useless, but what about in the 20mm? Is the finderscope reasonably easy to align, is the image bright enough to star hop and follow a star atlas/chart?  And so on.

If you're not sure about your own evaluation, or require a second/third opinion, why not get along to an astro-club in your area and ask for some help and useful advice. Most folk would be only too happy to help.

A 4.5” Newtonian on a solid mount and with two or three decent eyepieces is a really fantastic performer. I'm sure the scope is a cracking bit of kit, but my gut feeling tells me its accessories are going to let you down and be very frustrating to work with.

Incredible post @vlaiv. Expertly explained and wonderfully written for a dummy like me. I really appreciate your help and the time you've taken. Thank you 

Thanks guys for the great explanations. In particular to @vlaiv and @davidc135for patiently going through this.

If I've understood correctly, for a appreciation of these type of graphs would it make sense to assume that the nearer to 0 better is the RMS and Peak to Valley (P-V) criterion and nearer to 1 better the Strehl ratio? Together indicating a flatter wavefront 3D image?

I also recall Dob guys - especially when considering buying a new mirror - suggesting that when evaluating potential optical systems it's a good idea to look for a pair of numbers, for example: 1/6 wave = .93, 1/7 wave = .94, 1/8 wave = .95, 1/9 wave = .96, 1/10 wave = .97, or something like that. In this case, I imagine that the wave fraction is related to the P-V and the decimal number to the Strehl ratio. Again, better the optic flatter the wavefront, lower the fraction towards an ever smaller portion and higher the decimal towards 1?

From time to time when discussing a scope's optics or performance, I often see folk posting up optic reports. The problem is being a bit dim witted, I just can't make head or tail of them.

I've picked out this comparable report - not entirely by random - and was wondering what it is I should be 'reading' and what it is those figures/colour images are telling me?

Below are the images simply cut and pasted from the link:

Vixen 102s:

Tak 128:

Hopefully, you've had a little more luck today @Merlin66. I was out a little today and although there was some activity there was nothing as significant as yesterday. The surface itself also remains inactive with hardly a filament insight, let alone with plages or sunspots. Oh well

There was some interesting solar activity this morning around the sun's limb. A number of surges at 3, 6 and 9 o'clock were observed whilst at around 11 o'clock a large dinosaur shaped prominence arched the length of about 10 planet Earths lined in a row. It was a warm, cloudless and sunnny day but seeing wasn't great with quite a bit of 'boiling' turbulence around the sun.

I think any of FLO's beginner recommendations are woth looking into and personally one of the Heritages or 200p would be a lovely present. The scopes come pretty much assembled and generally only need the finder attaching. They're all well made, very sturdy on their wooden Dobsonian mounts and look very attractive. The Heritages in particular can be packed up and stored away quite easily. There's a large knob for altitude tension adjustment and a nut and bolt for azimuth, so they're also as easy to use as the 200p. The little 76mm weighs in under 2kg, the larger 100mm just under 3kg and the 130mm just over 6kg.

@Fozzie, I think any of FLO's beginner recommendations are spot on and personally one of the Heritages or 200p would be a lovely present for the boss' granddaughter. The scopes come pretty much assembled and generally only need the finder attaching. They're all well made, very sturdy on their wooden Dobsonian mounts and look very attractive.

If one could handle the mounting issues and weight, I figure a 140mm apo would be a gorgeous scope. Despite its acknowledged drawbacks compared, say, to a bigger aperture dob, each night I use the little FL 102, I'm simply drawn in by its fabulous contrast, colour correction and lovely, gleaming tight stars. For all its irrationality, the lure of a decent refractor still gives me a buzz .

- - - -

P.S. The OP's link didn't work for me, so have no idea of the particular scope's specs, price etc.