Got a Skywatcher 8" Dob, What Eyepieces/Filters should I get?

[Telescope_Tumult]

It's been raining pretty hard for the past week, and it doesn't look like it will let up anytime soon. I have been dying to try the used 8" dob I just fixed up, but the perpetual cloud cover and downpour will not oblige. 

In the mean time, I have completely disassembled and cleaned the whole telescope, stand, eyepieces, spotting scope, and mirrors. The spotting scope was inundated with water, and frozen inside. The eyepieces were dirty, so I had to clean them from the inside out, like just about everything else on that telescope. Hopefully everything works in the end. I have also collimated the scope by eye. My eye is in the center, so I assume that's all I have to do. If that's all that needs to be done, I won't bother with any laser collimating pieces that slot into the eyepiece holder.

To say that I know everything about the mechanical details of the telescope, but nothing about its visual capabilities is a definite understatement.

The telescope comes with a 10mm and 25mm eyepieces, that are the 1.25" I believe. I don't know if I my telescope can use 2" eyepieces, and if they will have better performance. I know that there are different types of eyepiece lens structures, but I know nothing about any of them. From what I have been reading, I should get one that's <10mm (5-8). I have also heard about Barlows, but they seem to have an ominous "focus range might not be sufficient" warning that has bothers me. I hope some of the kind folks here can recommend the eyepieces/barlow that would be guaranteed to work with my Skywatcher.

Since I have yet to test out the telescope with an eye piece inserted, I have zero expectations on what I should be able to see. I do know that the image will be inverted, so I'll have to get a rectifying eye piece. As silly as it may be, I do want to use the telescope for terrestrial viewing, so it's at the top of my list of things I want to get.

I have heard about solar filters, but they seem quite expensive for an 8" telescope, should I focus on lunar/planetary observations instead? I have read about lunar filters, but I don't know if the moon is actually irritatingly bright. I do have some sheets of polarized film, so I don't know if crossing them at 45 degrees will produce a similar effect to moon filters.

My budget is pretty limited, so I just want the best value out of the handful of things worth getting. I'm in Canada, so with our terrible dollar, I don't want to spend more than $80 per "thing". The fact that I don't know what I should get limits my decision making and budget.

I did order the cheapest and least important tool, a 5mW green laser.

Thanks for any help or recommendations.

[baggywrinkle]

Welcome to SGL.

The 8'' Dob is a very popular format and has good reviews. It is one of those OTA's that can work both well on DSO's and Solar System objects.

If you do not have one, invest in a collimator to ensure that the primary and secondary mirrors are properly aligned. Lots of 'bad don't do this ' stuff written about collimation but once you have done it it is simple.

I made my own solar filters from the Baader film. An evening cutting card board to make a holder to go over the fromt end of a 6SE I owned at the time. See the attached images.

Forget the Barlow to begin with and use the two provided ep's to train your eye. Later invest in a better quality pair of ep's. The second hand market (online) is a good place to look. Most astronomers look after their kit so second hand if generally OK.

If you are new to all of this get a copy of Turn Left At Orion. Well recommended on this site and I have a copy. Great book which shows a host of DSO's you can chase with good charts of how to find them and drawn images of what they actually look like with the eye rather than hours of data gathered on an imaging chip.

[BritAngler]

Hi, and welcome to SGL

You have the potential for a very good scope there, as baggywrinkle says, it's a popular for both planets and DSO's.

You can collimate just by eye, but it's much easier if you use a collimating cap (to align the secondary mirror) and a Cheshire eyepiece (for the primary). At first, collimating will be a bit of a pain but in a very short time you will get the hang of it until a quick colly-check before a viewing session will be second nature. The website made by Astro Baby is probably the best and most informative when it comes to collimation.

Did your scope come with both 1.25" and 2" adaptors? If so, only use one on the scope at a time otherwise you will not be able to achieve focus. The 25mm eyepiece is a good bit of kit for the price and should serve you well for many years; the 10mm is not so good and although adequate, might be the first one you want to replace. Follow that up with 5mm, 15mm and 20mm and you will have a good set of eyepieces that will cover almost all your needs.

I don't like barlows....

A Moon filter is useful when it is approaching full, but there are other filters that could serve you better, there are plenty of threads on the forum that deal with filters

Making a solar filter from an A4 sheet of Baader film is easy, I've made one for my 'scope and also for telephoto lenses and 15x70 binoculars. Stiff card, double-sided sticky tape, wood glue and (inevitably) duct tape are the only other things you need.

+1 for Turn Left at Orion, also Norton's Star Atlas and the free-to-use Stellarium program.

Hopefully any clouds will soon go and you'll get your first views through the 'scope

[spike95609]

I'd say the only equipment you need to start off with is some means of collimating the scope, as the others have said a collimation cap and cheshire is a cheap and accurate way of doing this. As for eyepieces, you'd be best off spending a month or two having a good play around with the ones you have, as although they're quite cheap they will be good enough in a well-collimated 8" scope, and by looking at different targets with them it will start to give you and understanding of what you want from an eyepiece, in terms of magnification and field of view. The 25mm and 10mm are 48x and 120x respectively, and have a field of view of 50°. You might find you want a wider view than that. Above all take your time before putting any money down on the table as it's a hobby that can soak up cash like a sponge. Think twice, buy once.

[Size9Hex]

How to Collimate an Orion Dob using a Collimation cap or laser

They really mess one up and then put it right

Nice one Ed thanks. These videos were very handy. I've previously collimated my scope, getting it from a passable state to a very good state. These have helped me get it absolutely bang on.

[Size9Hex]

I'd say the only equipment you need to start off with is some means of collimating the scope, as the others have said a collimation cap and cheshire is a cheap and accurate way of doing this. As for eyepieces, you'd be best off spending a month or two having a good play around with the ones you have, as although they're quite cheap they will be good enough in a well-collimated 8" scope, and by looking at different targets with them it will start to give you and understanding of what you want from an eyepiece, in terms of magnification and field of view. The 25mm and 10mm are 48x and 120x respectively, and have a field of view of 50°. You might find you want a wider view than that. Above all take your time before putting any money down on the table as it's a hobby that can soak up cash like a sponge. Think twice, buy once.

This is great advice. There's an entire universe to see, and you won't be short of things to look at with the supplied eye pieces, which (from personal experience) are more than up to the task. A collimation cap or cheshire eye piece is essential though. When you've used it for a while, you'll have a good idea of what aspects of the hobby you enjoy the most, and which aspects of the kit you feel are limiting you from enjoying it more than you are. If you really enjoy planets, the recommendations would be different to if you really enjoy big faint DSOs for example.

Good luck, and welcome to SGL

[Telescope_Tumult]

Welcome to SGL.

The 8'' Dob is a very popular format and has good reviews. It is one of those OTA's that can work both well on DSO's and Solar System objects.

If you do not have one, invest in a collimator to ensure that the primary and secondary mirrors are properly aligned. Lots of 'bad don't do this ' stuff written about collimation but once you have done it it is simple.

I made my own solar filters from the Baader film. An evening cutting card board to make a holder to go over the fromt end of a 6SE I owned at the time. See the attached images.

Forget the Barlow to begin with and use the two provided ep's to train your eye. Later invest in a better quality pair of ep's. The second hand market (online) is a good place to look. Most astronomers look after their kit so second hand if generally OK.

If you are new to all of this get a copy of Turn Left At Orion. Well recommended on this site and I have a copy. Great book which shows a host of DSO's you can chase with good charts of how to find them and drawn images of what they actually look like with the eye rather than hours of data gathered on an imaging chip.

OTA? Distant Space Objects (DSO)?

Thanks for the tip on the Baader film, I will keep an eye out for a 200mm sheet. I got the book yesterday, and have been enjoying very much.

Hi, and welcome to SGL

You have the potential for a very good scope there, as baggywrinkle says, it's a popular for both planets and DSO's.

You can collimate just by eye, but it's much easier if you use a collimating cap (to align the secondary mirror) and a Cheshire eyepiece (for the primary). At first, collimating will be a bit of a pain but in a very short time you will get the hang of it until a quick colly-check before a viewing session will be second nature. The website made by Astro Baby is probably the best and most informative when it comes to collimation.

Did your scope come with both 1.25" and 2" adaptors? If so, only use one on the scope at a time otherwise you will not be able to achieve focus. The 25mm eyepiece is a good bit of kit for the price and should serve you well for many years; the 10mm is not so good and although adequate, might be the first one you want to replace. Follow that up with 5mm, 15mm and 20mm and you will have a good set of eyepieces that will cover almost all your needs.

I don't like barlows....

A Moon filter is useful when it is approaching full, but there are other filters that could serve you better, there are plenty of threads on the forum that deal with filters

Making a solar filter from an A4 sheet of Baader film is easy, I've made one for my 'scope and also for telephoto lenses and 15x70 binoculars. Stiff card, double-sided sticky tape, wood glue and (inevitably) duct tape are the only other things you need.

+1 for Turn Left at Orion, also Norton's Star Atlas and the free-to-use Stellarium program.

Hopefully any clouds will soon go and you'll get your first views through the 'scope

I'm starting to get worried about the mine adjustment capabilities of my 'scope. The previous owner stored it, like a sad old BBQ, under a tarp outside, pointed up, with the dust cover missing. So it comes as no surprise that the central screw that adjusts secondary mirror depth has completely rusted shut on the two pieces it joins. I tried to pull it out, but it stripped without any resistance. I followed the collimating procedure from the manual I downloaded for my telescope. In the end, my eye is square in the sight picture, so I think I have it done correctly. Since the scope got put away in a collimated state, I might get away with just using fine adjustment screws, which I replaced with 2" M4 screws.

I might have to bust out the left handed drill bits to drill and pry that darned screw out.

Thanks for the advice on the A4 sheete of Baader film, I'm excited to make a screen to look at the sun! I already started reading Turn Left at Orion, but I'll take a look at Stellarium as well, thanks for the suggestion.

I'd say the only equipment you need to start off with is some means of collimating the scope, as the others have said a collimation cap and cheshire is a cheap and accurate way of doing this. As for eyepieces, you'd be best off spending a month or two having a good play around with the ones you have, as although they're quite cheap they will be good enough in a well-collimated 8" scope, and by looking at different targets with them it will start to give you and understanding of what you want from an eyepiece, in terms of magnification and field of view. The 25mm and 10mm are 48x and 120x respectively, and have a field of view of 50°. You might find you want a wider view than that. Above all take your time before putting any money down on the table as it's a hobby that can soak up cash like a sponge. Think twice, buy once.

I can tell this is sound advice. I collimated by eye, and have my eye perfectly centered in the view, but it took a while compared to what the cheshire can do. I'll add that to my Christmas list. From what I have read, as long as I stay away from astrophotography, I'll never completely break the bank on this hobby. Considering I have started with an 8" dob instead of a 2" refractive telescope, I'm already putting money on worthwhile equipment. Thanks for the advice.

Good luck with the new scope. Sounds like it was water damaged.  

I put a good amount of TLC to clean it up, but the secondary mirror has a rusted and stripped central screw. It seems like the secondary mirror is correctly adjusted for depth, so I'm only slightly worried about negative impacts. I still have a week of overcast weather to mull over negative side effects of prolonged improper storage of a telescope.

This is great advice. There's an entire universe to see, and you won't be short of things to look at with the supplied eye pieces, which (from personal experience) are more than up to the task. A collimation cap or cheshire eye piece is essential though. When you've used it for a while, you'll have a good idea of what aspects of the hobby you enjoy the most, and which aspects of the kit you feel are limiting you from enjoying it more than you are. If you really enjoy planets, the recommendations would be different to if you really enjoy big faint DSOs for example.

Good luck, and welcome to SGL

Thanks! I always wanted a telescope, and to know more about astronomy. It's nice to finally snag a good piece of kit, and finally get going on such a humbling hobby.

[baggywrinkle]

DSO...deep sky object....OTA..optical tube assembley..the scope.......before long you will be fluent in TLM...   Three Letter Memonics..

[rockystar]

DSO...deep sky object....OTA..optical tube assembley..the scope.......before long you will be fluent in TLM... Three Letter Memonics..

Apologies in advance, but some of my pedantry is going to come out now: A Mnemonic is a phrase that helps remember something (i.e. My Very Easy Method Just Speeds Up Naming Planets), an initialism is an abbreviation using the letters (DSO, OTA) and an acronym spells out a word (NASA)

Back to the OP (Original post), nice bit of kit you've picked up there; I've only recently got myself a Cheshire, I do recommend as my naked eye check seemed good, but the Cheshire showed many (albeit small) things not quite lined up. Give yourself plenty of time (these clouds help with that), as it took me over 1.5 hrs the first time and that just on the secondary, hoping not to have to do that one again. The primary was easy.

As above really - get out with what you've got and then decide what you think you need. In the traffic thinking about it the other day and decided that if I had no more money to spend on it I could get by with what I had, if someone gave me £5000 to spend on it, I could very easily spend it all!

[Telescope_Tumult]

Quick update of my first outing. We had cold crisp partly cloudy skies, good enough for a couple of hours of observing.

I left my scope to cool after Christmas dinner, and came out to look at the moon and Orion. The moon was perfectly sized in the 25mm ep, and well magnified in the 10mm. Thoroughly blinding with both. Since it's a full moon, not all that much else could be seen in the way of stars. I took a look at orion belt and Betelgeuse, but didn't have a chance to narrow in on the nebula before the clouds moved back in.

I was pleasantly surprised that the focus on stars was so crisp, and that no extra adjustment of the primary mirror was needed. I'll probably order a better quality 10mm ep before summer, some moon filters, and a 6-7mm ep.

Thanks for the answers. I'm extremely pleased to be getting into such a soothing and entrancing hobby. Can't wait for clear moonless skies to go planet hunting.

[rockystar]

Glad to hear that you managed to get out to have a play, I'm sure your family were thrilled

The moon won't have too much affect on the planets, they are bright enough - I could see Jupiter the other night with the full moon. The planets are morning creatures at the moment.

[ronin]

Which bit of BC ?

It's a big bit of land - there are 2 astro shops in Vancouver and there was 1 on the island but I think that has gone now.

There are also a couple of clubs around, Victoria club used to meet for coffee somewhere around Cook St on a Sunday morning.

There has to be a club in Vancouver but oddly it gets mentioned almost never here. Actually think there may be 2 clubs.

Look up RASC for their list of clubs.

If the scope works well leave it all as it is. Just go looking through it.

Filters - the only one I suggest is a moon filter, there are simple ones that block say 30% of the light and bit more advanced ones that are 2 bits of polaroid that you rotate to set the filter level. You do not need one, all that happens is you look at the moon, come away from the scope and all you can see is a residual image of the moon for about a minute. Good fun but childish - I do it often.

Eyepieces you say 25mm and a 10mm and it seems they both perform well.

Taking into account the $80 a bit limit the obvious eyepieces are the Astro-Tech Paradigms, were/are $60US. Try the 8mm it tends to be good. The 5mm may be a bit high power, AT's come in 5, 8, 12, 15, 18 and 25mm formats. There is a 6mm but that is a William Optics item and will be over $80.

Often it is a good idea to pick up a 30mm or 32mm plossl, they enable a wider field oif view and so useful for big objects and also to find the others in.

One thing to say is M31, Andromeda, will not fit fully in the view of your scope, so all you see is the central core (blob), people get puzzled by this and usually report "All I saw was this blobby thing?"

Solar viewing, leave it for now, not difficult to make your own solar filter - Baader No5  solar film - but it is also not a 2 minute job either. So until you decide it is a requirement I suggest leaving the sun off the viewing list for a while.

[BritAngler]

Glad to hear you finally got to look through your 'scope   When you get your first view of the Orion nebula, you will be blown away (use a low-power eyepiece for that).

[Telescope_Tumult]

Glad to hear that you managed to get out to have a play, I'm sure your family were thrilled

The moon won't have too much affect on the planets, they are bright enough - I could see Jupiter the other night with the full moon. The planets are morning creatures at the moment.

Yes, family was totally impressed. I now have access to some Nikon microscope eps to try out in my telescope. I'll take a shot at the planets when we have clearer skies. Thanks for the help.

Which bit of BC ?

It's a big bit of land - there are 2 astro shops in Vancouver and there was 1 on the island but I think that has gone now.

There are also a couple of clubs around, Victoria club used to meet for coffee somewhere around Cook St on a Sunday morning.

There has to be a club in Vancouver but oddly it gets mentioned almost never here. Actually think there may be 2 clubs.

Look up RASC for their list of clubs.

If the scope works well leave it all as it is. Just go looking through it.

Filters - the only one I suggest is a moon filter, there are simple ones that block say 30% of the light and bit more advanced ones that are 2 bits of polaroid that you rotate to set the filter level. You do not need one, all that happens is you look at the moon, come away from the scope and all you can see is a residual image of the moon for about a minute. Good fun but childish - I do it often.

Eyepieces you say 25mm and a 10mm and it seems they both perform well.

Taking into account the $80 a bit limit the obvious eyepieces are the Astro-Tech Paradigms, were/are $60US. Try the 8mm it tends to be good. The 5mm may be a bit high power, AT's come in 5, 8, 12, 15, 18 and 25mm formats. There is a 6mm but that is a William Optics item and will be over $80.

Often it is a good idea to pick up a 30mm or 32mm plossl, they enable a wider field oif view and so useful for big objects and also to find the others in.

One thing to say is M31, Andromeda, will not fit fully in the view of your scope, so all you see is the central core (blob), people get puzzled by this and usually report "All I saw was this blobby thing?"

Solar viewing, leave it for now, not difficult to make your own solar filter - Baader No5  solar film - but it is also not a 2 minute job either. So until you decide it is a requirement I suggest leaving the sun off the viewing list for a while.

I'm in Victoria. I have read about a shop north of Victoria, but it's far, and doesn't offer particularly good prices judging by the online store. I'm in no hurry, so the convenience of in-store buying isn't essential for me.

Rest assured, I cleaned and lubed every component of my telescope. It doesn't look even remotely as sad as when I first got it.

Back when I was still in school looking at rock thin sections, I used two polarized sheets to see the minerals in cross polarized light to aid identification prior to using the microscope. Maybe I'll press them up against the eyepiece at a 45 degree angle to see if that will enhance the darker parts of the moon when it's full.

Thanks for the advice on the eps. I might invest a bit more, but over a greater period of time.

Glad to hear you finally got to look through your 'scope   When you get your first view of the Orion nebula, you will be blown away (use a low-power eyepiece for that).

Thanks very much! I'm off to a good start.