200mm(8") Dobsonian or TAL 100RS what would you keep?

[TwoPi]

Woo-Hoo! The fire in my pocket is out? Ive just purchased the Sky-Watcher Skyliner 200P Dob. Now awaiting delivery......................................is it here Yet?

Now to review the tweaks and enhancements for this scope. Not sure of the quality of the lenses supplied, but no doubt they can be bettered at a price. Will probably buy the collimator first.

Nice, you'll love it!

[Charic]

My Skyliner 200P was dispatched Friday, arrived Monday. Time to check everything. 30 mins to set-up the base unit, noticing the first fault in the Parts List. Package 1 (NO SCREW CAPS X 14) not to worry, will contact the supplier tomorrow, so 30 mins later and the base was completed, minus the screw caps. Also noticed 3 of the screws had the slightest kink through their length, but did not impede the build. The 9×50 scope was a tight fit, trying to get the rubber seal to stay put, whilst trying to fit scope into its holder. A little washing liquid helped in the end. Then to the tackle box to get the 35mm film canister, a 1mm hand drilled hole, and in goes the collimation cap. looks OK, should be, as its brand new! however, where is the Primary Mirrors third mirror clip? Its not visible, must be me. Then its into the living room to wait for the arrival of the Mrs..... " Thought you were getting a telescope, not a human cannon, and where the?**? you gonna keep that" she said. “Its a lot bigger than I expected too" she added. So its out into the garden, and waiting for its firstlight. Ive tried to get the focuser aligned, however, there’s so much around me, that I cant see more than about 50 feet in any direction, so its wait for the stars.

Stars are out and I’m straight onto M31. This Dobsonian is much easier than the equatorial mount Ive been using for the last three weeks. This Dobsonian mount is easier to use than the............yes, said that twice. what an improvement for my style of viewing. So 1st good decision getting the Dob. Now M31 is not showing me any spirals, just a bigger blur than Im used too, but so much easier to find the target. UP/Down and left/Right. Just perfect. The 9×50 is very bright, and easy to find your target(keep both eyes open, and as both images from each eye overlap, bingo, on target. The stars are much clearer too than my 127EQ. I tried the Celestron lenses on the 200p ( I’ll get those lenses out of the bin tomorrow? ) I’ll find time to test the Sky watcher lenses in the Celestron, to see what improvements if any are achievable. Then I noticed how much light pollution there was tonight, and the seeing condition was also bad.

With scope in the kitchen now, Im having a look through the collimator cap , thinking, it cant be that difficult for a first timer! Caution, the secondary mirror screw is VERY VERY tight and it looked like I was going to bend the vanes that hold the mirror in place, but it came loose eventually? about 10 mins later, the secondary, appears to be dead central, and I can now see the three primary support brackets, and with enough light going down the tube, I notice that the primary mirrors centre spot is just off centre on the inside of my white faced collimation cap. so scope level I notice the second and third problems. Firstly out of the three Hexagonal keys I have, the smallest fits the adjusters on the secondary mirror, the fattest one fits the two bolts for the handle, and none of them fit the lock nuts for the primary mirror, so cant adjust that at present. But I didn’t think collimation was this easy. as I look through the collimation cap, I just need to drop the primary mirrors mark by at most 2 mm to centre the ring over the pinhole. Then a Star test to satisfy my adjustments. Maybe wont need that laser now? The fnder scope is better/brighter and so are the "super lenses (They will still get an upgrade.) lastly, should there be a plate at the bottom of the OTA. I see three small holes which looks like you could fit such a plate, but all I see is the base of a mirror. So I`ll be onto the supplier tomorrow to see if they can arrange some screw caps and a hex key for the mirror, as they should be in there. But I can get those bits tomorrow myself, if I was so inclined. So not the best first light. M31 was not as detailed as I would have thought, but the light pollution was bad tonight. so a real dark spot is planned, for its proper First light, once these adjustments have been sorted. But I’m really happy with the scope apart from the little issues raised here. Hopefully , Ill have an update shortly.

[Avocette]

the first fault in the Parts List. Package 1 (NO SCREW CAPS X 14)

The user guide needs updating - the screws are black allen head ones these days - so don't worry and don't bother your supplier!

Mrs..... " Thought you were getting a telescope, not a human cannon, and where the?**? you gonna keep that" she said. “Its a lot bigger than I expected too" she added.

Spot on - exactly the response my wife had - but happily she's grown to accept it if not exactly love it!

As far as collimation is concerned I've now collected a laser collimator with modified Barlow lens, a home-made optical bench for adjusting the laser, the Cheshire collimator with sight tube and cross wires, and 35mm film can with small drill hole. I've learned to relax about the variations in the laser spot position when used without the Barlow, I don't trust it in that mode. I now use the Cheshire after everything else as a confidence check (and it does that job well).

My Dobs were bought second hand. The 250px had probably been mis-collimated by its first owner

Two additions I've made that have transformed usability are a water butt stand to raise the scope 30cm above the damp lawn and place the eyepiece at an appropriate height for my eye (I'm 5ft 10), and a setting circle and WIxey to make locating objects more direct.

But in any case congratulations on your new purchase - enjoy!

[JonnyP]

I've never seen spiral arms in M31 with my 200mm dob. It's always a bright blob for me, regardless of LP or how dark the observing site.

[TwoPi]

Congrats & nice job Charic, I'm sure you'll have plenty of fun!

Your tale of adjusting the secondary for the first time made me smile - I had exactly the same problem when I first got mine, the screw was so tight I thought I was going to bend the vanes. Fortunately no damage done!

Yes, for some reason they don't provide the allen key required for the primary mirror lock nuts - mine was exactly the same but fortunately I had the correct size in my toolbox already. Also, as Avocette says, there are no screw caps.

Regarding the base plate, I think that was just on the older 200P scopes, mine like yours just has the base of the mirror cell visible and the primary adjustment screws directly accessible from the bottom of the OTA. Much simpler to be honest.

Like Jonny says, my experience of M31 is just a fuzzy blob too so don't be disheartened - there are plenty of other DSOs that will look great!

One thing I would do is check once you've collimated the scope that it stays in collimation at both 0° and 90° altitude - one of my primary mirror clips was loose and allowing the mirror to move slightly when I got mine - full story here. And for what it's worth I've only ever used a Cheshire, much prefer it to a laser personally.

Enjoy second light - it's a great scope!

[TwoPi]

Oh, one other thing. Someone posted this link recently on what views to expect from an 8" scope (from a dark site!). I found it quite inspiring what's possible - you're in for some stunning views

That said, you'll see that M31 even from a very dark site only reveals a hint of the spiral arms in an 8" scope. Plenty of other targets though

[SnakeyJ]

Oh, one other thing. Someone posted this link recently on what views to expect from an 8" scope (from a dark site!). I found it quite inspiring what's possible - you're in for some stunning views

That's a great link to Michael Vlasov's site, some great sketches here of a lot of the common objects. NELMs of 6.7+ in the Negev desert certainly help!

[Charic]

many thanks ....

Avocette... read your reply after my call to Pulsar, screwcaps are no longer supplied.

JonnyP...my expectations are to high maybe?

TwoPi...points noted!

I`ll finish off the primary alignment later, and contemplate some basic cover for the base. It just seems to exposed. Maybe some fine wire mesh.

Size for storage: the whole assembly is just over 26Kg and stands 130CM from floor surface to the top face of the finderscope, and the base is 52cm wide. I would allow a floor space of 60 x 60cm (2` x 2` Feet)

I also noted the 3 simple sliders stapled to the upper face on the base board. Not sure of their wear rate, But could start scoring the underside of the upper base unit (you know what i mean). Might consider some teflon sheets, but thats a minor issue at present. And lastly, I removed one of the screws to check the countersink in the baseboard, and the malamine chipped slightly, but again, a minor issue, hidden by the screw. Its not like the unit will be sitting in water.

Going to check out some lenses next. will need 3 for starters, all best quality at budget prices. Liking ES,Kellner,Plossl at present, but nothing out there for under a tenner? Lol !

So, New lenses, possibly a reflex finder scope.( Will try to use the two existing screw holes to mount the reflex).

More to follow as and when. Take care.

[JonnyP]

26kg? That explains why I get knackered after storing it upstairs (with the rest of my kit over my shoulder!).

[Charic]

As the first respondents to my initial thread, and putting me on the right track with your thoughts and experiences, I just thought its time to thank you all................

 john, ronin, rowan46, twotter, nightfisher, foundaplanet, dweller25, NGC 1502, cotterless45, Naemeth, AlexB67, Rob63, TwoPi, AndyWB, Avocette, JonnyP, SnakeyJ, 

I've learnt a huge amount since,  and I'm now able to share some of my views and experience to newcomers alike. My Skyliner 200P is a joy to use. Thanks again.

[brantuk]

"Given a budget of @ £350 what would be your choice today and why?"

To put the cat amongst the pigeons here - forget the dob - it's only advantage is a simple floor floor standing up/down/left/right mount which is beneficial only for complete beginners to get up and running quick, or experienced chaps with very large apertures lol.

If you're getting (or already have) a half decent GEM - then you can afford to get a 200P and a Tal 100RS on the second hand market with this budget - and still have change for fish and chips and a bus ride home left over.

Seriously - I got both for under £300 in total in excellent condition and perfect working order - and they're both worth having just to experience the differences between them.

[Charic]

To put the cat amongst the pigeons here - forget the dob - it's only advantage is a simple floor floor standing up/down/left/right mount which is beneficial only for complete beginners to get up and running quick, or experienced chaps with very large apertures lol.[sic]

Forget the Dob! The UK's most popular  telescope?

brantuk........as bambuko has already said to me ......." Proponents...{deleted}...are sometimes given to a bit of exaggeration [sic)"

If you're getting (or already have) a half decent GEM - then you can afford to get a 200P and a Tal 100RS on the second hand market with this budget - and still have change for fish and chips and a bus ride home left over .

I've already got a GEM (basic) but  you've  still got to  mess about and rotate OTA at some stage or adapt the focuser, and faff about with set-ups, and maintain power supplies  ect. I've got both support systems, I prefer the Dob."Its only advantage", that you depict, is actually its biggest advantage, for beginners and experienced chaps/ladies alike.

[brantuk]

"Forget the Dob! The UK's most popular  telescope?"

But why's it popular? The 200P dob is easy to use and set up, excellent for a beginner, respectable aperture, cheap, pretty light to lift and move around, highly portable, fits easily in most family cars, and allows you to see a lot of objects, etc, etc.

But popular or not - a scope is a scope and a dob is merely a base/mount to put it on. The biggest benefit of a dob base is for large aperture newtonians for which an EQ mount would otherwise cost a small fortune. And for a 200P ota there's little difference between a dob model and an eq model - about 200mm focal length if I recall and one step in focal ratio.

So whether or not to "keep a Tal 100RS or a 200P" for me is a matter of ota rather than mount. And an eq mount represents the best option for owning both ota's - which is what I'm advocating. Or you could do what I do and pop 'em both on a Skytee-2.

So yes - forget the dob is my recommendation - it's only a mount - the important bit is the bit that lets you see the sky.

[Charic]

So yes - forget the dob is my recommendation - it's only a mount - the important bit is the bit that lets you see the sky.

 brantuk..........its how I read it. I thought you were dismissing everything. I see your point now, Your referring to just the mount. Point taken. Its easy to interpret the wrong way when your tired?

EDIT* besides this is an old thread title, and  the TAL has long gone out of my shopping list,  I was merely just thanking those who initially helped me here, as its Christmas, a time to be jolly Ho Ho Ho!