Thinking of moving to a Dobsonian

[Tugboat]

Hi all

I currently own a Celestron Omni XLT 127 scope. Although I like the scope very much, I find that I'm not using it as much as I ought to due to the time it takes me to set up (no space to leave it pre-set up unfortunatley!).

One of the main reasons I bought my current scope was to save space, but to be honest although the OTA is relatively small I still need a fair amount of space to store it all. So I've been toying with the idea of a dobsonian...

I had discounted them originally as they seemed big and bulky, but thinking about it they would probably take up less space than my current scope, and setup time would be as long as it takes me to carry it from the shed to the middle of the garden.

I quite like the look of the Skywatcher Skyliner 200P Flextube Auto, as it can store to a relatively compact size, has good light gathering ability, and the benefit of auto tracking which would aid my visual observing and allow me to take a few planetary photos should I be so inclined in future. My viewing mainly consists of planetary work, but I would like to start viewing more DSOs too.

I've never used a Dob before though, so I have a few questions:

- How do you manually track an object with a Dob? Just by moving it by hand? If so, how do you achieve small enough movements so as not to overshoot? I'm used to EQ mounts where a rough polar alignment will allow me to track easily and smoothly at the turn of a knob.

- How would the quality of image in the 200P compare to my current 127 XLT?

- Would you recommend the auto tracking option on a dob, or should I save the cash and invest elsewhere?

I'd be grateful for your thoughts

Thanks in advance!

[twotter]

I can only speak for the solid tube Skyliner 200P, but I have it stored in our conservatory with the OTA tipped upright. So it only takes up the floorspace of the base. Then it's just a few steps out on to the patio and let it cool for an hour (in fact it's outside now).

The 9x50 finder has been replaced by a cheap red dot finder and it's simply a case of starhopping to my target. I tend to be more of a 'drifter' than a 'nudger' when it comes to manually tracking, selecting an eyepiece that gives enough magnification so I can see detail but allowing enough time to let the target 'drift' across the field of view, before I have to nudge the telescope round. It's simpler to do than to explain

As for tracking...I've not got it but I would make use of it if I did. In fact I'm looking forward to seeing the price of Skywatcher's dob goto mounts when they're released this year

[cotterless45]

The Skyliner 200p is a super scope.It's handy enough just to put out and use. I'd ditch the supplied finder and fit a Telrad finder.You can then use the Telrad charts on the net.

I'm not a fan of any tracking/go to system. You soon get used to moving/tracking by hand.

[ollypenrice]

You do just move by hand and it is not a problem at low powers. A good Dob has near identical static and moving coefficients of friction on the bearings so does not 'overshoot.' However, I do find it intrusive for planetary magnifications where the time you get to observe between movements is short and I imagine a tracking Dob would be far better. We do all our planetary observing on tracking mounts. I would hesitate before buying a manual Dob for the planets myself.

Storage wise I agree that floor space is the key and remember being shot down in flames on a thread a while back for suggesting that tripods/GEMS are a pain to store. I'm glad someone agrees with me!

Olly

[A McEwan]

I agree, but I'm not sure you need the flextube model. Once stored pointing vertially there is no advantage to the space taken up by a collapsible 8" Dob. I'd go for the solid tube and save some £. Unless you want the tracking of course, in which case you must go for the Flextube Auto model.

Visually the 8" Dob will show a lot of planetary detail. I too am a drifter, letting the object drift across before repositioning. That's why 82, 84, 100 degree eyepieces were really invented!

Ant

[NGC 1502]

Dobs are often thought of as low to medium power scopes. Although they are

not ideal as planetary scopes, as long as the movements are smooth, then I

find that hand tracking at 200x is ok. Given the skies I usually observe under,

there is not much to be gained by going higher. Others with steadier skies may

find different.

But if you get the autotrack, then there is presumably no problem keeping objects

in the field of view. It's difficult to give advice, as what suits one, may not be good

for another. For me, I'm happy to track by hand, just let the object drift across,

and then nudge. When you get used to it, it's just like steering a car - you hardly

know your doing it, if, as I've said, the movements are smooth. A "sticky" dob is

a right royal pain, and would put me off entirely.

A 200mm should beat a 127mm on DSOs, fast set up and no alignment either.

Regards, Ed.

[Tugboat]

Thank you very much for all the replies so far

From what has been said I think a dob would suit me best based on my current requirements.

There were some interesting points raised about not going with the flextube to save some cash, as indeed it will only save on vertical space which isn't too much of a problem in my shed. Which dob I go for is going to come down to whether I decide on auto tracking or not, so I'll do a little more thinking and review reading to decide what I really want.

Thanks again for the initial suggestions (and the agreement that eq mounts can be a pain to store!). I'll let you know what I decide on, and in the meantime if anyone is interested in a 2nd hand omni xlt 127, watch this space... (or at least keep an eye on the for sale section )

[sherr03]

Hi mate i was looking at an XLT 127 as my first scope. Have you seen any DSO's through it and what are the planets like. Also how long does it take to set up? Thanks

[russ]

I don't think you would regret a move to the dobsonian. But the full manual nature of a basic dob I'm sure is an aquired taste. I prefer my dobs without tracking, without motors. I have been using a couple of Skywatcher 300P Goto dobs at our dark site. They are very nice and the collapsible tube is a god send for a 12" dob. But i really wish there was a way to disengage the drives because i just want to grab the tube and spin round the sky. And while you can move them manually, there's too much friction to make it a pleasant experience.

As Anthony says, quality widefield eyepieces are almost a must for untracked dobs. Just let the object drift through the field. And the nudging to reposition becomes second nature. I was observing Mars with a 200P at 350x and never once considered putting the tube on the EQ instead, even though i had the option there.

[valleyman]

I have just got a Dob 200P and it is the best thing I did. I made a seting circle as described on the Dob group forum in Communites from some strips or cardboard and covered them in cellotape. marked 360 degres and use some two sided tape to stick it to the bottom base plate. then made a simple pointer using a bit of card and a pin.

Bought a Wixey didital level from Flo. and all ready to observe.

All you need then is to point the Dob at a known object and read the Az from stellirium. then stick the pointer using Bluetac to that point on the top base plate. The Wixey uses magnets to attach to the OTA and will read out the Alt. Works perfect for finding DSO's using a 30mm EP

[Tugboat]

Thanks for the continued replies

sherr03: WRT the XLT 127, I've only ever looked at planets through it. Jupiter and Saturn can be quite sharp given the right viewing conditions. Another forum member pointed out this site in a post earlier today:

http://www.12dstring.me.uk/fov.htm

If you switch to "visual view" and then choose the relevant eyepiece and telescope, you can get a rough idea of the size of image you are likely to see relative to your apparent field of view. The quality of the image will vary widly though according to viewing conditions.

If you were able to set up in the light, then probably 10 mins or so to put it together (assuming you store it disassembled) then once you've carried it outside, another 5 minutes or so getting a rough polar alignment. It's reasonably heavy thanks to the good quality EQ mount, so I wouldn't want to have to carry it too far! You'll then need to leave it for a while to cool, and I've found a dew shield a necessity as it does tend to attract dew! Hope that helps!

russ: Thanks for your positive comments regarding dobs - I have to admit I'd have trouble tracking Mars at that magnification using an EQ mount!

valleyman: Thanks or the tips regarding the setting circle and angle finder. I'll head over to the dob community forum for a more thorough read.

Cheers

Steve

[Tinners]

r.e. tracking

Wide view angle eyepieces allow the image to stay

in view longer ....less hassle.

[sherr03]

Thanks for the info and that website is great!