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dob question

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Merlin999

Merlin999

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One "alternative" is to install an azimuth-only slow-motion mechanism. That should give you many minutes of stable observing around the meridian.

That sounds really interesting, but in my ignorance as a noob I'm afraid I have no idea what that is. But if it does give minutes of stable observing that sounds good. Any chance you could explain what it is and how it works? Sorry to be an ignoramus.

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themos

themos

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It only exists as an idea in my head. You can make or purchase "equatorial platforms" which are flat surfaces on which you can plonk a Dob and they tilt (driven by an electric motor) so as to counteract the rotation of the Earth. They involve roller bearings and fancy curved surfaces. They work for objects anywhere in the sky and provide about an hour's tracking.

Objects crossing the meridian move horizontally. So, for some minutes before and after Jupiter, say, crosses the meridian, it's only going left-to-right. So, a Dob whose base was horizontal would only need azimuth nudging which could be provided by a small motor-and-screw device.

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Merlin999

Merlin999

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Ah yes I think (though not entirely sure) I get what you mean.

I guess if you could ensure the base was horizontal then you would only have to nudge on one axis under those conditions.

I know an EQ mount would make tracking much easier but I am shying away from them because of the weight and having to align it to Polaris.

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Merlin999

Merlin999

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Thanks for that themos. 20 minutes is certainly a decent viewing time. :)

dobs are kinda heavy too by the way, the 8 inch weighs in around 20kg but the 10 and 12 inchers really tip the scales

Glad I'm not planning on going any higher than the 8" at the moment. I reckon I'll leave the heavy lifting to my husband. Thankfully he likes astronomy too so he shouldn't mind too much.:)

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Merlin999

Merlin999

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not as heavy as a scope on an EQ mount though, and you can carry it in two parts.

That is what put me off the EQ mounts. I know what we are like in the evening and if it involved lots of heavy lifting and setting up, I just don't think we would use a telescope much. Life is life.:)

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Ogri

Ogri

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Must admit I'm finding the 200p dob to be as fast to set up as my ST120 on the AZ3 mount (which is pretty darned quick!).

It's a little more awkward to carry around in one piece, but not too bad, and a piece of cake if the base is put out first and then the OTA after.

The handles johninderby (who I bought the 'scope off) put on the OTA are an excellent aid in speedy and comfortable setting up, and also very nice for keeping planets in view (I've managed 300 x magnification ok on Jupiter, which was a very nice surprise). :)

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sammiefields22

sammiefields22

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Congratulations! Let us know how the tracking goes. I really don't see it as a problem myself, I have an Orion SkyQuest XT8 Dobsonian and it suits me just right. As long as you're just observing, tracking is never really all that much of an issue. It's only during astrophotography that you need to track a deep space object for a couple of hours that you need to worry about tracking.

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Moonshane

Moonshane

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Congratulations! Let us know how the tracking goes. I really don't see it as a problem myself, I have an Orion SkyQuest XT8 Dobsonian and it suits me just right. As long as you're just observing, tracking is never really all that much of an issue. It's only during astrophotography that you need to track a deep space object for a couple of hours that you need to worry about tracking.

I agree with this. the only slight exception is when someone is taking over the view from you. BUT just reduce the magnification so the targets moves slower and then guide them as to what they need to do and it's simples.

I added a 'dob knob' to mine which makes nudging easier. you can see it on the pic below.

post-17776-133877484453_thumb.jpg

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Moonshane

Moonshane

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it was a small ceramic drawer handle from homebase. I bet most DIY stores would have similar. you could use anything really but something with a ready made bolt hole which also looks aesthetically nice is a good move.

other people have used similar things but I found this first and just added it - makes life a lot easier.

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Moonshane

Moonshane

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is that a telrad? Does that replace the finderscope using the same bracket?

hi there, yes, it's a Telrad and it comes with its own base. you can also buy a spare base if you want to use it on two scopes (obviously not at the same time :)).

I stuck it on with car number plate double sided pads from my local auto bar they stick things like the proverbial 'stuff' to a blanket - no drilling and easily removed if you sell the scope. I normally remove the Telrad when storing the scope though. The cover was £3 from AstroBoot but you can make your own too http://stargazerslounge.com/diy-astronomer/99727-telrad-frost-dew-cover.html

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Moonshane

Moonshane

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Do you need to take out the finderscope or can you have both on?

Dob should be arriving tomorrow, and I've just looked outside and the sky is amazingly clear, I can see the moon and Jupiter is looking sweet as well with the naked eye, can't wait to check them out tomorrow!

yeah right - new scope = cloudy for weeks - it's the rules you know :)

I use both the Telrad for initial placement and then the finder for fine tuning and in theory the target is then in the eyepiece.

that said, for many things, the Telrad gets you straight there.

good luck with the scope - you'll be shock when you first look through it.

tips to avoid disappointment first night :

  1. get the scope set up early and allow it to cool down outside for at least an hour - preferably more
  2. if you can (and while the scope is cooling) get the finder lined up - look at something as distant as you can (SERIOUSLY make sure you know where the sun is and avoid it - even the finder can burn a hole in your ear after a while with the sun shining through it!! :icon_eek:) and get this in the eyepiece. then look through the finder. see the object? line it up with the centre of the cross by adjusting the small thumbscrews. check it's still in the eyepiece in the centre and in the finder cross and you're lined up.
  3. check the collimation at least roughly - make a 'collimation cap' with a film canister and a small 2mm hole. look down the eyepiece and check everything looks liked up - see the various guides online. It is possible it may be OK.
  4. have a go at some easy targets first - the moon and Jupiter - just to get used to the motion
  5. always make sure everything is secure before and during the session (thumbscrews, finder bracket/shoe etc etc)

Hope this helps but don't panic and enjoy it! :)

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johnkirkpatrick

johnkirkpatrick

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Just jumping back to the weight comment, I have the 200p dob and find it lighter and easier to move than my 5" reflector on the tripod, I think when moving the tripod with the weights and the mount its self weighs quite a bit on its own. so my advice is don't worry about the weight am a small build and move it really easily. As for the weather I hate it sat my 200p to cool and in comes the cloud!!!! had the scope two weeks now and only had 2 hours viewing lol.. I hate scottish weather!! You will love it mate I know I do, and even seen the transit of one of Jupiters moons and the GRS at the same time with my 15mm ep. Stunning!

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Moonshane

Moonshane

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Just jumping back to the weight comment, I have the 200p dob and find it lighter and easier to move than my 5" reflector on the tripod, I think when moving the tripod with the weights and the mount its self weighs quite a bit on its own. so my advice is don't worry about the weight am a small build and move it really easily. As for the weather I hate it sat my 200p to cool and in comes the cloud!!!! had the scope two weeks now and only had 2 hours viewing lol.. I hate scottish weather!! You will love it mate I know I do, and even seen the transit of one of Jupiters moons and the GRS at the same time with my 15mm ep. Stunning!

it's not just Scotland where the weather's cack. I am sat here in Stockport getting very brief glimpses of the moon between the cloud - really very frustrating. ironically, the seeing seems quite steady too. I bet it would take good magnification. 250x is easy based on the glimpses I have had even with dark clouds in front.

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Beulah

Beulah

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I came home from work quite excited to see the package, but I realised there should have been two boxes...

Turns out they sent me the wrong thing!

I got the explorer 200 OTA... it will be picked up tomorrow and I'll get the right item on Thurs hopefully...

:)

Aw no, sorry to read that!! ;) What a bummer!!

I hope it gets sorted very soon.

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