Dobs and EQ Platforms

[sweatysock]

Evening all,

I currently have a Celestron 8SE, but I am looking for my next step to help me get a better look at DSO's. I dont have any previous experience with Dobs.

As most people say, I have been using this site as a great resource, and have pretty much settled on a Skywatcher 350P.

I see almost a £500 difference between the Goto and non-Goto. If I go non-Goto I think I can cope with setting circles plus I could then invest in an EQ Platform. For example these guys do one at around £450 that would take the weight - equatorial-platforms-uk - this is a bit beyond my own DIY skils. At least then I would stand a better chance of photographing some fuzzies with long exposure using my DSI Pro II.

Does anyone have any thoughts on choosing an EQ platform over tracking, which would in the end only be Alt-Az ?

Regards

[sixela]

If you're not worried about having to locate objects yourself and the extra height for the eyepiece doesn't bother you, I prefer a platform. It leaves the scope as intuitive and smooth to move as the native scope, plus if you keep your old ground board you always have the option of not using the platform.

Platforms are a bit of a pain in the neck to use with digital setting circles. Unless you're a nit and drift-align your platform, the best thing is to reset the platform each time you look for a new object and then engage the drive only when you've found it.

[Jon65]

Hi,

That does seem an excellent bit of kit for dobsonian telescopes purchased prior to eg. Skywatcher Skyliner 300P FlexTube AUTO models.

There is about a £300-£320 difference between the Skyliner 300P FlexTube AUTO and a standard tubed 300P Dobsonian (non Auto & GoTo) and the platform is £445, so not too bad a difference if unable to stretch to the Auto dob model when making the scope purchase.

As you state GoTo is quite a bit more expensive with the Skywatcher Skyliner 300P FlexTube GOTO model.

Do you intend to make setting circles and put them on the 300P dob base unit,find an object, track it with the EQ Platform and possibly do some imaging with this set up?

Cheers

Jon

[sweatysock]

Hi Jon,

Yes, thats what I was thinking. I have the NexStar, so I am used to the issues of short exposures in order to get an image when using an AltAz mount - so I was thinking that if I was to buy a 350P for observing DSO , then an EQ Plattform would be more useful than a dob tracking system.

Many good articles and links to be had on setting circles, I've even come across ready made PDF's. Printing those out is not an issue, adding some thin perspex from a DIY shop for protection. I also have the option of a Wixey for inclination.

So finding objects should be possible, EQ platform is advertised to track for an hour, I am hoping that this would give me a good visual/imaging combination... But like most things it sounds great on paper until you discover its not as simple as all that !

Thanks,

William

[Jon65]

William,

That all does appear to be a great idea and a lot lighter in weight and on the wallet than putting a 300mm or 350mm scope on an EQ6 mount.

I 'm hoping to have a 250mm PX dob this week,should have come today, but if ever I thought about tracking objects for sketching purposes this platform does seem a good idea.

Another advantage it raises the height of the 250mm.

From what i've read both the EQ platform and the SW Auto scopes will track for an hour.

For a final decision I suppose it depends on how much can be put towards the initial scope outlay at the time of purchase.

Cheers

Jon

[Moonshane]

I am working on an EQ platform that would cost about £50 to build and you'd only need basic skills (no need for a router etc).

I am running a thread on this currently and trying to show daily updates. I'll eventually make another one which won't need the routered sector, just a straight cut. the one you mention is good value for a purchased version though.

I have not used mine yet but expect it will work http://stargazerslounge.com/diy-astronomer/127311-equatorial-platform-dobsonian-telescopes.html

[Jon65]

Moonshane,

Thats some neat handy work there and way above anything I would even dream of attempting,plus I dont have the workshed and tools anyway.

All the best with the finished product, looking forward to reading about its first outing.

Jon

[brianb]

I suspect an EQ platform would not track accurately enough for long exposure DSO imaging with a moderate to long focal length ... there's no provision for autoguiding. But it should work OK for wide field (piggyback) work, and having essentially no field rotation is a major boon if attempting lunar mosaics. EQ platform certainly ought to track well enough for planetary / lunar imaging at large image scales.

Personally I wouldn't consider a 14" scope without motorized tracking of some sort, objects scoot across the field pretty sharpish at even a relatively low power in such a large instrument.

I guess the sane alternative is to upgrade your CPC800 to CPC1100 ... pricey though ...

[Moonshane]

Moonshane,

Thats some neat handy work there and way above anything I would even dream of attempting,plus I dont have the workshed and tools anyway.

All the best with the finished product, looking forward to reading about its first outing.

Jon

cheers Jon

when I finish this one (designed for my planetary scope) I will be making another for my larger 12" dob. this will be with more basic cuts and all you'd need is a saw, a drill and a screwdriver (possibly you'd need to get a couple of parts machined - I have) but if you have even a remotely average DIY skill you could do it. this type of mount is really quite simple and I'll certainly be making one for each future dob I make. follow the thread - might be worth a go.

Brian is quite right (of course) that really a dob type mount is not the one for long exposures but planets, moon and some of the brighter ones, some wide field would be OK.

most use a small refractor on a big mount for 'proper' AP.