Go-to and Dobs

[Benno]

Hey all,
Is it possible to have a goto system and auto tracking set up on a Dob?
reason I ask, is that a mate has a dob and doesnt see the need in upgrading as yet, but would love to be able to do long duration imaging without having to constantly move the scope.
cheers
benno

[Kokatha man]

Hi benno - "John" has a Mel Bartels" GoTo/tracking type set-up that he had previously installed on his 10" dob. I was interested, but because of other commitments am unable to pursue it further: it is in the IIS classifieds at the moment under "Accessories."

Should be well worth you or your mate checking it out!

Regards, Darryl.

[gary]

Indeed it is. By far the most popular commercial system is the ServoCAT
manufactured by StellarCAT in Sierra Vista, Arizona.
See http://www.stellarcat.com/

However, first a disclaimer. StellarCAT is a reseller of our Argo Navis
Digital Telescope Computer in the United States and we have a close
working relationship with them.

There are a couple of variants, the ServoCAT and ServoCAT Jnr.
The Jnr is targeted at scopes in the 8" to 18" aperture class whereas
the regular ServoCAT is targeted at scopes in the 16" to 48"-plus class.

Both systems use servo motors rather than steppers. Servos have distinct
advantages over stepper motor systems in telescope control operation, including
smoother operation when imaging.

See also my posts in the following threads here -
http://www.iceinspace.com.au/forum/showthread.php?t=8493
and here http://www.iceinspace.com.au/forum/showthread.php?t=17457
and here http://www.iceinspace.com.au/forum/showthread.php?t=23184
and here http://www.iceinspace.com.au/forum/showthread.php?t=11729

You will also find suggestions there for other controllers, equatorial platforms
and other important considerations related to astrophotography. I won't
repeat them here so as to keep the response succinct.



Due to what is known as field rotation, long duration photography on an Alt/Az
mount should be avoided unless using a field de-rotator. However, Dobs can
be used to image even deep space objects and the above cited threads have
links to examples of the results being achieved by some people.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[OneOfOne]

If he just wants to take long exposure, you just need an equatorial platform. Once the scope is pointed to an object, the motor will continue to follow the target for several minutes. The cost of something like this is much less than a full blown "goto" conversion.

[Kokatha man]

Correst O'nO, in fact I've just baptised my new Round Table Platfrom (you can read my travails in the "Equipment" section.)

But personally I thought it worthwhile to point out John's set-up, that he's asking $850 for; and without being too presumptive he may be negotiable over - an interesting option perhaps.

I'm thinking that you may really be referring to Gary's (Wildcard) response: that is not my provenance but it would be interesting to see the cost comparisons between (most likely) apples and bananas so to speak!

At $900plus including shipping I considered the RTP a darn good purchase: but I was naively ignorant of the fact that even though I'd paid for air-freighting, that an "Aussie" middleman (profiteer?) would extract another $200 to "tell me when it had arrived" and then another $100 to provide the broker services needed to get it through customs.

An exceptionally expansive (imho) customs officer explained to me that because the goods cost less than $1000 there was no GST (which I already knew) - but that as an item below that value I could make a "self-declaration" which customs had 48/72 hours to just respond to, then an indeterminate period to process this application.

Without commenting verbally on my polite comment about "quasi-monopolies," he explained that they had "preferred agents" whose electronic (ie emailed) applications would be automatically processed more quickly than any individuals: this presuming the individual could manage to fill the forms in correctly, with all the codes etc necessary!

I'm more than happy with the possibilities for my platform and any intended usages, as my thread indicates; and am already "upgrading" its' versatility; but I would be interested in Gary posting costs for an Argo Navis with drive options (mini version) as per his post below.

Cheers, Darryl.