Goto dob 12 Vs 14 ? - Page 2

Stu Ward · #21 19-04-2011, 01:47 PM

I've now been informed that andrews don't have stock.

KenNo2658 (Ken) · #22 19-04-2011, 04:31 PM

Hi Stu, I use a jump start pack I picked up from Autobarn for around $70. It's designed to jump start a four cylinder car at a cranking amperage of 600 amps. It has a standard 12v cigarette lighter plug that has a steady output of 10 amps if needed. It also has a light that makes packing up very easy. I've used it to power my CPC 8 for around four hours straight without a problem. Just leave it on charge when I'm not using it and grab it and go when I want.
Easy to carry with one hand and fits easily under a tripod.
I think you can get them from any autoparts shop, so it might pay to have a look.
Ken

ausastronomer (John Bambury) · #23 19-04-2011, 06:05 PM

Hi Stu,

I recommend getting something with a bit more "grunt" than the 7ah. This is really only adequate to power fans and the like on scopes without dew heaters and "goto" capability, IMO. I have 3 power packs for my 14" SDM and 18" Obsession. I have 2 x 17ah packs which will run either scope for 1 nite only and a 32ah pack which will run either scope for 2 nights.

The GOTO drives on the Skywatcher scopes would have a lower current draw than the Servocat Drives on my scopes. I amj alos running 4 dew heaters on my scopes. If you get a jump start power pack with a 17AH battery you will "easily" get one full night and most likely at least two full nights, from this unit. The 17AH packs aren't too heavy and have the added advantage of being able to be recharged from mains power or the car, in addition to having a light inbuilt and a voltmeter to tell you the battery condition.

Cheers,
John B

Stu Ward · #24 19-04-2011, 06:11 PM

Thanks for the info guys, what lead do you require from the power box to the dob ?

Any links for where to purchase them would be appreciated

Stu

Groboz (Gino) · #25 19-04-2011, 06:36 PM

Hi Stu

This is my first ever post here so I'll have to properly introduce myself to the community soon elsewhere.

I'm also researching my first serious telescope purchase and have the Sky Watcher 14" flex tube GOTO as my most preferred option. I've lurked here and CN long enough to know what will suit me best and being 6'3, 110kgs and owning a 4x4, I think I could handle something that big. However now that we are finally into our dry season up here, I will be attending some observation nights and speaking to the local experts before I pull the trigger on the purchase.

Anyway, the reason for this reply is that Andrews replied to my query on the 14" yesterday by saying that they are expecting a shipment in 1 to 2 months time. I suspect the 12" telescopes are probably on the same boat. They also stated that they didn't sell the nylon shrouds so I'm going to have to source one from somewhere else.

Good luck with your eventual purchase, I'll be paying particular attention to this thread as like our telescopes..... we're in the same boat.

Gino
Darwin

ausastronomer (John Bambury) · #26 19-04-2011, 07:54 PM

Hi Stu,

In all cases my leads have a male cigarette lighter plug on one end whch goes into the power pack and a 3 pin male din plug on the other end which goes into one of the feet on the powered ground board. It is simple to make up leads to suit your scope. I am not sure what is required for the Skywatcher Scope, but from your comments (I thought the 2.1mm plug was the female, allowing a mains unit to be plugged into it ?) I guess you are going to need a male ciigarette plug on one end for the power pack and a male 2.1mm plug on the other end. All the components you need to make the power cable are available on line from Dick Smith (the shops these days only have computers, TV's and Game consoles), or Jaycar; and its a very easy handyman/solder job to make the necessary cable. If you can't do it, or have a friend that can do it, I would be happy to make the cable for you for the cost of parts and postage. It's a 5 minute job.

Cheers,
John B

Osirisra (Ken) · #27 20-04-2011, 12:10 AM

I use a car Repco 900amp Jumpstart battery pack for both my Meade SCT and my 14" Dob as well as powering the scopes computers it powers my laser finder, DSI cooling fan and skyfi wireless. I can run multiple sessions on both scopes and only ever charge it every now and then. The only way to go in my opinion. Grab a few bits from your local electronics store and or wire up all the cables your self and you are set.

I got a bit of rubber matting from Bunnings that was some type of floor matt that only cost me around 25 bucks. A bit of cutting and some sticky Velcro and it one great light shroud. Just make sure you stitch or add your own glue to the Velcro as it will come off.

overlord (Charles) · #28 21-04-2011, 09:44 AM

LOL Don't worry about it guys, I use a 8" f/5 since 2003 and it's perfect for everything!

overlord (Charles) · #29 21-04-2011, 09:47 AM

BTW, the other things u guys may or may not be considering is that being able to sit down while looking thru the eyepiece adds a pseudo-inch or two to the diameter. Initially I was gonna go for a 10" f/6 Orion but York Optical didn't have it in stock so I went for the 8" They were like the largest available for a decent price back then. So yeah, don't worry too much. in the 80s everyone had a 6" reflector and that was considered pretty decent.

So yeah, I can't imagine sketching without being able to actually sit down, so consider that lol.

mozzie (Peter) · #30 22-04-2011, 04:23 PM

how did you go with melinda's dob for sale stu i see you pm'ed her.there could be a bargain there for you !!!!!!!!

Stu Ward · #31 23-04-2011, 06:51 AM

Hoping to do a deal after the Easter weekend

mozzie (Peter) · #32 23-04-2011, 09:00 AM

Quote:

Originally Posted by Stu Ward

Hoping to do a deal after the Easter weekend

excellent it's amazing how you miss out earlier in the week and something else turns up a few days later.....

Stu Ward · #33 23-04-2011, 09:25 AM

Fingers crossed !

Stu Ward · #34 29-04-2011, 07:58 AM

Its all gone a bit quiet on the 14 purchase. I might have to buy that brand new 12 again. Talk about frustrating

mozzie (Peter) · #35 29-04-2011, 01:21 PM

Quote:

Originally Posted by Stu Ward

Its all gone a bit quiet on the 14 purchase. I might have to buy that brand new 12 again. Talk about frustrating

don't rush into it stu...be patient it will fall into place and you'll grab a bargain

Stu Ward · #36 29-04-2011, 01:39 PM

It could be a sign, buying a 14 with no warranty.
Daytime demonstration ?

I dont know

Stu

The_bluester (Paul) · #37 29-04-2011, 02:23 PM

Regards the power pack. I am using a 1200A jump starter, no idea how many amp hours it is, but powering my Celestron goto scop by itself it powered it for somewhere near 24 hours before it needed charging. Once I have a dew heater that will obviously reduce but I can not see myself getting less than a full nights observing out of it.

overlord (Charles) · #38 18-05-2011, 10:25 AM

Quote:

Originally Posted by madbadgalaxyman

Let's put some numbers into this discussion......

A 10 inch has 1.56 times the light gathering power of an 8 inch, which is a colossal difference, as we appreciate when trying to see detail on galaxies.

A 12 inch has 1.44 times the light gathering power of a 10 inch. This difference is noticeable to the observer, but it is not
overwhelming.

A 14 inch has 1.36 times the light gathering power of a 12 inch.

In fact, the difference between what you see in a 14 inch and what you see in a 12 inch is not that great;
the level of experience of the observer, the contrast of the optics (e.g. baffling, stray light, and freedom from reflections) , the reflectivity of the mirror coatings, and the quality of the eyepiece, could well make a much bigger difference than the difference in aperture.

In the old "physical size versus aperture dilemma", that is , "I want that extra oomph in my viewing, but can I handle the larger sized instrument?", long experience with owning many and different telescopes taught me the following wise sayings:

The usability of a telescope generally decreases greatly, with increased size. A 10 inch is still "luggable", a 12 inch is a massive brute, and a 14 inch is already an "ultra-brute" when it comes to its size and convenience of use.

The best telescope is the one you actually use, and use a lot.

It's not how big it is that counts , it's what you do with it......

( These opinions are the result of 27 years of regular visual Deep Sky observation )

cheers, madbadgalaxyman

If 14" is ultra brute what is the 25" obsession? I want to get one later this year since I can't find a better planetary solution. It is f/5 btw.

Stu Ward · #39 18-05-2011, 10:38 AM

Quote:

Originally Posted by The_bluester

Regards the power pack. I am using a 1200A jump starter, no idea how many amp hours it is, but powering my Celestron goto scop by itself it powered it for somewhere near 24 hours before it needed charging. Once I have a dew heater that will obviously reduce but I can not see myself getting less than a full nights observing out of it.

I too have abought the same unit, $45 from Super Cheap Auto.
Ran a 3 hour session the other night, and will continue to run it till its out of juice to see what i can get.
This is only running the drives.
No heaters or anything just yet

Stu

rmcconachy · #40 18-05-2011, 11:32 AM

Stu, unless your jump starter contains a deep cycle battery (unlikely) you might not want to run it until it is out of juice. Typical larger (not AA, C or D cell type) batteries don't like being drained below about half capacity before recharging. If you do drain them to almost empty the life of the battery may be shortened. Good luck with the big Dob!