Seriously considering the purchase of a brand new goto as I'm having little luck in the classifieds.
Now the thing is I have an 8" solid tube standard dob now, and I'm considering either a 12 or 14.
Thing I would like advice on is there $800 worth of value on the 14 over the 12 ?
Whilst the 12 should give me much more than my 8 will I be missing out if j don't get the 14 ?
I have been going through the exact same dilemma. I really had my heart set on the 14, however I have the 12 on order. The biggest deciding factor for me is the size of the base on the 14. The base has a diameter of 775mm and is about 920mm high. This means it will not fit through a standard doorway. I suppose the positive thing about the 14 incher though is the base is designed to be disassembled and reassembled. My only concern is that eventually I would iamgine the nutserts would become sloppy in the particle board. In addition, a number of people who do have the 14 incher, have commented that the base on the 14 cannot really be picked up by 1 person as the handles are too far apart (more so from an ergonomic point of view rather than weight). I suppose the solution to this would be a trolley.
From an aperture perspective of 12 versus 14, from what I have read ( I have never compared 12 versus 14 myself), yes there is a difference at the eyepiece. It is not a wow type factor, but there is a difference.
So in summary, I have the 12 on order. I know I will be always wondering "shoulda gone the 14", but the size and awkwardness of the base really had me concerned. Furthermore, no supplier in Adelaide has the 14 incher setup, therefore could not really have a look at one "in the flesh".
Size isn't everything - best is the ONE YOU USE MOST
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 )
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
Makes good sense. I am more and more comfortable with the fact that I have opted for the 12 over the 14. Just makes travelling to dark skies that little bit easier.
Thanks for all the comments guys. I reckon a 12 will be my best bet. I reckon I could handle a 14, but the extra effort might be the difference between going out or not on those fringe nights. Also the extra $800 looks could be spent in something else if the 12 is approx x2 my current 8
Increased Aperture vs useability - the numbers don't lie
I will submit a Spreadsheet (a table), this evening, giving precise numbers for the relative Light Gathering Power (and telescope Magnitude Limit) compared to the relative Telescope Volume (and Telescope Weight), for telescopes of 8, 10, 12, and 14 inches of aperture.
[ obviously, the assumption here is an invariant mount design, a specific optical design and coatings, and a specific tube design(and materials) ]
The Light Gathering Power of a telescope increases a lot when we move from 6 to 8 inches of aperture, and also when we move from 8 to 10 inches of aperture. The L.G.P. gains between 10 and 12 inches of aperture are distinctly smaller but still quite noticeable to the eye.
In contrast, the modest L.G.P. increase that we get when we move from 12 to 14 inches of aperture is swamped by many other Very important factors such as: varying light transmission, varying eyepiece type, different levels of observer skill, etc., etc.
Telescope Volume and Telescope Mass :
These are usability quantifiers (numbers) that inexperienced people do not understand intuitively; even a slight increase in overall Telescope dimensions leads to a significant increase in telescope volume and telescope mass. And your lower back feels the difference!
Nearly every 14 inch telescope is a massive object that is hard to cart around. In fact, for rather a lot of people of middling observer experience, only 10 inches of aperture is about the upper limit for reasonable convenience and fairly easy transport & setup of the instrument.
I will shortly submit some numbers, in order to prove my point.
There have been a lot of terrible 14 inch telescopes around, and a lot of reasonable-to-good 10 inch telescopes around. For instance, many 14 inch Dobs, and also the very old model C14s, have really mushy star images, so some experienced observers actually prefer to look through a 4 inch apochromatic refractor, because of the crispness and contrast of its images. Mechanically and Optically, it is just that much harder to produce a really big Scope that performs well and has reasonable ease-of-use.
We all know a lot of people who own Giant telescopes that lie idle all the time!
Hi all. I have owned 8" f8 planetary dob better than 1/10 wave pv. A 12" f5 flexitube skywatcher and currently a 14" f5.1 hubbleoptics powered home made dob,(cost of the latter about 2/3s cost of skywatcher). At one time on a night of good seeing all three were set up with two observers and the following was noted: Jupiter 8" and 12" were similar on detail resolved, 14" had a noticable edge on over the others. Moon again not much between 8 and 12, but 14" was in a different class it seemed fine detail resolution was cleaner on small surface luna detail. DSO 14" ruled clearly (made looking through the 8 like looking through dark glasses by comparison) and clearly the 14 showed brighter and better resolution (on for example Tuc 47). So yes a 14 is bigger than a 12 but you do get a bigger brighter picture. Optical quality probably plays a part as well. My 14" Hubbleoptics mirror is rated at better than 1/25 wave front PV.
Quick question about the goto power. Does it come with mains power ? I know that the unit takes d batteries and has a dc adapter in but doors it come with a power lead ?
Quick question about the goto power. Does it come with mains power ? I know that the unit takes d batteries and has a dc adapter in but doors it come with a power lead ?
Hi Stu,
They don't come with a 12V power lead to plug into the wall unfortunately.
You will need to get a battery pack of some sort (yet something else to add the the growing list of accessories). I ordered mine from Bintel and they recommended their 18Ah Lead Acid Battery, which came with a 12V adapter. It has worked brilliantly so far, I charge it after every viewing session as recommended. They said you'd be able to get around 12 hours out of a full charge or there abouts. It wasn't cheap coming in at $149, but worth the money.
The other alternative is to get a jump start kit from Super Cheap/Repco etc. However, I can't vouch on how well they work, longevity et al.
I was fully committed to buying the 12 goto today. So I turned up at Andrews and they don't stock them at the store. Also some concern is that there is no supplied power option !! You have to buy a battery cell separately. Crazy that it doesn't come supplied with something to at least put batteries in until you invest in a more robust power system.
I was fully committed to buying the 12 goto today. So I turned up at Andrews and they don't stock them at the store. Also some concern is that there is no supplied power option !! You have to buy a battery cell separately. Crazy that it doesn't come supplied with something to at least put batteries in until you invest in a more robust power system.
What are current goto users using for power ?
most things don't come with batteries.. imagine the cost of 12v worth of D cells VS the cost of a 1/2 decent lead acid and charger.. jaycar has 7ah batterys and charger for about $50.
that will give you about 1.5-2 hours of observing..(ya wanna use about 1/2 the capacity.. my goto uses 2amp)
pics attached... i pulled out a battery for another project but you get the gist.. there is the risk of running 3 batteries in parallel that the weaker 1 will drain the stronger ones.. i have found as long as you keep them charged the chance for a weaker battery to be created is reduced. I also never use them below 12.4v, battery monitors are cheap on ebay i paid about $6 for mine. or u can just use a multi. there is space under the socket for the charger to store so i always have it.
Alternatively buy a larger single battery.. still keep above 12v tho.
My Goto uses 2amp.. so keeping to the 1/2 usage for a night of observing lets say 6 hours id want around 24amp battery, this will allow your battery to remain in peak condition and last many years.
Sorry for ranting a bit, i love electronics, batteries, power etc.
you could even go an old car battery and charger with the right plugs made up
I didn't expect it to come with batteries included, but to have something to put the batteries in ! That would be nice.
nah unfortunatly no.. i guess to keep weight and simplicity.. 12v of d cells is heavy where as an external pack can be managed better.
A bit of wiring and u will have a decent pack ready to go. just remember to keep it charged and u are good 2 go.
they are also hand for other things, I use it to power my 12v air compressor for the car tyres as well as run some lights etc around the place. great when the power goes out 2. computer fans and leds make good summer cooling and lights when the lights go out.
