View Full Version here: : GSO 12" Dob Questions
30-09-2008, 06:44 AM
I am almost ready to make my purchase. I have decided on the NEW GSO 12" Dob that Andrews Communication is selling.
I am also going to be a WO Binoview...can anyone comment on the use of these? They sound a real treat to use. Can I use different eyepices with a bino view? (Like by aditional ones to the ones that come with the scope and use them on the bino view?)
Also, to use an illuminator I would have to drill a hole in the side of the finderscope and then thread it to accept an illuminator. Is this Hard to do?
Apparently I can buy a SW illuminator finderscope but its a straight through finder scope. What would serve me better. A finder scoper that have upright correct image, or a straight though but with illumination?
Time to go to work. If anyone could advise me...Thanks...I am also getting the three sets of filters the sell. Let me know If there are any other accessories I should get to make my sky viewing all the more better. I fully intend to get everything I need for a better nights experiance.
30-09-2008, 09:33 AM
My advice is very simple. Get the scope with a cheshire eyepiece so you can collimate it and use it as it comes for a while. Then it is time to add the bino viewer, etc. Remember that you will have to double your eyepiece collection so it would be best to do this when you have started getting your "good" set so you don't just keep buying eyepieces forever.
Enjoy your scope.
30-09-2008, 10:35 AM
Congrats! You are going to have fun!
Binoviewer - not sure. You need to be able to reach focus - some will and some won't, in your GSO focusser, as I understand it. Adding a barlow can allow you to achieve focus but the weight you have to balance goes up considerably. Plus you need to double your eyepieces. Plus you are dividing your light in half and sending a half to each eye. My experience of a binoviewer on my previous 8" reflector was a preference to shove all the light into one eye through a single eyepiece. I don't plan on buying a binoviewer. I suggest you wait until you can borrow a binoviewer at an astro night and see for yourself. Perhaps on the Moon and quite bright objects (Jupiter? and globulars Omega Centauri and 47 Tuc?), a binoviewer performs the best.
For every finderscope, some form of illumination is useful in very dark skies when chasing targets through faint starfields. Your crosshairs just disappear in the dark. Best option - buy a finderscope with illumination. Second option - drill hole and fit a red led just in front (eye side) of the crosshairs - make the crosshairs "light up". Can be done - easy to stuff up as well. Third option - fit some red leds inside a dew shield at the field lens end. They make the sky a little brighter so the crosshairs stand out. Downside is that it's a bit harder to see faint stuff in the sky. This approach doesn't stuff the finder. I found a ciggie ash cup in the Reject Shop that was just the right size for a dewshield when I cut the base off and fitted four red leds with adjustable brightness control. If you stuff up - finder is untouched. Fourth option - search for those glow bracelets in novelty shops. Buy some red ones - 50c or $1? Hopefully when you activate one and wind it into a circle, it can fit inside the dewshield and provide the illumination you need for a few hours.
Straight through versus right angle finderscope: Right angle easier on back and neck, but you have to be pointing at the right bit of sky to be effective - so suggest you need a red dot finder or a laser pointer to get there first. Straight through can be used alone because the technique is to keep both eyes open and superimpose the image seen by the eye looking at the sky on the image seen by the other eye through the finderscope, then move the scope until the location of interest is in the finderscope FOV. Works well (neck and back hurts - but we all suffer for our hobby!)
There are erect image versions of both finderscopes (different makes - I bought this one - illuminated, straight through, erect image - it's great
http://www.iceinspace.com.au/forum/showthread.php?t=29890 Yen/AUD exchange rate is probably less favourable now.)
Filters - which ones do you plan on getting?
30-09-2008, 02:30 PM
I completely forgot about the extra weight with the binoview & your additional points are very good ones as well. Binoview is on hold!
The three 1.25” filters I see for sale are:
NEW! UV/IR blocking filter = $29.00
Neutral density (ND) filter = $12.00
Polarising filter = $19.00
I thought I would just buy all three, unless of course you think I don’t really need one of them?[/font]
I’ve never ever used a 2inch eye piece. Apparently I will be getting a 32mm 2” EP.
Because I am no longer getting the Bino View…I am thinking of putting that money towards a special eye piece that will maybe give me that little edge or little more wow factor. I will be happy with even slight emprovements as I’m just that kinda guy that looks for every pixel with new games and graphics cards! So even if eye special eye piece only boast a slight improvement, I reackon I will see it & be pleased with it.
I just don’t know weather I should be going with a 2inch or sticking with a 1.25” (I am just about to turn 40 years old…quit smoking about 16months ago and like to think of myself as pretty healthy with reasonable eye sight—does this impact on my choice of 2” or 1.25” EP?)
ROB…I am not quite sure what a Cheshire eye pice is & I have to get back to work…BUT I will be sure to check that out. I also forgot about what I will need to collimate as this is something I look forward to learning and becoming good at for everytime I land wherever for the evening.
I guess I will just buy whatever laser collimater is available or recommended by Andrews communication for the job…I take it that a special eye piece is important…I’ll read up later Rob…have to go back to work…THANKS HEAPS for that pointer!
Guan Sheng deluxe Newtonian laser collimator...A$49.00
The filters & other accessories I am thinking about are at the bottom of that link as well.
Eric…Cheers also…you explained everything really well & I will be going with Skywatcher 9X50 illuminator finder. I was using an old 60mm Tasco before this and it was just held together with fencing wire, so I am sure this finder will surfice. Especially now I know how to use one correctly…LOL
Will check back later to see if any recommendation on that special eye piece I am after. How do the Guan Sheng SUPERVIEW 68° differ to the normal Guan Sheng 1.25" Super Plossl eyepiece series ?
30-09-2008, 03:57 PM
I reckon its a good idea to put binoviewers and even good eyepieces on hold until you get familiar with your scope and what it can/can't do and what you like doing. The laser collimator is a good idea imo - I find mine very easy to use. You may find that Bob's Knobs will be a good investment down the track. The collimation knobs that came with mine were a bit tedious. Have a look at the modification projects for these scopes on IIS once you've had a play.
If the 32 mm ep is the 3 element Kellner, it helps you find things but is not great to look through. I still found it enough to be going on with and the plossl eps that came with my scope were certainly good enough to keep me happy for a while. A telrad is a very good investment to help find things.
Also, have you looked through telescopes much? Some people buy a big scope expecting to see things as they appear in images, but bear in mind that you will only see monochrome in direct observing. And some objects like galaxies will take a bit of observing with averted vision to really appreciate. I may well be telling you something that you already know, but it seems to me that many people new to the forum get a bit disapointed with their new telescopes if they haven't had previous experience to set appropriate expectations. Apologies if I'm saying something that you're already aware of.
30-09-2008, 03:57 PM
Man, you got da bug!
OK, starting with filters. If you really want, buy two of the polarising filters. The neutral density filter is to reduce the brightness of the Moon (and occasionally Jupiter or Venus). It will be a fixed reduction - something like 5% to 25% transmission. If you fit two polarising filters, you will be able to reduce the brightness of the Moon down to almost nothing - so you have variable brightness control. Yes, you have to lift your eyepiece out each time to adjust the bottom filter (rotate it) to get to the brightness level you (or other observers) are comfortable with. You can hold the eyepiece above the focusser and adjust the bottom filter while looking through it at the Moon. It will be out of focus, but you can see how much light is being reduced. Several people wonder what the problem is - they blast full Moonlight through their 26-30mm eyepieces and don't blink! Mind you, when they turn away from the eyepiece they stumble over everything with a big purple splot in that eye's vision! :P By the way, AOE will sell you a pair for $25 ( http://www.aoe.com.au/filters.html )
The UV/IR blocking filter is all about imaging (isn't it guys?) You don't need it? :help:
Better search "collimation" and "cheshire" and "laser collimator" on this site and read up before you invest in a laser collimator or a Cheshire collimating eyepiece.
40 years old - ye're a youngster! ;) Your eyes should be great. Actually 2" versus 1.25" eyepiece is nothing to do with eyesight. If you are getting the 32mm 2" eyepiece - part of the package, no choice - then work with it for a while. Then you can see whether you want to get a better one. Some people stick solely with 1.25" eyepieces to cover the desired magnification range. You also don't need 2" eyepieces to get a wide apparent field of view (AFOV). Televue's 13mm Ethos gives you 100 deg with a 1.25" barrel (but I notice the coming 17mm Ethos will be in a 2" barrel).
But if you must spend some money, buy this one from Bintel:- Bintel SG Wide Angle 20mm (2"). Yep, it's cheap ($79), not going to be brilliant off-axis, but fun to experience 80 deg AFOV. Plus, screw the attached lens off the end and you get a 30mm 80 deg eyepiece. The 30mm has been my main wide field eyepiece for some time now. Just about to get first light through a 35mm Televue Panoptic I've acquired. I drop back to 68 deg AFOV, but get much better performance across the entire field, as would be expected from an eyepiece that retails for over 7 times the price of the 30mm!
One point to note - your 2" eyepieces need 2" filters. 1.25" eyepieces use 1.25" filters BUT you can always put your 2" filter on the 1.25"-->2" adapter that comes with your GSO focusser. So 2" filters cover all your eyepieces. Except, check carefully. I recall some of the GSO 1.25" plossls have barrels long enough that they would hit a filter surface if fitted to the adapter! :scared: If that is the case, tighten your 1.25" eyepiece in place not fully inserted, then attach the filter - but you always run a risk of damage to the 2" filter with that situation. My other makes of 1.25" eyepiece - Vixen and Televue - do not have a barrel long enough to cause this problem.
30-09-2008, 08:05 PM
Yea thanks Guys…awesome feed back! I’m feeling pretty relaxed about m purchases now! No worries Erick…will be ordering of AOE + Bintel, just for your response alone J I hope you get some good chills using your new 35mm Televue Panoptic! Thanks for those tips…Noted! Roger that on the imaging filter, as well.
A little about what I am expecting!!! J
I think I know what you’re getting at Patrick…when I first pointed my little Tasco refractor, with its whopping 60mm aperture towards M42 in Orion’s Belt I had mixed feelings. Like WOW I finally found a DSO, followed with awwwwwwwww “it’s a little smudgy and very small. I can’t remember the size of the eye piece & I only ever used one at that. I would look at Omega Centuri cluster (I think it was) in-between the two pointers of Crux but up a ways at a point where it forms a triangle with the pointers as the base. I still looked like a smudge of stars as if still looking at it with my 10X50 Binos, BUT took up most of the eye piece. I have to say that I did not really expect image material, but yes…you are right…I was a little disappointed with what I could see through my little refractor…HOWEVER>>>I learnt a new appreciation of the FACTS!!!! “The distances”, “The Size of Dust lanes/stars/gas” ‘mmm whats happening inside of that that nebula” “what perspective am I looking at all this….yadda yadda yadda.
I guess I just start to wonder more about what I am looking at and have a much bigger interest in that object than I thought I had before regardless of how colorless, smudgy or tiny is looked in my little tasco refractor. I got some pretty good views of the planets with that toy scope and even enjoyed looking at the Magellan clouds and resolving double stars + found myself dreaming of the seven stars sisters & what not.
I think I have the right attitude & will be totally blown away with this new 12” Dob…there is so much I have not been able to see, but yet enough to keep my attention. I could not care less about colour, but I am hoping to at least see some of the stars within M42 that I could not make out with my little tasco. I know what you mean Patrick…But at the same time… I AM CHOPPING AT THE BIT & yes I have high expectations…but only in comparison to my little tasco that has now fallen apart completely.
What I would give to spot the andromada galxy…can we even see that from the southern hemisphere? I would be over the moon to just make out the glow of it alone. I was unable to find such targets & probably will be laughed at to say that I actually spent hours with my little telescope trying my heart out to find such targets………LOL…….I think I am about to enter a new age with regards to what this 12” Dob has to offer me.
I don’t know much as to what targets I am suppose to see with such a scope, but it’s going to be a hell of a lot more than my old broken down faithfulJ
Thanks AGAIN all!!!!!!!!!!!!!!!
As soon as my new Scope arrives…I’ll let you know just what my reaction is, with respect to what I was expecting to see…:)
30-09-2008, 10:14 PM
Well Dave, given your experience, you WILL be blown away! I am night after night by my 12" dob and this week have had the thing out nearly every night. I don't get to see a lot of the Andromeda galaxy because I have some trees on my northern horizon, but there are plenty of galaxies that I can see. I reckon you're in for a serious obsession and I hope you have a lot of fun with your new instrument!
30-09-2008, 11:06 PM
In M42, you want to go chasing the stars in the Trapezium (the "Trap"). You've got the firepower now! The A, B, C, D stars are usually readily resolved unless the seeing is really bad. Then you want to pull out the fainter E and F stars. It's a good night when you see them cleanly!
For photos of the Trapezium stars see here:-
Look at Pane 2.
See here for more info, including a good diagram of the stars:-
(Diagram attached as well)
M31 - the Andromeda galaxy. Mate, under dark skies we can see this naked eye from Victoria! Furtherest steady object one can see with the naked eye - 2.4 million light years! I remember the first time I saw it - by the side of a road somewhere between Ballarat and Geelong having driven kms out of Melbourne to escape bushfire smoke in the summer of 2007! True, it is not much above our northern horizon. Right now it is about 7 deg up towards the North. Tonight it hits maximum elevation of 11 deg about 30 minutes after midnight. Actually the scope will be overkill, M31 is such a big target. Your 10x50 binos will do just fine to start with. You just need to know where to look but it is an easy find. Get down behind Pegasus, find Mirach (Beta Andromedae), draw a line through Mu Andromedae, go the same distance the other side and there it is! See attached. Your problem is to find a location with a clear northern horizon that is dark. Hint, go north, east or west of Melbourne, not south!
Now, go back to the otherside of Beta Andromedae about the same distance as M31 is from it and you'll locate M33, the Triangulum galaxy (see attached). A bit tougher since it is a face on spiral so low surface brightness - you'll need your 12" of aperture now.
01-10-2008, 08:23 AM
Thanks on the home address of M31...I feel a little silly now :whistle:
Nice Link on M42...I feel I will be taking in so much more, with a new ambition to do so.
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