First light and first post

[Scooter]

Hi Ya Folks,

Been a lurker on the site for a while now and thinks it’s a great site with a wealth of information (sometimes so much it can do your head in). It has been probably 20 years since I owned a scope but I will occasionally head out with the camping binoculars and over that 20 odd years I have often considered getting into the hobby properly. Until I got the hardware I have messed around virtually (using things like Starry Nights etc. On that score everyone know the free space sim orbiter? Can spend ages messing around with the views etc. Worth checking out if you haven’t http://orbit.medphys.ucl.ac.uk/ ) and keeping my hand in with mags from the library (drooling over expensive equipment) and sites such as this.

To be honest for the last few years I have been in a position to throw some money at it but the wealth of options and considerations (did I say it could do your head in) coupled with justifying the spend has just been a barrier so over the last few weeks I have thought “just do it”, set a relatively low cost entry point ($1000) and then sought to get the best value for that spend. Following the maxim “more aperture is better” this has seen me purchasing a 12” GSO Dob from Andrews. To round out my $1k I also got a laser collimator, 2x EP Barlow and moon filter.

SO…………

Got the package this morning, put it together this afternoon and had first light tonight J

Here are my observations and questions (you knew they were coming right?):-

Very much the newbie but had fun with the new toy. Had a play with all the lenses etc. and viewing was mostly of the moon and Saturn. Looking forward to learning to use the scope properly so question after the first viewing below:-

Assembly:-Hmm not much to the mount is there. Easy enough to put together

Instructions:- Or lack of – Would have been good for things like the collimator etc. to have some basic instructions (so I know how to change the battery etc.)

Laser collimator:- likewise with what has been mentioned on the site it’s a slit. Not huge over a several meters. Doing the roll test (using stable platform and crossed nails etc. over say 3 meters) given that it is a slit how accurate do you need to be? Should it be a centered cross or is it staying within say a 10ml box (over 3 meters) be close enough? Just read that I could do the roll test in the focuser so will try that (how accurate is turning it on nails anyway?)

Collimation:- Well provided I did the secondary OK seemed easy enough with the laser and didn’t take long at all. Used a old film canister to line secondary up then inserted laser, centered beam into middle of primary with collimation screws on secondary then centered beam onto the laser using the collimation screws on the primary. Am I right in thinking loosen off the lock screws, collimate, then gently tighten lock screws on the primary?

Finder scope – big issues with this. There is no focus (that I can see) so stuff in the foreground is in focus (maybe 10 – 20 meters) stars on the other hand are just hazy smudges. Makes it bloody had to actually use as a finder scope so am I missing something? As I don’t have an eyepiece with cross hairs I have basically been centering an object in view than adjusting the view accordingly in the finder scope. Then I just use my hazy light to try an center on the cross hair (which is hard cause it is out of focus) the adjust main.

The mount:- Tracking stuff is gonna take me some learning methinks. Stuff that was low in the sky (like Saturn) with the Barlow (or without it as well) was an issue as the scope would drift down. I have read that magnets make a good counter balance so I will look at that. Assume it’s not such a big deal as you go more vertical. Any tips on how to track with this thing or indeed locking it in place if you wanted to?

Tracking:- Damn Saturn drifted across the view pretty damn quick (see above for some of the cause been even when I thought the scope didn’t move it was damn quick). What’s the secret to high power planetary viewing with a dob? Is the slewing less as you get more vertical? It was hard work for only a few seconds view J

Saturn tonight:- Anyone in Brissy see Saturn before 11.00pm tonight? Very bright, see the rings etc. but not no color or real detail. It was hot on the heals of the full moon so wondered it that was factor as well or is it because it is still reasonably low in the sky?

Moon filter - damn its green! Is that really a moon fileter?

Anyone want to thro some must check out objects in the 12”

Transport:- Yet to look at the logistics of getting it in the car but everyone talks about it being a big scope, hard to transport etc. Now I got no issues lugging the separate parts around but wondered what would be the issue of having 1/3 (so like 50cm’s) hanging out of the boot (properly padded etc.) I am being too rough to think I can just whack the OTA in the boot?

Clubs:- I was going to join a club to facilitate learning and there are a few in Brisvegas so rather than me just picking one at random would anyone care to make some recommendations (by PM or in the thread)?

Well that’s about it and apologies for so many questions. The crew next door turned the carport light on at about 11.00 (and it’s still on) which really killed it for me as I was on the back deck so all in all I was happy to be finally able to play with a scope. Now I just need to make myself a level patch in the back yard (just built 2 decks and regretting putting roofs on them) and then starts the learning :).

Have fun

[ballaratdragons]

Hi Scooter,

Welcome to the 12" club

1. Focusing the Finderscope:
You will notice that the front of the finderscope unscrews (the black bit) and also has a lock nut section. Just unscrew, or screw in, the black section, then when stars look focused turn the lock ring against it. That will hold it there.
Tip - If you need to screw the focus section towards you, (screw in) screw the lock ring in a fair bit so it doesn't stop the focus section from screwing in. If you need to screw the focus out, no problem with the lock ring.

2. Planets zooming across the Eyepiece:
Use a lower magnification. Yep, the planet will look smaller but you'll be able to follow it with the scope a lot easier. After a while you will get used to how the scope moves and you will do it automatically. Then you can bump the Magnification up and be better at following it.

3. Tracking with a Dob:
Yes it can be done. You will need to buy or build a Tracking Platform.
Those that know about them will help you further.

I hope that is a start for you :thumbsup:

I don't want to give away ALL the trade secrets in one post :lol:

[desler]

Hey Scooter,


Yep, found out how to focus the finder scope tonight, 2nd night. makes a heap of a difference!

Darren:eyepop:

[iceman]

Hi Scooter, :welcome: to IceInSpace!

Great first post and first light report, look forward to more!

[Scooter]

Ahhhh - glad I'm not the only one Darren ;) because damn that finderscope was annoying so thanks for the prompt reply Ken (first thing to fix tonight).

The expectation was for planets to zip across the view (it does in Stellarium etc. ) so no supprises there I just thought I would be better at moving the scope (didn't find the movement that smooth at high mag). What sort of magnifications would you other 12" dob users recommend for the planets?

Like I said this was start and will see where it goes :D

Potential upgrade path would be a decent goto mount for the tube in the future but I note that some of you (like yourself Mike) you have commented that's a pain for visual observing because of where the eyepeices end up. I just figured that relative range of montions of the scope on the goto mount would be comparable to the dob mount just maybe higher thus worst case needing to use a step. Was that the case? Must confess I do like the thought of a computer keeping a planet centered in view :)

Cheers,

Scott

[erick]

Hi Scott

A few additional thoughts:-

Laser collimator. My second-hand one came with no instructions, so I've had to work it out myself. The elongated spot moving 10mm at 3m distance on rotation, sounds too much. Your focal length is 1.5m so down and back for the laser beam is 3m. So I'd suggest you want the spot to stay almost on the same spot (say <2mm) at 3m. Another tip - the other day someone mentioned that they had trouble getting the batteries out and found they had to loosen the set grub screws in the collimator (compressing the case a little at the battery end, I guess). I had the same problem a while ago but didn't discover that solution. Of course, one would have to reset the laser collimation after batteries have been changed and grub screws put back into place. I'm going to look for a small red laser that throws a small circular spot and replace the laser in mine (sick of the sausage - it was OK in the 8", but the extra focal length in the 12" just tips the balance to "YUCK") As long as your nails aren't bending, they should be fine - but making a wooden "V-block" would be the best move.

Primary lock screws. Try with and without the lock screws done up. Most feel that the supplied GSO primary mirror springs are too soft and replace them from the hardware shop or specialist suppliers ("Bob's Knobs" etc.) Tip the laser from zenith to horizon while watching the return laser beam and see what happens, with and without locking screws done up.

Finderscope is just to get an object into the FOV of an eyepiece - probably in your 25-30mm fl eyepiece. Don't expect any more of it that that. The GSO finders seem to be hit and miss - some give shocking views - but you should be able to adjust it to focus well enough on stars at the centre of the crosshairs. Play with it during the daytime on distant TV towers or mountain top - BUT don't point it at or near the sun!!

Scope "drift" - in altitude, I expect? Need to find a way to increase friction on the alt bearings usually by maximising spring extension in the GSO models (downside is likely increased "stiction" meaning it is difficult to hand track at higher magnifications) or balance the scope with weight. Do a bit of searching. There are many methods - magnets, weights and velcro. Even hanging a piece of chain off the mirror end down to the ground. As you go down in elevation, more links hang off the end and increase the balancing weight. I haven't done this yet - it would be funny to see a scope with a chain tail!

Search around the site for ways to improve the motion of your scope in alt and azi - search "stiction", "teflon", "ebony star" and you'll find examples. Check the Projects & Articles and Equipment Reviews as well.

Yes, once you get down to a 9mm or 6mm eyepiece and barlowed, the earth's rotation is very pronounced! Forget those planets - stick your scope on the edge of 47 Tuc or Omega Centauri and let it drift through the field. You'll get a few minutes of joy!! With practice and improved alt/azi motion, you will be able to move the object back across the FOV to have another many seconds look at it. Otherwise you'll need another $900+ to buy a quality equatorial platform (or try to build your own for a few $00s). Rings plus GEM to use a 12" for visual? Well, some do - good luck.

Yep, some moon filters are green. When my cheese is green you just gotta scrape it off. I prefer blue! Invest in two polarising filters instead. There is a recent thread on filters - you should find that easily.

Forget seeing any detail on the planets until they are well elevated in the sky (except Mercury and Venus where you don't really have that choice, but you won't see detail on them apart from crescent phase.)

Happy viewing!
Eric :)

[rmcpb]

All good advice above but I would say to persevere with the nudging to track. It will become second nature very quickly, I can easily track at 400x, but for continued high power planetary work consider an equatorial platform, mine keeps the object in the field of view for many minutes at a time which lets you really study the object.

Cheers

[madtuna]

ahhhh! thankyou! we were having all sorts of dramas with the finderscope on a GSO dob..you've just answered our problem.

[ballaratdragons]

:thumbsup: We aim to please (no pun intended)

[coldspace]

Hi Scooter,

Regarding clubs there are a few around Brisbane. If you are on the southside then you may want to consider the SAS. Great club,very active. Go to web site for more details or come along to monthly meeting and say hi. www.sas.org.au (http://www.sas.org.au) Try also M42 great orion neb. looks fantastic through 12 inch scope.

Matt.

[Night Owl]

Howdy Scooter, and fellow GSO Dobs owners. There must be plenty of us now! You and I have much in common, as it looks like our experiences and motivations are very similar. I was at a New Years party in a friends back yard and the seeing was fantastic, and after someone aksed me the names of the stars I said to myself (I really should get a good scope now), and now here I am!

The GSO laser collimator. You can't knock the machining or finish of it, it is mil spec and is never going to wear out in the remainder of my lifetime. However, the working guts of it are what I expected. It contains a $5 kids toy junk laser pointer.

After I got the batteries out after they went flat (it was me Erik), and realigned the sausage beam so it roll tested ok I noticed that as the light exits the aperture, it develops a series of concentric reflective rings that are reflected back on to the target! So I can slowly alter the primary with the aid of these reflective concentric rings, which are the result of a bad quality laser! I have then star tested the results and it was so sweetly collimated I can't fault it. If I ever see a good quality laser in the same can size as the one buried in the GSO collimator, I may install it. Unscrew the back, undo the three grub screws, and gently pull the laser can out through the rubber O rings in the body of the collimator. Other than that I don't think the 'red sausage' is a real problem, if you learn to live with it and work with it.

You also don't need to use a collimation cap with the laser collimator.

Slap in the 'hot dog' projector in the focuser, then adjust the secondary mirror to align the laser sausage on the primary mirror center dot. Rotate the collimator in the focuser to check to see if collimator is centered, and if the sausage stays on the primary center dot your done there. If not you might have to work on the collimator and align that.

Now rotate the collimator so the 45 target window faces the mirror end of the tube, check secondary one last time. I backed off all primary screws a few turns, then worked my way around like doing the sequence of torquing the head bolts on a car, slowly at a time, working up to the target on the collimator. Once on target, I tightened them all just a touch over finger tight, then to test I rotate the OTA up and down to see if anything slips or moves, and if it does I gradually tighten all the screws a bit more till I detect no movement by the laser during changes in elevation, so you have balance of no movement during elevation etc, and a minimal amount of force that may distort the mirror.

The spotter scope I have isn't too bad, but its never going to win awards! To get the focus anywhere near right for me I had to screw the front lens all the way in, then ran out of thread! Its still a little bit out, but it does spot. Once on the scope I picked Orion out, and starting with a 25mm GSO plossl I started zeroing the scope on to the target. Now I can spot and guide to target with the 9mm eyepiece fine.

The mount I gave a bit of a treatment. I scrubbed the base with metho where the teflon pads travel, let dry and then gave the surface a spray with Sellys Ezy Glide...http://www.selleys.com.au/Selleys-Ezy-Glide/default.aspx
This really improved things on the rotation, and it isn't oily so it won't attract dust and grit etc. And as soon as I find my pack of powdered graphite I'm going to apply some of that to friction points as well. I expect the graphite will make an even bigger improvement. Other than that I might make up a roller bearing mount soon. I don't expect that to be much of a chore.

Transportation. I bought a 12" GSO Dobs because I heard here that it fits across the back of a GL Ford Falcon back seat, with a few cm to spare! Other than that I have a 4X4 van as well!

Anyway Scooter, have fun with it in Brisvegas.

[Scooter]

OK - second night out

Thanks for everyone’s comments/suggestions (looks like I have a bit to work through hey Eric ;))

Sorted the finder scope - much better (mind you it was right at the limits in screwing down to get the stars in focus).

Messed around with the laser collimator this afternoon and have come to the conclusion it is near on impossible to ensure the laser collimator is 100% collimated!! Ran out of batteries (should have read your post Eric as I couldn’t get the last one out either – my solution was drill a small pilot hole in the top and then use a screw to screw into the pilot hole and pull the battery out). All of the jigs I made allowed for at least some movement (even used a holder ring clamped down) so have decided that what I have is good enough. Thing is it can be seated (locked) differently in the actual focuser so I guess it depends on how you initially seat it.

Not sure about collimation. The laser and barlowed laser tests appear to be pretty close so I did many star tests tonight and they are all the same. I don’t get concentric rings as per all of the pics but I get a single sold ring around a centered black dot (inside and outside focus) so does that mean I am good or did I need the concentric rings (come right out on focus the spider makes it look like crosshairs thus aiding telling wether it appears centered)?

Might have to wait for an expert to check it out and show me how its done :)

Setup in the backyard and checked out M42 (Orion neb) as suggested. Cool but no color at all just appeared as black/white (probably expected – I have seen those drawings of what to expect).

Did some more viewing of Saturn and it was as yesterday. Noticed I seem to get better focus using the straight plossel a mag x vs similar mag with Barlow and plossel combo….. any thoughts?

Then moved back onto the deck and just did some random checking out. One thing that stood out was all the satellites tracking across the sky. Seen em before of course but noticed heaps tonight so I guess that’s what happens when you start looking skyward J

Spent some time viewing the K Cru Cluster (NGC4755) and wasted a heap of time trying to find the Sombrero Galaxy (NGC4594) with no joy. Sure I was getting stars around then moving the scope across where it should be (15, 25 and 32mm lenses) but no joy. Guess trying to find a galaxy is the job for tomorrow.

Thanks for the recommend coldspace. I think there is a club that meets at Mt Cootha so that might get a look in as Pimpama is out of the way. Is it a silly question or did you folks do viewing at these regular meets?

Anyway that’s it for me – time for bed.

Have fun

[Scooter]

Hey Night Owl - looks like I was typing that whilst you posted :) and you are right much in common (damn the focus on that finder scope!!).

Thanks for all the info :thumbsup:

You know no one has commented on if say 1/3 of the OTA was hanging out the boot. By my thinking this would negate transport issues on most cars and I do't see a problem with it (often get 2-3+ meter lengths of wood that I transport with some hanging out the back and secured etc.).

[ballaratdragons]

1/3rd of the OTA hanging out sounds scarey :scared:

[Night Owl]

There is only one problem mate. You don't look at the stars through a lenght of wood with 750 times magnification! And I think people thought you were only joking about it! :lol:

Also, had another look at my GSO 8X50 finderscope, and found I had a few more threads of focus adjustment left (just was binding a bit). Now I can get the focus damn nice and crisp. Nearly as crisp as half of my trusty Pentax 10X50 binos, which is pretty stiff competition.

[Scooter]

Forgot to mention Mars. Even at high mag appeared as just a glowinging disc so was a bit dissapointed :(

Looking forward to having a go at Jupiter :) (just gotta get up early I guess)

[bird]

Scooter, using a laser for collimation of the primary is very tricky, you can see how sensitive the whole arrangeent is at the focusser, if you wriggle or press on the laser you can make the spot on the primary move to anywhere you like, not very useful!

A much better arrangement is the barlowed-laser which does the same job but is insensitive to the laser alignment in the focusser.

They are easy to make (provided you have a barlow!). Put a barlow into your focusser, say a 2x barlow would do fine, and then put the laser into the barlow. Now the laser will project a cone of light down to the primary, and some part of the cone will hit the centre of your mirror and be reflected back up to the focusser. If you put a paper disk over the end of your barlow (with a hole in the centre to let the laser through) you'll see the shadow of your centre spot. Adjust the primary collimation to centre that shadow and you're done.

You can wrigle the barlow and laser around and the shadow doesn't move - all that happens is that different parts of the laser cone will hit the centre of the primary.

cheers, Bird

[Scooter]

Hey bird - yeah been messing around with the barlow and laser and think I have gotten a good result (easier using the paper over the end of the barlow as opposed to the view in the laser return screen).

Problem is that if I use the laser to do the secondary (center the beam in the primary centre ring) then this can be off (not by much) depending on how the laser is seated in the focuser.

Oh well it all looks ok visually as far as collimation allignment but I do have an issue with star tests but will ask in its own thread :)

[Brian W]

H
hi I have been lurking for a while but thought I would put in an opinion where collimation is concerned. the collimation cap is low tech and low cost but yields great results with a little practice. it is also impossible to have it wiggle or loose battery power. Just my opinion.
Brian

[cahullian]

Scooter a lot of the deep sky objects are hard to see during the full moon, wait until closer to the new moon and a whole new night sky will be available for you to explore.

Gazz