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Help with my new "old" free sky cannon.

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#1 Chihlidog

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Posted 19 November 2017 - 05:57 PM

So, I'm embarrassed to say this, but I dont know what to do with this thing. I've never had much money to be able to put towards any observing. I observe from the city (Pittsburgh) and going from a 70mm up to an Orion starblast was a big deal for me. Nailing M81/82 was tough, SOOOOO faint from where I am, to give an example of my limited experience. I've managed M3, M13, M31, M81/82, obviously M42 and a few others, everything else has been beyond my scope's abilities in my light polluted conditions,. I've tried for m51 countless times. The desire has been there, but the money hasnt been. So more aperture has always been a huge desire, I've always wanted to get something like a 10 incher to try for more.

 

Well, a friend texts me and tells me her sister has this monstrosity in her house leftover from a previous owner and she wants it gone. If I want it go get it. I flew over there. Problem is, I dont even know what to get to make it usable. The eyepieces are certainly NOT going to be what I am used to....I am going to need a finder scope....I have no idea how to collimate this thing...it has been sitting uncovered for who knows how long and I can see the main mirror is dirty, no idea how to clean it. So, in short, I'd like to show you guys this thing and get your advice on how to start making it usable. One or 2 eyepieces and a finder scope and advice on how to clean and collimate it would be appreciated. It's a Tectron, from what I can see by googling is a quality scope. I cannot wait to get this thing up and running. It's more than I ever thought I would have.

 

 

y6XzPBz.jpg

 

 

I really appreciate any advice.

 

Also .... check out my new sky cannon!!!! :-D

 

 

 

 

 


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#2 NochesNubladas

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Posted 19 November 2017 - 06:17 PM

Hi Chihlidog,

I will leave the advice to the experts on this but wow, what a great find!

If the mirror is good, then you have definitely got something to work with!

Wish I was this lucky!



#3 kfiscus

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Posted 19 November 2017 - 06:19 PM

Congrats and welcome!  It would be great if the moderators could move this thread over to the Reflectors Forum.  You've lucked into a potential deep sky workhorse.  Here are some questions we'll be asking you:  Any pictures of the primary?  What is the diameter of the primary?  (If you just measure the diameter of the tube, we'll know what size of mirror is down there.)  What type of focuser is on this?  (Assuming a stock helical focuser but someone has installed a fan down by the primary mirror- definitely not stock and a good sign.)  Any pictures of the secondary?  This list will go on.

 

This scope may have started out as a second-generation "red tube" Coulter dobsonian.  IF you are handy with tools and like seeing immediate gratification for your efforts, working on scopes like this can be very fun and affordable.


Edited by kfiscus, 19 November 2017 - 06:26 PM.

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#4 Myk Rian

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Posted 19 November 2017 - 06:35 PM

Nice. You don't always have to remove the primary from it's cradle for cleaning. It makes collimating it that much easier. Then again, you might want to go whole hog and dis-assemble it totally. Up to you. I did my 8" still attached. Just remove the whole assembly from the tube.

50/50 mix of 91% iso alcohol and distilled water works great.

 

$70 will get you a nice 8x50 finder scope from GSO . I bought one for my Hardin 6".

 

A couple eyepieces in 24mm and 10mm will get you a good start.

Enjoy it.


Edited by Myk Rian, 19 November 2017 - 06:40 PM.


#5 Chihlidog

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Posted 19 November 2017 - 06:44 PM

Congrats and welcome!  It would be great if the moderators could move this thread over to the Reflectors Forum.  You've lucked into a potential deep sky workhorse.  Here are some questions we'll be asking you:  Any pictures of the primary?  What is the diameter of the primary?  (If you just measure the diameter of the tube, we'll know what size of mirror is down there.)  What type of focuser is on this?  (Assuming a stock helical focuser but someone has installed a fan down by the primary mirror- definitely not stock and a good sign.)  Any pictures of the secondary?  This list will go on.

 

This scope may have started out as a second-generation "red tube" Coulter dobsonian.  IF you are handy with tools and like seeing immediate gratification for your efforts, working on scopes like this can be very fun and affordable.

 

The focuser seems stock. In fact, it all looks stock to me. But I am no expert.

 

9RmT9b3.jpg

 

Here is the mirror, hard to get a shot of.

 

L4ib3Av.jpg



#6 Chihlidog

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Posted 19 November 2017 - 06:45 PM

Thanks for the responses so far, exactly what I needed!!!

 

But what eyepieces do I get? Both small scopes I have just take very small ones, certainly not like this one would, I dont even know what size to look for!



#7 Myk Rian

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Posted 19 November 2017 - 06:49 PM

Measure the opening of the focuser. Probably 1.25", or could be 2". If 2", you can get a 2" to 1.25" reducer. Help you save $ on EPs.

 

Looks like the primary could use a cleaning. Many videos on doing it. Might seem like a daunting task, but it really isn't.


Edited by Myk Rian, 19 November 2017 - 06:50 PM.


#8 JamesMStephens

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Posted 19 November 2017 - 06:55 PM

You don't have the mount?



#9 Chihlidog

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Posted 19 November 2017 - 06:55 PM

Just measured and this sucker is 16".

 

Allow me a moment to catch my breath. Holy crap. I just brought home a 16 inch dob.

 

 

Thanks Myk, like I said, I am just not used to equipment this size. I guess it IS as simple as getting 2 inch EPs (its definitely 2 inches). And yeah, first thing I looked at before bringing it home a few hours ago was the mirror and saw it was dirty and that scares me more than anything.

 

I'm still in shock I got my hands on something like this. It'll be a month or more before I have the cash to shell out to get it functioning, but my gosh once I do ....


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#10 Myk Rian

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Posted 19 November 2017 - 06:56 PM

You don't have the mount?

He has the Dob mount. Very first picture.



#11 Chihlidog

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Posted 19 November 2017 - 06:56 PM

You don't have the mount?

 

I do, it's just behind it. In front of the old stove in the pic.



#12 Myk Rian

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Posted 19 November 2017 - 06:59 PM

Put a towel or something over the opening. You don't want to drop something on that mirror. Even a bucket will work.



#13 Muddman97

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Posted 19 November 2017 - 07:10 PM

Congrats! 

 

As far as cleaning the mirror goes, I'd highly recommend using the O.W.L. method.

 

https://www.youtube....h?v=9Y8xFnXFVGQ

 

It may appear a bit crude and to simple but it works and it works very well.  I use this technique and have never damaged my mirror.

I take it a step further with a distilled water final rinse then 91% isopropyl alcohol.

 

Works like a charm.


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#14 coopman

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Posted 19 November 2017 - 07:25 PM

The mirror is 13.1" in diameter. Quite a light bucket you have been given there. With some TLC it should perform nicely again. You could also sell it if you don't want to be bothered with the hassle.

#15 BlueTrane2028

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Posted 19 November 2017 - 07:42 PM

The beauty of dobs are their simplicity, whatever you do, try to keep it simple.

I'd clean it up, remove those gigantic finder brackets and slap on a Telrad or similar.  Beyond that, I'd leave it alone, unless something was so amiss that it couldn't be used.



#16 TX4812

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Posted 19 November 2017 - 08:07 PM

I used to have one of those, mine was the original blue model.  The mirror has a focal length of about 1500mm.  It was originally supplied with I think a 1.25" 25mm eyepiece, giving 60X magnification.  Measure the focuser tube inside diameter to determine if it is 1.25" or 2", looks like it might be a 2" from the picture.

 

You can get an adapter if it is 2" to use 1.25" eyepieces.  20-25mm eyepiece would be a good one to start with (just an inexpensive plossl) for deep sky objects.  After that, maybe a 32mm for wider field and a 10mm (or a 2X barlow and the 20mm) for lunar / planetary.   A barlow will help clean up the coma from the f 4.5 primary.

 

Get a Telrad and mount it up near the eyepiece end of the tube using the double stick tape to attach the base, but clean the red tube good with alcohol to remove dust where the Telrad is going to go first.  The ideal combination for this scope would be a Telrad AND a right angle correct image 50-80mm finder, but just a Telrad would be acceptable,

 

Collimation will be easy, there should be three bolts behind the primary mirror for tilting the primary.  The secondary is probably OK the way it is but you may want to remove that for cleaning depending how it looks.  Definitely take the primary out and give it a thorough cleaning using the method described above.  Hopefully that is just dirt/dust on the surface and not a sign that the coating has deteriorated.  Even if it has deteriorated it would be worth it to get both mirrors recoated since you got the scope for free.

 

If you get this scope cleaned up and/or recoated, and take it to a dark location it will really impress you with the views!



#17 Chihlidog

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Posted 19 November 2017 - 08:11 PM

The beauty of dobs are their simplicity, whatever you do, try to keep it simple.

I'd clean it up, remove those gigantic finder brackets and slap on a Telrad or similar.  Beyond that, I'd leave it alone, unless something was so amiss that it couldn't be used.

Understand, I have read about Telrads and 2 inch EPs and lots of other stuff, but literally I have had one 70mm tripod telescope and one Orion Starblast and three small EPs. So everything else has all been theoretical from reading about all the cool stuff everyone else uses. That's the thing. I dont know what to get, and all I want is simple. Simple usability. It's actually not bad to move for its size, and I know that the light collecting potential is ginormous and I  have an idea what this much diameter might open up for me, but what I dont know is specifically what to get to make this thing usable again.

 

Things like the 8x50 finder scope are exactly what I needed to hear. Because I flat out do not know, nitty gritty, the exact items to get that will work with this monstrosity to get it functional. It's a whole different realm from what I am used to. I went from kindergarten to college in one fell swoop. So specific product recommendations as given above would be awesome like with the finder scope. (I'm thinking a right angle is going to be my best bet with this, right? Looking from behind it seems like it would be a serious pain).

 

Like, even links to suggested eyepieces would be awesome. Treat me like I am a moron, because I basically AM.

 

 

The mirror is 13.1" in diameter. Quite a light bucket you have been given there. With some TLC it should perform nicely again. You could also sell it if you don't want to be bothered with the hassle.

No way!!!! I've wanted a bazooka like this for a long time, but other things take priority with 3 kids, 2 cars, a mortgage, etc I just was never able to do anything like this. I've always wanted to.



#18 Chihlidog

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Posted 19 November 2017 - 08:16 PM

TX4812 - that is EXACTLY what I needed!! Thanks! Im not so worried about planets. My 70mm works just fine for those. This'll be a DSO hunter. It's why I've wanted something so big, I LOVE seeing DSOs and I want to see as much of them as possible. I know there is no substitute for dark skies but with the amount of hours I work getting to a dark site is hard, so aperture is the next best thing.

 

So, I know I need to get a good 8x50 finder scope and a 20-25mm EP to get going. I knew I'd have to clean it up, and I've got to figure out how to collimate.

 

Thanks guys.



#19 scottmm2012

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Posted 19 November 2017 - 08:36 PM

What EPs do you have for your Starblast?  You should be able to save some money by re-purposing those.  Obviously they will be 1.25", so you'll probably have to get an adapter.  I wish I could be so lucky.


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#20 kfiscus

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Posted 19 November 2017 - 09:33 PM

Thank you for the photos.  They make our input more accurate.  The spider for the secondary is not stock.  You can see empty holes at the top of the tube and there are collimation bolts visible.  The original configuration was much less adjustable.  There is more and more hope that this freebie will be quite usable.  You lucked into a 13" scope, you lucky dog.


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#21 Richie2shoes

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Posted 19 November 2017 - 09:49 PM

Nice find!  I'm in Pittsburgh also - are you a member of Amateur Astronomers Association of Pittsburgh?  I recommend joining if you aren't.   I found an 8" Dob on Craigslist and Youtube has been very helpful with collimation and general how-to. 

 

What is the black box on the bottom?  Is it some type of push-to system?  Like others have said, an adapter for 1.25" ep and a telrad should be your first purchases.

 

Rich



#22 Chihlidog

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Posted 19 November 2017 - 10:12 PM

Thanks Richie. I am not. I work an obnoxious amount of hours so getting out to any events is incredibly difficult.

I get a few hours here and there and that's about it.


The black box at the bottom is a cooling fan. No other fancy stuff on it.

Edited by Chihlidog, 19 November 2017 - 10:13 PM.


#23 BlueTrane2028

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Posted 19 November 2017 - 11:33 PM

I only have one "premium" eyepiece, an Orion Stratus 8mm that I use for planetary viewing.  The rest are basic Plossls, mostly celestron branded, and they do fine in my 12" Skywatcher.

Try the eyepieces you already have before buying anything else.

A Telrad/red dot of some sort, a low power eyepiece (25mm or larger, I have a 25 and a 32), a higher power eyepiece and a barlow can get you quite far with that scope IMO.  Many scopes come with 25 and 10mm Plossls, your existing ones may fit the bill nicely.

Use the Telrad to get close to your object, low power to zero in on it farther, higher power to observe if necessary.  That's how I do it anyways.

You may surprise yourself with how much you will still use your smaller scopes.  Some days the truck has too much stuff in it to pack up a big dob, or you know you will be short on time.  A big dob takes a while to cool off, where smaller scopes don't.


Looking again at eyepieces, assuming you have a Starblast 4.5, it would have come with 17mm and 6mm Kellner eyepieces.  Not as nice as a Plossl but not unusable either.  Add a 25 or 32mm Plossl and you're set for now.  

Also, when you increase aperture, you increase the resolving power of your scope on planets.  You will be amazed to look at Jupiter and Saturn in particular through a scope this large, coming from a 70mm refractor or 4.5" fast reflector.


Finally, if I didn't say it already, congrats!  I missed out on a 13" Coulter on Craigslist by about 30 minutes, they sold it for $100.  I had to spend quite a bit more to get into the one foot mirror category.


Edited by BlueTrane2028, 19 November 2017 - 11:37 PM.


#24 izar187

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Posted 20 November 2017 - 02:57 AM

Thank you for the photos.  They make our input more accurate.  The spider for the secondary is not stock.  You can see empty holes at the top of the tube and there are collimation bolts visible.  The original configuration was much less adjustable.  There is more and more hope that this freebie will be quite usable.  You lucked into a 13" scope, you lucky dog.

Lucky indeed. Somebody has already added improved modifications to your scope, upgrading it from it's original configuration. I see a better focuser, secondary mount and side blower for active cooling.  

 

Any ep's you have can work, if they fit the focuser. If it's a 1.25" focuser, then consider a 32mm plossl, or 24mm 68 degree ep as a next ep option. They will work well as a largest field ep for 1.25" focuser, in both scopes.

 

The mirror image in the picture is honestly not that dirty. If so, then it needs to be significantly worse than that before it needs cleaning. You can cover the top end of the scope for you, with a trash bag and a bungee strap.

 

If you can, find the Moon, a radio or water tower, or any distant target in your present lowest power ep. Then sight along the tube, through the finder scope brackets on the scope, and line up any two parts on the front and back bracket with the distant target you have found in your ep. You now have a working temporary open peep sight on your scope. Move something or string a rubber band or two, to help make alignment points for your temporary peep sight, as needed.

 

Begin observing.


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#25 Chihlidog

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Posted 20 November 2017 - 07:55 AM

Problem is my EPs dont even remotely work in that tube. Id have to at least get an adapter. The size difference is massive.

I really appreciate the advice here. Now I feel like I know where to get started and first things first are EPs.


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