Junk scope? Please advise.

[Soldant]

(I feel really, really stupid about this.) :help3:

Hi guys,

Recently my 6" Newtonian Reflector I received as a Christmas gift last year has been playing up lately. It refuses to focus properly, and when it does, the colour is terrible and it's impossible to resolve any detail in anything at all. When I first got the scope it wasn't like this. I've checked that everything is aligned and as far as I can see, it should be working. I've tried a number of different eyepieces (very little change), swearing at it (helped me feel better but didn't do anything else) and finally researching it online.

I'm now deeply disturbed and worried that it is a junk scope. I'm a binocular observer myself, I love wide views with a bright nebula and milky way, however I got the scope for a bit of planetary viewing and for increased apeture for other DSOs. Lately it's been impossible to use.

(I'm not great with astronomy terminology, I'm a IT hardware services technician so please bare with my basic terms)

The scope is an Optisan (alarm bells already ringing!) 150mm Newtonian Reflector, with Focal Length: 1400mm. I've done some research online (there isn't much, the Optisan site is Polish, I'm entering panic mode...) and from what I've gathered, the scope has some serious problems. Most notably, apparently the scope has a spherical mirror, and the tube is too short?

I don't know how to test this so any information on what to look for would really assist me. My parents (who gave me the scope) took me to the store to talk to the guy about it, who went on with a lot of rubbish and threw Tasco into the conversation claiming that it was a good brand for astronomy (I'm really, REALLY in panic mode here) and also saying all the mirrors for every scope (he even mentioned Meade) are produced by the same people, and they're all the same quality (I almost walked out of the store).

Making matters worse, the equitorial mount doesn't seem to be of good quality either, it has a lot of slack in the controls and even when secured can move around a lot. The finderscope is definately rubbish (plastic! I can see better without it!) but I didn't expect much from it anyway.

What else can I look for to determine if the scope is junk? If it is... ouch, I'll go back to my good ol' trusty 10x50 binoculars (still the best bit of optics I've ever owned). The guy has offered to take a look at it and try to fix it, and then call Optisan (they speak English?) to find out how to fix it. My confidence isn't high after all the things he said in the shop.

Please advise me on this. If it is junk I'm going to be on 10x50's for a while until I can afford another scope, at which point I'm going to buy it myself instead of asking for one as a gift. I don't blame my parents for the gift (the guy seemed to be versed in social engineering when it comes to people who know little about scopes, probably used the ol' magnification line) since they're not well versed on telescopes. Either way, I need to know if it's rubbish and I can turn it into a pointless fishtank (don't laugh, I might actually do this) or do something else with it.

[ballaratdragons]

Soldant,

I can take a very good guess and say it wasn't a telescope shop.

There are a thousand brands of junk telescopes out there and they may all be made in the same factory, but good ones aren't. Even Tasco aren't as bad as what you are explaining.

I would certainly try for a refund. If not, make a jolly good fish-tank.

Just another question before you destroy it though. The little arms that hold the small mirror up at the Eyepeice end, are they thin flat strips of metal only about half a millimetre thick or are they a few millimetres thick?

If they are thick it is certainly one of those $2 scopes.

If they are nice thin flat ones the scope may be salvagable and made to work better.

Some cheapies can actually be improved, but not the $2 ones.

[asimov]

Hmmm. Interesting. I'm at a loss on how a telescope can give reasonable views & then deteriorate over a period of time to a point that you can see.....as you explain. Or did this suddenly happen? Did you give it a hard knock at any stage?

Sounds like collimation to me. Never actually heard of that brand. I would hesitate to say it's a piece of you know what. Gonna do a bit of googling & see what I can come up with.

[Kieken]

My first thought was collimation to. Soldant, are you sure that you alligned the mirrors correctly? Have you used some sort of tool?

I've also looked on the site and noticed that the only 6" scope they is a 150mm with focal length 750mm making it an f5. And the mirror is said to be a parabolic one.

One more thing, this scope is not as bad as you think. I own the 4.5" version (http://users.pandora.be/willy.geys3/Astronomie/Telescoop/Kleine.jpg) (mine is from Spectron) but trust me, Optisan scope = Spectron scope ;). I've had a lot of great times with it. Nice views of the planets, couple of DSOs. One thing I've should have done in the beginning was buying new EPs. Mine were made out of plastic optics (same for the 2x barlow and 1.5x Image corrector). So try to get your collimation good, and if that works, by yourself 2 new EP's (made out of glass and with coatings) and a decent barlow.

[asimov]

Yes Kieken I saw that website as well. If it's F/5 it's going to be sensitive to 'ordinary' collimation. It needs to be fairly spot-on for good views. Perhaps a combo cheshire/sight-tube would be a good idea to purchase Soldant :poke:

Sounds like the mount could be a problem. In the pics on that polish site, it looks to be way under-mounted!

[Kieken]

If you would compare it with other chinese mounts I would say this would be an EQ-2. Not the best mount for the scope indeed. Tripod is rather crappy to. Still, the tube should be good enough for beginners, giving nice views of the moon, planets and bright DSOs.

[asimov]

Yep. Once it's collimated, All the back-lash eliminated on the mount. (If it's possible) A decent finder scope & perhaps a couple of good plossl eyepieces, You'll have yourself a nice scope to last you for a while.

BTW try Andrews communications for the cheshire collimating eyepiece. Get the one with the cross hairs in it. You may have to take the primary mirror out & centre spot it, although you can star-test to get the primary within reason too.

You could hunt for a second hand EQ5 mount? That would hold that tube nicely.

[janoskiss]

Kieken & John: Short tube reflector, with focal length = 1400mm; not an f5.

Soldant, short tube + long focal length can only mean one thing: short focal length mirror with cheap barlow built into the scope (unless it cost thousands). These are meant to be the worst kind of cheap scopes. (Sorry)

Does this look familiar: link to optrons 6" (http://cgi.ebay.com.au/optrons-1400-150mm-6-Reflector-Telescope-Set-NEW-A-649_W0QQitemZ7534868777QQcategoryZ3 636QQssPageNameZWDVWQQrdZ1QQcmdZVie wItem)? If it does, then it's probably fishtank time.

My guess is that if initially the views were OK and now suddenly you are getting a lot of false colour, the built in barlow lens may gotten misaligned. Maybe you can rip it out and try using a real barlow, but it's a long shot.

[asimov]

Re-position the lens then. If it has one. According to the site (the original site) It's a parabolic mirror. But who know's. I guess Soldant will let us know if it's got the xtra lens in the focuser. :poke:

[elusiver]

could u salvage the mirrors outta those? Be a shame to junk everything.

el :)

[asimov]

I wouldn't really know EL...Never had much to do with junky scopes. I've got a little 4.5" reflector, but it aint' junk judging by the views it gives.

[asimov]

Just scrap it Soldant! Save up & score the 16" dob from Andrews!!:thumbsup:

[Soldant]

Whoa, thanks for the reply guys!

janoskiss hit the nail on the head: except for the color of the tube, that is EXACTLY the same as my soon to be fishtank scope. So exact I'm actually laughing about it.

I've had a friend come over and try to collimate it, and after playing with it for three days we couldn't get it at all. The guy at the shop is offering to do the exact same thing, if the scope is indeed junk, hopefully he'll either break it or won't fix it and refund, though I highly doubt that he's going to do anything of the sort.

About the lense in the focuser: would it, by any chance, happen to look like this?
http://img.photobucket.com/albums/v230/Soldant/isthisit.jpg
That's the only lense in there.

Thanks again for the feedback guys.

[elusiver]

so there is a piece of glass in the focuser? Your focuser shoudl have nothing in it.. i.e you should be able to stick your finger through the focuser and touch the secondary sort of thing.. but don't touch the secondary.

I really don't know how it all works.. but i woulda thought u coulda used the existing mirrors in a proper 1400mm tube.. and end up with a decent(as long as the mirrors were ok) f9 reflector.

But yeah.. if u can get a refund, get it. Then.. GO FOR A DOB! cause then u can be part of the dob brigade™. :D :D

el :)

[asimov]

Not all that cluey on it myself. But I think it go's something like this: The lens is there to correct a sperical mirror. In order for a mirror to work sucessfully, it most be parabolic. The lens corrects for this, turning it into a parobolic? Hey janoskiss, is this right mate?
I'm only guessing here, lol.

[asimov]

Parabolic shape eliminates spherical aberration in telescope mirrors<!-- InstanceEndEditable -->

<!-- InstanceBeginEditable name="right" -->http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/basics/g12/graphics/g12_spherabmirror.gif<!-- InstanceEndEditable -->
<!-- InstanceBeginEditable name="left" -->Spherically shaped lenses and mirrors share a problem: their shape. Parallel light rays that bounce off the central region of a spherical (http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/glossary/term-full.php?t=spherical_lens_or_mirror ) mirror focus farther away than light rays that bounce off the edges. This results in many focal points (http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/glossary/term-full.php?t=focal_point), which produce a blurry image. To get a clear image, all rays need to focus at the same point.

Changing the shape of a mirror from spherical to parabolic (http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/glossary/term-full.php?t=parabola_vs_sphere) solves the problem. All light rays focus at the same point and the resulting image is sharp and clear.

<!-- InstanceEndEditable -->

[Soldant]

Hmm, looks like it's junk then.
Might have to do a bit of social engineering myself to try to get a a refund out of the guy, but I don't think I have any legal legs to stand on? The guy (interestingly) doesn't advertise them anymore, I was hoping he might have advertised them as parabolic so I could catch him out. Damn.

Oh well. Guess I'll have to wait to win lotto then ;) thanks for the info.

[asimov]

re-position the lens, then flog it off to someone you don't like! :lol:

[Soldant]

How would I go about that? It just screws into the end of the focuser, and the glass piece doesn't move inside that black ring thing?

[janoskiss]

The lens is not meant to correct for spherical aberration. That would be too sophisticated for a cheap scope. It is merely there to act as a barlow, i.e., increase the effective focal length (FL). Notice that the length of the tube is about half the FL = 1400mm. The mirror FL is probably 700mm. This is done to save on construction & shipping cost. Shorter & lighter tube means they can get away with a flimsier mount.

Here is a ray diagram illustrating how the barlow works:

http://members.optusnet.com.au/~janosk/misc/barlow.png

Soldant, if the scope is not fit for its intended purpose, then you have every right to demand a refund. Squeaky wheel gets the grease. So go in there and squeak! ;)

[asimov]

Very good explanation Steve. The diagram speaks for itself.

[Soldant]

Really? I might just do that. I'll go see the guy soon and confront him with it. Though I'm pretty sure it'll be like talking to a brick wall, it's worth a shot :)

[janoskiss]

Soldant, I hate it too when I have to get a bit nasty to get people to do the right thing. It all depends on whether the effort is worth it. If you paid less than $200 for the scope, then probably not. It will be a good learner. (Pull it apart & the mount, experiment with collimation etc.) You could make a little Dob mount for it and use it to take to the beach. That's what I did with my 4.5" dud scope:

http://members.optusnet.com.au/~janosk/misc/mydobmount.jpg

Without the internal barlow, you might even get some half decent wide field views of the night sky.

If you paid around $300 or more then it's worth being firm and not taking no for an answer. I would nicely repackage the scope and ask for a refund. Talk to the manager or owner. If all else fails you can always go to the ACCC (http://www.accc.gov.au/), but just threatening to go that way will probably be enough.

[Soldant]

My parents paid $700(! I never knew it was that much!) for it. I don't really care about the guy's feelings anymore, he sold junk (and even admitted there might be a barlow in there when I asked him again about the issue!) to my parents and is trying to cover his tracks by making a pathetic story. The only question is if it's worth going after him, because I'm relatively sure he won't budge unless I file a complaint. I'll investigate the legal side of it later, but $700 is a sizeable amount that could have gone to a much, much better scope.

..that said, if I can't get anything, apart from learning is there any other practical use I could put it to, apart from a rather lovely fish tank?

[Astroman]

you could buy some baader solar film, make a cover for the front and use it for a solar scope.
If that doesn't suit your needs, buy some fish :)

[Mick]

I've seen a problem like that in a scope I had a look at for a friend. But he had bad view from the beginning, no sharp point of focus. Someone at the shop were the scope was brought cleaned the internal barlow lens and reinstalled it in upside down. We turned the lens around and it was fixed, can't remember which way the lens went.

[Soldant]

Well, this one only goes one way :(
the other plan I've got is to try to cram a computer in there :) it would be an awesome case mod. Just got to figure out a safe way to do it :P.

[Mick]

We had to remove the focuser from the OTA and unscrew the metal (Plastic) ring, drop the lens out, roll it over, refit the lens and then screw the ring back in gently to just hold the lens in the bottom of the focuser. We then refitted the focuser and adjusted the collimation. The focuser lens on that scope is the same as your photo.

[Soldant]

Ah, okay. I might give it a try if the guy at the shop can't fix it (which he probably won't be able to).

[ballaratdragons]

$700 is a very expensive fish tank or PC case!

Push for the refund! You can get an amazing Dobbie for that kind of money.

[Soldant]

Yeah but what am I supposed to say? Really, what law says that I can get a refund out of him, considering it was in December last year that I got the scope?

[ballaratdragons]

Get him to collimate it or refund.

If he does collimate it, your scope works again. If he can't collimate it, he will have to do something! Refund or Replace!

[janoskiss]

Soldant, you have left it a bit long, but Ken's got the right idea. BTW, whereabouts are you?

[MiG]

Ouch, $700 is a lot for that scope.
Check out this bait!!!
"Eventually you'll know you're ready. You'll have spent pleasant evenings poring over the ads and reviews. You'll know the different kinds of telescopes, what you can expect of them, and what you'll do with the one you pick. The telescope you want has two essentials. One is a solid, steady, smoothly working mount. The other is high-quality, "diffraction-limited" optics. This is exactly what the optrons 1400-150 Reflector-Telescope offers you for a very reasonable price."

That is so nasty.

But I must say that there should be a lens there. The E-bay ad says it's catadioptric which means it uses lenses and mirrors, so it isn't lying. Really the description should be "catadioptric Newtonian".

[ballaratdragons]

Mig,

Don't they also go by the name 'Newtonian Cassegrain' or is that a different style all together?

[janoskiss]

That's capitalism at work for you! :lol: But at least they're only asking for $279, not $700.

The issue is not that there is a barlow in the focuser, but whether it works. If it was a good mirror with a good barlow lens, then it would be a good scope! But the reason a built-in barlow rings alarm bells for me is that it does not give the user the option whether to use a barlow or not. It says to me: this mirror is so bad that you don't want to see how it performs at its native focal length.

[MiG]

That's a Cassegrain without a hole in the primary. Instead a flat diagonal (3rd mirror) reflects the light out of the side of the scope. At least that's what Googling it told me.

[cristian abarca]

Hi Soldant. I'm a little late for this post but heregoes anyway. I have a scope similar to yours except it's a saxon. I've tried taking the barlow out of the focuser and putting a normal barlow at the eyepiece and it doesn't work. Like you I 've tried to colimate it on many occasions and I can get close but not close enough. Also with mine the focuser is not made properly so it comes out of focus easily. I managed to modify this so that it is acceptable. With these cheap scopes the focuser sometimes is not aligned properly (not at 90 degrees) and the secondary mirror may also be too small (like mine). I have been told by my astronomy club that I could put the mirror on a longer tube and eliminate the barlow in the focuser. My mount is also flimsy and one thing I did was replace some of the knobs with Allen key ones to get a tighter grip. In one of the magazines they showed putting weight on a string from the centre of the tripod to stabilise it. They need a lot of modifications and I can still see through it but it could be much better, That's why I'm making my own.


Regards Cristian

[asimov]

The guy it was purchased from must have a warranty of some description on it. If it's within the warranty period, he is required to fix it, or replace....or money back.

[Soldant]

I'll take it back to him maybe tomorrow if I get the time.

I'm in Wellington Point, Redlands (for those who don't know, just outside of Brisbane. So close actually I don't know why we're separate).

I'm hoping he still has the advertisement that my parents saw when the scope was still on display (curiously, it's not on display anymore...) but I think his advertisment is different from the eBay one. He's not too interested in answering questions about the scope (hence like talking to a brick wall) which leads me to believe he either doesn't know what he's on about or is trying to hide something.

[ballaratdragons]

What type of shop is it? Camera Shop, Discount Store, ???

[Soldant]

A terrible camera shop, filled with all sorts of rubbish.

[ballaratdragons]

That's amazing.

As a Camera shop the guy should know about problems with optical equipment!

[asimov]

I would say he know's all about THIS scopes optical configuration for sure. If all else fails (warranty wise) I would be putting the squeeze on him to at least fix the scope to it's original condition ie: being able to actually see something through it! If not, report him.

[Soldant]

Will do. I'm likely taking it back tomorrow.
I think he knows about the optics, but he's not willing to tell me. When I asked him what mirror he had, he went "Uh hmmm... dunno." He later actaully said there would likely be an inbuilt barlow.

Not adding up good :(

[Apollo]

This is a bit late, but read the problems you are having with this. Not sure if you still have the scope but if you do there is a little trick I use to collimating these beauties. You can get reasonable images from it provided you dont go off axis too far. I am hoping it has the adjustable spider arms. Firstly remove the built in barlow from the inside end of the focus draw tube and try to collimate as per normal daylight collimating as best you can. Replace the built in barlow and prepare yourself for some tedious night time collimating. Forget about collimating on a star for the time being, use a planet like Jupiter, Saturn or Mars even a very distant light bulb might work. Keep the image centred and focused as best you can, you may notice considerable flaring. Working on the secondary mirror, adjust the centre axis (rotational) to reduce the amount of flaring. The centre position of the secondary now needs to be collimated, this is done by using the spider arm adjusters. You will notice as you pull the secondary from one side to the other the flaring will be drawn in or away from the main image, adjust so that the flaring is drawn in toward the main image, keep adjusting until most or all of the flaring is gone. Keep checking your focus and repeat as necessary. Now get yourself a reasonably bright star and perform a traditional collimation by very small adjustments on the primary mirror and possible the traditional three set screws on the secondary. Check back again on a planet and repeat the procedure again if necessary. I know it sounds like a lot of work and its not what you call a conventional collimation procedure, but it does work and you might be able to put the scope to some use. If you still have problems there may be a defect with it. Good luck.

[asimov]

That's a very interesting method Apollo. And welcome to the forum by the way!

[Apollo]

Well, good evening there asimov and thanks for the welcome...Saturday night and I thought I would have a little look around.. Yes Its a very unconventional method. I think most people on the post are fortunate enough to have scopes that dont require this level of TLC, but Ive been exposed to this type of scope and it drove me nuts trying to get it right. I dont think you can ever get them totally right but you can get them to do a respectable job for you.

[asimov]

I'm into 'unconventional' methods. Whatever works. Luckily, I've not had to deal with a telescope such as the one described. A conventional F5 newt is hard enough to collimate correctly.