4.5" reflectors from Dick Smith - Page 2

janoskiss (Steve H) · #21 22-01-2005, 03:07 PM

I found a film canister that I managed to just squeeze into the focuser, so I gave collimation a go following ballaratdragon's instructions. At first it looked like I stuffed it up so bad that I'll never be able to fix it; loosened the screws holding the secondary too much. After regaining my composure, I managed to secure the mirror again and a 1/2 hour of fiddling later, it's as good as I'm gonna get. I really wasn't game to take the primary out for "spotting", so I used a laser pointer blutacked to the inside of the tube to shine on the centre of the primary.

All the screws on this thing are badly corroded, which makes adjustments all the more difficult. They are just covered in what looks to me like zinc oxide, and I think a fair bit of that powder ended up on the main mirror.

After all this the image quality is not really any better. With the 30mm EP everything looks nice and clear. With the 10 & 6mm it's hazy, even in daylight. These smaller EPs did look pretty dirty, so I attempted to clean them, dried them with a hair dryer on low heat, and then they fogged up on the inside.

Now I'm waiting for them to dry.

ballaratdragons (Ken) · #22 22-01-2005, 03:24 PM

Not having much luck are you Janos.

What ever you do, don't touch the mirror to clean off any muck.

20 odd years ago I had an EL-Cheapo set of eyepieces (Huygenians) and the 20mm was fantastic (for a Huygenian) but the 12mm & 6mm were useless. I took them to our club and had them optically tested and they were stuffed. They came from K Mart, what do you expect!!

You really have to have good E.P's (eyepieces) from a telescope shop, not the supermarket ones that come with it.

Don't worry, you'll soon have your 8" Dobber (with good E.P's).

janoskiss (Steve H) · #23 22-01-2005, 03:38 PM

The EPs are all super ploessls (at least that's what's written on them) and it's looking like its gonna be a nice night if those clouds keep moving like they've been over the past few hours:

http://www.bom.gov.au/products/IDE00902.loop.shtml

ballaratdragons (Ken) · #24 22-01-2005, 03:49 PM

In other words, they are Plossl's. 'Super' is a sales gimmick these days. Meade do make a Super but now everyone likes to use the name to help them sell.

They are very good EP's.

Weather chart looks promising!

janoskiss (Steve H) · #25 22-01-2005, 05:20 PM

EPs are not clearing up. It looks like there is a lot of moisture inside them and it's got nowhere to go. They'll probably take days to clear up! Has anyone had this experience after cleaning EPs?

ballaratdragons (Ken) · #26 22-01-2005, 05:25 PM

You shouldn't let them get wet!

Stick them out in the sun for a few hours. Hopefully you won't have to diss-assemble them.

janoskiss (Steve H) · #27 23-01-2005, 10:31 PM

Thank you all for your help so far. Collimation looks OK and the EPs have finally dried. The higher power EPs do give a clearer view than before. (Still waiting for Saturn to rise higher.) I tried the star test, and based on what little I know, I've probably got a pinched mirror. I'm gonna go look for some info on how to deal with that...

(I'll have to get a cheap digital camera one of these days, so I can share the EP view with others.)

Jimmy · #28 23-01-2005, 10:46 PM

haven't given up yet have ye!

haha good luck

janoskiss (Steve H) · #29 23-01-2005, 11:15 PM

No, I'm not giving up!

This scope has brought me a lot of joy! ... even though I've spent more time fixing it than I've spent looking through it! It's probably not all that different from other more expensive $400+ camera shop scopes.

ballaratdragons (Ken) · #30 23-01-2005, 11:19 PM

On ya Janos, enjoy whatever you've got at the time. Tinkering is half the fun.

janoskiss (Steve H) · #31 24-01-2005, 12:29 AM

Thanks Ken! I could finally distinguish Saturn itself from its rings! I think I'm staying up for Jupiter!

I'll try to fix any pinched optics tomorrow night (unless of course I get my 8" Dob by then).

janoskiss (Steve H) · #32 30-01-2005, 08:11 PM

I centre spotted the mirror today for practice, before doing the same to my new GSO 8". Then I loosened the three clamps around the primary to make sure there's no pinching. Then I put the mirror back in and did my best to collimate the scope using the barlowed laser method, but things do not look properly centred from the focuser. The secondary should be moved a few mm away from the focuser, but the spider is not adjustable. So the star test does not work, because the diffraction pattern is that of an off-centre diagonal, even though the mirrors are correctly oriented.

Even though this scope is very poorly made, I can't help being fond of it. It has been an interesting learning experience, and it got me interested in astronomy, and I'll never forget the first time I saw Saturn through it.

ballaratdragons (Ken) · #33 30-01-2005, 09:59 PM

I know exactly what you mean. As I have said before, my first scope (4.25" reflector) was a hunk of junk (I made it myself) but I would dearly love to have it back.

Ah yes, those first memories . . . . .

rumples riot · #34 30-01-2005, 10:06 PM

Well just read through this marathon, and the first thing that comes to mind is, I am sorry you have had such trouble with your first scope. You can be assured though that you are one of thousands that are caught by this trap (myself included many, many years ago),

Yes get a laser collimator and do everything you can to improve the collimation of the scope. The laser collimator will help with your 8" that is on the way.

Second, start investing in better EP's. The cheaper scopes are notorious for having very poor quality EP's. You will want to get these for your new scope, so buying one or two along with a good barlow will give you better images and a bit more range.

The mount that came with the scope is predictably unstable, they always are and should be avoided like the plague. Glad to see you made a dob mount for it. This will be much more stable and much wiser.

So the bottom line is follow what Starkler said ( good advice that should be followed) and I suggest that if the mirror is fine and the collimation is set right, you could use this scope for limited but useful viewing. One day you could use it for a guide scope, you never know. I am glad that you just did not give up on the hobby and you came to ask how it could be fixed.

Best of luck

janoskiss (Steve H) · #35 30-01-2005, 11:43 PM

Thanks Paul, for reading this long thread.

I got my GSO Dob since I bought the cheap DSE. The DSE came with 3 good Ploessl EPs, and I'll keep using these with the Dob (they're as good as the GSO Ploessls that came with the Dob). Don't know what I'll do with the rest yet. I was hoping to properly collimate it before selling it or giving it away. But that's not possible w/o throwing yet more money at it...

The GSO (at twice the price) has its flaws, but it's awesome compared with the DSE!