Celestron Powerseeker 127 collimation advice needed

[Bucky1379]

Hi

I'm old (51) but new to taking this "stuff" more seriously and am after some advice.

I recently bought a short tube Celestron Powerseeker 127 (due to portability, price and a good review I saw) but I believe it is in desperate need of collimation. The potential troubles I've found so far in doing this (and I've never done it before but want to) are -

1. With the additional lens mounted in the focuser to lengthen the effective focal length, I can only use a short length Cheshire/sight tube (I'm looking at getting the Andrews)

2. I haven't bought that yet because all I can see through the focuser anyway is the secondary and the spider arms. There is no sign of the edges of the primary or clips.

I am willing to centre spot the primary but I'm worried that I won't be able to collimate it myself anyway due to it's configuration.

Can anyone offer some advice?

Thanks for any help.

Steve Ma****er

[iceman (Mike)]

Hi Steve

to IceInSpace!

Newtonians with built in barlows are always going to be very tricky to collimate. I've not done one myself so can't offer any specific advice - hopefully someone else will.

I hope the scope gets you hooked, you'll be looking to upgrade to bigger and better in the future

[janoskiss (Steve H)]

Welcome aboard Steve. I haven't any experience with built-in-barlow scopes either, but in principle it should be the same procedure as for a normal Newt. Whereabouts in Melbourne are you?

[Bucky1379]

Hi guys

Thanks for the welcome and the interest in my less than leading edge scope. It is intimidating seeing your equipment lists but....... I do have aspirations. At this stage I think an achievable aim is for a 8" Dob with motorised tracking so I can use a webcam to get some reasonable photos. Does this seem like a practical possibilty?

I live in Donacaster, Vic. and already have a scarey list of "must haves" and to be honest, I'm not convinced that joining IIS is going to help at all. I see lots of articles on the internet inducing me to buy things but very few tutorials on balancing astronomy, finances and family life. Oh well. I must say that already, it looks like the weather helps. Maybe that is the real reason for rain and clouds. In fact I've suddenly decided that I'll have to publish my theory on the how the reason for poor weather is simply to try (it doesn't always work) to curb men's lack of willpower.

On the subject of "must haves" I can offer some helpful advice already. My wife didn't want to but is quite impressed with my new 20 mW green laser pointer (for which I'm making a mount for at the moment). It does help if your friends and (especially) loved ones can see where you (and they) are looking. On top of that, everyone thinks it is way cool. The only trouble is that I've just discovered that I "must have" a Telrad. Doh!

Even if I can't get any help with my collimation, I'll experiment and perhaps I'll become the Subject Matter Expert at IIS on collimating internally barlowed scopes.

Got to go as I need to look for or start a post on how I might make my flimsy tripod legs more rigid.

Thanks again.

Steve

BTW the **** in my name is due to internet censorship which has caused problems before. Sorry, but it's not my fault.

[janoskiss (Steve H)]

I'm sure some of us could get your scope sorted. Come along to a viewing night and bring your scope. Snake Valley and Mornington astro societies have regular get togethers. And there is also the ASV of course... some links for you:

http://www.iceinspace.com.au/forum/s...ad.php?t=16091
http://www.iceinspace.com.au/forum/s...ad.php?t=16412
http://www.asv.org.au

You don't have to spend a lot to have a lot of fun with this hobby. You can buy excellent equipment for ridiculously little money. 8" Dob and maybe later an EQ mount if you want to dabble in photography sounds like a good next move.

[tjquoll]

I recently made the mistake of getting one of these from a certain "electronics" retailer and found that it was very much out of alignment. It was very disappointing. Lots of coma on stars, Saturn was an elliptical blur and the moon lacked detail. Attempts to collimate were made difficult by the Barlow lens in the focuser and by the large amount of play in the focuser tube. Due to the Barlow, the view through a collimation cap is screwy - the scale of everything is exaggerated - and a laser was expanded to a blurry smudge. The wobble in the focus tube was sufficient to throw the collimation out every time you changing the angle of the OTA.

Anyway I just love to pull things apart and fix them, so in short I was able to address these problems by:

1. improving the fit of the focuser tube by removing it from the focuser and wrapping a bit of paper around it (low tech fix).
2. carefully removing the Barlow from the focuser tube, collimating (I did the secondary with a collimation cap and the primary with a laser), then putting the Barlow back in - making sure of course that you put the lens back in exactly the way it was before.

The results... outstanding, Saturn is clear - even looks reasonable with the 4mm eyepiece -, Alpha Cen seems to be 2 stars and , omg, the moon has craters .

Of course this make me wonder if I should just remove the lens in the focuser altogether and put everything into a longer tube?

Otherwise there was a lot of play in the mount. The RA was particularly bad but a bit of tightening has smoothed it out. The supplied counter weight is way too light and I'm going to have to look at some way of adding more weight.

I suppose the upshot of the whole exercise is that in the last few weeks I've learnt a whole heap about telescopes - well reflectors anyway - and I have a reasonable idea of what I should have bought for the same money (6" dob...?) and I've worked out how to get a reasonable performance from my cheapy.

Anyway, as a musician, I am often struck by GAS, or Gear Acquisition Syndrome (or if you're like me, "Guitar Acquisition Syndrome"). I'm interested to know if astronomers have an equivalent condition?

[jjjnettie (Jeanette)]

LOL
It's called Apeture Fever.
The fervant desire to own a bigger and better telescope.

[Bucky1379]

Hi tjquoll

Thanks for your advice. I had gotten to the stage of deciding I had to remove the focuser's barlow lens but wasn't sure about going ahead. Once I knew it can be done, it was easy with the end of a 30 cm steel rule. I have finally finished my initial collimation but it is hard to find a long enough straight period for it to happen with a 3 year old son who is always wanting to "help" but I was very encouraged with your reports once you had completed yours and went for it. I didn't have a laser collimator but ended up buying one and with your advice, have it much improved (I also used the primary centre marking technique posted on "Ice In Space") but I now think I can do better and will also do it next time with it cooled down to normal night temperatures. It is sad that Celestron can produce the parts for a good product but just not set it up to realise it's potential. Maybe the 1/2 page in the manual on collimation maybe being required due to possible transportation bumps absolves them of this.

In my travels with my Powerseeker 127 I've been working on improving it as well because I enjoy getting things working as well as they can be almost as much as using them (yes, I also have to pull everything apart as soon as I get it). I also found the focuser fit to be unusable but have improved it no end by removing the 3 plastic strips and replacing them with strips cut from a 4 litre ice cream container. That also provided a low friction washer for the azimuth bearing surface.
I've also replaced virtually all of the bolts and nuts with "real steel" replacements and with hex cap heads where suitable. This really helps collimation. I also cleaned all the gunk off the mount bearings, etc and re-greased with real grease and made what adjustments I could. I'll let you know what I can work out about a reasonably neat increase in counterweight mass as I agree about this problem.

I'm also replacing the tripod brace/accessory tray with a much more substantial aluminium/mdf structure with inbuilt bubble levels, compass and clock (I'll post a picture soon) and have fitted a 20 mW green laser pointer in a home made adjustable mount to supplement the abysmal finder scope supplied.

My other improvements have been the purchase of several Andrews Series 500 eyepieces and their 2 X Barlow which, while fairly inexpensive, make the Celestron supplied units look and perform like toys.

On your other subject, I think you are right about "GAS" in both fields (music and astronomy). I guess it is a cross we have to bear. I have managed to aquire a current count of 10 guitars over the years and while I can't totally agree with my wife, maybe I don't really "need" quite so many. I am also already planning my next telescope but I do have some points up my sleeve due to selling my early "department store" 'scope.

Thanks for the posting

Steve

[Moonboy (Gus)]

Originally Posted by tjquoll

Anyway, as a musician, I am often struck by GAS, or Gear Acquisition Syndrome (or if you're like me, "Guitar Acquisition Syndrome"). I'm interested to know if astronomers have an equivalent condition?

I'm exactly like you..... I want a better guitar (and amp) and a bigger telescope.
When will it end??

cheers
Gus

[bobson (Bob)]

I collimated one of those for my friend. I bought proper springs for primary mirror 'cos there were rubber washers instead and virtualy impossible to adjust. You can get springs for about $2.50 from Bunnings or Mitre 10. They come in pack of 2 and are long so you have to cut them in half and end up with one spare

The focuser have 1.5x Barlow built in and you have to take it out to be able to collimate it either with Laser or Cheshire or film canister. Mark the centre of the primary as you looks like already did and collimate it then. Make sure you put 1.5x Barlow back where it was otherwise you will not be able to focus unless you have tube extension.

cheers

bob