Pixies

From a previous thread, @johninderby said that the base diameter of the 150p and 200p are the same. The OTA lengths are the same. too.

So they will both take up the same amount of storage space.

So 200p it is then! Unless someone knows how big a 250p is?

I imagine the previous owner has overtightened everything. Once you have things loosened, you might want to check the secondary mirror holder where the adjuster screws meet it, ok case they have dug in. That would make it hard to do any rotational adjustment.

I think once you have loosened then, you'll need to think about replacing them! They are easy to source, and you can get some better thumb adjusters, rather than the little hex headed machine screws.

Keep the scope horizontal, there might be some swarf knocking around.

Does the laser have 3 adjuster screws on the side of the body at one end. Like this:

They might be covered up with this black rubbery filler. If you have them, you can collimate the laser collimator! Adjust them very slightly using an allen key - one at a time (like adjusting the primary mirror) until you can rotate the laser and the spot stays in one place.

2 minutes ago, Philip R said:

If you make a 'V-block'; (i.e. piece of timber and four long nails at an angle); rest the collimator on that then with a sheet of paper on the wall, place marker on it where the 'dot' is, then rotate the collimator a few degrees and check its position. If it is off centre from the first 'dot' the collimator may/will need collimating. If you can go further back, better still.

As per:

10 minutes ago, Gummy said:

6 metres away onto wall

My bad... I meant a close up of the diffraction pattern. As per the following (10 m distance for me).

Just want to confirm that the laser isn't duff.

Is it adjustable? Try turning the brightness down and do the collimation in a darker environment.

Also - at full brightness, shine it onto a light surface as far as you can go (5-10 m) and see what the beam looks like. (send a pic)

My first 2". AN OVL Aero ED SWA 30mm

2 minutes ago, Philip R said:

Hi @Gummy and welcome to SGL. 

Assuming your 'scope/OTA is not a 'Bird-Jones'* type... then that looks OK to me!
If it is... there is a video showing you what to do and also how to collimate your collimator on YouTube.

Sorry I cannot help much more.

 

* 'Bird-Jones' is a type of reflector that has a magnifying element somewhere within the focus/drawtube assembly.

It's NOT a bird-jones! 

https://www.celestron.com/products/starsense-explorer-dx-130az

The Black Diamond 325 (as mentioned above) is on sale at Wiggle.co.uk for £20.99 just now (for some colours).

Have just ordered one and I'll give a quick review when it arrived.

That's a Circle-T volcano-top ortho EP, isn't it?

If that's in good nick, it's worth £40-£50

Just seen the brightest meteor I have ever seen before! It was around 23:45 (sorry, I didn't make a note). SE to NW, greenish in colour.  Around 30deg in travel.

But the thing was, it left a pale trail for a brief second after it had faded - like smoke. It was visible in the light skies here. I'm sure it wasn't an after-image as that would have been a dark line. This appeared to 'spread out' after the meteor, a bit like a thin wake.

Am I imagining it, or is this an actual thing? I haven't been drinking!

One thing to consider, regarding how the collimation changes if you move the scope. Make sure the spider vanes are tight. After I had replaced my secondary, I found collimation would change when I raised or lowered the scope. After tightening them up, that was fixed. 

I've got a shorty collimator. The problem with that I find, is that I'm so short-sighted I can't focus on the cross-hairs with my glasses on, or focus on the doughnut with my glasses off.

5 minutes ago, Jamgood said:

I could with the collimator cap but not with the Cheshire. The photo below is how it looked before I adjusted the primary slightly. Is it because of the focuser tilt, maybe?

How big is the Cheshire?

I notice how you can't see the outer edge of the primary any more?

Hi,

Sorry it hasn't been a success, today. Yesterday looked so positive!

It's odd how that flat spot doesn't appear in the silhouette. The secondary mirror is quite large though, so as long as you can see the whole of the primary in it, that shouldn't have an effect. Can you see whether the whole of the primary is visible over the whole range of the focuser?

Alacant says - you can see the end of the focuser tube when it is fully in. As long as you don't need to get in that position when focussed, that shouldn't matter. Mine is similar.

Try A's suggestion and get it as close to collimated as you can, then move it to various extremes on the mount and see whether it stays in collimation.

It might be worth putting a call-to-arms for the 130PDS owners in the general equipment forum, with an obvious title, like: "130-PDS owners - help!" and direct them to the end of this thread.  Someone might have seen this issue before.

Have you spoken to the supplier?

P

Just now, Apprentice said:

Hi @Pixies This looks like a good replacement for secondary collimation screws, mind if I ask if you already received them (use them)? I am thinking of buying this for my scope its 5" newt, so I am htinking the 30mm would suffice.

 

Mine is a Bresser 8". You will need to find out the size of the current secondary adjusters. Take just the one out (horizontally, mind you!) and measure it up. These will need to be a little longer, obviously.

If you want just some hex-headed machine screws, to add your own cap, message me, as I have quite a selection and I'll send you 3 for postage costs. if I have the right size.

25 minutes ago, galaxy-gazer said:

with my own research i have kind of selected starwatcher 200p (but not sure if i will be able to store it in the house, without annoying the wife!)

Indeed, there is a whole thread devoted to the storage of dobs (or not annoying the SO):

1 minute ago, Jamgood said:

Geez! At least you managed to sort it out.  I don't think I'd know where to begin on your problem.  That would've been a total nightmare for me.  Interesting to see you mention Bobs Knobs in that thread. I could have used some of them over the last two days instead of messing around with a tiny allen key. One day I'll upgrade them

Don't. You can buy them cheaper on Amazon. Mine were replaced by:

Or just buy the caps to go over stainless steel hex-headed machine screws. Someone more familiar with your scope will be able to give you the sizes required. See: 

No problem! It was good to get my understanding of it down on 'paper'. I made some mistakes when I got my new scope and nearly mucked things up well-and-truly!

Cheers!

I know - it can be a bit brain-bending. This offset is only there for fast scopes. Ones with longer focal lengths don't have them and their secondary silhouettes are central.

So - stage 1. You've aligned the secondary under the focuser (length and rotation), so that the outer circumference of the secondary is concentric with the focuser tube. You won't have to do this again unless you've had to loosen the secondary for some reason.

Stage 2. You then adjust the tilt of the secondary so that the outside edge of the image of the primary is concentric with the above - which should mean that the doughnut is centred too. This only needs checked occasionally, esp after the scope gets bumped. Ignore the silhouette of the secondary in the primary mirror.

Stage 3. You adjust the primary so that the eye-hole 'dot' is centred in the doughnut. You'll do this a lot, and get quick at it.

All the above with the Mire de Collimation can be done with a Cheshire. The final stage too. @johninderbywill be along later to sing the virtues of the 'Concenter' collimation tool.

Now - beer time!

And they are. The only thing that isn't is the image of the secondary in the primary, and that's because of the offset. That's normal. 

The doughnut is in the centre of the cross hairs, isn't it?

That looks great? What's the problem?

No. You're almost there. I just think you could rotate the secondary a wee bit. Looking from the adjusters, that would be slightly clockwise. Looking from the focuser, the top of the secondary would move towards you.

That would mean, that in your pic, the image of the secondary would rotate slightly anticlockwise:

Does that make sense?