Self-centring adapter advice please

[rory]

That's good news Jules . I had one permanently fixed to my old. 8 " ( not a paralleliser just a big standard twist lock adapter )I had focus with all my eyepieces , BUT it was a strange 2" adapter I had. I bought the scope second hand and the previous owner lost the 2" adapter so I had to pick one up second hand. Luckily for me ( although I had no idea at the time) I'd bought a short version compared to the standard supplied. I suspect it may have been machined down or something.

Which meant I had enough movement to get focus.

As well as keeping the barrel central and helps keep the collimation tool straight, there's also the advantage of not marking your e/p barrel.

Clear skies matey.

[Jules Tohpipi]

Some interesting things I thought I’d share from my recent experiences...

(Albeit sorry for the long posts, if anyone is still reading).

Given how the Howie Glatter Parallizer is intended  to work, I was worried that its effects would be spoiled by the need to insert the 2” EP holder first.  Totally by accident, I discovered the answer to that question.  Well, partially...  there’s a story.

As mentioned earlier, I collimated the scope at the weekend with the 2” EP holder, Parallizer and Cheshire in place.  Scope collimated, I then removed everything.

Immediately, I put everything back into place only to discover this - the circle marked on the primary mirror (doughnut I think it’s called) had moved way off to the right!  It wasn’t even touching the solid black circle in the Cheshire, let alone overlaid or overlapping. ‘Well, that was an complete waste of time and money!!’ were my immediate thoughts.

So, what was the problem?  I had not inserted the 2” EP holder squarely.  You see, I’d always assumed that the act of tightening the screws would guarantee the EP holder went in square. Wrong.  Totally wrong.  Turns out I had only part of the EP holder’s collar touching the draw tube - some of the collar had a tiny gap to the draw tube - which meant the 2” EP holder was inserted at a very slight angle, and clamping the EP holder into place maintained that angle – not straightened it out.   The outcome being I was staring down the Cheshire with the primary doughnut significantly off target.

The solution:  I re-inserted the 2” EP holder making sure that the entire circumference of its collar was pressing against the draw tube while tightening the screws.  Then, with Parallizer inserted also, and Cheshire into Parallizer, the doughnut was always in the exact right place.  By implication, it means my EPs would be as well.

This accidental discovery has really highlighted to me just how important it is to get everything *parallel* (not just centred).  Otherwise your best efforts at collimating will be compromised.

As a follow-up crosscheck, I then removed the Parallizer and inserted my regular 2” to 1.25” adapter.  This adapter has to be inserted into the 2” EP holder meaning it’s effectively a two-piece adapter (unlike the one-piece 2-1.25” adapter supplied with the 200p).  Anyhow, added the adapter, inserted the Cheshire, and the primary doughnut was a mile off again!!  Clearly the 1.25” adapter was not in square but, because of its design, I couldn’t find any easily repeatable way of inserting it at a consistent angle.  The design of this adapter always felt and looked a bit rubbish anyway.

So, for my particular case with the 250px, the Parallizer appears to be providing two benefits.  Firstly, its design ensures that it goes parallel into the 2” EP holder.  Secondly, it ensures the 1.25” EPs go into the Parallizer in...  parallel.   The viewing was terrible last night, but nonetheless my gut reaction is that I’m going to get my sharpest ever views some time soon because alignment errors in the adapters and EPs are being removed.

The question remains though: is the 2” EP holder going into the draw tube parallel?  Well, I don’t know the answer to that question.  But at least I can collimate everything to that current baseline safe in the knowledge I can consistently recreate it.  If I had some extra collimating kit e.g. laser that could fit into different-sized tubes, then I could determine how square the EP holder is.

It’s early days but I might be a convert to Howie’s declaration that “centering is nice, but parallelism is golden”

[sbooder]

This is why I tried to get an adapter ring made, about 2" in depth with a thread to match the focuser tube when collar is removed at one end and the thread the other end of adapter to fit my Orion SCA, this way everything is in line, no need for thumbscrews at all.

[andyman]

I had a antares sca which was useless when collimating the secondary with a laser.every time you inserted the laser and tightened it would throw the laser off in one direction.then repeated the process and yet again it would throw the beam off to another point on the primary mirror.dont know how good other sca are but judging on the antares version a total waste of money.but if it was throwing the laser off it would have been doing the same when using eyepieces

[Jules Tohpipi]

For anyone who’s interested, here’s my interpretation of how the Howie Glatter Parallizer works. It’s not an explanation of the whole principle behind the Parallizer, just a part explanation of how it actually keeps things parallel.

(My profuse apologies to all concerned if I’ve got any of this wrong).

Background

I’d read some explanations online, and watched the video on HG’s website, but personally just wasn’t able to understand the descriptions of how it worked and kept things parallel.

So, now that I’ve got one, I think I understand. I hope the diagram I’ve created below helps shed some light for thickies like me who didn’t understand the official explanations..

Diagram

The diagram shows a cross-section of a 1.25” EP inserted into a Parallizer, which in turn is inserted into a draw tube (or 2” EP holder).

Please note the diagram is not to scale and I’ve exaggerated the size differences between the different elements to aid seeing how it all works.

EP into Parallizer

The first thing to notice is that the Parallizer is not intended to be a perfect cylinder. On first inspection, the inner diameter seems like a circle; however, look under the green EP and you’ll see a white space. That’s because an extra smaller scoop is taken out of the inner barrel of the Parallizer. It means the EP will come to rest not at the bottom of the tube, but slightly raised up on the ‘shoulders’ of the two (machined) intersecting circles. This inner profile extends the full length of the barrel – meaning that the EP is resting on two lines that extend all the way down the Parallizer. The Parallizer then has a single clamping screw from above. This clamping screw is made of brass with a plastic thingy on the end, both of which ensure your EPs won’t get marked (Howie has emphatically asserted this on another forum). The EP is now held parallel inside the Parallizer.

Parallizer into draw tube (or EP holder)

A similar principle is applied to the outside surface of the Parallizer barrel. Note how some extra cutting out is performed on the outside surface (at the top in the diagram). It means that the outside of the Parallizer will contact at two points to the draw tube. I say points, but it’s actually contacting along two lines all the way down the outside of the barrel.

All that remains is to clamp with a *single* screw from the draw tube. The supplied little instruction note states to use only one of the two screws on the draw tube (or 2” EP holder) and to orientate the Parallizer such that the draw-tube screw is opposite the Parallizer screw. Looking at the diagram it’s obvious to see why this instruction is given i.e. it ensures pressure comes from the right direction in order to keep the “shoulders” of the Parallizer pressed against the draw tube. It then sits inside the draw tube parallel with the inserted EP.

Summary

So I hope that helps explain – if it was needed – how the Parallizer works. After my experiments with the Cheshire, it certainly seems to be achieving its goals. I think £40 is a little steep for what you get, but then it is a beautifully made speciality item, built in small quantities, and FLO need to make their money too. As it does its job very well, then I’m not displeased.

[michaeldurban]

i also found that the antares SCA does not give repeatable results..

i have to take out -and centre- my cheshire more than once.

i now put in the cheshire to the hilt and tighten the SCA very firm..

seems to work..

[sbooder]

i also found that the antares SCA does not give repeatable results..

i have to take out -and centre- my cheshire more than once.

i now put in the cheshire to the hilt and tighten the SCA very firm..

seems to work..

I do the same.  It lacks a little depth of the compression ring and allows for movement unless tightened very hard.

[Jules Tohpipi]

I guess it depends on your eyepieces but I always assumed you'd still need the 35mm 2" eyepiece adaptor in the draw tube to reach focus. That's what I have with the Orion adaptor and I think the Parallizer adds about the same distance. I would be very keen if you could confirm that you can reach focus and with which eyepieces

There was opportunity to try the SW 200p Dob last night with the Parallizer. The overview is that I was able to achieve focus with all EPs when putting the Parallizer directly into the draw tube, but *only* if I did not insert the Parallizer fully. So I think it's a very good result that focus could be achieved in this configuration and the views were excellent.

Attempt 1

Inserted Parallizer into draw tube all the way to its collar. At this point the Parallizer provides zero extension because the inside of its collar is chamfered i.e. like a funnel. I could not achieve focus with any of my EPs (6mm - 24mm).

Attempt 2

Inserted Parallizer approx 80% of the way in (didn't measure this accurately). Achieved focus with the 16 and 24mm MaxVision EPs. But no focus with the 6mm WO.

Attempt 3

Inserted only 10mm of the Parallizer's barrel (this I measured with the calipers). Could easily achieve focus through all EPs 6mm - 24mm. For cross-reference, the supplied SW adapter (2" to 1.25") only has 10mm of barrel below its collar for the screws to clamp onto; even with only 10mm inserted the Parallizer had no slop or movement in the draw tube. Of course, this fitting of the Parallizer need only ever be done once and you then leave it in place.

Attempt 4

Inserted the Parallizer approx halfway into the draw tube. Could achieve focus with the 16mm and 24mm MaxVisions. Could not achieve focus with the 6mm. So, I inserted the 6mm not all the way in, but very roughly halfway in, and was then able to achieve focus with ease.

Conclusion

Were I to be keeping the 200p, then I would definitely be putting the Parallizer directly into the draw tube. It allows you to perfectly collimate the scope and then definitely keeps everything parallel and in collimation across all EPs, whether the Parallizer is inserted partially or fully, and regardless of how many times you've removed/inserted it. My Cheshire confirmed this. It's a very clever and effective design that ensures sharp reliable views for visual, and maintains the focal plane in the correct orientation for AP.

Footnote

There's only one minor negative thing to note - other than the price - which is the Parallizer's clamping screw can foul on wide EPs. This was the case with my MaxVision 24mm. The issue is that the screw used to clamp the EP goes in at approx 45 degrees, and if you have an EP the size of a grenade then the screwhead will hit the outside case of the EP before it is able to clamp it. Thankfully there is a workaround, which is to simply pull the EP out about 5mm and then clamp it (the design of the Parallizer will still keep it tight and parallel) - but if you're not paying attention there's a danger you will scratch the outer barrel of your EP, if it's a biggy like the MV 24mm.

[RikM]

Thanks for the feedback Jules. That sounds exactly as I expected

[wookie1965]

Glad you worked it out on the 200 and if you go by your 3rdd attempt and leave it in place there wont be any messing about just means getting another for your other scope lol.

[michaeldurban]

well...I have decided to go and order the Parallizer..

I'm getting sick and tired of trying to 'quickly' check my collimation

only to find it is way out...

I now lock the cheshire into the Antares SCA, tighten it and check

(way out, even when inserting the same way, at the same angle..)

So I actually move the cheshire so that the ring of the cheshire is

round with the tube (as it was during the first original collimation.

Ofcourse this is not the way to do it...

I hope the Parallizer eliminates my frustration..