Corroded ITF PST Mod

[Paul73]

17 minutes ago, Solar B said:

Understood Paul and can see what your saying about the image scale .... however I'm still pro the DS (have to be honest)

so trying to save yours ... you need not set your sights as high as a D-ERF ! ... a C-ERF would do or even an old AE one like

i used to use and how's about placing a wanted Ad?

It would be great to keep it (the DS unit) if the cheaper alternatives to the D-ERF's give similar views and still protect. I had assumed that Baader D-ERF were the GoTo filter. As mentioned, it will be going in a 100mm f10 scope.

[Solar B]

I'm no ERF expert but it is accepted that the D is the dogs (esp for imaging) ... most will reject UV/IR expect the Daystars ... 

Beloptik also do one of choice ... I reckon a C or an old AE one would more than suffice though.

 

Brian 

[Moonshane]

Do remember that the erf is protecting your kit not your eyes. The etalon and bf protect your eyes.

[spaceboy]

OK so new ITF installed. Hats off to http://maierphotonics.com/656bandpassfilter.aspx for the speedy delivery.

I am just going to go out with it in standard PST guise for a quick check but wanted to confirm first as it's different to the Coronado filter that the reflective side is objective side and the red side is eye piece side.

[Moonshane]

In mine the original was shiny side to objective in the pst? ?

[Moonshane]

That said both sides are shiny in mine albeit the shinier side is objective side.

[spaceboy]

My thinking was reflective side to objective. Have just been out to give it a quick blast and there is no doubting it's a lot brighter. Great for higher magnifications but probably a bit too bright for lower magnifications now On closer inspection I wouldn't have said that the filter I removed was all that bad TBH and given the size of the blocking filter in comparison to the ITF I'd have thought I'd get away with it to some degree. Id say it resembles a halo with a relatively clear centre but clearly any degradation to the filter has an effect. Makes sense I guess as overall light through put is being restricted but a shame none the less as almost half of the original filter looked OK ??? It is interesting to compare the two filters. As you say the Coronado is reflective both sides where as the Maier is reflective one side and a red colour the other. Maybe this helps give a brighter view ??

[Rusted]

Better late than never?

Image attached of PST ITF from recent purchase. 101xxx

Removed the prism and then put a small mirror at 45° in the housing for a "head-on" flash photo of ITF.

ITF front surface flawless blue coating by reflection yet looks orange from most angles.

The focuser spring is retained with a circlip, next to the black ring and can be pushed off sideways with a small screwdriver.

Replacement ITF 656 /17 duly ordered from Maeir Photonics.

Is the "glue" on the eyepiece holder a slow heavy drag?

Or does it need a good wallop to break the thread locking agent?

Is there such a thing as a PST "Locktight" solvent which might help remove difficult fittings?

More images of disemboweled PST on my blog. 13+ ?

[Rusted]

Just me talking to myself as usual:  PST dismantling Pt. 365.

By sheer luck I found an old stock 'Constrictor' strap wrench in a rural timber yard.

With the prism removed I could clamp the PST body down flat on the B&D bench with a plastic padded Bessey F-clamp.

Don't forget some packing underneath to protect the finish of the prism housing if you still value it.

Remember not to compress the tuning ring when clamping the PST housing down.

It needs the gap in the workbench to avoid the tuning/etalon being crushed.

The gold tube needs padded protective support at the objective end as well.

This is to avoid bending the tube at the thread end as you lean hard onto the BOA strap wrench.

Your weight would otherwise be cantilevered by the thin, gold tube, which isn't very kind.

 

It feels incredibly violent as the parts unscrew in noisy jerks.

With lots of very loud creaks, as the thread literally fights every degree of movement.

I now have the gold tube free along with both sections of the eyepiece holder.

The gold tube would not shift until I tried the old trick of tightening it first.

Only then would it give under loud protest and lots of hard pressing on the BOA!

The now naked threads are left with a powdery red residue. Red Loctite?

 

With the workshop a nose dripping minus something I've brought the almost bare housing indoors to warm up the rubber tuning ring. 

At the moment the tuning ring looks and feels like very hard, shiny plastic.

I need to get the tuning ring off, to get at the tiny screw, which drives the inner tuning ring.

Try tapping your hand on the tail of the BOA lever while still leaning on it if your tube pretends it won't unscrew.

Keep the BOA's rubber strap as tight as possible.

It will work just like a ratchet so doesn't need to be re-wrapped each time.

I'll post some pictures when I have managed to get the etalon free.

[Merlin66]

5 hours ago, Rusted said:

At the moment the tuning ring looks and feels like very hard, shiny plastic.

The standard PST tuning ring is a soft knurled rubber ring easily removed....

I've requested on numerous occasions to both Meade and their distributors to remove the Red loctite from the assembly - general answer "No user replaceable parts within"

Are you considering a Stage 1 or Stage 2 Mod? - or just pulling the PST apart to see what's there?

 

 

[Rusted]

Hi and thanks,

I am modding my old 6" f/8 Celestron refractor for H-alpha.

It will go on my Old Fullerscopes MkIV.

A nice bit of daytime observing will keep me off the streets.

Used PST? Check.

Boa strap wrench? Check.

Rusty ITF? Grrr!

D-ERF? Ouch!

And so it goes on. 

What really surprised me, apart from the cost, is the extreme violence required to dismantle the PST!

PST modification is certainly not for the feint hearted. Nor peace loving hippies.

Well, not unless they built serious muscles 'hugging trees' and have their own ear defenders.

[Rusted]

Managed to get the etalon off my PST housing after an hour of cranking uselessly. Now I can do Stage II.

I added a bit of plumbing PVC to make the Boa handle more comfortable and add a little extra leverage.

It also trapped the rubber strap more securely than by hand.

New ITF and D-ERF are in the post along with a set of Beat Kohler's PST etalon adapters at AOKSwiss.

Not a great picture but you can see what is happening. It might help somebody who is on the verge of giving up.

 

 

[astrorg]

HI
Just got a second hand PST and it needs the ITF replaced - got a whitish ring in it.
See my open Thread here - I did not see this thread before I opened mine - not sure what the filter in the ocular receptacle was called - but I am learning!

Where can I buy now [Feb 2019] a filter - just the glass to slide in in place of the old one - so, finally get clearer views?

Thank you 'experts' !

Clear skies
M

[moriniboy]

http://maierphotonics.com/656bandpassfilter.aspx
But it looks like they are out of stock ?

 

[Moonshane]

The Maier one works really well and is an easy replacement assuming you can get the retaining ring off. It looks like someone had had a go already maybe.

I found mine worked ok but with the new filter is much brighter with binoviewers. I converted mine to a PST mod.

Other options are probably more expensive than the Maier to be honest.

It is a consumable item. How long you get depends on how stored and a bit of luck I think 

 

[astrorg]

Thanks for reply.

It seems the only cheap option available, but out of stock.

I emailed them and hope to get a reply soon.

Strange thing is the enquiry form have low characters max limit!

[astrorg]

Anyone know if there is a problem at Maier Photonics ?

Sent 2-3 emails + enquiry form and again an enquiry form to ask to read emails as the enquiry form itself is set to only take about 35-50 characters!
My wife called them by phone about 15 minutes ago and over there is 5h earlier and nobody replies.

Are they closed for holidays or closed for good or ...!



ADDITION

Manage to speak on the phone and ordered one.