Planning my first PST mod and need some help

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Planning my first PST mod and need some help

Post by solarchatted » Tue Apr 09, 2019 2:56 pm

Hi
Now I have a new ITF, things are 'clear' !

What I wish to do is the obvious mod to use PST as a Quark and use it on various scopes, including my AR152 F/6.5

My 'practical' questions:

1. Do I need to warm tube to unscrew it from PST? I do not wish to break anything or scratch tube!
2. I do not wish to cut original tube, what do I use that fits or step-down adaptors or even if I need to use PTFE ?
3. I do also not wish to modify any telescope [if possible] and simply modify PST and use it with a standard 2" nose piece, any clear procedure to do it 'clean' and without ruining the PST ? - i.e.so I can re-mount it, in case I need or want to re-sell it in the future, or use it as portable - I am a keeper!
4. future questions will be which filter to use in front of the larger AR152, that does not break the Bank?
I plan to mainly use it with my smaller scopes 72mm and 80mm and in theory I will not need the front filter and maybe just use a good Baader IR/UV one!
Maybe a 100mm [cost much less] and use it with all scopes and make a reducer for 152mm and still use 100mm
5. Is it really worth the hassle and expense? - well, it is if one does not wish to buy a DS expensive adaptor for PST and still be in the 'small' magnification.
This might be another solution - https://www.meade.com/coronado-30mm-blo ... rough.html - Straight through ?

You cannot have the best for very little and since I will never be able to afford to buy 'anything' expensive, I have to do as much as possible myself and using the PST with a new ITF and still a little 5-6mm hole!

I am really in a limbo, desiring something more powerful [when needed] and be able to use my telescopes without buying a Quark - I still need to see, how long they actually last - in particular the electronics!

In short, I need the less expensive and but DIY doable solution to use PST SS as a Quark, over my telescopes - AR152 F/6.5, AR102SX [short tube!] and SW 72ED.

I could use my old SW ST80 and modify it - I never use it now - but is is F/4 or get a cheap ~ £. 70 70mm F/10 and modify it as others have done.

It is all about a balance of money spent and 'real' results worth doing a mod or not and look at what others can afford to do!

Thank you for putting up with me.
Mauro

PS sorry if I might have mixed up anything, I am not stupid, but I am no expert in Solar and Optics
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Re: Planning my first PST mod and need some help

Post by solarchatted » Tue Apr 09, 2019 3:00 pm

You can PM me, if you wish ...
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Re: Planning my first PST mod and need some help

Post by solarchatted » Tue Apr 09, 2019 3:33 pm

Finally found a little time to look and yes the best tool is the car oil filter tool [the one with a belt to avoid scratches], to remove PST tube.

Which way?
The normal anticlockwise movement? With left hand holding body [or vice with padding!] and right hand turning left or towards me if parallel in front of me?

I might try and make an adaptor, modifying what I can find sizeable.
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Re: Planning my first PST mod and need some help

Post by marktownley » Tue Apr 09, 2019 8:08 pm

Hi Mauro, have you tried unscrewing the gold tube by hand? I've had some PSTs that just unscrew with little force.

If you're going to use your existing scopes you will need to get them working at f10 for the PST etalon.
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Re: Planning my first PST mod and need some help

Post by Merlin66 » Wed Apr 10, 2019 12:49 am

Mauro,
I have a write up available for the PST mod drop me an email address for a copy.
A couple of critical things.
The etalon assembly must be positioned 200mm inside focus.
The etalon works in an f10 beam. If the donor scope is faster (f5) the aperture will be reduced.
Adaptors, front and rear are available.
An ERF is recommended (front or internal) above 60mm aperture.
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Re: Planning my first PST mod and need some help

Post by MalVeauX » Wed Apr 10, 2019 10:29 am

Hey Mauro,

Some PST's are a bear to open up and are glued. I have opened two of them now. One was hard. I scratched it up good. The other was easy, it just came apart. You can use things like a heat gun or hair dryer to help warm up bonds (glue) and gently work things until they give. The most important thing about taking apart a PST is to NOT ruin the etalon housing. It's delicate. After you remove the gold tube, you need to peel off the rubber around the tuner. There will be tape and a small screw. Mark where the screw was and the holes it lines up with so you can put it back exactly. But take all that out. THEN try and take off the etalon from the black box. This way you are not twisting the etalon housing and breaking that little screw, which will totally ruin the PST etalon housing tuner.

Ken (Merlin66) wrote the book on this. So check out his information.

Also, I have a log showing how I did mine, and what I've done with it. Also the adapters I bought from AOK Swiss and all that. More info here:

viewtopic.php?f=9&t=25420

Since you do not want to cut a tube and you're looking to do things inexpensively, I recommend you forget looking at big 150mm+ apertures. Instead, look at 102mm aperture achromats at best. You can get away with a Baader 2" HA 35nm filter as an ERF, or a Baader 2" Red CCD-IR Block filter as an ERF in front of the etalon housing using a 2" extension in front of it, in an unfocused beam of light to cut costs. The collimation lenses are F10 on the etalon, and require +/-200mm on both sides to reach focus. So you have to find a really short tube with a short focuser to avoid cutting a tube. But in reality you will need to just cut a tube most likely. Alternatively, you can get different collimation lenses to go to F8 or something. Another option to avoid cutting a tube is to get an F8 scope and then get a Baader Glasspath 1.25x corrector (typically used for binoviewers) to bring the scope to F10 natively. Then it will work for PST modding. Another option is to get a native F10 scope all together. Celestron's 102mm F10 Omni XLT is a great option and inexpensive. And again, you can block the heat with one of the 2" filters I mentioned just above. You will want to get a bigger blocking filter (Stage II mod), so a Coronado 10mm blocking filter is a good way to go. You are not likely going to use sensors much larger than 10mm anyways (mono sensors that is), so it should be fine. If you're at all worried and have larger sensors like M43 size, then get the 15mm filter. Since you're on a budget, I doubt these are options, so the 10mm filter will be good. Then, to match it, something like an ASI290MM camera or ASI178MM camera would be worth looking at.

Very best,

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Re: Planning my first PST mod and need some help

Post by solarchatted » Sun Apr 28, 2019 6:00 pm

marktownley wrote:
Tue Apr 09, 2019 8:08 pm
Hi Mauro, have you tried unscrewing the gold tube by hand? I've had some PSTs that just unscrew with little force.

If you're going to use your existing scopes you will need to get them working at f10 for the PST etalon.
Sorry for very late reply, I went on holiday and then back to work, I am now getting back to it.

I did try - not too strongly - unscrew it by hand.

Then I go the leather puller and unscrewed it straight away and screwed it back in by hand.
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Re: Planning my first PST mod and need some help

Post by solarchatted » Sun Apr 28, 2019 6:16 pm

MalVeauX wrote:
Wed Apr 10, 2019 10:29 am
Hey Mauro,

Some PST's are a bear to open up and are glued. I have opened two of them now. One was hard. I scratched it up good. The other was easy, it just came apart. You can use things like a heat gun or hair dryer to help warm up bonds (glue) and gently work things until they give. The most important thing about taking apart a PST is to NOT ruin the etalon housing. It's delicate. After you remove the gold tube, you need to peel off the rubber around the tuner. There will be tape and a small screw. Mark where the screw was and the holes it lines up with so you can put it back exactly. But take all that out. THEN try and take off the etalon from the black box. This way you are not twisting the etalon housing and breaking that little screw, which will totally ruin the PST etalon housing tuner....
Hi
Sorry for very late reply!

I am thinking either use a Bresser 102sx I have - but is a fast one at F/4.5 or get a ... I have seen cheap 100mm F10 easily modifiable ... !
The Celestron's 102mm F10 Omni XLT seems a very good choice.
What do you think of the Bresser 102SX? It is very short?

I think the first thing to do is to get the PST block ready to be used and then start playing with scopes!

A lot to think about.
Mauro

PS thanks for the links!
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Re: Planning my first PST mod and need some help

Post by marktownley » Sun Apr 28, 2019 6:30 pm

Any of the 100mm f10 scopes are excellent for PST mods.
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Re: Planning my first PST mod and need some help

Post by solarchatted » Wed May 08, 2019 12:24 pm

Thanks
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Re: Planning my first PST mod and need some help

Post by solarchatted » Fri Jun 14, 2019 8:30 am

I am 'slowly' getting along [time permitting] to understand 'the works' by testing and already the SCT focuser mod is better than PST standard setting - even using bath-tub splash-proof insulators as spacers within 1.25" adaptor to hold PST eyepiece holder! :P
With SCT focuser I already got rid of the PST block with prism that interferes with beam, in fact (as mentioned on another thread) I now have a clearer and brighter image as is ... but beam has intensified too.

One question, just to be sure - for the time being, is it OK to use a Meade series 4000 RED #25A filter + IR/UV in front of etalon at adaptor length - i.e. in out of focus beam?
I already used the #25A as it is with PST or SCT mod and it does help in certain circumstances - I guess when it hazy.
Then if necessary I will probably get a Baader 2" HA 35nm or a Baader 2" Red CCD-IR Block filter.


I understand also this way I will have heat currents ... not having an ERF in front of telescope ...

If I can get away with 25A, then next expense will be a 100mm ERF to use with AR152 (possibly).

I am just trying to have 2 scopes, PST standard (when needed) and a I can dismount PST and use (mostly) with a 100mm or the AR152.
I am not greedy, but I would like to put one foot inside the 'better' side of Solar.

Thanks for taking the time to help
M

See images with SCT mod - https://tinyurl.com/y5qfdrns - although it was clear, it was quite hazy and if I am not wrong used the RED #25A filter and got away with it ...
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Re: Planning my first PST mod and need some help

Post by AndiesHandyHandies » Fri Jun 14, 2019 11:26 am

Hi

I am in the process of doing the same PST 'Combat'.

Now I have a new ITF, things are 'clear' !

What I wish to do is the obvious mod to use PST as a Quark and use it on various scopes, including my AR152 F/6.5

My 'practical' questions:

1. Do I need to warm tube to unscrew it from PST? I do not wish to break anything or scratch tube!
Follow Merlins advice on removing the rubber ring and small screw. Two of us used a rubber filter wrench, held black box in vice and a small rubber filter wrench on the etalon. It moved when I used my hand on the Gold tube as well. Obviously its a lottery as to whether the gold tube comes off on its own or with the etalon even so. We managed to get the etalon off the black box.

I soaked the screws in the black box with ethanol for a day but I still wrecked one using a small rachet wrench and had to drill out the top. The grease on the prism slide migrates onto the prism and I wanted to put stops in the front of the black box and at the bottom of the blocker / eyepiece holder. We tried to get the eyepiece tube off. Only the top part with the Comb Blocker in came off. A blowtorch did not get the base to move. Rod had to turn up a little ring to push fit down the useless ribbing in the base and bodge on a repair washer and holding random rubber ring to make a stop. Looking down the Comb Blocker, with no front on the black box, there are reflections off the top and bottom of the prism so the stops help to hide those. Also as the prism is not coated there are lots of transmitted and reflected spots in the box. So I painted the front, bottom and lid Black2 and flocked the back sides where the worst reflections are.

It would be usefull if front ERFs are called DERF and intenal ones ERF and the actual Comb Blocker that as there does not seem to be a standard.
Refections of the Sun inside the telescope are an issue. Use on the Moon first, etalon only, to find the brightest reflections.
Then on the Sun look into the blocking filter with no eyepiece to see what reflactions there are.
In the Vixen VMC I had to stop stray daylight coming in, commercial Maks are not baffled well enough as they are struggling with fully illuminated field issues, and limit the light to whats being used.

Put on a long front baffle, put a baffle on the edge of the secondary, and the corrector lenses edges are not blackened, put a stop on the front of the rear baffle. Made a smaller one to start with and then found the Suns size on it and turned it down to that. With the black box and 5mm Comb Blocker you are observing off axis for proms so you do not want any other light to get in. I found that ribbed baffles in the SH Barlows used and the black box are useless. In the Barlows Rod turned them down to have forward and rear facing angled knife edges. An angle into the wall to act as a 'beam dump'. With the bit between turned down so the knige edge vignettes it and the sloping edge of the far knife edge then reflects the out of field light onto the Black2 wall opposite. For the black box Rod made a nice baffle after the PST etalon, bright reflections off the etalon as it reflects out of Comb light. You need to get to the point where there are just a few very thin bright rings, off the kinife edges, and the rest is black as possible. I have the Vixen and black box now so the Sun has a inky black background to the eye,imaging will probably show scatter, and with it just outside the field there is no light visible to the eye.

2. I do not wish to cut original tube, what do I use that fits or step-down adaptors or even if I need to use PTFE ?
AOK Swiss sells standard and custom adapters. I had a custom front one to T2 made for my Vixen VMC110. I am about to order a standard AOK Swiss rear PST to 2" adapter for a DS with Bobs H-alpha filters, one for proms and 2 for chromosphere? We have tried a Omega Bobs 1.5A (0.15nm) as a Comb Blocker and it worked. Its narrower than the PST one. It is a cosmetic second so some variations across it. And allows the full etalon aperture to be used.

3. I do also not wish to modify any telescope [if possible] and simply modify PST and use it with a standard 2" nose piece, any clear procedure to do it 'clean' and without ruining the PST ? - i.e.so I can re-mount it, in case I need or want to re-sell it in the future, or use it as portable - I am a keeper!
I have made the etalon into a 'Combat' by taking out the two lenses, they should be marked with an arrow or mark them and check which side the flat face goes. I have put a Omega Bobs 25.4mm 40nm ERF in the front. It blocks long IR the Baader 35 nm lets through and it has dimmer reflections. And a KG1 25.4mm in the back to protect the etalon. I have used the PST Combat on a 127mm refractor on its own, with black box on the back, with no issues. But I am using a 2" Baader IV-IR in the 2" extension tube set on front of the PST adapter about 13cm in front of the etalon as well to spread the heat rejection out. Good up to 7" I would think. I found a 48-43mm filter ring adaptor on the front worked to baffle reflections from the 7cm of focus tube in front of it. For visual I am using a 1.25" Beloptic UV-IR on KG3 in the eyepiece for additional safety.

4. future questions will be which filter to use in front of the larger AR152, that does not break the Bank?
I plan to mainly use it with my smaller scopes 72mm and 80mm and in theory I will not need the front filter and maybe just use a good Baader IR/UV one!
Maybe a 100mm [cost much less] and use it with all scopes and make a reducer for 152mm and still use 100mm
MarkT says he only uses his 127mm once a month, in the UK so I am sticking with a Lunt 110mm DERF I bought SH. 100mm clear in a holder. You can use the PST with a telescope shorter than F10 it just vignettes it to F10. Just use a DERF or stop to suit or internal ERF, though the external DERF is better but more expensive.

5. Is it really worth the hassle and expense? - well, it is if one does not wish to buy a DS expensive adaptor for PST and still be in the 'small' magnification.
This might be another solution - https://www.meade.com/coronado-30mm-blo ... rough.html - Straight through ?

You need to get a bigger Comb Blocking filter. Daystar use Andover filters 12.5 or 25.4mm as I recall. They are soft coated so need a good DERF/ERF up front to make them last and stored in a moisture free environment.
I am trying Omega Bobs 40nm 25.4mm ERF and one of his H-alpha 'seconds' filter 1.5A at the moment as the Comb Blocker.

On my 127mm F7.5 I tried a bodge to stop cutting the tube. I put a nose piece off a 2x ED barlow with T2 to 48mm infront of the AOK adapter / PST etalon and black box. With no PST lenses. I got a good image. Rod has tested Barlows at the position they need to be for the PST and black box on a double star and they give about 4x. So I was working at F30 straight through. Looks as good as Pedros images and with the Bobs H-alpha just dropped onto the Beloptik in the eyepiece good for chromosphere (needs to be in a tilting holder for Stage 2 Mod).
From the Daystar site the PST looks like 0.7A and with Bobs filter 0.5A.

The problem with the PST Etalon is it needs to be outside the focusser to tune it. So there may not be enough back focus when doing a Stage 1 mod as the black box needs 200mm back focus.
MarkT shared a cunning mod where you move the collimating lens up into the focus tube. There may be a slight issue with the 'collimated' beam drifting out?
On my Vixen VMC110 mod, PST lens vignettes F9.4 to F10, I gambled that I would reach focus doing that and I was lucky that it does, just.
Rod made me a push-in, masking tape filler, holder from an old barlow. And the PST Collimator lens held in a little nose piece Barlow holder with a plastic Celestron Moon filter holder pushed in to hold the PST lens, as they use 25.4mm filters. (Anyone found a Chinese metal holder for 25.4mm Moon filters?)

Rod gets a full sun with a 2250mm fl refractor through the PST. For rare good days I will try a F10 180mm Mak, fl1800mm, as it nearly fills the PST and using the full aperture helps reduce instrument angles for a larger sweet spot. All PST mods will only have a small sweet spot in the middle due to collimation off band, acceptance angles and instrument angles.

You cannot have the best for very little and since I will never be able to afford to buy 'anything' expensive, I have to do as much as possible myself and using the PST with a new ITF and still a little 5-6mm hole!
A stage 1 Mod does make things larger and have more resolution. Though the sweet spot if not central will drift out of view. You may need to centre the etalon, MarkT did make a custom ring but has lost the CNC file unfortunately.

I am really in a limbo, desiring something more powerful [when needed] and be able to use my telescopes without buying a Quark - I still need to see, how long they actually last - in particular the electronics!

You can use the PST as it is on any scope. With suitable DERF or ERF.
Move the collimator forward to save sawing up your scope to reach focus.
It vignettes less than F10 to F10. So you can use a 100mm DERF on the small scopes and the longer refractor for larger image.
You can use a weak barlow, Baader 1.25x glasspath seems popular, to make a faster scope F10.
Or use a shorter collimator and re-focusser on a faster scope to use its full aperture, matching singlets or achromatic doublets for better quality.
solarchatforum.com/viewtopic.php?f=9&t=24425&p=219615#p219615

For the PST as is MarkT uses a UV-IR to block IR as it softens the picture when imaging.
I use a 2" Beloptik UV-IR on KG3 to block all IR. With a 52mm to 48mm adapter.
www.diane-neisius.de/coronado_pst/index_E.html

In short, I need the less expensive and but DIY doable solution to use PST SS as a Quark, over my telescopes - AR152 F/6.5, AR102SX [short tube!] and SW 72ED.

I could use my old SW ST80 and modify it - I never use it now - but is is F/4 or get a cheap ~ £. 70 70mm F/10 and modify it as others have done.

It is all about a balance of money spent and 'real' results worth doing a mod or not and look at what others can afford to do!

An AOK Swiss front end adapter lets you do Stage 1 mods for £50ish. 48mm or T2.
You can move the front collimator lens forward to reach focus without cutting tubes down.
You can use a weak Barlow £95, or ES achromat? £75 on shorter F no scopes to reach F10. Remember to check its power used in front of the PST at its position inside focus.
Or you can replace the PST Collimator and re-focusser lenses to use all a shorter F No telescopes aperture.
You should block UV and all IR for your safety and to make Comb Blocker last longer.
Long IR KG3 or Omega Bobs 40nm 25.4mm ERF.

Andrew


Thank you for putting up with me.
Mauro

PS sorry if I might have mixed up anything, I am not stupid, but I am no expert in Solar and Optics

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