PST Etalon Assembly / Disassembly Video

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poita

Re: PST Etalon Assembly / Disassembly Video

Post by poita »

Sorry, I'm a bit dense when it comes to lenses.

Quick question, if the collimating lens is at the -200mm position then, could the rest of the etalon be moved backwards as the beam is now collimated?

Just wondering if it might be a way for people not to have to cut down their tube?


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Re: PST Etalon Assembly / Disassembly Video

Post by Merlin66 »

Basically yes.
If the barlow were separated from the etalon assembly and placed independently at -200mm then in theory the rest of the etalon could be positioned at any distance behind it.
In practice...this may be a bit more difficult. The f ratio of the donor still has to be respected and the "cell" used to hold the barlow would then have to be positioned, I assume inside the focuser/ donor tube accurately on axis and at the -200mm....then the PST etalon still has to be mounted on the donor scope..
Note: As the barlow/ etalon never has to be moved once it's in the design position there's really no advantage in placing a focuser between the barlow/ etalon and the donor objective...
On the 102mm PST Mod I'm doing with the Lyra Optics/ TS IN1021/ Kumning United Optics 102/1100 donor, the original focuser can be removed and replaced with a 30mm spacer...no cut tubes...


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colinsk

Re: PST Etalon Assembly / Disassembly Video

Post by colinsk »

Sorry, I'm a bit dense when it comes to lenses.

Quick question, if the collimating lens is at the -200mm position then, could the rest of the etalon be moved backwards as the beam is now collimated?

Just wondering if it might be a way for people not to have to cut down their tube?

Collimation s achieved when the distance of the two lenses are the sum of the focal lengths.


poita

Re: PST Etalon Assembly / Disassembly Video

Post by poita »

Something I didn't notice before, on the back of the etalon housing, an 'M' or a 'W' is scribed into the black metal (on the outside facing the eyepiece side of the scope).

I got another PST in today to repair, and it also has the M or W on the etalon housing. Anyone else noticed this? I had to really tip the assembly to the light to see it, it looks hand done, not stamped or anything.

Also on the one I just got in, it has a square of foam under one side of the foam ring, and it is opposite (180 degrees) the pencil number/marking on the side of the etalon glass.


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Re: PST Etalon Assembly / Disassembly Video

Post by swisswalter »

Hi Peter

my SM90 has such marks too


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Kees

Re: PST Etalon Assembly / Disassembly Video

Post by Kees »

Hello,

Your modificatios are great, I love it.
Me too I would like to have an acrylic ring v2 or v3 , of course a good donation will follow and then improved pics I hope
Give me the adress for a donation.

Regards Kees.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Hi folks, been away for a couple of days, back now...

If you would like an acrylic ring drop me an email marktownley2000 at yahoo dot co dot uk I plan to get some out in the post at the start of the working week.

Kees, I have your message via my website however I don't have a reply email for you, would you mind saying hi to me on the email above. Getting the acrylic ring out to you is no problem :)


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Re: PST Etalon Assembly / Disassembly Video

Post by Kees »

Mark,

Thank you very much for your answer.
I am happy and I will wait.

Regards kees


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Thanks to the people who have messaged me regards the acrylic ring. I have finally got round to packaging these up, and unless have clear blue skies in the morning (monday) - which is highly unlikely - I will get up to the post office first thing and get them off to you.

I've enclosed 2, incase one snaps etc. They are 'split' to allow it to slide over the etalon easily. There will be a small amount of play at the bottom when it located in place in the etalon housing, which is normal.

Peter, regards the marks on the etalon housing where exactly is it? I've looked on mine but can't see it - but that doesn't mean i've been looking in the right place... Do you have a pic?


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poita

Re: PST Etalon Assembly / Disassembly Video

Post by poita »

I'm having trouble getting it to show up in a photo, but it is on the outside back of the assembly, facing the eyepiece.


Kees

Re: PST Etalon Assembly / Disassembly Video

Post by Kees »

Hi,

I've also looked on mine but can't see it.
Maybe I look on the wrong place.

Regards Kees.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Thought I would post this here as think it demonstrates the fruits of the work i've been doing on my PST mod; sweetspotting effects are not noticeable at this image scale allowing large mosaics to be easily put together. This is an 18 pane mosaic taken with the 127mm SS @ 1900mm fl. Stacking done in avistack2 with all post processing done in PS CS4. It's a very large image so hopefully you have a big monitor! Make sure you use the ctrl+ to zoom in...

Black and white... http://farm8.staticflickr.com/7280/7826 ... dfeb_o.jpg

Colour... http://farm9.staticflickr.com/8288/7826 ... 2e8c_o.jpg

I'm really pleased with it, and reckon can give the Lunt152s a run for their money now, pretty good seeing as this works out at 1/5 of the cost ;)

Hope you like,
Mark :)


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poita

Re: PST Etalon Assembly / Disassembly Video

Post by poita »

Which camera is that using Mark?
It looks fantastic.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Thanks, It's a DMK31 Peter. :)


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Kees

Re: PST Etalon Assembly / Disassembly Video

Post by Kees »

Hi Mark,

Its look good and very nice.

Kees.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

OK, everyone who ha contacted me so far your acrylic rings have been posted today, via airmail if abroad or snail mail in the UK. I hope you find them of use and hope you can make a small donation to CBSAP http://www.charliebates.org/

Thanks, Mark


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Ibbo

Re: PST Etalon Assembly / Disassembly Video

Post by Ibbo »

thanks for the acryliic rings they arrived today




while the et was out I took this pic

is it normal for this offset




Steve

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Re: PST Etalon Assembly / Disassembly Video

Post by solarchat »

Thank you for supporting the nonprofit Mark. Winship sent a donation but his paypal email was bad so the receipt got bounced back. Tim if you're there, THANK YOU!


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Glad the rings have arrived Steve, wow, those etalon plates are offset quite a bit. Mine are certainly set square, not sure about anybody elses?


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Kees

Re: PST Etalon Assembly / Disassembly Video

Post by Kees »

Mark,

Today the acrylic rings are arrived.
Thank you vey much for that work and sending me the rings.
The donation is on the way.

Regards Kees.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

Mark,

Today the acrylic rings are arrived.
Thank you vey much for that work and sending me the rings.
The donation is on the way.

Regards Kees.

No worries mate! ;)

Ironically it's taken less time to get to Oz than some of the other Ebay stuff I posted at the same time that's just going internally in the UK :unsure:


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Re: PST Etalon Assembly / Disassembly Video

Post by kornfeld1 »

My rings came in today; both in good shape. Thanks for shipping those. :thumbsup:




Now for the bad news. :(

I disassembled the etalon assembly, and in a moment of sheer stupidity, picked up the etalon itself by the foam. The foam had stuck to the etalon, so it stayed stuck just long enough for the etalon to lift up in the air...and then unstick and crash back down onto my work surface and decontact.

Two of the spacers are still contacted to one plate of the etalon. The third spacer is completely free.

I've tried several things to get them recontacted. Both surfaces have been cleaned with isopropyl alcohol, and I've brought the two plates together at an angle and tried rotating them relative to one another.

I've heard a few unexpected clicks that sound like things stuck back together, but when I check, they are definitely not stuck.

I've come to terms with this. It's an expensive toy; but it's still just a toy.

So, any tips on things I should try with getting it back together?

And anyone want any measurements of anything?


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Re: PST Etalon Assembly / Disassembly Video

Post by colinsk »

Can you open a new thread on recontacting etalons?

:(


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Re: PST Etalon Assembly / Disassembly Video

Post by kornfeld1 »

Good call.


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Re: PST Etalon Assembly / Disassembly Video

Post by Merlin66 »

OUCH!
That's bad news...sorry to hear of your problem.
I've never had an etalon apart, but I believe others have....
Let's see what get's posted to the new "Recontacting" thread....


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Re: PST Etalon Assembly / Disassembly Video

Post by sullij1 »

E Gad man, Lesson to us all as we mod the thing. Anayway, Mark, I hope I amde the spacer list. I know I am across the pond and it may take a while but really don't know if you recieved my email.

Joe


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kornfeld1

Re: PST Etalon Assembly / Disassembly Video

Post by kornfeld1 »

Yep. My message to pass on to everyone else: put a towel or something on the surface you're working on to provide some cushion. My etalon basically fell directly onto the granite counter top on the island in my kitchen. Not smart.


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Re: PST Etalon Assembly / Disassembly Video

Post by marktownley »

E Gad man, Lesson to us all as we mod the thing. Anayway, Mark, I hope I amde the spacer list. I know I am across the pond and it may take a while but really don't know if you recieved my email.

Joe

Yes, i posted one for you, if still not here in a couple of days let me know and will send another out...


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Re: PST Etalon Assembly / Disassembly Video

Post by sullij1 »

Thanks Mark! :hamster: :hamster: :hamster:


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Re: PST Etalon Assembly / Disassembly Video

Post by sullij1 »

Hello All,

In the vernacular of the good Mr. Townley;

The postie dropped a post today emblazoned with the golden image of the queen, conspicuously marked as ROYAL MAIL.

WOW, I get mail all the time but never Royal Mail! :cheer: Yes it contained my ceramic spacers. Happy-Happy-Joy-Joy! :rockon: :hamster:

And in all seriousness; Thank you Mark. :thanx:

Cheers,

Joe


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