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#1 Special Ed

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Posted 13 April 2019 - 09:19 AM

Hi Everyone,

 

I am a long time PST owner--got mine back in 2005--and I recently became aware that many PST's share some common problems that degrade the view they provide.  Just about everybody knows about "rust" on the objective (the glass on the front of the scope)--mine developed rust in 2006.  I shipped it back to the manufacturer for a fix and they shipped it back to me with a clear blue objective.  No problems with that since.  If you have a clear blue objective you are probably OK there, too.

 

However, the fix involved putting a filter at the base of the eyepiece barrel and these filters can degrade over time and get "rusty".  The problem is, the filter is buried in the innards of the PST and many owners don't know it's there--I didn't.  And it's not as easy to check as just looking at the objective but it's not that hard, either.  It involves taking the side cover off of your PST.

 

The rust happens gradually and kind of creeps up on you.  You can still see through the scope, but detail becomes less sharp--like when you're observing through poor transparency.  People even think that's the cause--unaware that actually it could be the scope.

 

Anyway, the views with my PST were not as good as they used to be and when I stumbled across a couple of threads in this forum describing the problem (and the fix) I decided to investigate.  Sure enough, my filter was rusty--not completely clouded over but covered with little splotches--which was enough to affect the view.

 

While checking the filter, I also found that my scope had another common problem--a misaligned pentaprism.

 

The fix for both these problems is relatively easy to do.  I had to buy a couple of tools but they weren't expensive and hey--it's always nice to have a reason to buy new tools, right?  smile.gif   My PST performs better now.

 

Here are some links to threads that have info, pics, and embedded links to more info and pics.

 

 https://www.cloudyni...rice/?p=9105739

 

 https://www.cloudyni...eade/?p=9114688

 

 https://www.cloudyni...-pst/?p=7109201

 

These are links for the replacement filter.

 

 http://maierphotonic...ssfilter-1.aspx

 

 https://beloptik.de/...acement-filter/

 

I passed on this information to a friend in Germany who was unhappy with his PST.  He found that his scope had the problems, fixed it, and was rewarded with much better performance.  He passed it along to a friend of his with the same happy results.

 

You will see if you read the above threads that DavidG provides much useful information and advice.  He suggested I make this post to let others know about the problem and the fix.  Dave helped me a lot and I thank him.  flowerred.gif 


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#2 WadeH237

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Posted 13 April 2019 - 10:56 AM

What a fortuitous posting.  I came over to the forum just this morning to investigate these exact problems.

 

I had an opportunity a couple of weeks ago to compare my PST to another one side by side, and found that mine was much dimmer.  I did a little bit of research and determined that I probably have a rusted ITF.  A quick look inside the scope confirmed that mine is completely rusted.  I also have a tilted pentaprism.

 

I would like to fix these problems, and appreciate the links that you've provided.  The one issue that I have is that whoever assembled my telescope was quite heavy handed with the lock-tite.  I was able to the the top of the eyepiece holder off with a strap wrench, but the lower part will not budge from the body of the PST.  Also, it looks like I'm going to have an adventure trying to remove the old filter because there is a giant glob of lock-tite on the threads of the filter retainer.  I've attached a couple of images of the scope that show the current state and my concern with the filter retainer.

 

I would appreciate any suggestions on proceeding to remove these parts without damaging the scope.

 

Thanks!

-Wade

 

 

Attached Thumbnails

  • IMG_0696.jpg
  • IMG_0697.jpg

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#3 Special Ed

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Posted 13 April 2019 - 11:23 AM

Hi Wade,

 

I couldn't get the bottom part of my eyepiece barrel off either but you can replace the filter from the top.  You just unscrew the retaining ring--see the slots?  DaividG provided me this link to an optical spanner wrench that works well for unscrewing the ring.

 

 https://www.ebay.com...&frcectupt=true

 

That black goop might not be loc-tite.  It might be silicone.  Mine had some on it, too.  It just strips off when you take out the ring.

 

Once the ring is off, I just turned the scope upside down and the filter dropped out.  Then I put the replacement ITF filter and retainer ring back in with needle nose pliers.



#4 PETER DREW

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Posted 13 April 2019 - 11:24 AM

I have dismantled many PST's for various reasons. I have never yet seen one that didn't have a slight forward tilt of the pentaprism. This leaves me to suspect that this tilt is intentional and the possible reason is to deflect unwanted reflections from the image train.

Edited by PETER DREW, 13 April 2019 - 11:24 AM.

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#5 WadeH237

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Posted 13 April 2019 - 12:07 PM

Thanks for the replies!

 

I have ordered the filter and a spanner wrench.  I'll do a bit more research on the pentaprism before adjusting it.



#6 Special Ed

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Posted 14 April 2019 - 07:01 AM

I have dismantled many PST's for various reasons. I have never yet seen one that didn't have a slight forward tilt of the pentaprism. This leaves me to suspect that this tilt is intentional and the possible reason is to deflect unwanted reflections from the image train.

Has anyone ever contacted the manufacturer to see what the alignment specs are for the pentaprism?



#7 MalVeauX

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Posted 14 April 2019 - 07:30 AM

I have dismantled many PST's for various reasons. I have never yet seen one that didn't have a slight forward tilt of the pentaprism. This leaves me to suspect that this tilt is intentional and the possible reason is to deflect unwanted reflections from the image train.

With how the pentaprism is attached, essentially "floating" in place, with some sticky lubricant, at that angle it's positioned with the scope, it has it's own moment arm and sags forward.

 

Very best,



#8 microflite

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Posted 14 April 2019 - 12:03 PM

Seems dicey to try to fix a solar scope by yourself.. I would contact the manufacturer. The risk of eye damage seems to be not worth the savings.

 

regards

Ashok


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#9 DAVIDG

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Posted 17 April 2019 - 04:17 PM

I have dismantled many PST's for various reasons. I have never yet seen one that didn't have a slight forward tilt of the pentaprism. This leaves me to suspect that this tilt is intentional and the possible reason is to deflect unwanted reflections from the image train.

 No the penta prism is not suppose to be tilted. They are tilting because the glue slowly cures and allowed them to move and this is an  almost universal defect like the rusting ITF. A  tilting prism introduced astigmatism into the image. It is the same has having a  misaligned secondary in a Newtonian. When badly misaligned one side of the Sun will be in focus and other side will be out. You'll see the limb won't be sharp on one side. Everyone that has done these repairs has reported an improvement in the image.  Just in this thread " I passed on this information to a friend in Germany who was unhappy with his PST.  He found that his scope had the problems, fixed it, and was rewarded with much better performance.  He passed it along to a friend of his with the same happy results." 

 

Align the prism and replace the ITF and you see a much improved image. 

 

          - Dave 


Edited by DAVIDG, 18 April 2019 - 09:07 AM.

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#10 WadeH237

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Posted 28 April 2019 - 04:22 PM

We've had mostly clouds for a while now, but we had a sunny day yesterday.

 

I just wanted to circle bank and mention that my PST is working like new.  The replacement filter from Maier Photonics as a direct drop-in replacement for the rusted filter.  The retaining ring was no problem at all with the spanner tool.  And while I was inside, I straightened out the pentaprism.

 

It's like new again.  Now if only the sun was doing something interesting...

 

Thanks,

-Wade


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#11 Jairo

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Posted 04 June 2019 - 08:10 AM


These are links for the replacement filter.

 

 http://maierphotonic...ssfilter-1.aspx

 

 https://beloptik.de/...acement-filter/

 

There is a huge difference in price in these two options. Do you know what are the pros and cons?



#12 LesB

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Posted 04 June 2019 - 09:57 AM

Do the problems discussed here extend to the larger aperture Coronado SolarMax scopes?

 

Don't know how sturdy the PST is but a loctited fixture needs to be heated to facilitate removal.  Sometimes a hair drier might soften up the gunk.



#13 Special Ed

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Posted 07 June 2019 - 10:54 AM

There is a huge difference in price in these two options. Do you know what are the pros and cons?

No, I don't.



#14 Maxtrixbass

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Posted 10 June 2019 - 08:43 AM

There is a huge difference in price in these two options. Do you know what are the pros and cons?

Having just started research on this I was told the BelOptic differs in a design that would last much longer. The Maier is more like the original ITF filter although the general feedback is that they are still longer lasting than the stock ITF filters.

 

So: Pros and cons= price vs lifespan

 

A great resource is Bob Yoesle (BYoesle here on cloudy nights). He seems to know all about solar scopes and the PSTs in particular and was very helpful in answering all my questions.


Edited by Maxtrixbass, 10 June 2019 - 08:47 AM.


#15 DAVIDG

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Posted 10 June 2019 - 09:32 AM

 I have one of the very first ITF's  that Maiers made in my PST and it is still perfectly clear. It's been at least 5 years now.

 

                - Dave 

 

 

 

maiersitf.jpg


Edited by DAVIDG, 10 June 2019 - 09:34 AM.


#16 viewer

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Posted 10 June 2019 - 12:54 PM

Sounds reassuring. Mine is a couple of years.



#17 Bagwell

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Posted 12 June 2019 - 09:50 PM

Well, I found my Pentaprism was tilted.  I have that straightened up now.  I cant tell if my ITF filter is clouded over or not.  I do need to separate the two filters in the eyepiece holder to check the ITF correct?  I got the eyepiece holder upper and lower sections out of the PST Prism housing but they didnt separate and The bottom of the eyepiece holder has two holes instead of a slot to remove the ITF filter from its holder.  I guess I need a very small pin pliers or whatever they are called.  Any ideas?  

Thanks, 

Vaughn



#18 DAVIDG

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Posted 13 June 2019 - 12:52 PM

  You don't have to take the ITF  filter out to inspect  it, you can take the side cover off and look at the bottom of the  filter See the image in posting #2 in this thread and you can see that it looks hazy.  If you got the eyepiece tube off then you should be able to tell if the filter looks hazy. Post a picture of it.  

   You can get an inexpensive optical spanner wrench that has pin attachments  that makes unscrewing the retainer ring very easy.  Here is a  typical one on Ebay https://www.ebay.com...5.c100005.m1851

 

                 - Dave 



#19 Bagwell

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Posted 13 June 2019 - 10:27 PM

Yeah I did look inside the cover but either due to reflection of prism on the ITF or too much light at the wrong angle I couldn't tell for sure.  

 

IMG 20190609 000811
IMG 20190609 000751
IMG 20190609 000744
IMG 20190609 000735

Edited by Bagwell, 14 June 2019 - 12:57 AM.


#20 DAVIDG

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Posted 14 June 2019 - 08:56 AM

 It looks fully rusted over to me which is very common. So it looks uniform and hence you believe you don't have a problem. 

    If the eyepiece tube doesn't easily unscrew from the body of the PST you should be able to heat the eyepiece tube with a hair drier and unscrew the two sections. That will allow you  to remove the retainer ring that is on top vs the one inside next the prism. The filter will then just drops out. Put the the new one in place and reinstall the top retainer and screw the two pieces of the eyepiece tube back together and enjoy the much sharper and brighter image. 

 

            - Dave 


Edited by DAVIDG, 14 June 2019 - 09:03 AM.

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#21 Bagwell

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Posted 14 June 2019 - 10:41 AM

Thanks Dave, yeah I got the EP holder off of the body now just need to use a pin tool of some kind



#22 Bagwell

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Posted 17 June 2019 - 05:59 PM

I got my new ITF in the mail today.   I notice one side has a reflective coating on it and the other side doesn't.  Both look red when you hold them up to the light to look thru them, but only one side shows a reflective silver side on it when you reflect light off the face of the filter.   Any ideas on which way it goes in the cell?   Im going to go look back at the posts in the threads about solving this problem to see if there is any clue.  I could also msg Maier Photonics.  

 

Thanks, 
Vaughn



#23 Bagwell

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Posted 17 June 2019 - 06:11 PM

Ok, I found the info   David posted that you want the Red side facing the eyepiece.  I think there is another smaller Red fliter above this one closer to the eyepiece just to be clear.   So, I do want this new ITF filter to have the red side facing the eyepiece.   

 

Funny the older ITF filter from Meade Coronado has a reflective silver side on both sides. 

 

Thanks David, 

Vaughn


Edited by Bagwell, 17 June 2019 - 06:16 PM.


#24 Mike McShan

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Posted 05 August 2019 - 10:46 AM

I replaced the ITF from my 2006 vintage PST with the Beloptik filter, and I have to say that the difference is dramatic. I attached a picture of my original ITF filter to show the level of deterioration it had undergone. Yikes! Part of it was practically opaque.  The image of the sun is now bright with beautiful details.  I went with the more expensive Beloptik unit because it seems to be a permanent solution.

 

PST ITF

 

I had recently bought the double-stack unit for my PST and had not been particularly impressed, thinking that it hadn't been a good investment.  After replacing the ITF, the view through the double stacked PST is quite nice and really shows extra details.  So, if you were like me and not impressed after purchasing the DS etalon, you might take a look at your ITF. 

 

Clear skies, Mike

 

 

 


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#25 highfnum

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Posted 05 August 2019 - 11:03 AM

i had this issue 

replaced filter as per DAVIDG Instructions 

there are other  threads about this

 

a very common problem 

older filters allowed moisture 

in time that killed the filter




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