PST CaK issues and possible solutions?

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
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theastronomydude

PST CaK issues and possible solutions?

Post by theastronomydude »

Hello, I am a new user here on the Solar site, but I am heavily involved in astronomy outreach. I currently have an Astronomy Mobile Outreach Vehicle that carries 12 telescopes, all of which are capable of either white light solar, Ha Solar, and CaK Solar. My issue is with my recent addition of the PST CaK Solar Telescope. I bought this telescope knowing that there was a possible issue with the filters in the scope. The seller sent some images, but they were poorly focused, and the seller said he was using the scope fine with a CCD camera. Upon receipt of the scope, I noticed that the filters were a bit worse than I could tell from his photos. I asked a question on the Solar area of CN, and was directed to this group by a responder.
I am attaching some images of the filters that I see damage. Can anyone give me any help or ideas on how I can fix this scope for CaK use once again? Any help would be appreciated.





Michael


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Re: PST CaK issues and possible solutions?

Post by solarchat »

Michael,

Unfortunately, the objective, etalon and/or blocking filter in that CaK PST is completely rusted into an unusable state. The only way to fix it is to send it to Meade to have it repaired. I would return it to the seller immediately if possible. This is at least a 6 month process and will cost at least $150 plus shipping.

I have owned 4 of these and given them away to others for outreach and this is the worse case of rust I have ever seen.


By the way, if you click the "insert" button when you attach an image, it will show it in your post. I edited yours to show this.


Stephen W. Ramsden
Atlanta, GA USA
Founder/Director Charlie Bates Solar Astronomy Project
http://www.solarastronomy.org
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Re: PST CaK issues and possible solutions?

Post by marktownley »

Hi Michael :)

What part of the PST is the second photo a picture of?

It is possible to replace the 'green' filter in the first image with a Baader K-Line or an Omega CaK filter off EBay. I think by just replacing this you will get this scope up and running again.

Stephen is right about sending it to Meade, it will be a lengthy process and will be costly. I have to be blunt and say there are several members on here who would happily buy this scope off you in its current condition - these scopes are as rare as hens teeth...

Mark :)


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Re: PST CaK issues and possible solutions?

Post by swisswalter »

Hi Michael

welcome to that wonderful TOS free site. Have sun, have fun. I would go the way Mark is pointing to before I would sell it


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: PST CaK issues and possible solutions?

Post by Pedro »

Hi Michael:

I also agree with Mark. Just replace 'green' filter with a Baader K-line filter. Check out my CaK PST mod at:

http://re.apaaweb.com/pst_CaK_mod_20121213.jpg

I guess that the main objective lens will be easy to clean.

best regards


theastronomydude

Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Some good tips here. Thank you for your time. I checked on the cost of the Baader filter. Yikes!!! That is an expensive filter. I have already contacted and spoke to someone in Meade Customer Service last week, but I have not received a response from them at this time. The first image is a filter that is at the bottom of the vertical tube that the eyepiece inserts into. The other image is from the back of the gold tube, looking forward to the front objective, that has been removed from the blue ring that is at the front face of the body. As these telescopes are hard to find, I would rather try to get it repaired if at all possible. However, I might be willing to sell it as is if it becomes too much of a hassle to get back into use.

Michael



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Re: PST CaK issues and possible solutions?

Post by marktownley »

This is a bit cheaper as an alternative to the Baader...

[ebay]310478646991[/ebay]

or for slightly more...

[ebay]310515954638[/ebay]


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Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Wow, how did you do that? I did a search on EBay for CaK and only got two related hits, which did not include either of these. Okay, which should I get? I am curious as to what I would do if I get the filter. The filter that is bad is noticeably smaller than this filter, so it would not be a direct replacement. Would I have to get the filter I bought cut down, or do I just remove the bad filter completely and use the new one in the light path? If that is so, where in the path do I need to put the replacement filter?


theastronomydude

Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Well, things have gotten pretty quiet here the past day or so. I just got a chance to check out the PST CaK with the current filter visually. I was able to clearly see the solar disk in that beautiful deep blue color, but was not able to see any details on the surface as I was using a 25mm eyepiece on a tripod, and the skies were mostly cloudy, so I could only get quick views through sucker holes. So, I know the scope works, but that filter is the questionable part of this equation. If anyone has any tips on how I should set up the scope using the replacement filter that Mark told me about, I would appreciate the assistance. I am not an optical genius, so I need to have it spelled out for me.

Thanks,

Michael
www.astronomyoutreach.org


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Re: PST CaK issues and possible solutions?

Post by swisswalter »

Hi Michael

congratulations on your first light through the PST-CaK. You must be very young to see the blue disk, I can't see it any more. Mark will lead you to the correct position of the K-Line filter, I can't, because I have never worked with a CaK-PST


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: PST CaK issues and possible solutions?

Post by marktownley »

Hi Michael,

Sorry, slow on the reply here, festive frivolities have been interefering...

I think I would go with the first of the ebay links above just on the grounds of simplicty - the second is a stacked pair that could well involve some tilt.

Putting it in place is relatively straight forward, you just remove the 'greened' filter (just unscrew the housing it sits in), when you get the omega filter buy one of these filter cells

[ebay]310397188819[/ebay]

mount the new filter directly into this and just screw it into your camera nosepeice when imaging.

Simples! :)


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Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Thanks for thinking I must be a young guy. I am 55 years old, but my eyesight has always been very good. I first looked through a CaK scope at NEAF quite a few years ago and I was then one of the few people that could see it visually, so I figured that I probably still could. Yes, Mark has been a great help on this endeavor, as have you. I appreciate any info that I can get to make me more rounded in the solar arena.

Michael
www.astronomyoutreach.org

Hi Michael

congratulations on your first light through the PST-CaK. You must be very young to see the blue disk, I can't see it any more. Mark will lead you to the correct position of the K-Line filter, I can't, because I have never worked with a CaK-PST


theastronomydude

Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Thanks Mark. That is a simple solution. Will this also still allow me to use the scope visually as well? Also, I talked to a friend who runs a machine shop. I was looking into making a replacement part for the PST CaK that will completely replace the portion of the barrel that holds the small Coronado CaK filter with a custom made barrel that will be designed to hold the full size replacement filter. If I make and anodize one for myself, do you think that this would be a part that others would be interested in to possibly help bring other bad filter PST CaK scopes to life? Just curious on your thoughts.

Michael Overacker
www.astronomyoutreach.org


Pedro

Re: PST CaK issues and possible solutions?

Post by Pedro »

Hi Michael

I mut confess that I do not see a thing with my Cak PST (only a very faint blue disk). With my LUNT 1200 CaK module it's the same...

Old guys like me have that problem (I'm 56). Glad to know that you can still see details on the disk.

best regards and please keep us posted


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Re: PST CaK issues and possible solutions?

Post by marktownley »

Will this also still allow me to use the scope visually as well?

Hi Michael,

It would be irresponsible for me to say that this modified configuration is safe visually. I have never used my modded CaK PST visually - when the filter module is on my 70mm frac i'm gettig an exposure time with my DMK31 of ~1/2000s, compare this to when was on the 40mm CaK PST body and the exposure was more like 1/30s - now, obviouslly a difference in aperture but also a difference in energy. Pedro found that on the PST body changing this filter caused his exposure to drop from 1/15s to 1/125s, so you can see here it is letting more energy in. Given this fact I can only recommend this modification for imaging work.

There's been quite a bit of discussion on the CaK PST, how it works and the bandpass of the individual filter elements. While nobody has been able to get a spectrographic plot of the individual filter elements, use of a handheld visual spectrometer suggests that your 'greened' filter is just a UV cut (hence it's yellowy original appearance). As CaK PST is designed (unmodified) to be used visually, I would hazard a guess that the 'greened' filters purpose is just to reduce the UV-A to a safe visual level.

Mark :)


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Re: PST CaK issues and possible solutions?

Post by marktownley »

Also, I talked to a friend who runs a machine shop. I was looking into making a replacement part for the PST CaK that will completely replace the portion of the barrel that holds the small Coronado CaK filter with a custom made barrel that will be designed to hold the full size replacement filter. If I make and anodize one for myself, do you think that this would be a part that others would be interested in to possibly help bring other bad filter PST CaK scopes to life? Just curious on your thoughts.

Pedro used an 'off the shelf' eyepeice holder to acheive the same result, maybe he will give us more details on this, I know he has post pictures of it previouslly...


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Re: PST CaK issues and possible solutions?

Post by solarchat »

Mike,
I feel the need to interject here as you and I are on the same wavelength..no pun intended..outreach.
This is the description of this foum on the main page:
***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
The CaK PST you have is very much rusted over. If you can return it, do so. If not, I would be very cautious about using hammers and taking it apart, etc... to get it to work. Whoever sold this to you either has no knowledge of solar scopes at all or knew full well that it was unusable.
I would strongly recommend that you stick with an authorized repair facility if you plan on letting the public look through this scope.
These guys are knowledgable about tinkering with this scope but no one here is going to stand behind you after yours or someone elses eyes get permanent damage from tinkering. Just a reminder.

carry on gentlemen.


Stephen W. Ramsden
Atlanta, GA USA
Founder/Director Charlie Bates Solar Astronomy Project
http://www.solarastronomy.org
Pedro

Re: PST CaK issues and possible solutions?

Post by Pedro »

I have to say that I totally agree with Stephen. If your intention is using the PST CaK for outreach you should return it to be repaired. Like Mark I have never used my PST CaK for visual observations, I use it only for imaging. Taking the PST apart can be an interesting move but you should be careful. Most of the people would not see much with a PST Cak anyway.

best regards


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Re: PST CaK issues and possible solutions?

Post by marktownley »

Hi Michael.

There's a much easier solution to this whole thing that has been under my nose for days...

As I mentioned I modded my CaK PST, primarily because the penta prism in the black box was mis aligned and was producing astigmatic images. As such I have a replacement for the filter you need just lying around - I removed mine and replaced it with the baader K-Line.



As you're wanting to use this for outreach I would be happy to donate it to your cause. Drop me a message at [email protected] with your address and i'll mail it over to you. It is a genuine Coronado part in full working order so you would still be able to use the scope safely for visual purposes if this is what you want to do.

Is this any help?

Mark


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Re: PST CaK issues and possible solutions?

Post by Pedro »


Mark took the words right out of my mouth. I can also donate my PST CaK original nosepiece adaptor for your outreach programme.

pedro.re(AT)netcabo.pt

best regards


theastronomydude

Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Thanks Stephen. This is exactly the directional information that I need. I know a bit about solar viewing, but I need to learn more. I do value the eyesight of attendees, so I will always err on the side of caution. I most likely would not have allowed attendees to look through the CaK scopes if they were modified in any way, but it is good to find out why, which you explained well enough for me to grasp. Thanks.

Michael
www.astronomyoutreach.org


theastronomydude

Re: PST CaK issues and possible solutions?

Post by theastronomydude »

Mark and Pedro,

Thank you for your kind offers to help me with this issue. I have sent both of you a private email. Thanks for the support.

Michael
www.astronomyoutreach.org


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