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#1 stevenwav

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Posted 20 September 2020 - 10:07 PM

Hi - I know pretty much zero when it comes to solar filters and etalons etc. I have a 90mm Pre-Meade Coronado 90mm double-stack. I unscrewed the filter in the back of the scope that sits  directly in front of the diagonal and ep, and this is what I found (please see pic). Pretty obvious circular damage, I imagine this is like rust or some other kind of corrosion. What can I do about this? 

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#2 Lost in Space

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Posted 21 September 2020 - 12:07 AM

Hi - I know pretty much zero when it comes to solar filters and etalons etc. I have a 90mm Pre-Meade Coronado 90mm double-stack. I unscrewed the filter in the back of the scope that sits  directly in front of the diagonal and ep, and this is what I found (please see pic). Pretty obvious circular damage, I imagine this is like rust or some other kind of corrosion. What can I do about this? 

Hi Stevenwav,

 

Yep, this is the "rusted" filter problem.  As I understand the issue, you can still safely use the diagonal with the rusty filter in place, but the brightness of the image will be diminished.

 

I had this issue many years ago with my Coronado BF15 filter.  At that time, it was still under warranty.  There have been several threads here with information on replacement filters, but I would rather one of the more experienced members here advised you on that.  Someone will chime in soon.

 

Meade is really iffy as far as repairs, and likely way more expensive.  It took 5 months for mine to come back, and that was around 2009 or so, IIRC.  I had to mail it to Meade in California, and Meade collected these things up like a pack rat until they had amassed enough pieces to make it worthwhile for them to ship to their repair center in Mexico.  It took several weeks before it was fixed, and sat there for who knows how long before they - wait for it - had amassed enough pieces to make it worth sending back to Meade in California.  And then it took however long for Meade to pack it up and ship it back to me. 

 

You can likely fix this yourself and save a lot of money in the process.  I don't have the links handy for the sellers of these filters, but if I find them before someone else answers, I will post them here.  



#3 stevenwav

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Posted 21 September 2020 - 08:51 AM

Ah - Thanks Ed! I figured it might be rust. Looking forward to learning about possible fixes and or where I can buy a replacement. The scope is so great, I can't wait to get it performing up to snuff. 



#4 vincentv

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Posted 21 September 2020 - 10:14 AM

"rusted ITF" is the magic search string.

 

Maier photonics and beloptik manufacture the replacements. There's plenty of discussion about the differences. If you have the 30mm blocking filter I believe beloptik is the only 3rd party option.



#5 SloMoe

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Posted 21 September 2020 - 10:14 AM

Morning Steven, you might find your answer in this thread, you can search the forum for Coronado threads by entering  Coronado in the search forum box in the upper right of the topics page too.

 

https://www.cloudyni...t/?hl= coronado



#6 stevenwav

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Posted 21 September 2020 - 10:30 AM

Great info guys - thank you! I will do some digging and figure this out. Much appreciated!



#7 SloMoe

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Posted 21 September 2020 - 11:49 AM

Gotta help where I can,,,,,,,



#8 BYoesle

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Posted 21 September 2020 - 05:39 PM

Hi Steve,

 

Your BF30's Induced Transmission Filter (ITF) has "rusted" significantly, but is likely still usable due to the central area being unaffected. However, it will eventually be totally clouded and severely affect image quality. Store it in a moisture-proof container with a desiccant at room temperature to prolong its life.

 

There is no fix for this other than replacement, and I'm surprised your BF30 ITF has lasted this long! BTW - having a double stacked pre-Meade SM90 is pretty fortunate waytogo.gif

 

This is the ITF replacement filter you want for double stacking use - ask Oliver to turn it down to about 35-37 mm so it will be a direct drop-in replacement for your rusted OEM ITF.

 

It is the same as Oliver's ITF replacement filter, but lacks the additional (redundant) RG630 filter: One or both of your etalons already have this RG630 as an ERF (and therefore a second or third RG630 filter is unnecessary), and it will give you a much brighter image for double stacking visual and imaging.

 

You may find this thread of interest. PM me if you have any questions.



#9 stevenwav

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Posted 21 September 2020 - 08:37 PM

Wow Bob - Thank you very very much for this information - I really appreciate your taking the time to let me know these details. I will read through the links to learn more and take care of the fix right away . Once fixed, I will keep the filter dry and separated from the OTA itself.

 

I am very fortunate indeed to own this scope. The views are just spectacular (towards the center anyway- lol) and that is why I want to make sure to try to keep it in great working order for a very long time. I obtained it just last year from a good friend. 

 

Thanks again to all who have helped. Best Regards -Steve




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