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Filter for BTs...

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33 replies to this topic

#26 oldmanrick

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Posted 25 May 2018 - 11:00 PM

Looks like a shot the next couple of days.

Have you had a chance to try, and compare, the UHC filters yet? fingertap.gif  I think I'll try a set for my 100 mm Lunt 45 degree binoc's for use between 25X and 45X, but don't want to re-invent the wheel, when you have possibly already picked out some that are better than others. confused1.gif



#27 Mr. Bill

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Posted 26 May 2018 - 09:47 AM

Haven't had a chance to do any real astronomy for a month....tongue2.gif

 

Looks like Milky Way will be in good position next new moon cycle and I'll post a report.



#28 Rich V.

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Posted 26 May 2018 - 01:50 PM

Been needing a cloud filter here lately; early monsoon season this year.  The good news is that all the rain has our precipitation caught up for the year and the wildflowers are doing great...

 

Rich



#29 Fiske

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Posted 14 July 2021 - 05:35 PM

Reviving this topic after going OT about filters with binocular telescopes in another thread.

 

The Pentax XW 1.25 inch focuser barrels are too long to work with normal filters -- not enough back focus. One possibility might be a filter that threads inside the 1.25 inch extensions. Not sure anything like that is actually made, though something could probably be machined.

 

Kevin at Oberwerk followed up with me to say that the XL22 and XL14mm eyepieces have shorter 1.25 inch extensions and will come to focus with filters in the OB XL BTs. So I am going to try that. 

 

The Baader UHC-S filters mentioned earlier in this topic seem promising for binoculars.

 

Fiske


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#30 Allan Wade

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Posted 18 July 2021 - 06:23 AM

I have a Baader UHC-S 2” filter I use occasionally in mono mode. It’s a nice filter, but very wide, and lacking the contrast from traditional narrow band filters. My Lumicon UHC 2” is my favourite filter, and I bought a pair of 1.25” I use in my binoscopes. They are a great match for bino observing and would be my number 1 recommendation.


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#31 Fiske

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Posted 18 July 2021 - 10:15 AM

I have a Baader UHC-S 2” filter I use occasionally in mono mode. It’s a nice filter, but very wide, and lacking the contrast from traditional narrow band filters. My Lumicon UHC 2” is my favourite filter, and I bought a pair of 1.25” I use in my binoscopes. They are a great match for bino observing and would be my number 1 recommendation.

What eyepieces do you use the 1.25" UHC filters with in your BT, Allan?

 

Fiske



#32 Allan Wade

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Posted 18 July 2021 - 05:47 PM

I use my 24 Pans and 12.5 Docters with the filters. The Lumicon UHC work well with those larger exit pupils.


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#33 Fiske

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Posted 18 July 2021 - 05:56 PM

I use my 24 Pans and 12.5 Docters with the filters. The Lumicon UHC work well with those larger exit pupils.

Understood about the exit pupil. The length of the eyepiece 1.25 inch extensions is a factor in using filters with BTs -- the extensions on my preferred BT eyepieces (Pentax XWs) are too long for them to come to focus with the added length of the filters. I have several Oberwerk XL eyepiece sets and will be trying those next. 

 

Fiske



#34 Allan Wade

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Posted 19 July 2021 - 07:33 AM

Understood about the exit pupil. The length of the eyepiece 1.25 inch extensions is a factor in using filters with BTs -- the extensions on my preferred BT eyepieces (Pentax XWs) are too long for them to come to focus with the added length of the filters. I have several Oberwerk XL eyepiece sets and will be trying those next. 

 

Fiske

Oh, I see. No problems with the Pans or Doctors coming to focus with the filters.




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