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Lunt blocking filter heaters.

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7 replies to this topic

#1 GUS.K

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Posted 22 July 2019 - 02:58 AM

Just had a look at the Lunt website and noticed this item for sale.https://luntsolarsys...heating-module/

Looks like the issue with their blocking filters and cold weather use has been acknowledged and remedied by them. 


Edited by GUS.K, 22 July 2019 - 03:01 AM.

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#2 RickV

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Posted 22 July 2019 - 04:03 AM

Good observation Gus!

I wonder what Boozo wrote the advert?  "Produces operating temperature in below freezing temperature".

Does that make any sense to you?

 

Best,

Rick


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#3 rigel123

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Posted 22 July 2019 - 07:12 AM

Rick knows I don't need this since I shoot through my magic window when it gets that cold!!lol.gif


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#4 RickV

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Posted 22 July 2019 - 07:26 AM

I send Lunt an email about the wording of their advertisement... let's see what happens!

 

Yes Warren... you and your 'window'.  I do admit that it works... why I don't know - maybe it is 'magic'. lol.gif

 

Best,

Rick


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#5 GUS.K

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Posted 22 July 2019 - 07:38 AM

I know others have had issues with lunt block filters in colder climates, my weather conditions are quite mild compared to northern U.S,  Canada and Europe.  I have two lunt block filters that struggle to produce any Ha detail below 10 degrees C. I have used dew heaters to get them on band, but it makes a quick set up a pain. They work fine, no issues in summer. I've gotten around this by using Coronado block filters( I have three to choose from) and all work without issue all year long. It's come to the point where I rarely use the lunt filters 


Edited by GUS.K, 22 July 2019 - 07:53 AM.


#6 BYoesle

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Posted 22 July 2019 - 01:33 PM

Most filters, including etalons, will have CWL (central wavelength) drift with temperature. Curtain designs are more susceptible than others depending on substrates and filter construction, and it sounds like this may be the case with the Lunt BFs.

 

Another issue for blocking filters is how they match with the FSR (free spectral range) of the etalon. Coronado BFs typically seem that they can be used  with Lunt etalons, but the opposite is generally not the case due to etalon FSR differences.

 

However, due to differences in UV and IR blocking, it may be preferable to use cold weather heating/insulation (OEM dedicated or DIY) to keep the OEM BF at the proper operating temperature versus changing the brand of BF...



#7 George9

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Posted 23 July 2019 - 09:37 AM

Good to see them add this. I just use a Kendrick 3" dew heater (which I already had) connected to a 12v lithium battery without a controller. But if I hadn't already solved it, I would have checked this out. (I wish the photos showed the other side.) I think their 5v approach is more convenient nowadays than my 12v. I have used mine down to around 10F (-12C), and the view remains good, which means all the other unheated optics are sufficiently stable.

 

George



#8 marktownley

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Posted 23 July 2019 - 01:05 PM

Doesn't surprise me tbh.  Maybe they will specify a working range.  I've observed blocking filters 'drift' going from a warm room to a cold winters day.

 

The night guys have been letting their scopes acclimate for ever, just a shame the blockers acclimate outside their specs.




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