Blocking Filter, Mini ERFs and Alternatives

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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Re: Blocking Filter, Mini ERFs and Alternatives

Post by christian viladrich » Sun Sep 30, 2018 8:46 am

Thanks for the feeback Raf. Can you confirm it was a Baader Red CCD filter ?

Which Ha filter are you using now ? With what instrument, diameter, F/D ratio and filter diameter ?

We should make a list of the success / failed attempts ;-)
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Re: Blocking Filter, Mini ERFs and Alternatives

Post by krakatoa1883 » Sun Sep 30, 2018 10:05 am

Yes, Christian, it was a red CCD filter, I removed the telecentric from my Quark and was experimenting some different solutions (which all proved to work better...) the filter was mounted just before an amplifier with my 150 mm achromat reduced to 110 mm i,e, @ f/6.8. The mistake was to mount the filter before the negative lens, I think, where heat is more concentrated. Or it may be (it was during winter) the glass broke when suddenly exposed to the ambient air, anyway I do not intend to repeat the experiment in summer :lol:

Since then I purchased a Baader D-ERF however its cell fits only my 150 mm, for my other scopes I am using a 35nm H-alpha filter as internal ERF with apertures not greater than 90 mm from f/5 (Taka Sky 90) to f/11.7 (TMB). Not tried greater apertures yet.

Based on what I read here I am tempted to purchase a 3.5nm....
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Re: Blocking Filter, Mini ERFs and Alternatives

Post by MalVeauX » Sun Sep 30, 2018 12:27 pm

krakatoa1883 wrote:
Sun Sep 30, 2018 6:53 am
MalVeauX wrote:
Sun Sep 30, 2018 12:25 am
Do you guys think a Baader Red CCD Filter (IR block) would be ok with a 6 inch refractor?
I broke one just few months ago. Probably the fault is mine, may be the filter was too close to focus, however since then I make use of a H alpha CCD filter instead, no problems at all.
Interesting, is that with a 6 inch refractor? Was that in the focuser or some where else? Mind sharing a link to the H Alpha CCD filter you're using?

Appreciate it!

Very best,

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Re: Blocking Filter, Mini ERFs and Alternatives

Post by krakatoa1883 » Sun Sep 30, 2018 3:04 pm

It was mounted just in front of a Powermate in my 150mm refractor. As I said above it was a cold winter day so it doesn't seem unlikely that it broke by a thermal shock.

The filter I am now using is this https://www.baader-planetarium.com/en/b ... ilter.html however for some unknown reason it is not compatible with my Quark in its original configuration, I had to remove the telecentric for making use of it. Same with my front Baader DERF.
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Re: Blocking Filter, Mini ERFs and Alternatives

Post by christian viladrich » Sun Sep 30, 2018 3:24 pm

Interesting ... thanks for sharing.
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Re: Blocking Filter, Mini ERFs and Alternatives

Post by TheSkyBurner » Sun Sep 30, 2018 4:03 pm

It could have broke from the metal cell shrinking. Thermal shock works in both directions. Ug11 glass will break almost instantaneously because it is black in a 150mm scope.

Cant say the same for all filters, but baader planetarium keeps the filter glass loose and shakey in the cell to accomidate for glass expansion, and would also protect against the stress caused by the metal ring holding the glass when it shrinks in cold.

I have persoanlly tried to kill all three baader planetarium colors , r g b, with a 203mm plano convex lens at f/4. They all survived the test.

I could sacrifice them to deep freeze if there is interest, but i doubt anyone will be using these things in negative 30 degrees faranheigt

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