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Hydrogen Alpha Filters for 5" Refractor

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#1 Dredger

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Posted 19 January 2018 - 05:11 PM

Does anyone know if they make hydrogen alpha filters to fit over the end of a refractor?  Mine is a 5" is its on the larger size.  Everything I've found is in the 2" range.  



#2 DaveJ

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Posted 19 January 2018 - 08:28 PM

For what purpose? If for H-a solar viewing, do NOT do any such thing!!!!!!!!!! H-a solar viewing requires an energy reduction filter, a front mounted H-a etalon, and a pre-eyepiece blocking filter. These come to about $7,000.00 for a 90mm refractor. The 2" H-a filters you're probably talking about are for narrow-band imaging in the H-a band, NOT FOR SOLAR VIEWING!!!!


Edited by DaveJ, 19 January 2018 - 08:29 PM.

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#3 junomike

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Posted 19 January 2018 - 10:30 PM

Good catch Dave, I deleted my previous post as I  was thinking h-beta.



#4 sink45ny

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Posted 19 January 2018 - 11:06 PM

Lunt has a nice 4 inch front mounted etalon together with 18mm blocking filter goees for $6,496.00.

 

https://luntsolarsys...oduct/ls100fha/

 

They can make a custom mounting adapter to fit over your retractable dew shield.for an additional cost.



#5 SeattleScott

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Posted 20 January 2018 - 09:40 AM

Have you thought about Quark? Could be an option IF your 5” apo is a doublet. Not the most convenient thing but it would allow you for use that big 5” aperture for H alpha viewing.

Scott

#6 mclewis1

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Posted 20 January 2018 - 10:02 AM

DayStar (Quark), Lunt and Meade (Coronado) have offered (and in some cases continue to offer) a variety of packages to retrofit existing refractors (and sometimes Cats too) for solar work (Ha or sodium observing). There are specially made adapters for specific scopes and there have also been some more generic mounting setups. Most folks will go for a smaller aperture Ha setup compared to what their existing refractor actually is to keep the money spent down to a dull roar.


Edited by mclewis1, 20 January 2018 - 10:02 AM.


#7 mclewis1

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Posted 20 January 2018 - 10:10 AM

Does anyone know if they make hydrogen alpha filters to fit over the end of a refractor?  Mine is a 5" is its on the larger size.  Everything I've found is in the 2" range.  

If you are looking at Ha work for DSOs and not solar then you don't need any like full aperture filtering. Putting an Ha filter into the optical path gives you the same results and allows you to use a much smaller diameter filter. Most filters come in either 1.25" or 2" mounting so that they can be attached to eyepieces or diagonals. For imaging (with larger sensor cameras) there are also filters available in different formats (unmounted for example).

 

It's usually only when you have a camera/external lens combination that you want a filter larger than 50mm. It is however rare to find good quality Ha filters in the 55, 56mm or similar lens filter sizes. Most folks here will get an adapter to go from say 56mm down to the standard 50mm filter size to be able to use a high quality Ha filter on a telephoto lens.



#8 Dredger

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Posted 22 January 2018 - 03:10 PM

For what purpose? If for H-a solar viewing, do NOT do any such thing!!!!!!!!!! H-a solar viewing requires an energy reduction filter, a front mounted H-a etalon, and a pre-eyepiece blocking filter. These come to about $7,000.00 for a 90mm refractor. The 2" H-a filters you're probably talking about are for narrow-band imaging in the H-a band, NOT FOR SOLAR VIEWING!!!!

Hello, thanks for the input.  Yes I was hoping to do solar viewing with my 5" apo, but looks like the filters/setup for that run a couple of thousand, so I think I'm going to hold off on that.


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#9 noisejammer

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Posted 22 January 2018 - 04:56 PM

One option might be to look at the Thousand Oaks offering.

 

You would need a 5" energy rejection filter and an etalon. That would get you going for around $900. It's not the best H-alpha system in the world ... but it's very far from the most expensive. Your scope would be stopped down to ~f/15 but that still means a few inches aperture which is sufficient to resolve quite a lot of the visible structure.



#10 DaveJ

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Posted 22 January 2018 - 05:28 PM

 

For what purpose? If for H-a solar viewing, do NOT do any such thing!!!!!!!!!! H-a solar viewing requires an energy reduction filter, a front mounted H-a etalon, and a pre-eyepiece blocking filter. These come to about $7,000.00 for a 90mm refractor. The 2" H-a filters you're probably talking about are for narrow-band imaging in the H-a band, NOT FOR SOLAR VIEWING!!!!

Hello, thanks for the input.  Yes I was hoping to do solar viewing with my 5" apo, but looks like the filters/setup for that run a couple of thousand, so I think I'm going to hold off on that.

A "couple of thousand" will only get you less than 1/3 of the way there!



#11 mich_al

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Posted 22 January 2018 - 07:12 PM

Are you really looking for a 'white light filter' for solar viewing ?  Lets you see sunspots & granularity & etc, fits over the front of a scope ?



#12 noisejammer

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Posted 22 January 2018 - 09:33 PM

I think the OP was mostly interested in H-alpha observing but since you raised the topic of white light observing, I recently tried a Baader solar continuum filter in my Herschel wedge. I was able to resolve a lot more structure than was possible in white light. If you have a wedge and a yellow-green sun won't cause you to squirm, I believe it really is worth the price of admission. 

 

It's strictly for refractors after light goes through the wedge and an OD3 (10 stop) filter. It might work on other scopes with a Baader astrosolar film. (Baader says this is ok; I haven't tried it.)

 

As always, caution is strongly advised.



#13 sink45ny

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Posted 22 January 2018 - 09:42 PM

Cheapest (inexpensive) ticket to Ha solar viewing IMHO is the CORONADO PST 40MM H-ALPHA SOLAR TELESCOPE $548.00

 

Right now OPT is running a sale, normally they are $700 - https://optcorp.com/...solar-telescope

 

Maybe a moderator can move this thread to the solar forum - https://www.cloudyni...ng-and-imaging/

 

A lot of people have them and get good results.


Edited by sink45ny, 22 January 2018 - 11:13 PM.


#14 Ken Sturrock

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Posted 22 January 2018 - 11:06 PM

Moving from generic Equipment to Solar.


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#15 FlankerOneTwo

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Posted 23 January 2018 - 11:23 PM

There are two main options for h-alpha solar observing, front mounted etalon or rear mounted. Lunt, Coronado, and Solarscope all make front mounted etalons, they start at $1000 for 50mm and climb rapidly from there. The largest is 100mm. There are two main manufacturers of rear mount etalons, Daystar (Quark, Quantum, etc) and Solar Spectrum (much more expensive). You will also need an energy rejection filter to use these over 80mm aperture, at 125mm (5") you can use a Baader 35nm h-alpha (preferred) or UV/IR filter as an ERF. The Quark works quite well although they do not guarantee a specific bandpass and is $1200. I run one in my FLT132 with the 35nm filter and it works great.



#16 MrRoberts

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Posted 25 January 2018 - 12:41 PM

I use a Quark chrom  in my 115mm with a Baader uv/ir filter and a Quark Prom in my 80mm.




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