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Questions about suitable Energy/Heat Attenuation filters for Sol'Ex solar imaging.

Orion ST80 Filters Spectroscopy Sun
SOL'EX USERS GROUP •4 replies•31 views
morrienz avatar
morrienz avatar
Hi. I have an Azur3d printed Sol'ex 2 Pro, and a Shelyak slit/grating kit for it on the way to me for solar imaging and I am trying to work out what energy attenuation I can use with my WO ZS66 and Orion ST80 refractors. I have some questions that maybe some of you can answer on that. I know I can use a Hoya PROND ND filter on the front of the scopes, but I'd need to get probably 2, or more if I also use some of my larger refractors eventually with the Sol'ex, different 3d printed adapters made for the HOYA filter(s) and I don't have a 3D printer.

Could I use Baader astro-solar film (the visual or the photography) film for the energy attenuation on the front of the scopes, which I have used in the past for white-light solar viewing?

Could I alternatively just use an IV/UR cut filter for energy attenuation, at the focuser end of the scopes, as I do for my Daystar Quark with my refractors?

Or are there are any other suitable energy attenuation 1.25 inch filters I could use at the focuser end of the scopes other than a simple UV/IR cut filter, rather than have to get large ER filters and adapters for the front ends  of the scopes? I see that TS and Player One both have 1.25 inch Energy Rejection filters (not just UV/IR cut) for use in front of a Quark, and I wondered if one of those might be ok?

Thanks in advance for your help
Chris
Jérémie avatar
Jérémie avatar
Hi Chris,
You should ask Christian Buil, the man behind the design and conception of the Sol'Ex.
I am not sure he posts on Astrobin, but you can also join the Facebook group where he posts his results : https://www.facebook.com/groups/solex
There was also a forum, but it doesn't seem to work by now... : https://groups.io/g/Solex-project
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morrienz avatar
morrienz avatar
Jérémie:
Hi Chris,
You should ask Christian Buil, the man behind the design and conception of the Sol'Ex.
I am not sure he posts on Astrobin, but you can also join the Facebook group where he posts his results : https://www.facebook.com/groups/solex
There was also a forum, but it doesn't seem to work by now... : https://groups.io/g/Solex-project

Thanks Jeremie.
Jérémie avatar
Jérémie avatar
@morrienz you’re welcome.
By the way, the forum works (didn’t yesterday): https://groups.io/g/Solex-project
Christian Buil is very active and answers your questions there (I asked a similar question about energy attenuation, on an Esprit 150ED)
morrienz avatar
morrienz avatar
Jérémie:
@morrienz you’re welcome.
By the way, the forum works (didn’t yesterday): https://groups.io/g/Solex-project
Christian Buil is very active and answers your questions there (I asked a similar question about energy attenuation, on an Esprit 150ED)

Thanks again  Jeremie. I looked at the Sol'ex forum and  I can see a discussion there recommending (not Christian, but aSol'ex user) that for smaller refractors a simple 7nm to 18 nm Ha filter designed for Deep Space Object imaging will work fine for energy rejection, mounted on the nose of the Sol'ex if only doing Ha work with the Sol'ex (which is all I'll be doing, at least initially), and has been tested to pass the palm of the hand heat transmission test. So I will firstly try the 1.25 inch DSO imaging 7nm Ha pass filter I already have when I use my Sol'ex with my WO 66mm and Orion 80mm scopes, to start with at least (I'll still do the hand heat test myself to double check it does work ok).  It's a much simpler option for me than getting big front mounted ERFs and having to get custom scope/filter adapters made.

In another discussion there was some concern expressed by one user that a rear-mounted deepspace night-imaging Ha filter wouldn't be designed to handle that amount of heat/energy rejection without getting damaged, but another user says he also uses a rear mounted  deepspace/night-imaging Ha filter for energy rejection, for hours at a time, and it handles the heat fine.

Interestingly, in the discussion one user also said they can see that their (recommended) Hoya PROND front mounted filter actually degrades the image quality  quite noticeably when used for energy rejection.  They wrote "After put the (PROND) filter on, I can visibly see the small doppler shift granules become less defined and less detailed. Also putting the filter on and off on a scope (without solex) also shows some reduction in sharpness when shooting ground target".
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