DIY Hydrogen Alpha Solar Filter

[Remedyworld]

TL;DR Summary

DIY Hydrogen Alpha Solar Filter

I'm interested in doing more detailed photos of the Sun using my solar filter and a 1.25" Hydrogen Alpha (Ha) filter. Is this possible to do or is it best to purchase a Coronado telescope?

 

[sophiecentaur]

Summary:: DIY Hydrogen Alpha Solar Filter

I'm interested in doing more detailed photos of the Sun using my solar filter and a 1.25" Hydrogen Alpha (Ha) filter. Is this possible to do or is it best to purchase a Coronado telescope?

Oh I wish . . . . . .
Your Hα filter will be great for looking at nebulae etc. To get good images of Hα in the presence of all that wideband Solar radiation, you need a filter (bandpass) of only a few nm. You need an Etalon filter which will cost you a minimum of £1k. (Also a pukka filter to reduce the illuminance to something safe for you and your image sensor)
Now and then I try to search for a DIY version and I realize that you will need a pretty good Optical Lab production facility and some pretty good quality glass. Shame!
The images I have seen in a Coronado are pretty impressive, considering the reasonable entry level cost but I ask myself if I bought one, how long would I be satisfied. Also, (if you don't already have one) you would need a good mount so that you can take images to reduce the atmospheric distortions etc. etc. So would it not be worth while starting off a level or two above the Coronado? Get thee behind me Satan! The kids need new shoes and food on the table.

 

[Remedyworld]

hmmm, thanks for the info. Look like I need to budget for a Lundt :)

 

[sophiecentaur]

hmmm, thanks for the info. Look like I need to budget for a Lundt :)

If you will use it enough, I cannot think you'll regret it.

 

[Remedyworld]

Absolutely will use it a lot. Most of my solar photos are of sunspots, but solar proms are the next step. Just thought I could speed up the process a bit.

 

[davenn]

hmmm, thanks for the info. Look like I need to budget for a Lundt :)

I can recommend the LUNT ( there is no "D") I have the 60mm THa model for a couple of years now.
There is a thread in the astronomy section on my solar observations

1.25" Hydrogen Alpha (Ha) filter.

You didnt say what bandwidth you Ha filter is ? if it is just a normal astro Ha filter, then it's
bandwidth at ~ 7nm will be just way too wide. Bandwidths of less than 1nm are needed to see
prominences, filaments and other surface features. my one tunes between 0.5 and 0.7 nm

cheers
Dave

 

[sophiecentaur]

I can recommend the LUNT ( there is no "D") I have the 60mm THa model for a couple of years now.

Is there a good reason for having a different OTA for solar and for nighttime? I have an 80mm Skywatcher Equinox and could buy a solar wedge which could be followed by any appropriate filter. Total cost could be less (?) than a Lunt for a given performance.

 

[Remedyworld]

I actually don't have an Ha filter yet. I have a glass solar filter I use for my observations and was thinking I can combine with an Ha filter.

 

[Remedyworld]

I can recommend the LUNT ( there is no "D") I have the 60mm THa model for a couple of years now.
There is a thread in the astronomy section on my solar observations
You didnt say what bandwidth you Ha filter is ? if it is just a normal astro Ha filter, then it's
bandwidth at ~ 7nm will be just way too wide. Bandwidths of less than 1nm are needed to see
prominences, filaments and other surface features. my one tunes between 0.5 and 0.7 nm

cheers
Dave

Also thank for the feedback Dave. I'm searching for 2 Ha filters one between 0.5 and 0.7 nm (solar viewing) and one for deep sky objects.

 

[davenn]

Is there a good reason for having a different OTA for solar and for nighttime?

yup, sheer ease of use. you would have to dismantle the full back end of a solar scope so that
you could remove the etalon etc and then install a suitable focusser etc for your night time use
I couldn't think of too many things more annoying and time consuming than having to do that
swap over all the time, not to mention the probability of getting dust into the OTA and other bits

I have an 80mm Skywatcher Equinox and could buy a solar wedge which could be followed by any appropriate filter.

Then just get a Daystar Quark either the Prominence one (0.5-0.7nm) like I got for my 120mm Skywatcher
refractor or the Chromosphere one ( ~0.4 - 0.6nm)

https://www.daystarfilters.com/Quark.shtmlDave

 

[davenn]

I actually don't have an Ha filter yet. I have a glass solar filter I use for my observations and was thinking I can combine with an Ha filter.

No, that isn't a plan. You cannot put a normal white light glass filter on a scope followed by a solar filter
it won't enough light through.

Either buy a Coronado, a Lunt or a Daystar system Dave

 

[sophiecentaur]

you could remove the etalon etc and then install a suitable focusser etc for your night time use

I don't have a permanent setup (apart from my heavy mount) so everything has to be re-assembled before any activities. I can see how an 'observatory lifestyle' makes things different for people.

I am clearly going to have to read around more and more before I make any decisions. I have to say the low level of sunspot activity at the moment makes it all feel less urgent and I am not gagging for new equipment. That will allow me to be more sensible about it all.