Homemade H-Alpha scope?

[stefski]

Hi All,

After SGL 5 and seeing the H Alpha scope someone (sorry, I've forgotten who:icon_redface:) had made using a Vixen refractor and bits of a PST, I got to thinking. Is it relatively easy to make one of these? I have a Meg 72 and thought that if I get a 'Thousand Oaks' (or equivalent) solar filter for the front end of the OTA and somehow get hold of the H alpha cell from a pst to put at the ep end, will that work? Or what about the solar filter at the front + a CaK filter on an ep?

Any ideas/suggestions?

I just though it would be nice to get some daytime use out of Little Meg as well as at night!

Stef:)

[brianb]

After SGL 5 and seeing the H Alpha scope someone (sorry, I've forgotten who:icon_redface:) had made using a Vixen refractor and bits of a PST, I got to thinking. Is it relatively easy to make one of these?

Not hard but you need to know what you're doing. Do not cut corners / omit energy rejection filters etc .... especially if you intend to put your eye in the line of fire. Cameras can easily be replaced, eyes can't.

Solar Ha filters consist of three parts - energy rejection filter, etalon & blocking filter - the etalon is the heart of the system & gives the very narrow bandpass required but "leaks" a lot of energy at other wavelengths, which is why you need the blocking filter (removing "spikes" near to the wanted transmission band) and the ERF (removing dangerous radiation which is way out of band). The PST makes it look easier than this because the etalon & blocking filter are in the "black box" & the ERF is a simple coating on the objective. When you increase the aperture you'll want a more effective ERF than this & it's gonna cost!

You do NOT need an ordinary solar filter as well - this will absorb far too much light - the narrow bandpass of the solar Ha system means no extra filtering is usually necessary.

CaK - the most cost effective system available is the Lunt CaK module which again does not require an ordinary solar filter but is limited on safety grounds to 4" aperture & needs to be used in a "conventional" refractor (not a Petzval type, nor one with a field flattener fitted). The Baader CaK eyepiece filter (which needs to be used with the special "photo" solar filter - ND 3.8 rather than 5.0 like the usual visual type) has a much wider bandwidth & does not give very good results. In any case most people are blind or very nearly so to CaK wavelength radiation; think of CaK as "imaging only" & you won't be far wrong.

[Keiran]

Hi Stef,

I have asked a similar question to this, and i would recommend having a look at my thread on solar viewing.

I hope that this helps. I have just bought a Meade 70mm refractor, and I picked up a solar filter from Scopes n' Skies for a tenner.

I am going to see how this goes, and try and use it as a solar scope, or atleast until I get my Synscan GOTO for my EQ5, and if it doesnt work out i will use it as a guide scope.

Please keep me and the rest of use, trying to do this on the cheap, updated.

Thanks

Keiran

[GuillermoBarrancos]

I was looking into this as well.

But when I saw what a H-alpha filter costs seperately.

You better as well just buy the PST scope and just use that one.

One thought that DSO imaging is an expensive bussiness. Well, it seems Solar observing surpases that pretty quickly when you start entering the H-Alpha domain.

[Keiran]

Yes I will agree, Its crazy how expensive this equipment is. I did see, a little while ago though, an ERF go on her for £250 I think.

[Merlin66]

For a "good" PST mod for Ha you ideally need a good ERF ( Baader) and a f10 "donor" telescope OTA ( Vixen).....and that's just the beginning.

I've done/ assisted in some 15 PST mods so far.....and the number is climbing!

Ken

[GuillermoBarrancos]

For a "good" PST mod for Ha you ideally need a good ERF ( Baader) and a f10 "donor" telescope OTA ( Vixen).....and that's just the beginning.

I've done/ assisted in some 15 PST mods so far.....and the number is climbing!

Ken

Baader Prominence Attachement (on Teleskop-service.se):

B2459020 1.5 Angstrom Prominence Attachment IV 14995.-

14.995 SEK = 1,324.41 GBP

Then you have the stuff that comes with it (also in SEK):

B2459100 VIP Excenter For scanning the sun's rim at high magnifications 1830.-

B2459011 Cone modification for other refractor focal lengths (between 800mm and 1200mm 1045.-

B1508153 T2 Extension Tube 40mm for photographical use 169.-

And here you have the real stuff: http://www.solarspectrumfilter.de/ with prices going even a lot higher.

[stefski]

Hi guys, thanks for the response:)....The chap at SGL 5 had one of those white light glass filters at the front and had taken apart a PST and put the 'business' bits at the other end and was viewing using a camera+ laptop.

PST ~ £500 new, TO white light filter ~£80...+ DIY...seems a bit cheaper than above...am I missing something?

Stef

[Merlin66]

"am I missing something?" - yes...the expensive bits!!

The filter up front is NOT a white light filter but a special safe energy rejection filter ( Baader D-ERF), the PST etalon and original PST "black body" can be used, but the performance is improved dramatically by adding a large blocking filter (BF10).

Excluding the cost of the PST the mods can cost from 400 to 800gbp. Still cheaper than the alternatives.

Ken

Brian has presented a very good overview - you need to re-read it.

[Mark at Beaufort]

Stef

The guy with the Vixen modification at SGL5 was Nick H (Howes). He did not have a white light filter at the front as Ken (Merlin 66) has indicated. I am sure that Nick had a Baader rejection filter at the front and an additional blocking filter as well. I am sure Nick will provide you with his details if you send him a message.

Whatever you do don't take a risk, as BrianB stated eyes cannot be replaced.

Mark

[stefski]

:DThanks guys...Seems it's all out of my price range...Didn't realise its was a more expensive filter at the front of Nick's 'scope. Don't worry though, I wasn't intending to have my eyes lazered in a hurry:). I am aware of the risks, just trying to find possible cheaper alternatives! Thanks loads for the concern:) and advice.

Cheers all.

Stef

[GuillermoBarrancos]

:DThanks guys...Seems it's all out of my price range...Didn't realise its was a more expensive filter at the front of Nick's 'scope. Don't worry though, I wasn't intending to have my eyes lazered in a hurry:). I am aware of the risks, just trying to find possible cheaper alternatives! Thanks loads for the concern:) and advice.

Cheers all.

Stef

I ran into the same. H-alpha is just out of my league financially. Especially as I want to focus on Astro Photography first. Wich isn't cheap either.

You can just start with stuff like Baader Solar film on the Tube end, together with their Solar Continium and CaK 1.25" EP filters tho. Those are really affordable and get you started.

[Keiran]

So do you need any thing else if you are just looking at white light and sun spots with baadar solar film.

'Solar Continium and CaK 1.25" EP filters '

Are these needed and what do they do.

I have seen special EP for the PST is it recommended to use thes, with out a PST just with the solar film, and are there any advantages.

thanks keiran

[GuillermoBarrancos]

So do you need any thing else if you are just looking at white light and sun spots with baadar solar film.

'Solar Continium and CaK 1.25" EP filters '

Are these needed and what do they do.

I have seen special EP for the PST is it recommended to use thes, with out a PST just with the solar film, and are there any advantages.

thanks keiran

No you don't need the EP filters. The Baader Solar film on the tube end is enough to view the sun in white.

The Solar Continium EP filter gives a higher contrast on sunspots.

The CaK filter gives that famous blue'ish view. It enhances the contrast even more than the Solar Continium filter and they say it even allows you to see some solar flares.

[brianb]

And the "special" EPs for the PST are very ordinary & seriously overpriced ... Baader Genuine Ortho perform better, but ordinary budget range Plossls work very well in the PST.

[Keiran]

Thank you for the clarification, so will it be worth getting any 'Solar Continium and CaK 1.25" EP filters ' will it make a difference when viewing wit baaadar solar film?

Will you be able to see any sun proms, or will it just be sun spots, i think you answered this.

What happend if you use R, G, or B filters will it just do the obvious and the the image a colour.

[brianb]

Solar Continuum is a very expensive green filter. An ordinary green filter at 10% of the price is 90% as good.

CaK is for imaging only, IMHO. I reckon 90% of the population see nothing at all in CaK light (393 nm) and 90% of the rest can't focus the dull purple/violet blob they see. It helps if you're under 5 and/or have had your natural eye lenses replaced by glass ones (cataract repair).

[stefski]

Solar Continuum is a very expensive green filter....QUOTE]

Solar Filters - Baader Solar Continuum Filter

£60 doesn't sound like much to me!

So for about £80 (Baader film + Baader Continuum filter) + a web cam, one should be able to see sunspots well. Any granulation visible with these babies?

Stef:)

[GazOC]

It is when an "ordinary" green filter costs a fiver!!

[Merlin66]

Yes, with that set up you'll see the sunspots and surface granulation.

[Keiran]

Okay, Thank you for your help. I have ordered my solar filter for £10.00, and i have also bought a green filter from astro boot for £1.00.

Can any body recommend any tube rings for cheap for a Maede 70mm refractor to fit an 8" Newt.

Thanks

[stefski]

Yes, with that set up you'll see the sunspots and surface granulation.

Hi Merlin,

Was this reply to me re film+filter+web cam or were you replying to 'bulldog-keiran'.....Just that when you look at the thread the responses are not quite in order, I think:)

Stef

[Merlin66]

Probably both:)

A white light filter ( with or without an additional green filter) will only show the Sunspots and surface granulations......

Ken

[stefski]

Cheers,

Ken

[Tim]

Question: Will any f10 telescope be suitable for the mod? ie, does it have to be a refractor?