Solar Observing with Thousand Oaks Ha filter (off axis) and ERF

[keramos]

Hello,

Has anyone got experiences to share with Thousand Oaks H-alpha filter Unit (HAU) (off axis) and Energy Rejection Filter (ERF) for solar observing (pics attached).

I've got the system which I am using with Celestron Nexstar 6 SE SCT but I'm having trouble with viewing the sun.

I attach the ERF to the opening of telescope, and the HAU mounts on to the star diagonal but when I mount the eyepiece to the HAU I cant see anything. I've even tried focusing using the focus knob on the scope.

I can see the red image of the sun in the H-alpha filter Unit but the moment put the eyepiece nothing!

I have tried 25mm (came with the telescope), 18mm and 9mm (Celestron X-Cel LX) with and without Barlow but no luck.

I know I'm doing something wrong but don't know what...please help.

Got mixed emotions as looking at the sun via the HAU was so exciting, but not being able to see it with eyepiece sooo disappointing.

Thanks in advance.

ps : I've used some of the techniques described on this forum to align the sun (shadows mainly, takes a few mins but works well).

[Floater]

Hi, keramos.

Afraid I can't help with an answer to your question because I have no experience of the filters you mention.

But I see you have had no replies at all and that is contrary to my experience of SGL.

You might try reposting your topic in the 'Solar-Observing' section and see if anyone picks up on it there and can, perhaps, help.

Hope you get sorted. I know how frustrating these things can be ...!

[keramos]

Thank you very much, it was very kind of you to respond. Words of encouragement are always appreciated and welcome.

I was getting dissapointed on two aspects, one being not being able to see anything in my scope/eyepiece and second no response on SGL

But things are turning for the better got a response and made some progress

I thought my scope must be damaged or faulty so I went out and pointed the scope at some houses and trees, and after faffing with the focuser knob I could see through the eyepiece (25mm).

So I think I need to get out there again and faff around with the focus knob but this time whilst looking at the sun via the filters. I read on some threads that SCT can have a lot of travel...and boy they do....

Well everything is an experience

[Floater]

That's the spirit! Everything is an experience; an adventure. And, eventually, a result.

I'm still surprised that you have had no responses, 'cos there are people around here who know an awful lot about an awful lot of things.

I have only one thought - and I didn't want to throw it in earlier because solar viewing can be just too dangerous to take a chance. (You don't get two chances!) But is it possible that you have 'over-filtered'?

Now of course it's important that you you have safety first. Too much filter may mean no view, but not enough filter may mean no eyesight. And there's no contest about which is more important.

With respect, I don't know how experienced you are with solar viewing and don't want to appear to be 'teaching granny how to suck eggs'. But I also don't wan't to pretend I know the answer to your problem; I'm guessing at a possibility.

It's just that with the ERF front-loaded and then adding the HAU filter you may have cut out just about all the light-gathering ability of the scope. I really do not feel comfortable in suggesting this and I certainly DO NOT want you to try something on my say-so that could, potentially, blind you!!

Hang about a bit before you try anything radical. I'm hoping somebody who is more experienced than I may come in ...

[RichieP]

I suspect that the Thousand Oaks HA filters aren't that widely used. I have never seen anybody on this site mention them. It's a shame because I have seen them advertised, was curious about them and hoped somebody would comment who had experience of them.

[keramos]

Oh yes, before I began indulging in telescopes I used Solar filters to capture the Sun via DSLR's. So am well aware of the dangers of looking at the sun without proper protection.

The Thousand Okas ERF and HAU are meant to be used together on the scope, I double checked on Thousand Oaks Website.

Unfortunatley I haven't got the chance to get out and try again....today.

ps: I also suspect I'm not pointing the scope to the sun. I'm trying to figure out how to mount my DSLR (with Solar Filter attached) on to my scope so that I can use Live view to point to the sun...or I'll just buy a solar finder available on FLO.

[Peter Drew]

Hello Keramos. Although I'm an experienced solar scope user and builder I've held off commenting on your issue as I've only "half" used the Thousand Oaks Ha system. I bought a 125mm aperture offset ERF for a project but not the HAU unit. As far as I know, the Thousand Oaks system requires around F30 effective focal length to operate properly, the aperture supplied for your telescope probably produces this. As you say you can see a red light through the unit it sounds as though you have been pointing accurately, I can only conclude that for some reason you have not yet achieved focus. The HAU unit appears to have some considerable optical path length which could call for substantial use of the SCT focus knob, have you tried its complete range?  Good luck.