Solar Advice Please...

[Keiran]

Hi All

I now have a some what redundant Megrez 72. I dont see it getting a whole lot of use and i am now using my GT81, and i dont really want to sell it.

I was thinking of buying a Lunt B600 Blocking filter diagonal, and an ERF.

Would this work??

Thanks Keiran

[garethmob]

im not sure hopefully merlin66 be around here soon as he is an expert in solar

one thing iv been toying with is using baader film on mine, perhaps you could do the same althrough this would only be white light

[johninderby]

Not sure if you mean the PST mod type project or a front mounted etalon, in which case no need for a separate ERF.

The front mounted etalon approach would work really well but £££££££

http://luntsolarsystems.com/blog/the-new-ls60f-unobstructed

John

[E621Keith]

I think you will need an etalon as well. From what I understand it's the etalon that isolate the Ha line, and the blocking filter removes the secondary peaks the etalon produces.

Edit: I typed too slow

[johninderby]

If it's the PST mod project then yes you'd need the PST etalon. The PST mod project works best with an OTA of about f/10 though.

John

[Merlin66]

You can't just use an upfront ERF and a rear blocking filter to observe/ image the sun in Ha....

The "heart" of an Ha solar filter is the very specialised etalon filter....

The external etalons, like the SM40/ SM60 from Coronado have a built-in ERF so they just need a matched Blocking filter to work.

Internal filters like the one on the PST, if used in a PST mod to a larger aperture, need an additional ERF up front to drop the energy levels and either the blocking filter from PST or an upgraded BF10/ BF15.

Hope this helps...

[Keiran]

Thanks for the info, so will the megrez be usable with the PST mod?

[johninderby]

It would be better to sell the Megrez and get something like this which is a more suitable focal length and makes a great basis for a PST mod project.

Vixen A80MF Refractor

http://www.firstlightoptics.com/vixen/vixen-a80mf-refractor.html

John

[Keiran]

I dont want to sell the megrez, and i really dont want another long FL refractor. I just want to put the megrez to good use. I may have to look at that front mounted Etalon, is there anywhere else that sells them. Thanks for the suggestion though.

[Merlin66]

Yes, for a really successful PST type mod you need a f10 type scope, something like the Vixen 80 or the TAL.

I think OPT in the US still sell them....

[johninderby]

The Megrez would make a great Ha scope with the front mounted etalon. Not sure where you can get the filters now in the UK. You could try asking IanKingImaging to see if he can order them.

If you win the lottery the filters from Solarscope are probably the best but expensive.

http://www.solarscope.co.uk/sf-range.html

John

[E621Keith]

Star Telescope and Widescreen centre have front mounted etalon listed on their site.

Lunt H-alpha Solar Filters - Telescopes UK: Telescopes & Telescope Accessories in your only London shop

Tele Solar lunt

as well as APM in Germany

Teleskop online Shop , TMB, APO , Dobson , Professionelle Teleskope, Kuppeln , Teleskopabdeckungen , Teleskope , Ferngläser , Teleskope online kaufen , APM Telescopes - Verkauf Beratung Herstellung Sonnenfilter

[Keiran]

Thanks very much for the info guys, Merlin, I know you get great results with the vixen mod, but i just cant part with the megrez, I hate selling things, but i really dont like them just sitting around either.

John, I noticed them ones on solarscope, i quickly left lol, i imagine they are great, but i really dont have that kind of money.

Keith, thanks for them links, that german link, APM, seems to be good. Are they all front Etalons? and if so am i right in thinking you will still need a blocking filter with it?

Thanks again all.

[johninderby]

Yes you need both the front mounted etalon and the blocking filter.

There's also Telescope Express

http://www.teleskop-express.de/shop/index.php/language/en/cat/c61_Acc------Solar-Observing.html

Yes the Solarscope stuff is great but the prices are definitely scary.

John

[E621Keith]

Coronado blocking filters are designated BF##. Some of those are double stack etalon, while some appears to be packages with front etalon and blocking filter. It's best to contact the dealer to confirm it.

[Keiran]

What do the BF## mean?

[johninderby]

What do the BF## mean?

It's the diameter of the blocking filter. In other words a BF10 has a 10mm dia filter etc. The larger the diameter of the blocking filter the wider the FOV.

John

[Keiran]

Thanks very much