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They don't 'arf glue them PSTs...

Andrew*

By Andrew*
in DIY Astronomer

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Merlin66

Merlin66

Posted
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Nick,

there's definately a couple of guys successfully using the Lunt BF1200 in Australia.

It would n't take much to test them out....just a matter of seeing if the narrowband Ha wavelengths match up with the etalon resonance spacing. A two minute job with a spectroscope. Anyone offering a Lunt BF for testing????

Ken

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Merlin66

Merlin66

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Nick, et al,

I'm uploading a spreadsheet which let's you calculate the vignetting on the etalon for any donor telescope. It also shows the movement of the back focus with etalon positioning.

I was going to add a "sweet" spot factor based on the non-collimation due to an out of position etalon, but it didn't seem worthwhile.

Feedback welcome.

Ken

PST mod calcs.zip

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Andrew*

Andrew*

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Great spreadsheet, Ken :D

Steve, Apparently Star Telescopes can supply the B1200 or BF10 cheaper than it would cost from US+charges. Helen has made some enquiries.

Saw about 3 seconds of sun peek out this afternoon, but wasn't available to get out the scope.... just typical!

Cheers

Andrew

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NickH

NickH

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Nick,

there's definately a couple of guys successfully using the Lunt BF1200 in Australia.

It would n't take much to test them out....just a matter of seeing if the narrowband Ha wavelengths match up with the etalon resonance spacing. A two minute job with a spectroscope. Anyone offering a Lunt BF for testing????

Ken

That's good news... I guess with Andy having a hand in bothm it probably would match

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Andrew*

Andrew*

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after all a picture is worth a 1000 words :D

Bob

I thought actually looking through mine at SSP was worth more Bob :-)

Well, when I saw the image on the screen at SGL5, it was only worth two words, but they quite rightly can't be displayed on this forum! Here they are anyway:

******* ****!! :D

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Merlin66

Merlin66

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We also need to add to the kit list - a helical non-rotating focuser or a short body Crayford.....

Pete,

Don't get me into anymore trouble at the moment....the thought is VERY tempting though!!!:D

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Psychobilly

Psychobilly

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We also need to add to the kit list - a helical non-rotating focuser or a short body Crayford.....

Pete,

Don't get me into anymore trouble at the moment....the thought is VERY tempting though!!!:D

He's a dab hand at large diameter fine pitched threads and we used to get hin to send stuff off for anodising as well - he used to make articualted arm joints for our surgical lasers... now taht was a Collimation job and a half... :)

I think get the other jobs out of the way first though :D

Peter...

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Andrew*

Andrew*

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RED ALERT!!

Literally! The clouds cleared! :D

First views, snatched between evening clouds, with the sun under 20° altitude, with the worst seeing I've seen in a year, with the etalon completely in the wrong position (maybe 180mm from focal point)... are incredibly promising!

Viewing at f/8.5 (106mm clear ERF) at 180x (!), the surface detail was great, showing an active area with two mini sunspots, and filaments. Unlike with a 40mm PST, prominences actually showed lots of fine structure - two very nice ones there. I slipped on a very rough cardboard 90mm mask, and the surface contrast improved significantly, although it was interrupted by cloud. I stuck to 38x with the 90mm, but I do wonder if I would have got as good resolultion as at 106mm...

One interesting thing I noted is: a prominence was showing very nicely positioned at the edge of the eyepiece FOV. When I tried to centre it, it disappeared! I wondered if it might be a sweet spot effect on a poorly collimated light path? (there is some slop in the system).

Something tells me there are further improvements to be had on already very pleasing views... :)

I'd like to take this opportunity to say a huge thank you to Ken for all the patiently given expert advice, and to NickH for more expert advice, and a cracking deal on a very nice PST, and most importantly for the inspiration to do this in the first place! :D

Andrew

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NickH

NickH

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Mate...you're more than welcome...I think the main thanks from me go to Dodi for the inspiration in the first place, and Ken for the tech help in getting the optimal light path

That disappearing prom is the PST sweet spot...not much you can do about that...but try a 9mm widefield EP...:-)

And image at F20+... watch the magic really happen

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Helen

Helen

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I managed first light this morning with my prototype mod :D:hello2::):hello2::)

I'm still waiting for the purpose built attachment for the PST to Vixen, so improvised with an alternative focus mechanism. But it worked :D I managed to see some great proms on screen - didn't risk looking given the connections for the PST were temporary. I didn't get the chance to record an images though as it was around noon and the long tube Vixen was hitting the base of the SE mount ;) and then it clouded over :(

Focus was really challenging, and I know my PST prism is not properly aligned, so definitely going to go for stage2 mod.

Its really going to be fun playing with this once its finished :D

Helen

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