Newtonian f/4 to f/2.8 upgrade?

[Macavity]

Having [yesterday] reached eligibility for my BUS pass (Yay!), I have a modest sum

for Upgrades. On the other hand, after much effort, I rather *like* my basic setup.

8" - f/4 TS/GSO Newt on an HEQ5 mount (Watec 120N+, remote control etc. etc.)

Not looking for DSLR chip coverage (merely 1/2" Video Cams), I was wondering if

anyone had tried / considered the ASA 0.73x reducer / corrector for Fast Newts?

http://www.astrosysteme.at/eng/correctors_newton.html (I Think someone here has mentioned it?)

(And yes, I do know it's more expensive than my scope! lol)

For faint DSO imaging, an additional f-stop never hurt! But mostly the extra field!

Who knows, might even treat myself to a latest (4x more sensitive) Watec 910HX? 

Might then just about keep up with you "speed-king" (Lodestar II?) Guys? 

P.S. If anyone does use the ASA corrector, I'm still a tad confused...

Will it fit within my current (typical) f/4 Newt focusser, leaving the

general position of the Video Cam (chip) fairly unchanged?

[Dom543]

Chris/Macavity

I don't have the reducer but considered it at one point. I believe that you need to move your secondary and focuser closer to the primary. TS sells OTA's configured to be used with the ASA reducer under the moniker "Boren-Simon reflector". If you want to use those tubes without the reducer, then you need to add an extension tube between the focuser and the camera. This places the camera back to the same distance from the primary as you would have without the Boren-Simon modification.

I don't want to spoil your fun of spending big money on astro equipment. But on this thread http://www.cloudynights.com/topic/495160-cheap-fast-reflector-for-widefield-eaa/?p=6506581 I also tried out a run off the mill 1.25" 0.7x reducer on a cheap f4 reflector and got perfectly good results. These small sensor cameras work just fine with any optics. Glenn LeDrew has an explanation for this in one of the posts on the above thread.

Clear Skies!

--Dom

[Macavity]

Many Thanks, Dom!

Day-after-birthday celebratory bottle of wine may have got the better of me?

Interesting thread on CN though. Not completely perused, but food for thought!

Generally (I too?) have found Video Astronomy to be fairy forgiving of optics...

Even with "extreme" (low budget) focal reduction, images are often "not bad".

I suspect I will leave my "prime mover" budget Newt "as is" for the moment

For wider fields, I might invest my *modest* resources on a APO refractor...

[Martin Meredith]

Hi Chris

I've often wondered whether premium kit like the ASA corrector is 'wasted' on our small sensors, and have also thought it would be interesting to see how well a decent APO (e.g. WO 71mm 5-element) would render objects such as star clusters/globs. The ideal would be to borrow the kit for a night or two… perhaps at the local club, but in the case of the ASA at least I imagine these are quite thin on the ground. Dom, thanks for that link which I'll read later.

cheers

Martin

PS Congrats on the bus pass ;-) Now you can join the ranks of the 'twirlies' as they're called in certain parts of Yorkshire ("Amatwirly, love?")

[Dragon Man]

Bus Pass?

Must be a U.K. thing 

[Macavity]

Heheh... Ken! Now officially an "OAP" (60 y.o. Old Age Pensioner - Until

we were upgraded to senior citizens?). The time in a YOUNG man's life,

when he contemplates buying an APO refractor... or Superbike!

Failing the latter, I am generally interested in increasing my field of view...

Thanks, Martin - "Lovin' your work" as they say? We (video astronomers)

do seem often to be pondering (understand!) the same sort of issues?

None of my stuff is *expensive*. Frankly I've spent FAR more upgrading!

I SENSE an "Eight hundred quid" 0.7x focal reducer might be somewhat 

wasted on my (albeit upgraded) working *ersatz* steel-tube f/4 8" Newt.

I have my "kick-about" (Monorail focusser!) ST102 and the MAK150...

I am thinking seriously of a sub-500mm focal length for WIDER fields.

Essentially my "cluster buster" video scope (both open and globular). 

Considering 70mm APO's... Williams Optics.(?) Altair Astro(?) etc.

[Dragon Man]

     OAP!

We have to wait until 65 before we are eligible for OAP.

From the Oz Govt Website:

To be eligible for Age Pension you must be 65 years or older.

From 1 July 2017, the qualifying age for Age Pension will increase from 65 years to 65 years and 6 months. The qualifying age will then increase by 6 months every 2 years, reaching 67 years by 1 July 2023.

Date of birth:                                                                     Qualifying age at:

1 July 1952 to 31 December 1953                                      65 years and 6 months

1 January 1954 to 30 June 1955                                        66 years

1 July 1955 to 31 December 1956                                      66 years and 6 months

From 1 January 1957                                                          67 years

So for me it will be when I am 67   becuase I was born in '57

But I am stuck on a disability pension now