8 inch Rasa

[Zuts]

Hi,

not a really good question but..

The 11 inch Celestron Rasa seems to take great images for it's image scale, but it is rather expensive.

The OPT site has a just released 8 inch Rasa for 1600 dollars US, substantially cheaper. I know it is down to a 400 mm FL, but what do people think about this as a nebula imaging scope?

Cheers
Paul

[glend]

You could just buy a Edge HD8 or any Faststar compatible SCT, gives you RASA capability and speed. You just need to buy a Hyperstar lenses to replace the normal secondary.

[Zuts]

It's actually more expensive to go that route

Hyperstar for 8 inch Edge HD = USD 1088
Edge HD = USD 1349


Edge HD RASA = USD 1699

[glend]

Does it have to be a new imported (conversion +GST+Shipping) scope? Just wait for a used one to pop up on the classifieds here. Hyperstar gives you narrowband capability (if you order the neat little filter draw) which I think RASA does not support).

[h0ughy]

Not quite true, the baader filter draw for the 11 RASA allows you to do this, I suppose they will make a smaller version. But the central obstruction is massive?

[h0ughy]

Also compare the specs between the scopes. I really don't know why they never constructed these in carbon fiber? Would love mine to be in carbon fiber. For the record I have never used the fan cooling yet. Being out in the observatory it is at whatever the outside air temp is. Which then brings you back to the temperature shift focus issues....... But it's a brilliant scope

[Zuts]

I have an Edge HD 9.25 but would prefer to keep that ready to go for visual and long FL photography. I am thinking of the 8 inch RASA as I can keep that ready to go with a camera always bolted on and near focus.




Yes, there are many reviews that say the RASA is a great scope. At the moment it is on sale at OPT. I'm just trying to decide if the FL at 400mm is actually the image scale I want, as I would probably be limited to large nebula.

[h0ughy]

I found it similar to using a f7. 5 scope for field of view Like an ed80 etc, and it really depends on the camera specifications

[Marke]

Unless something has changed but Celestron wont allow US companies to sell to Aus you would need to get it buy other means.

[Zuts]

I have imported a C6 last year and a Celestron Edge 9.25 reducer last week from OPT with no issues. No GST on the reducer :)

[Marke]

The reducer yes but a couple yrs ago I tried to get a Celestron from OPT
and they cancelled the order because Celestron wouldnt let them ship to here due to protecting the market.

[Zuts]

I think this changed when OPT's ownership changed a few years ago. When I bought my C6 the invoice had a special note that my warranty was invalid if I tried to make a claim from Australia.

Cheers
Paul

[multiweb]

Unreal... they have no problem taking your money but won't service you. Nice... :shrug:

[LewisM]

Opt does this on a lot of product. I bought a Tak adaptor once from them, but on the proviso I signed a waiver and accepted a statement the item was 2nd hand (which it was not) therefore warranty voided. No problem really - it was only an adaptor that no one else had

[Zuts]

Life is a gamble; but for $350 USD including postage for a new OTA I was prepared to take the risk.

Not that I could afford it but I may not do the same for say a 6 inch Tak, or an expensive mount.

Cheers
Paul

[RickS]

Looks like the RASA 8 has some significant (potential) advantages over a Hyperstar set up. It's optimised for the fixed short focal length and should have better correction of optical aberrations, less vignetting and better colour correction over a wider range of wavelengths. Also an improved focuser.

Cheers,
Rick.

[multiweb]

Do I hear an addition to your short focal lens set up? :question:

[RickS]

It would be the natural next step up from the Borg 55FL that I have on order ;) Actually, a pair of RASA 8s would make a great fast imaging set up...

[Slawomir]

I actually considered getting an 8"RASA, but then I read it has only 25mm of back-focus...

[Slawomir]

8"RASA is about 8kg, while Borg 55mm is only 2kg...so with lightweight cameras instead of 2x8"RASA :eyepop: you could have 8x55mm Borg... :eyepop::eyepop::eyepop::eyepop:

[RickS]

With a custom adapter I think I can make a Baader UFC filter drawer and ASI1600 work for narrow band. And a second one with OSC :thumbsup:



Maybe I could build up to that over time :question:

[Slawomir]

That would be very nice. I guess a special set of narrowband filters that work at f/2 would be needed though.



I'm just trying to imagine multiple of issues with such setup- starting with continuously transferring short subs from 8 CMOS cameras to a computer and the number of subs for stacking :lol:

[RickS]

Baader have a set of wavelength shifted NB filters for very fast scopes.



The new 64 core Threadripper would be perfect. I have it all figured out, Suavi! Just don't tell my wife ;)