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Help me choose an 11" plus setup please

gurney

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gurney

gurney

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Hmmm, yes I had been wondering that. But I guess it's a case of being stuck between a rock and a hard place.

What would be a good compromise then Gaz?

ETA: sorry - crossposted with previous post.

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gurney

gurney

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It really is a bit of a minefield isn't it!

I'll tell you what - I'll just go and have a bit of a kip, when I wake up, if someone could have ordered my perfect setup for me (delvery to my address please), I'll put a cheque in the post! Many thanks! :)

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GazOC

GazOC

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If you want to do deep sky imaging AND want aperture then a 11-9.25" SCT is probably the way to go. They are compact for the aperture and you can use f .6 and f.3 reducers to alter the focal length/ ratio.

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FLO

FLO

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I think we might be up against the spectroscopy requirements Gaz. Reflecting surfaces are ok but not refracting. After saying that, there is very little refraction in an SCT corrector lens, there is probably more in the focal reducer... Not sure really. Otherwise I'd agree, a large-aperture SCT would certainly be more convenient.

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gurney

gurney

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Are there any technical reasons beyond convenience for going down the SCT route rather than the newtonian? Is that what you're saying Gaz - SCT would be better technically than a newtonian?

I would certainly like to get a C11 I think, for the convenience factor - but at twice the cost have to be sure it's worth the extra!

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John

John

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Those look great choices to me :)

I used to put my ED80 on an AZ-3 alt-azimuth mount for really portable visual use - they have slo-mo controls and are quite nice to use with smaller scopes.

Let us know when delivery is due so that we can prepare for the inevitable weeks of cloudy nights :lol:

John

You can tell I'm not an imager from my response above !.

Oh well ..... they would have been good choices for a visual observer :lol:

John

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GazOC

GazOC

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Sorry mate, I'd skipped the spectroscopy part...there is minimal refection in a correctoe plate, maybe it would be within acceptable limits? Or how about a Cass design with no corrector plate? There are quite a few but some of them are a tad expensive? OO do one, Tak Mewlon etc...???

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gurney

gurney

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Right then! ...deep breath...

Do you think I'd be ok with a 10" newt then?

What do you think Gaz - since you seem to have expressed concerns about the newtonian route the most?

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FLO

FLO

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I've just checked Steve, you're right about the corrector. People do spectroscopy with SCTs but remove the corrector plate to do it.

Blimey! A Newtonian sounds like the most practical option.

What about the TAL Klevsov? No corrector but it's darn expensive for the 10"...

how much are they? Who sells one?

It probably fails the spectroscopy requirements because it uses refractive optics in its design.

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gurney

gurney

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Ah - we cross posted there Steve!

By the way - the spectroscopy guy said this:

You will need three things ..

1] an equatorially mounted telescope of 20cm aperture or above - your suggested 11" Celestron ideal. Avoid refractors even APOs! - they refract light [like the spectroscope] and can spoil results so reflectors are best in this field.

2] Sensitive cooled monochrome CCD camera by Starlight Xpress, SBIG, Apogee etc.

3] hi-res spectrograph with slit like

a] LHIRES III at

http://astrosurf.com/thizy/lhires3/index-en.html

b] SBIG SGS at

http://www.astroman.fsnet.co.uk/sbig.htm

c] my homemade WPO spectrograph - link at my spectro homepage at

http://www.astroman.fsnet.co.uk/spectro.htm

You can get a taster of stellar spectro by placings a transmission grating by Rainbow Optics or Staranalyer before a regular DSLR camera coupled to a small static telescope as my homepage

http://home.freeuk.com/m.gavin/driftsp.htm

Yahoo groups has two friendly amateur spectro groups at "amateur_spectroscopy" and "staranalyser" where you'll get invaluable help. Good luck in your quest.

So he seemed to think the C11, even though an SCT, would be fine.

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GazOC

GazOC

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Right then! ...deep breath...

Do you think I'd be ok with a 10" newt then?

What do you think Gaz - since you seem to have expressed concerns about the newtonian route the most?

Its not so much concerns about Newts just that the learning curve for beginning imaging is going to be very steep. Have you considered a big Newt for spectroscopy and a 80mm-100mm apo refractor to begin imaging with?

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gurney

gurney

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Lol

yes - that was my post a few posts back. I'd decided on getting the 300P on an EQ6 Pro piggybacked with an 80ED.

But now I'm not even sure if I know what my name is anymore! :)

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GazOC

GazOC

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:)

I'd suggest you join one of the Yahoo spectroscopy groups and try to find out if an SCT can be used. If it can then a 11" SCT is your best option, if not then we are back to the Big Newt and the problem of learning imaging with it.

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Whippy

Whippy

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I've just checked Steve, you're right about the corrector. People do spectroscopy with SCTs but remove the corrector plate to do it.

Blimey! A Newtonian sounds like the most practical option.

What about the TAL Klevsov? No corrector but it's darn expensive for the 10"...

how much are they? Who sells one?

It probably fails the spectroscopy requirements because it uses refractive optics in its design.

Just out of interest Steve, where is the refractive part in the design? I was under the impression it was just two mirrors albeit a 'funky' secondary design.

Tony..

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