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Newt is just too big so....

Chubster

By Chubster
in The Astro Lounge

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Kaptain Klevtsov

Kaptain Klevtsov

Posted
Posted

OMC140? Much better for visual but a bit too slow for imaging. Based on personal experience.

Think like you are using the SW 200mm Newt with a 2X Barlow in, that's what you get without a Barlow lens. Much easier to zoom in and get up close and personal. I only swapped mine as I couldn't find an easy way to guide it for deep sky stuff and my plans for a 120mm f/8 guidescope got dafter by the day. On top of that I have a need to demonstrate what I have been up to to "our accounts department", which is why I do imaging, or the toy fund dries up.

Imaging wise, the 200mm SW Newt. is better as it has more aperture.

Window shopping wise, the SW maks sound like good value and ought to be worth it for planets and stuff. If I understand what I have read, a Mak. has spherical mirrors (as in simple and cheap to make) so as its not rocket science to make them, there's no reason why a SW Mak shouldn't be almost as good as an OO Mak. I can't remember what the chunky glass front bit looks like on a drawing, so that might be the hard bit to make. Having owned an OO Mak. I'm biased, especially as I've never had a SW version, but a Mak. would be on my short list.

Don't know anything about SCT 'scopes as I've yet to buy one (Birthday coming up, there's a hint guys!) but Rog just got the big monster C11 planet zapper, and he's a man who knows kit.

Captain Chaos

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John

John

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I can't make a comparison with what you've got, but maybe others can...

Helen

I've used 8inch F5 and F6 newtonians and I have a C8 SCT now (very similar to the Meade LX10). Assuming properly collimated scopes, the lunar and planetary performance is pretty much the same. SCT has the advantage of bigger image scale (due to longer focal length) which means you can get good high power views with longer FL eyepieces (which usually have better eye relief as well). Newts cool down a little quicker. On deep sky the detail you can see is about the same as well but the field is narrower in the SCT again due to the longer FL but you can use a focal reducer which gives you an 8 inch F6.3 scope.

An 8 inch fork mounted SCT is more portable and easy to store (as Helen says) than an 8 inch equatorially mounted newt.

John

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GazOC

GazOC

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SCT has the advantage of bigger image scale (due to longer focal length) which means you can get good high power views with longer FL eyepieces (which usually have better eye relief as well). Newts cool down a little quicker. On deep sky the detail you can see is about the same as well but the field is narrower in the SCT again due to the longer FL but you can use a focal reducer which gives you an 8 inch F6.3 scope.

But you can use a Barlow on a f5 Newt and have a 8" f10 scope...... :D

I've never really 'got' this SCT/ focal reducer thing, it gets repeated all the time, and sure its handy, but its no different or more flexible than a Newt/ Barlow combination.

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John

John

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But you can use a Barlow on a f5 Newt and have a 8" f10 scope...... :D

I've never really 'got' this SCT/ focal reducer thing, it gets repeated all the time, and sure its handy, but its no different or more flexible than a Newt/ Barlow combination.

I was just responding to chubsters need to find a more compact scope. If space and portability were no issue then I agree - an 8 inch Newt plus a quality barlow would offer better value for money and an equally competant and flexible solution. :D

John

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GazOC

GazOC

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I guess it just the number of times I've heard the SCT/ focal reducer line, like you're magically getting two scopes for the price of one (and I have heard it put like that).....don't mind me, I'm always befuddled for the first hour or so after I've got up after a nightshift. :D

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GordonCopestake

GordonCopestake

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I know that feeling. 4on 4off is the killer though, by the time you've sorted your head out for day light it's back to the land of the morlocks. Then by the time you've sorted your head out for night time it's back to day light again. Give me a nice easy 9-5 any day of the week (apart from sat & sun!)

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Chubster

Chubster

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Cheers all..

Sorry Husher not looking to spend that sort of money. :D

This is an 8" f/8 with an 18% CO

whats CO ?

I am leaning towards the mak....would I be better in selling my mount as well, would it be over kill for a mak?

Gordon what is that scope in your second pic?

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GordonCopestake

GordonCopestake

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Sorry, CO = Central Obstruction. The size of the central obstruction affects how much contrast is lost, with smaller being better. Anything less than 20% is considered to be unnoticable visually, most SCT designs are around 33%, maks tend to have smaller CO's due to there longer focal length.

The 'scope in the second picture is a C8 on a Vixen GP. It is a 1980's version with a flexible dew shield so perhaps not as obvious as it should be. Plus it was dark when the photo was taken hehe

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Kaptain Klevtsov

Kaptain Klevtsov

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Don't get rid of the HEQ5 unless you are upgrading. Ever.

If you want to do planets the last thing in the world that you need is a wobbly mount. Visually or for imaging, you need to be able to get a rock steady aim which tracks well and doesn't let the target go out of view. It's a pain refinding planets at high Mag. so I'd suggest that the HEQ5 is a minimum mount for that kind of use.

If you load up a lighter 'scope, the tracking will not degrade with the HEQ5 and you retain the option to upgrade to a bigger OTA in the future. Maybe a second hand C8 is in your future, you don't want to be hanging that off some wobbly thing as it will be nasty.

For a cheap option, I'd look at a previously cherished Skywatcher Mak., and hang onto the Newt. for when DSOs grab you again.

Captain Chaos

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