planetary set up ?

[BillP]

Here's the sketch closer up and not in relation to the AFOV.

[astroeddie]

Beautiful colourations on your sketch BillP.

  Thanks for your info. Much appreciated.

[scarp15]

Nice sketch

Maybe a 10" newt might be more stable on a dob base and equatorial tracking platform, in particular if this cost is more reasonable than an upgraded EQ mount. If the OOUK versions (which would be excellent) are a little too expensive, then perhaps Shane (Moonshane) might be able to make you one.

[Mr Spock]

For £2k I'd get a C9.25 ota and put it on an HEQ5. That will leave change for a good 10mm eyepiece - x235 is perfect for most planetary targets

[Laurie61]

I've just been intouch with OOUK.

 they can make me a 8" F8 newt for £783 plus VAT. This includes upgrade focuser and 1/8th PV.

This scope mounted on an HEQ5 Pro is exactly what I'm after.  

    Eddie H

Ammended .......  Would this scope offer more detail than the 10"F6.3 with 1/8th PV mirror. Same focal lenght, but 2" extra grasp on the 10".

The 8" would offer more contrast granted, but just wondering ??

There would not be a huge amount of difference between the two, the 10" would be a little brighter at the same mag compared to the 8" and you have a bit more resolution in reserve for good nights. As the 10" f 6.3 is a standard offering and the 8" would be a special? (increasing the cost per inch of aperture) you would probably be better off with the 10" f 6.3  

For a sense of scale here's my 8.75" f 7.3 on a CGEM.

[John]

My 12" F/5.3 Orion Optics dob has a 1/9th wave PV primary and a 21% secondary obstruction. It's fitted with curved secondary vanes in a figure 8 configuration. During periods of good seeing I've been very impressed with the planetary and lunar details this scope can show me. The optimal planetary observing magnification seems to start at around 250x and I've found 300x or more quite usable on a surprising amount of occasions.  I can track objects at high power using the equatorial platform which is so much more convenient to use than putting the scope on an EQ mount.

My ED120 refractor can get surprisingly close to the performance of the 12" on nights of more average seeing conditions though, seeming to "cut through" to the fine detail and it's still able to support magnifications of 200x - 250x readily.

This report from Martin Mobberley on his Orion Optics 10" F/6.3 is worth a read. My scope is the same spec but 12" F/5.3:

http://www.cloudynights.com/item.php?item_id=634

[kerrylewis]

Agree with Michael. Good combination

Kerry

[astroeddie]

There's a 6' fence around my garden, so dobs are really no good, unless they're on a high plinth. 

I used to own a 254mmF5.8 newt and it ran fine on the old style HEQ5.

  Is there any other manufacturers that make scopes to spec in the UK ?

In one of the other threads, Moonshane says its took him all his free, AND family time when he helped with an 18" dob.

The 10"F6.3 with dob mount and 1/8thPV mirror is £1,134. Thats very reasonable for such a cracking set up.

[John]

The 10"F6.3 with dob mount and 1/8thPV mirror is £1,134. Thats very reasonable for such a cracking set up.

I'm probably stingy but that seems quite a lot to me. My used OO 12" F/5.3 plus a "Moonshane" dob mount came out under £500. OO's depreciate like crazy for some reason 

[earth titan]

I think many forget about the mount, when it comes to planetary. Although you don't need the smooth tracking of an imaging rig, the ability to sit in the same place for hours with the scope tracking without 'nudging', is not to be underestimated.

I've had dobs, which are fantastic, but for planets my EQ mount is wonderful.

[MarkMittlesteadt]

I think many forget about the mount, when it comes to planetary. Although you don't need the smooth tracking of an imaging rig, the ability to sit in the same place for hours with the scope tracking without 'nudging', is not to be underestimated.

I've had dobs, which are fantastic, but for planets my EQ mount is wonderful.

I think mounts are, BY FAR, the most forgotten aspect of necessary equipment. Even the best, most expensive scope made is rendered a cheap, useless toy on a bad, shaky mount. And obviously, for high power detail viewing it is critical!!!

[John]

I agree that a steady mount is very important for planetary viewing. Despite the need for manual tracking / nudging on many of them, dobsonian mounts are really very steady at high power, given their relatively simple construction. My 12" F/5.3 would take a really massive equatorial to hold it steady - more than even an EQ6 I reckon - but the simple 18mm ply dob mount that it's on holds it really steady even at 400x. The vibration dampening times are just a second or two as well, even at these high powers. Smooth bearings on the alt and azimuth axis will make manual tracking pretty smooth and there is always the option of adding an equatorial platform to motorise tracking if needed.

John Dobson really did the astronomy world a massive service when he came up with this design

[StarryEyed]

In the context of good seeing and with visual planetary observation in mind, what percentage of nights would a 12" be optimal to a 10"?

For instance.

A 10" would be 10%

A 12" would be 5%

Then I can consider the price difference and the potential to get a return of this over a period of time.

I appreciate that planetary imaging increases the chances to utilise a bigger scope with high speed frame rates. But I am interested here in visual observation.