Ultimate planetary scope for a HEM15

[michael.h.f.wilkinson]

The C9.25 is around 9.4 kg, the mount will need a counterweight, but it should still fall well within the limits of the HEM15. I have seen plenty of sparkle in star clusters (especially globulars) with my C8. They are sensitive to collimation, but tend to hold collimation well. The MN190 mentioned earlier is 12.5 kg, or thereabouts, which is probably too much, especially when cameras or EPs are added. 

[Ags]

Yes, I thought the MN190 would be a bit much. If I could add a handle, the C9.25 would be a contender.

On reflection, I may keep the C6 for photographic duties. When the HEM15 arrives I will try it out through galaxy season. Instead I may sell my 90 mm refractor to fund the CC8. I find I am more happy taking the much lighter ZS66 out for grab and go sessions, so maybe the 90 mm was a case of aperture fever… I should have saved a bit longer and got an FC76DCU…

[michael.h.f.wilkinson]

10 hours ago, Ags said:

Yes, I thought the MN190 would be a bit much. If I could add a handle, the C9.25 would be a contender.

On reflection, I may keep the C6 for photographic duties. When the HEM15 arrives I will try it out through galaxy season. Instead I may sell my 90 mm refractor to fund the CC8. I find I am more happy taking the much lighter ZS66 out for grab and go sessions, so maybe the 90 mm was a case of aperture fever… I should have saved a bit longer and got an FC76DCU…

For really extreme portability, there's this, of course:

😉 Works well on lunar imaging, hope to test it on white light solar soon. Downside: only 62.5 mm aperture, but a decent FOV to capture the corona, should I be lucky with the weather on April 8

[John]

I read somewhere that the very early versions of the MN190 had a secondary diameter of 51mm which, at 27% of the primary diameter, made it potentially a decent visual planetary scope. Quite quickly though Skywatcher decided to put a 63mm diameter secondary in them (33% of primary diameter) to suit the needs of imagers better but perhaps moving it away from an optimal visual planetary scope ?

The Russian mak-newts I mentioned earlier in this thread are optimised for high resolution visual observing with secondaries of around 20% or even less, than the primary. They are still heavy instruments though, take time to cool, and have their quirks so I'm guessing that your considerations have moved on now 🙂

Edited January 23 by John

[Mr Spock]

I see the C9.25 is now £2995  I bought mine new for £900...

For me the Askar 140mm triplet at £2098 looks a bargain and just under the weight of the C9.25.

[johnturley]

2 minutes ago, Mr Spock said:

I see the C9.25 is now £2995  I bought mine new for £900...

 

That's for the Edge HD version, the standard XLT version is £1,895.

John 

[JeremyS]

And for visual, which I think was Ags main focus, the XLT is fine

[Ags]

I am still finding new ways of being indecisive, having narrowed the choice down to 1 scope, the CC8, I think I have come up with a cheaper and probably optically better option. How about the Orion Optics VX8L? It weighs 8kg, so it fits in the weight budget, and if it is upgraded to 1/10 PV option it comes to about 840 euros... It would beat the CC8 on actual aperture, be about the same weight (but a lot longer), and have a much smaller secondary. Obvious drawbacks are it would be very wind-affected, and visual use is a non-starter on an EQ mount. The VX8 is also a possibility - the secondary is still smaller than the CC8 and it is a kilo lighter. It will be a little easier to mount and a little less vulnerable to wind, but collimation at f4.5 (vs f6) would be more fiddly.

I used to have a 150pds that put up very nice images of Jupiter but sadly I didn't have the right mount for it, so I know a simple newtonian can do very well... The two things that go against either the VX8 or VX8L are (1) Orion Optics UK's reputation, and (2) I really think newts on EQs are unsuitable for visual use. However for visual use I can set it up on an alt-az mount like a skytee.

[davidc135]

If the Orion Optics VX8L upgrade is truly 1/10 pv and smooth I don't see it being easily bettered visually on the moon and planets.  David

[Ags]

Having used the HEM15 and RC6 for a while, my attitudes and plans have changed. I like keeping the RC6-HEM15 setup together as a single unit so much, I am thinking of adding more bits to eliminate more assembly disassembly steps, such as a small electric filter wheel to hold all the filters. I don't think I will ever use the HEM15 visually, or in combination with any other scope. 

So no CC8s or C9.25s for me! I am instead thinking of selling my Long Perng 90 lanthanum/FPL51 doublet and getting a Skymax 127 for night-time visual use and a Startravel 102 for solar duties. With a green continuum filter, the chromatic aberration of the Startravel would be irrelevant, and it could be rather nice to combine the scope with a Quark when I sell my Solar Scout. 

The SkyMax should do fine on planets, still be small enough for travel, and have much better aperture for DSOs and doubles than the Long Perng 90. I have a rule that a visual scope must be able to show a field of one degree, and the Skymax would give about 1.1 degrees with a 24/68 type eyepiece. Having considered a variety of exotic and very expensive options previously in the thread, I feel more comfortable coming back to some more homely options.

By the way, in terms of mounting options I may try a Sightron Alt-Az mount.

Edited June 13 by Ags

[Mr Spock]

8 minutes ago, Ags said:

With a green continuum filter, the chromatic aberration of the Startravel would be irrelevant,

That's what I've found, my 120 achro being incredibly sharp. One thing to think about though is how much SA a Startravel has.

[Ags]

Yes, spherical aberration might be a problem. On the other hand, at 102 mm the Startravel would have less "aperture aberration" than the Long Perng 90!

[Elp]

If you plan on using a quark a refractor around f10 is more ideal, but you could always stop the aperture down if needed.

[Ags]

well, I would use a telecentric extender to raise the focal ratio, and probably stop it down a bit to get to f30. 

[Elp]

Remember it already has a 4.2/4.3x barlow built in. I've used them on fastish refractors and haven't seen a need to stop them down anyway, imaging may benefit from it though.

Edited June 13 by Elp

[Ags]

Oh sorry, i should have mentioned I am looking at a Quark Combo, which gives me more control over the focal ratio.