Upgrade from 8 " f6 Newtonian.

[Guest]

I am currently enjoying my 8" inch f6 Newtonian mounted on an Altair Sabre mount. It gives very good contrasty views on good seeing nights. A few nights ago I went hunting some faint objects. The Hercules cluster,Ring nebula and M 81& 82. When seeing these objects,I just wish that I had a little more light gathering power. I had thought of a Celestrn C9 or a 10 " f5 Newtonian to also go on the Altars mount. Anyone gone down a similar road? Perhaps even an older 10" Meade SCT OTA.

[russ.will]

It's a balancing act.

Having had 12" Newts, a larger scope can blow an 8" away on the right nights. But there will be more nights when the seeing gets in the way of applying the magnification these subjects can take and a larger scope can deliver, because larger scopes cope less well with unstable seeing at a given magnification. Smaller scopes do some things better under UK skies, more of the time.

I'd say if the Sabre can take the weight, go for it, but don't dump the 8". Better still, just get a big, cheap and larger 12" Dob for those rare nights.

Russell

[Northern Soul man]

Hi Ya Grumps, its a bit hard to say that you want a little more light gathering power, as with the step up from an 8" to a 10 isn't going to be much of a difference from what you have now, the SCT will give you a larger image just because your moving up to F10, I think the stars will be a little more "bloated" in the SCT compared to the Newt, this really shows when the seeing is poor.  I moved from an 8" F8 David Hinds Mirror Newt to an 8" SCT - I must say that the quality of the Hinds mirror was very nice and thinking back now to when Shoemaker Levy blasted into the cloud tops of Jupiter, the actual detail visible from the Earth was just amazing - still wish I had that Newt - it was a very nice scope - the Planetary was just really nice.

I don't think you will really notice a large difference, the image will be a little brighter and just a little larger in the SCT - I think if you were going to a 14/16" you would notice a major difference, but it has a lot to do with portability (the SCT wins here, actual scope tube size (the SCT wins here again) even down to the way the EP sits for comfortable observing (a fork mounted SCT wins here as well) - I struggled with the Newt on a home made EQ mount, just trying to get the EP in the right place for comfortable observing - as well as having to keep rotating the tube on the EQ mount.

As you can see the "SCT" pops up here more than a few occasions - but there are Pro's and con's with both systems - I think that's why we all have more than one scope - I have settled on long focal length scopes, I have a lot of light pollution here where I observe from, the Planets/Luna and the brighter Messier's are more than enough for me and have just got used to the amount of light pollution and just learned to live with it - yes it would be nice for me to step outside and have the Milky Way "etched" on the sky, but learning to live with it and still being able to enjoy the night sky just does it for me - I know that we have just had the last 2 really great apparitions of Jupiter riding really high in the sky and I know that we have to put up with a very "southerly" Saturn for a few more years yet - but still enjoy setting up ready for a night behind the scope.

Not sure if you have a lot of light pollution where you do the most of your observing from - If i had a very dark sky I think my set up would be totally different from what I have now - you know you could have the best of both worlds - keep the newt and buy a second hand 10" SCT if possible??

Paul.

[John]

For the objects you mention and others similar, I've found aperture always produces better views. More extensive nebulosity, more star resolution in globular clusters, more form and contrast variations in the brighter galaxies and simply being able to see the fainter and more distant ones.

I agree that mediocre viewing conditions can reduce the advantage of the larger aperture on planetary and lunar observing but on deep sky targets I've found additional aperture consistently gives more satisfying views. Thats despite my garden, where I do 99% of my observing from, being far from perfect with regards to light pollution and other challenges.

You can get a used 12" dob for £300-£400. You could keep the 8" scope for sessions when you want a simpler setup perhaps ?

[Guest]

When I viewed the Hercules cluster and the Ring nebula recently from my light polluted garden in Hertfordshire they appear quite dim compared to seeing them in a similar 8 inch Newtonian in darker Dorset skies.

[damnut]

Hi Martin,

Glad to see you here. I have a skytee ii, the chap who had it before me had an 10" snt, a St 120 in the middle and a 152mm frac on the other side. Now, the only difference here is I have a 150mm mak instead of the snt.

I used to have an lx200 10", now that would be interesting. I bet that sabre mount would take it too!!.

[nightfisher]

When I viewed the Hercules cluster and the Ring nebula recently from my light polluted garden in Hertfordshire they appear quite dim compared to seeing them in a similar 8 inch Newtonian in darker Dorset skies.

Glad your still here, how about keep your present set up, and travel to a dark site on those super clear nights, this would only be a couple of times a year though

[YKSE]

Glad your still here, how about keep your present set up, and travel to a dark site on those super clear nights, this would only be a couple of times a year though

+1.

Martin, this is the best way get the Dorset skies obsevations. Here's a simple table I made to show the differences of an 8" under different skies:

The Naked Eye Limiting Magnitue(NELM) in my backyard is around mag 4.6 (I can see the head stars in Leo in naket eyes), while the dark site I travel to is around mag 6.2, that is 1.6 difference, it means that I need to get a 418mm scope (bigger 16") in my backyards which works almost , but not yet,  as good as the 8" in a proper dark sky.

[Stu]

Agreed, dark skies make all the difference. I've had some of my best observing sessions on the Purbeck peninsula with a 4" scope, lovely views of the Veil and NAN.

Aperture under dark skies is the ultimate though. This year's sglx was fantastic, my 16" on targets like M13 was mindblowing.

[Guest]

I may then just keep the 8 inch and explore adding an older much larger SCT to my collection.

[John]

I agree about dark skies if you can get to them. A few yyears back a couple of us had 6" scopes at the SGL star party under dark skies and the views of deep sky objects were as good as my 10" was able to give back home.

Buying a big SCT seems an expensive way to get more aperture for deep sky objects to me.

[YKSE]

I agree with Stu and John.

If your backyard is about the same light-polluted as mine, then getting a 14" may not get a better view of DSO than a 8" in a dark site, and using a 14" SCT without a permanent setup is a royal pain, IMHO.

[russ.will]

I agree about dark skies if you can get to them. A few yyears back a couple of us had 6" scopes at the SGL star party under dark skies and the views of deep sky objects were as good as my 10" was able to give back home.

Buying a big SCT seems an expensive way to get more aperture for deep sky objects to me.

But it is an easier mounting proposition on a alt/az mount due to it's shorter length. At a given magnification, it is less wibbly, if not quite so contrasty.

Russell

[michael.h.f.wilkinson]

Eight inches of aperture can show a lot of objects, and under good skies my C8 beat the university's 16"RC which stands in a light polluted campus. My C8 travels easily to dark sites, so it will certainly not go away soon. I do intend to get something bigger for visual work, and a big travel Dob like a Sumerian would certainly be an option. I could use that in my back garden AND take it to dark sites by car. I would certainly consider a travel Dobson