~ £600 scope to complement 200p newt?

[chemtom24]

or maybe i should think about going for a bigger dob? could push the price a little bit...

thoughts please

[foundaplanet]

I'm no expert but they do certainly make a difference.

I have a set of tv plossls and they are a delight to use. I started with the 32, 15, 8 and a 2x barlow. I have since added the rest. The 8 can is a bit of a problem for people with glasses but that 32 is just amazing. They all are..

A lot of people recommend the baarder hyperions..?

[ollypenrice]

Honestly, you need some kind of frame of reference with regard to what is possible. I might, on the right kind of thread, bang on about the wonders of a premium refractor. Or of a C14 on the planets. But on this thread I have the feeling that the OP might be after the impossible. The answer is to go to a star party or astrosoc meeting and try some telescopes.

It is very hard to speak for someone else. Lots of beginners ask to see the planets in the 20 inch Dob thnking that the view must be incredible. It is, but is better in the 5.5 inch TEC apo... usually. And there's the rub.

Olly

[chemtom24]

olly, thankyou for your advice. perhaps i do want the impossible i do appreciate what i can already see but i would like more!

im sure im not alone at almost being angry at the fact we are just being teased with the views we can achieve, be it affordable telescope size/type, seeing, light pollution, weather and so on.

i would just like to know i am getting the best views i can, because otherwise il always feel like there could be just that little bit more available that im missing out on.

maybe i have hit the limit of whats acheivable and nothing will greatly improve from here on in?

a reference frame would be good and i will only really get one by going to a star party - il have to look around locally.

thanks everyone for the posts, always appreciated

tom

[Madhatter]

i was going to suggest a bigger dob but you beat me too it:)

how about save a little more and buy a 12" mabey a flex.. and keep the 8" for a grab and go.?

[MorningMajor]

By the time you've read this thread your Uni fees will have gone up - savey your money!!

Sorry - I'll get me coat!

Good luck with whatever you decide on

[Moonshane]

Faster scope have a brighter image, slower is darker. It mainly applies to imaging (ie, fast/slow referring to the required exposure time), but is quite noticeable for visual, too.

Long FL scopes, ie slower scope, are generally used for planetary use whereas faster, shorter FL scope are better for dimmer objects like DS stuff.

They're not bad for planetary use, depending on the quality of the optics, but you are putting more demand on them to get the mag up enough for planetary use. A scope that have a long FL doesn't need pushing as hard to get the mag up enough. For example, I use a 5x barlow with my newt, but I used a 2x with my old Mak.

I really don't agree with the notion that for visual use a slower scope is darker or dimmer than a faster scope. A 6" scope is a 6" scope no matter what and the image brightness will be identical for the same magnification.

Aperture governs brightness other than in extreme cases where the exit pupil affects things in the faster system where you effectively lose light due to the light which misses the eye.

That said, I agree that for planetary use and similar (e.g. doubles and moon), and assuming the ability to use a smaller secondary is taken advantage of, a slow scope will generally have more contrast than a fast scope so more planetary detail will be visible more of the time.

DSOs will look exactly the same at the same magnification in an 6" f5 scope and a 6" f11 scope. After all the photons collected by a 6" aperture have no idea what the focal length is and 6" of aperture gathers a set volume of photons? After traveling from light years away, I doubt another 900mm will make a difference to the light levels.

oh yeah, for me and assuming you can handle and move about/store the weight, I'd buy a bigger dob! Perhaps a used 300 auto.

[chemtom24]

By the time you've read this thread your Uni fees will have gone up - savey your money!!

Sorry - I'll get me coat!

Good luck with whatever you decide on

tho luckily since im already at uni the fee rise wont affect me, or so i beleive

[chemtom24]

thankyou moonshane for your input - its nice to heat the other side of the coin.

its also makes me wonder - if i shouldnt worry 'too' much about getting better views cos im 'already getting em' so to speak - then why are bigger more expensive scopes made lol?? surely a 12 inch dob is gonna b better than an 8 inch ? and surely a little more contrast with an apo on the planets will give better views and yeild higher quality images??

[Moonshane]

it's all about compromise. the only thing that will gather more light is a larger aperture. larger aperture means more cost, weight and probably speed (so better eyepieces 'needed').

I doubt that the average 100mm ED refractor will come anywhere near my 6" f11 newt on planets or indeed most targets other than maybe double stars although even then double stars are also excellent in the f11. I am sure others may argue though that this is not the case and the newt has a very long tube which needs a good base to prevent wobble. A shorter refractor would be better in this respect - hence I built an equatorial platform.

you could try this - make an aperture mask for your 8" dob with a hole maybe 80mm which will fit between the spider vanes. this would give you an 80mm f12.5 'apo' scope which would be almost (if not) as good as an 80mm ED scope, albeit with a longer focal length.

a 12" scope would certainly provide better (substantially better) images than an 8" of DSOs such as galaxies, nebulae and clusters and in good seeing, jaw dropping planetary views but on the whole would be only as good or worse than the 8" on brighter objects in 'average to poor' seeing.

[chemtom24]

so i could just put the big end cover on and remove the small cap? il give this a shot next time ive got clear skies. thanks for the tip

i might just save my money. ahh its a little way off for now but its got me thinking and its given me a lot of information to mull over

[Moonshane]

you can do this but that's a small aperture - maybe 50mm

better to make one at around 80mm from e.g. cardboard painted black sit it sits inside the tube, resting on the vanes, with the hole inside two of the vanes.

better at full aperture really but this gives options for doubles etc.

[ollypenrice]

I suspect that when Shane says a 4 inch apo won't come near a 6 inch Newt he's speaking as an astronomer! I think that a beginner observing the planets in either would not, honestly, notice a vast difference. A difference, yes, but not a vast one. With experience you come to relish very slight improvements in the view and pay for them with reckless abandon!

Bigger scopes are not made for planetary observing so much as for deep sky, where the light grasp of a large aperture makes an enormous difference.

I'll continue to argue that by the time you've got to a premium 4 inch apo you are, what, 85 or 90 percent of the way towards what is possible on the planets. However, you are nowhere near what is possible on deep sky where aperture really does dominate.

I think that getting to a dark site would have ten times the impact of a change in scope.

And, yes, I do think the view we get is a kind of tease which is why I'm more and more into imaging these days.

Olly

[Moonshane]

quite true Olly. I was thinking about the APOs that mere mortals can afford such as the Skywatcher range and even perhaps William Optics etc. that said, I have never done a side by side of my 6" f11 and hope to do so this season.

[Beulah]

Are you going to take it to university with you? Make sure your insurance is up to date when you get it.

When I was at Uni, it was a free-for-all and people took what they liked.

[Macavity]

I bought an ST102 - which was nice in it's way... I bought a MAK127 - which was nice in it's way... I bought a MAK150 (idem)... a TS 8" F4 Newt (idem). Not to mention the various mounts. Sometimes, I wish I'd bought an 8" F5 (Equatorial) Newt first?

But, as they say, on "reality TV" programs: It's the journey that matters.

I say: It's been (overly expensive!) FUN - in it's way?

P.S. For £600, you could invest in a Videocam setup for the Newt? <ducks>

[Revs]

I really don't agree with the notion that for visual use a slower scope is darker or dimmer than a faster scope. A 6" scope is a 6" scope no matter what and the image brightness will be identical for the same magnification.

I'm always open to being corrected and I may be wrong, but having looked through three different scopes with the same EP's it seem to me the f-ratio has a visually noticeable relationship to brightness.

Of course, using the same EP in the three scopes resulted in different magnification. But looking at M13 with the 12T4; with the 5" f11.8 mak it was barely visible, with the 10" f/4.8 dob it was far brighter, but a bit smaller, and with the 8" f/4 Newt it was brighter again, but again a bit smaller.

EDIT: Just realised. You were talking about at the same mag and I was talking about with the same EP. Sorry, I should have been clearer