It Comes Down to Go-To vs Dobsonian + Argo Navis?

[Satchmo]

Originally Posted by rat156

The Newts win in cost per inch of aperture without doubt, but sometimes this is unuseable in cities because of the overwhelming LP.

Just to clarify here, the eyepiece focal length sets the magnification for a given amount of aperture. There is essentially no significant difference between say an 8" SCT and an 8" Dob newt used at the same power for DSO observing except perhaps convenience and usability.

[ausastronomer (John Bambury)]

Originally Posted by coldspace

What I mean is,

You will run out of objects to view visually if your light pollution is bad.

In general terms that comment is correct. With "most" deep sky objects you see infinitely more, from dark skies than you do from suburbia.

However, there are plenty of people who have spent a lifetime observing the Sun, Moon, Planets, double stars and variable stars from suburban light polluted skies and never venture from their backyard. All of these types of targets are of course unaffected by light pollution. If you focus on these types of objects and go deep enough into them, there is enough to keep you going for several lifetimes without using a drop of petrol.

Me personally, I observe the moon planets and double stars occasionally from home and regularly travel to dark skies to observe DSO's.

Cheers,
John B

[casstony]

One important consideration when choosing between 8" or 10" in a light polluted backyard is that, in my experience, a 10" will gather enough light to use a UHC filter whereas an 8" will not. The improvement in the 8" is so marginal that it's not worth bothering with the filter.

[rat156]

Originally Posted by Satchmo

Just to clarify here, the eyepiece focal length sets the magnification for a given amount of aperture. There is essentially no significant difference between say an 8" SCT and an 8" Dob newt used at the same power for DSO observing except perhaps convenience and usability.

Except that the eyepiece focal length for a shorter native focal length scope will be shorter. To put it more simply, to get 100x magnification with a 2000mm focal length scope (typical 8"SCT), you need a 20mm eyepiece, to get the same with a 1200mm focal length (typical Newt?(f6)) you need a 12mm eyepiece. Now, we all know that typically a 20mm eyepiece will usually have better eye relief and be less prone to "kidney beaning" at similar price range to the 12mm equivalent. So for high power stuff (lunar and planetary) the longer the native focal length of the scope (IMHO) the better. Of course there is the tradeoff between contrast and central obstruction, but this is the beginners forum and the views will be wonderful either way.

The 26mm Plossl that my 8" SCT shipped with was a fine eyepiece, I rarely used much else (I discovered Barlows and powermates), though I have a 13mm Nagler that I also love to use (but it suffers from the kidney bean effect). Now I don't know, but I've also heard that the widefield eyepieces are terrible on short FL Newts because of the coma towards the edge of field, is this also true?

For the beginner, with little knowledge of the night sky either scope is OK, but I feel that the SCT would be better if you can afford one. Of course there's always good ones coming up secondhand on here and fleabay if you're at all patient. Most of us succumb to "aperture fever" at some stage and will sell off the smaller scope relatively cheaply.

Cheers
Stuart

[GH1967]

Been looking around at various mounts and talking to people and decided I like the 12" Meade Lightbridge.

Its portable and has enough aperture (with filters) to allow city observation (true?). I regularly go camping so will use it in the darker bush areas.

I was going to buy an Ipad and I notice they have the Skyvoyager program which will assist me with learning night-sky navigation. Another reason I decided on the Lightbridge is in affect it forces me to learn the night sky which I should do instead of the lazy GOTO option

Thats where I'm at. I'll look around a few more days and speak to people at astronomy clubs/events etc.

Thanks for the input thus far.

[Steffen]

On the topic of light loss through light pollution filters, has anybody got experience with the Baader UHC-S and especially Neodymium filters that are supposed to let more useful light through (while still cutting out most of the common streetlight spectra)? Are those effective and useful for smaller scopes (6-10")?

Cheers
Steffen.

[GH1967]

Thanks for asking that because I meant to.

Keeping it simple, can anyone name for me 2-3 simple "must have" filters by brand (maybe with a link) ideal for (hypothetically) a 12" dob in Sydney?

The purpose being of course to combat light pollution.

Thanks.

Originally Posted by Steffen

On the topic of light loss through light pollution filters, has anybody got experience with the Baader UHC-S and especially Neodymium filters that are supposed to let more useful light through (while still cutting out most of the common streetlight spectra)? Are those effective and useful for smaller scopes (6-10")?

Cheers
Steffen.

[norm]

Hey Mate,

My recommendation would be the NPB filter by Omega Opticals in the USA.

Looks like they sell via ebay these days:

http://cgi.ebay.com.au/NPB-1-25-DGM-...item483a3d3e14


Comes in both 1.25 and 2" sizes. It covers a broad spectrum of what you can use it for.

If you search the thread, it receives many good reviews.

I don't use mine as much as I would like, but that's not to say there is anything wrong with it.....it more the hassle of screwing on/off from the eyepiece.

Cheers Norm

[Steffen]

Originally Posted by norm

I don't use mine as much as I would like, but that's not to say there is anything wrong with it.....it more the hassle of screwing on/off from the eyepiece.

I suppose getting 2" filters and screwing them into the 2"-1.25" adapter can reduce this hassle somewhat. After checking that none of the 1.25" eyepieces protrudes too far…

Cheers
Steffen.

[marki]

Originally Posted by Steffen

On the topic of light loss through light pollution filters, has anybody got experience with the Baader UHC-S and especially Neodymium filters that are supposed to let more useful light through (while still cutting out most of the common streetlight spectra)? Are those effective and useful for smaller scopes (6-10")?

Cheers
Steffen.

I have not tried the baader UHC-S but can recommend the astronomics CLS which cuts effects of mercury and sodium lights (most common street lights). I have found it to be usful on brighter objects through my 5" mak (F15), ok on most objects through my 8" SCT (F6.3) and great for the 10" ACF (F10) and 16" LB I once owned (F4.5). It is not good for small refractors 3.5" - 4.0" as it makes the object too dim.

Mark

[Suzy]

I was doing some research recently on filters and came across this terrific link- just about everything you need to know. Hope it helps.
http://pages.sbcglobal.net/raycash/filters.htm

[erick (Eric)]

Originally Posted by Suzy

I was doing some research recently on filters and came across this terrific link- just about everything you need to know. Hope it helps.
http://pages.sbcglobal.net/raycash/filters.htm

Yep, David is the filter Guru!