from 80mm achro to 127mm apo

[tomski]

Hi All,

I have a Vixen Custom 80M refractor and from what I understand it is a decent telescope for its size. Most of my observing is done from my backyard in light polluted South Eastern suburbs of Melbourne. The Vixen gives me beautiful views of the moon and the planets, however trying to see even the brightest DSOs like Omega Centauri is disappointing (can see a light grey cloud with no stars).

My question is whether upgrading to Explore Scientific ED127 Apo would give me significantly better views over the 80mm Vixen?

Looking forward to hear you opinion/advice. Thanks.

[Profiler]

A one word answer is Yes

However, I suspect there would be some here on IIS who would rightly suggest that a 8-10' Dob would accomplish the same task and probably cost you less

[Camelopardalis]

It'd be out of character for me to suggest a Dob, but an 8" SCT should do a decent job, was out resolving stars to the core last night before the Moon got too high. For contrast, not a patch on a darker sky mind...

Not a cheap option, but relatively easy to mount for the aperture.

[tomski]

I understand that there is the option of large apertures offered by Dobs and SCTs but in terms of refractors moving from 80mm to 127mm would that be a worth while exercise in light polluted suburbs or would the gain be only minimal?

[Satchmo]

Yes it would be very minimal....under a dark sky the difference would be more obvious. But there is no better way than to try and get a look through one side by sode and see for your self.

[dannat]

Tom I feel the diff would be significant, whereabouts in melb r u exactly..there is a big diff depending on what suburbs u view from

[tomski]

I'm in Dandenong North. I'm confused though, some of you say the difference would be significant and satchmo says it would be minimal. i would think that going from 80mm to 127mm is a big jump as far as refractors are concerned so in theory is should be able to view faint objects in more detail. Is that how it works?

[Satchmo]

A 5" telescope is not much good for deep sky observing in a suburban sky. It doesn't matter what kind of telescope it is.

[ZeroID]

Would also be hellishly expensive in APO I'd imagine. A decent DOB would be a fraction of the cost.

[dannat]

Dandenong should be ok for viewing, Melb in geneal is not good for DSO viewing..at Melb Obs in the botanic gardens in the city i use a 12" newt reflector & 8" long f/l achro refractor. the planetary views can be very good, but DSO's can be disappointing-- eta carina for eg. is almost invisible with the city light pollution.

At dandenong you are also close enough to head SE or NE to enjoy much beter views -20km there can make a big difference to viewing. i lived near Drouin for a yr which is about a 35-40min drive from you & the skyies there can be very good

[casstony]

Under light pollution you need larger aperture (eg. 12" Dob) and OIII or UHC type filters to get good views of the brighter nebulae. Fainter nebulae and galaxies will still elude you, while star clusters will be nicely resolved.

I think you'd be disappointed with a 5" scope.

[Retrograde]

Hi Tom,

I have a 102mm ED/APO and from a dark-sky site Omega Centauri is partially but not fully resolved.

There's no doubt a 127mm would be an improvement over the 80mm but it would likely still be marginal in a light-polluted sky.
If your main interest is deep-sky visual then aperture is king and you would be better off with something larger.

[tomski]

So, as I understand it, upgrading to 127mm refractor would make a significant difference however not significant enough to make viewing of DSOs in light polluted sky a pleasing experience. Thanks everyone, that's what I needed to know.

[Larryp]

An Apo refractor will give you more CONTRAST than any other design of telescope. Contrast is particularly important with light polluted skies.:)

[The Mekon]

Had my 130EDT out until just a few minutes ago. Sure Bowral is not Sydney but my backyard is illuminated by street lights, regular road traffic and there is heaps of light pollution, even in a town of 10,000. Easily made out the dark lane in Centaurus A, Globulars 6144 & M4 in the same field real easy. You can see plenty with a small scope.

[Satchmo]

John you are just muddying the waters of the discussion here- a little road traffic and street lights does not turn your town of 10,000 people into Sydney ! - Sydney has 4.6 million people . You are welcome to come and visit me if you want to be reaquainted with light pollution ( and i know my skies a better than most in Metro Sydney .

I live 40km Nth as the crow flies in as favorable area as I can surrounded by Kuringai national park and I can honestly say the deep sky views are so abysmmal in my 120mm ED that it stays in its box most of the time :)

Maybe I am demanding too much to see bright DSO objects as more than just faint smudges with no detail ? . My 14" dob on the other hand does a much better job , and I do take it out ocassionally. On the other hand the 120ED is fun to use in a dark sky where there is much better signal to noise from the sky for DSO's ...

[Wavytone]

(127/80) squared means the bigger refractor has a light grasp is a tad over double that of your 80mm. It will give better views of stars and clusters for sure, almost 1 magnitude fainter. But.. Here's the catch - DSO's are extended objects, not point sources, so a factor of 2 in light grasp isn't going to make much difference.

At Turramurra golf course on a clear night, i can just make out the nebulosity of the Milky Way. With a 100mm ED refractor most DSO's are just grey smudges, though admittedly the dust lane in Centaurus A is visible.

But many "easy" but faint DSO's are simply not visible as they are washed out by the sky glow.

You would have to step up to an 8"SCT or 10" dob to see a marked improvement over your 80mm refractor.

[tomski]

Thanks everyone for your inputs, I have decided to get something bigger, maybe a 10" dob.