Mass Produced 16" Vs Premium Optics Upgrade?

[Damo636]

Quick question guys!

How close would a 12" with premium grade optics come to a 16" mass produced scope with standard optics?

[johninderby]

As I found from my own experience a 14" with premium optics is as good as a mass produced 16" on DSOs and better on lunar/planetary. Simply a better all-rounder. I would expect that the mass produced 16" would be clearly better than the 12" with premium optics on DSOs but not much difference on lunar/planetary.

My 14" OO dob is not much different in weight to a mass produced 12" dob so it can be carried outside and set up in about 1 minute flat. Also the compact OO dob base goes through doorways so easily.

Of course you can get the OO mirror in several other brands of custom made dobs.

John

[Damo636]

Thanks John. I

[swamp thing]

There have been many threads about this very matter on CN. The problems with the mass produced scopes are:

1/ mechanics

2/ optical consistency

The second of these points has been getting considerably better. The early Chinese mirrors were known to be less than consistant on optical quality, but they have made huge improvements in the lasts few years.

There have been many people that have compared the mass produced scopes directly with some of the premium ones and could find little difference when used on DSO,s

Most it would seem, could see no difference between an obsession 15" and a 16" lightbridge when used alongside one another on DSO,s. on planets the obsessions quality was obvious.

If a 15" obsession with premium optocs cannot pull ahead of a 16" mass produced LB on DSO I doubt anything else can.

Remember you can always have optics recoated. It costs little. But you cannot add aperture.

[Mike73]

I was asking the same question to myself a while ago Damo and figured that for DSO's (which is my main interest) then I'd benefit from more aperture but this is where a custom made dob pays off as you can pick and choose your optics to suit your budget which in my case is a 16" GSO primary with Hi-Lux coating and OO secondary, it will also be 12kg lighter than my 12" SW!

In the future (way in the future!) a nice little planet killer dob similar to Moonshanes seems like a good way to go.

[Damo636]

Thanks guys. I would like a bigger dob somewhere down the line, but had wondered how much difference a premium mirror set upgrade would make in my existing 12". Your incoming 16" sounds amazing Mike. I look forward to reading all about it in due course :-)

[Moonshane]

given the choice I'd generally go for aperture. if you are asking should I pay for a refigure or premium optics set on your existing 12" or at about the same cost to change, get a 16" lightbridge, then I'd get the 16" every time. obviously for the same aperture premium optics would be great but at the end of the day aperture is what gathers the fainter photons and if you cannot see it then you cannot see it better either.

once you have the optics, you can always make a system to fit them in.

as much as I love my 6" f11 (and won't ever sell it) the views with my 16" masked to 6.7" are superior and if you want excellent planetary and double star views and a good aperture to allow a decent sized off axis aperture then this would be my recommended route.

[Capricorn]

I would agree with Swamp-Thing, the optics out of China could be poor to start with, equally they mass produced cheap optics so we got cheap optics, but they have improved a lot and they have also invested in new machinery that is more accuate and more consistant. It is that investment in new and better machinery that will make it difficult to tell the difference if any.

What was a premium mirror once will now be a mass produced one.

[acey]

Quick question guys!

How close would a 12" with premium grade optics come to a 16" mass produced scope with standard optics?

In terms of light-gathering not very close: both will have the same reflectivity and the 16" will gather 78% more light, or about 0.6 magnitude fainter. For DSO viewing I'd choose aperture every time: when we look at faint fuzzies we generally use averted vision, i.e. we utilise the part of our retina where there is the most optical aberration but also the greatest ability to capture photons. Premium optics aren't going to make much difference to that sort of view. If there are other requirements (planetary, imaging etc) then of course it may be a different story.

[Earl]

I would say your average seeing conditions will dictate far more that anything else.

Taking that into account if all things are good its going to be better.

The real answer is do you want to pay the premium to benefit on the nights when all things come together?

[scarp15]

I considered this aspect but between a 10" OOUK with the 1/10 wave mirrors or a 12" Skywatcher flextube. However I decided I would hang on to my 8" scope, so the aperture made more sense and the cost of the scope was reasonable enough to allow me to upgrade the focuser to a moonlight. I am also very happy with the optical performance and overall mechanics. Already possessing a good set of premium eyepieces is a marriage made in heaven to.

[Scosmico]

Your comments make sense, but reading them from Manchester, they sound like sci_fi. With the weather like this, from a light polluted site, upgrading a telescope is not a opition.

[Moonshane]

what do you mean? it's clear tonight according to your summary! I actually disagree with your summary too although I live 9 miles from Manchester and 3 from Stockport. upgrading from a 120mm frac to a 12" to a 16" dob was(were) the best move(s) I ever made.

[umadog]

It really depends. There are some great Chinese optics and there are some not so great ones. It's a lottery which you get. I've seen an 8" Synta mirror perform spectacularly side by side with my 18" Zambuto. I've also seen a 16" GSO that just produced nasty views where you hunt for focus and never find it. I would rather have a 12" with good optics than a 16" with genuinely bad optics. The bottom line is that buying premium glass massively increases your odds of getting a good mirror. You'll also get a thinner mirror, which will cool faster: a real boon!

The reason I think good optics matter on a large Dob is that you'll often be at high power on DSOs. Planetary nebulae at over 400x are a reality (e.g. NGC 7026). If you have major issues with your mirror then you won't be able to get that kind of power to work right. That said, it's unlikely a mass-produced mirror will be all that bad. Collimate, cool, and take a look at Jupiter in above average seeing. If the view consistently over many nights disappoints then you may have a problem. The difference between premium glass and a good mass-produced scope is probably not all that large.

If you're currently happy with the views through your stock 12" then don't change anything. It's only worth going down that route if you think you really have a problem.