four inch refractor .. or .. ?

[Logieberra (Logan)]

You mentioned 'mount' in your opening. Go good mount. Opens up your possibilities

[Profiler (Profiler)]

Hi Jellies

I have read your original post and some of the following comments and will give you a few ideas as food for thought from a refractor-o-lcoholic perspective.

1) Firstly - what you have read and the old adage "aperture wins" is absolutely correct. A 4inch high quality $4k+ refractor like a Televue NP-101 cannot beat a cheap mass-produced Chinese 10inche Dob in terms of light grasp.

However, the 10' Dob only beats the NP-101 provided you take it outside on every occasion. As time goes by convenience and your enthusiasm to drag out the dob will quickly wane in comparison to ease of taking out the refractor. I have lost count of the number of dusty dobs I have noticed sitting in garages from folks who gradually loose interest and find some reason to not observe because it is too much bother. SO - aperture wins but another even better phrase is that the best telescope is the one you use the most. IMO Pound for pound the telescopes that overall get used the most are small refractors (100mm and down).

2) You ask yourself "Why bother spending $4k+ on a NP101 or TSA-102 when you can get roughly the same thing in a Shywatcher ED102 for $1.2k or even worse - a big dob for roughly $6-$800"?

The reality is that this is a false premise and not true in practice - If these propositions were true premier manufacturers of refractors such as Televue, Takahashi, AP would have been out of business and non-existent decades ago. The reality is that "You get what you pay for"

Something’s gotta give in a Skywatcher ED102 or 10" Dob in comparison to the NP-101 to explain these massive price differences. The reality is that the "give" in the cheaper scopes is that they are only "similar" or "near" (ie not the same) to the premier scopes and "only for a defined period of time".

Simply put, the cheap scopes are not built to last and when they are operating at optimal performance they are only close to the premier scopes. This is why Tak and TV give 5 year warranty on their scopes and lifetime warranty on eyepieces while Shywatcher state 12months (if you are lucky in terms of the retailer prepared to honour it and not attribute the issue as some fault of your usage and thus not covered by warranty – this is another long story I won’t get into).

Provided you don't do something manifestly wrong in the care and maintenance of your NP-101 or TSA-102 after 4 years of usage you will still be going strong with the refractor and in many instances your children will be using it when you give it to them as part of their inheritance. After 18months use the particleboard in your dob will begin to deteriorate from the moisture (from prolonged exposure to dew) the mirror coating will also start to wane and thereafter it is only downhill and largely a basket case. Likewise the coatings, treatment and quality of the glass in the ED102 is simply not the same as the glass in your TSA.

The best way to discern the quality of the optical equipment is to look at the prices from cheap stuff, to moderately pricey to expensive high quality built to last.

3) I have tried astronomy and now I am sick of it and want to sell my equipment. Although your outlay for cheaper equipment is much smaller your likely return in terms of what you sell it for will also be manifestly reflected here as well. In contrast the premier brand equipment is always sought after and will commensurately attract a far better return. Basically, you can expect anywhere from 40-70% devaluation in the resell price of cheap mass produced astronomy products. In contrast you can anticipate about 20-35% devaluation in premier products irrespective of their age "provided" they are not damaged/faulty.

In conclusion, a TSA-102 or NP-101 are fantastic refractors both in their performance and have high price tags. Consequently, for a raw beginner wherein concerns for your "budget" exist I would not initially recommend either. If you are wealthy then by all means buy either or both!

However, assuming you are not wealthy and instead like the other 95% of the population it is worthwhile thinking of making your choice based upon buying a small amount of expensive but high quality equipment. In this context Takahashi have just released an amazing new 100mm doublet refractor using genuine fluorite for just over $2k or a Televue TV-76. Both have superb quality, will consistently attract a lot of use from you and as you progress in the hobby you will be able to decide what really suits you with lots of options for resell or adaptation of this equipment for other uses.

[goober (Doug)]

You are me several years ago.

Bought and adored at 8" Celestron dob - great scope. Sold it and upsized to a GSO 12" which was a monster, poor scope, tricky to collimate, store, transport, etc. I dabbled with a ED-102 on an EQ mount and hated that too. Cheap and nasty.

Got to spend a month with a TV-102/alt-az combo and knew this 4"/alt-az combo was "it" for me. 5 minute setup, could toss it in car, etc. Got myself a TV-101/Gibraltar and adore it. Expensive, sure. But the quality is sublime. Can't see myself ever getting another scope.

I have observed far far more with this scope than any of my previous... and that's the point, right?

[Profiler (Profiler)]

In a nut-shell - correct

Moreover - "if" you decide to sell your TV-101 at some point in the future to get a NP-127is you are likely to get roughly the same sort of money for your TV-101 as what you originally paid for it - they really hold their value - the same can't be said for the cheap mass produced stuff.

Additionally, there is some scope for debate about what differences you will 'see' with a high end refractor compared to the big dob in an urban light-polluted area - especially when you stick a big camera on the back of the refractor.

[Steffen]

Originally Posted by Profiler

Additionally, there is some scope for debate about what differences you will 'see' with a high end refractor compared to the big dob in an urban light-polluted area - especially when you stick a big camera on the back of the refractor.

Ah, now you're shifting the goal posts around a bit

Using your own eyes there is a LOT a 4" or smaller high-end refractor can not show you. A big Dob will always show more, even in light-polluted skies. Plus, with the amount of light you gather using filters to mute the light pollution becomes very practical.

For imaging on the other hand, there is no doubt that even an 80mm refractor is extremely useful.

Cheers
Steffen.

[Profiler (Profiler)]

As I said - 'there is some scope for debate'

What I am especially curious about are the new 'real-time' video cameras and what they can potentially accomplish with a high end refractor

[Steffen]

Yes, I'm curious about those video cameras and their capabilities, too. Unfortunately they still cost more than a 10" Dob…

Cheers
Steffen.

[Profiler (Profiler)]

Yes - exactly

It is the typical annoying situation all over again with a new product that everyone is interested in but no-one wants to go first in handing over their cash to give it a punt to see whether it works or not.

[ZeroID (Brent)]

Originally Posted by Profiler

3) .... Basically, you can expect anywhere from 40-70% devaluation in the resell price of cheap mass produced astronomy products. In contrast you can anticipate about 20-35% devaluation in premier products irrespective of their age "provided" they are not damaged/faulty.

Yes but a 40% drop in $300 for a 'cheap' 80mm f5 is still a lot less than a 20% drop in a $3000 scope. You could buy 2 cheap scopes for the price drop on the expensive one .

My 80mm F5 cost $200. If I ever sell it (unlikely) I reckon I can easily get that cost back. It's still the best grab&go I've got and currently is setup in the lounge for the short breaks in the clouds we are currently experiencing.

[Larryp (Laurie)]

Originally Posted by ZeroID

Yes but a 40% drop in $300 for a 'cheap' 80mm f5 is still a lot less than a 20% drop in a $3000 scope. You could buy 2 cheap scopes for the price drop on the expensive one .

My 80mm F5 cost $200. If I ever sell it (unlikely) I reckon I can easily get that cost back. It's still the best grab&go I've got and currently is setup in the lounge for the short breaks in the clouds we are currently experiencing.

I guess if you buy quality in the first place, you are less likely to sell it.
On my return to the hobby, I bought some cheaper refractors and sold them because I wasn't satisfied-I lost a lot more money doing that, than if I had bought a top notch scope in the first place.

[Profiler (Profiler)]

Originally Posted by ZeroID

Yes but a 40% drop in $300 for a 'cheap' 80mm f5 is still a lot less than a 20% drop in a $3000 scope. You could buy 2 cheap scopes for the price drop on the expensive one .

My 80mm F5 cost $200. If I ever sell it (unlikely) I reckon I can easily get that cost back. It's still the best grab&go I've got and currently is setup in the lounge for the short breaks in the clouds we are currently experiencing.

You have overlooked point (2) - the optical capabilities of your synta f/5 achro are not even in the same ball-park, not even in the same country - not even in the same universe as a F/5 NP-101is (or TV-85).

The real "strength/benefits" of cheap astro gear are:

1) Affordable for anyone on a budget

2) Due to their low/cheap prices they are a logical option for an absolute beginner who is uncertain how much they like the hobby before expending too much money.

3) They have a "care-free" benefit in that there is less concern of theft and/or potential damage due to natural use or accidents/misuse. Simply put, you are not really concerned/heart broken when, for example, you accidently drop and crack the objective on a $200 f/5 synta. In contrast, when you drop and crack the objective of a 4k refractor that is an experience you will be remembering and taking to the grave.

[Steffen]

Originally Posted by Profiler

You have overlooked point (2) - the optical capabilities of your synta f/5 achro are not even in the same ball-park, not even in the same country - not even in the same universe as a F/5 NP-101is (or TV-85).

There are both very similar though in failing to show a lot of things a $400 8" Dob will pull out of the hat with ease

Cheers
Steffen.

[Larryp (Laurie)]

Originally Posted by Steffen

There are both very similar though in failing to show a lot of things a $400 8" Dob will pull out of the hat with ease

Cheers
Steffen.

Steffen, I think you are overlooking the contrast advantage of a good refractor. Its no good having heaps of light grasp if you do not have good contrast.
I can remember many years ago on a club viewing night, I was using a Televue Pronto 70mm and observing Mars at 200x. I could see far more surface detail than a couple of 8" S/Cs, because of their poor contrast.

[Profiler (Profiler)]

No - the inference was that a f/5 synta achro was on par with a f/5 Televue APO Nagler-Petval design. If this was even remotely correct Televue would have been out of business and history decades ago.

The Dob v Refractor issue is another matter and deals with a set of different variables to be compared and contrasted - and argued over

[Steffen]

Originally Posted by Profiler

No - the inference was that a f/5 synta achro was on par with a f/5 Televue APO Nagler-Petval design.

I don't think that was the contention at all. Brent merely disputed your claim that one loses less money upon reselling an expensive refractor. Proportionally you lose less of course, but in absolute dollars selling a cheap scope incurs a smaller loss.

Cheers
Steffen.

[Steffen]

Originally Posted by Larryp

Steffen, I think you are overlooking the contrast advantage of a good refractor.

Hi Larry, not overlooking that at all. I know first hand that bright objects (planets, open clusters etc) look much nicer in a good refractor than in an 8" Dob. It's the dim fuzzies where the small scope capitulates.

Cheers
Steffen.

[Profiler (Profiler)]

Once again - no

Although Brent was making some comment about commensurate degrees of depreciation upon resale the initial premise upon which it is being related was invalid.

As I indicated in point (2) "Whatever" the characteristics of the f/5 synta acho maybe - one thing it certainly is not - is even remotely comparable to the optical capabilities of an NP-101is. As I have indicated numerous times already if this was even remotely valid every high-end refractor manufacturer would be out of business decades ago and we would all be using Shywatcher ED100s

The logic is comparable to viewing the relative merits of a push-bike as somehow analogous to a Ducati motorbike. Of course the outlay for the push-bike is cheaper and the proportionate loss upon resale will be less to that of the Ducati - logical. However, there is no contest or valid comparison between the push-bike and Ducati in terms of which can move faster. Consequently, it is invalid to assume there is some initial relationship between the two as you are essentially comparing the relative costs of two fruits such as apples and oranges but then
juxtaposing their cost with the totally different variable of their relative taste.

As indicated in point (2) - you get what you pay for. A $200 f5 synta achro will certainly be cheaper to buy and proportionately result in less of a loss (commensurately) on resale - but it will only ever be capable of showing you what can be achieved from $200 f/5 achro optics. It will never give you optical capabilities of a $4k tak or Tv for exmaple

[Profiler (Profiler)]

Post-Script

For anyone who is interested - "Jellies" who started this thread has purchased a AP 130GT.

So I guess he went for the high-end refractor even before my comments

[Steffen]

Wow, so the answer to the question "four inch refractor or…?" is "five inch refractor!"

I'm sure Jellies will be happy with that one. Me? I would have gone with a Mewlon 250 if I had that kind money lying around. Because aperture always wins

Cheers
Steffen.

[Larryp (Laurie)]

Originally Posted by Steffen

Wow, so the answer to the question "four inch refractor or…?" is "five inch refractor!"

I'm sure Jellies will be happy with that one. Me? I would have gone with a Mewlon 250 if I had that kind money lying around. Because aperture always wins

Cheers
Steffen.

Steffen, I would back the Starfire against the Mewlon any day. I used to own a 5" and later a 6" Starfire, and they were the best scopes I have ever looked through, bar none. The 6" was easily capable of showing as much faint detail as a C11-once again, contrast!