Orion Optics v Skywatcher!

[mik]

Nice one Phil how about APO vs .......... no sorry.

Thanks for the review.

Mick

[Tiny]

Don't forget they even got the Hubble Mirror wrong - but only found out when they used it in space!

[Psychobilly]

According to the progamme on Nat Geo the other night it was the measuring equipment that they use to check the mirror that was out ... a washer in the wrong place..

[ngc2403]

what hubble?

[darditti]

I've been following this thread, and there are some peculiar ideas in it, like:

Yes, I think you are right in saying that if one is observing from a "back yard" (or any urban, light polluted situation) then perhaps you are not going to get the best from an Orion Mirror, whereas the Skywatcher will be a little more forgiving.

Sorry, this is nonsense. Is there some confusion between light pollution and seeing conditions going on here?

The difference between a good telescope and a poor one is easiest to spot when observing planets, the Moon, or double stars under good seeing with high magnification. But to an experienced telescope user the difference will be apparent almost any time. Light pollution is irrelevant to this.

In virtually any location there will be excellent seeing on a small proportion of nights. It is on these occasions when you will get the full benefit of an excellent telescope. But you will get some benefit all of the time. Anywhere, most of the time, an experienced user will be able to spot the difference between a poor telescope and a good one.

The argument "you might as well get a poor telescope if you have a poor location" makes no sense. You want to get superb views on the occasions when the atmosphere allows it, whatever things are like on average (and I am not convinced there is much difference in average seeing conditions anywhere across the UK).

However, the idea that manufacturers' quoted P-V values, or indeed Zygo interferometry tests, are a good measure of actual performance is deeply suspect. OO in particular uses the Zygo test as a bit of a marketing gimmick. There are other much simpler and less expensive tests you can do yourself which will give you a good, probably better, idea of the quality of the mirror. (The simplest of these is just looking through the blinking thing on a night of good seeing, as has been pointed out several times here.)

I look at hundreds of high-quality images of planets taken through amateur telescopes. The very best of these are typically taken through telescopes that have not been rated at better than 1/4 wave P-V. This is telling me something about the relevance (or lack of it) of manufacturers' P-V claims to performance. Can telescopes actually be collimated to an accuracy higher than 1/4 wave? I doubt it. In which case, all this P-V stuff is just "sales-talk". Good mirrors have an accuracy of about 1/4 wave and smooth surfaces which scatter light minimally. The P-V measurement does not reflect surface smoothness, thus it does not tell you the true Strehl, or the true performance.

All the evidence I have is that both OO and Skywatcher make mirrors that are up to the job. You used to get plenty of poor mirrors on the market, back in the days when I started in astronomy (30 years ago), but seemingly not now. It is up to the purchaser to decide if the product overall is good value for money, based on all the features and optical and mechanical performance.

I agree with the comment that the puzzle about OO is why they seem to have a philosophy of putting excellent mirrors into OTAs which leave something to be desired. This reflects on the value-for-money calculation. I think the best chance of a small UK company competing successfully with a giant like Skywatcher/Celestron would be to adopt a philosophy of producing an all-round premium product that would be obviously better, and that some people would be prepared to pay more for. But they likely will not take my advice.

David

[philsail1]

Not that I want to start this "Orion v Skywatcher" "debate" off again - your "common sense" comments are (in my opinion anyway) spot on David.

For the "ordinary" amateur astronomer, the MK1 eyeball is always going to be the acid test of any and all telescopes - whatever the quality.

I think many manufacturing companies - of all types of goods - will use some "special" attribute that their goods alone have, as a mark of that extra bit of quality over and above the competition. The bottom line is that they want to sell stuff, and lots of it! More than their competitors.

I do think like yourself, that two different telescopes should show their respective abilities under the same skies, whether light polluted or not. If one scope is marketed as being "much" better than another, then (in my book) it should show its better quality, whatever the light conditions. They are competing under equal conditions after all. I must admit that I found it hard to comprehend "OO" telling me that their 200mm would easily outperform the Skywatcher 200mm under a clear night sky?

Finally, like you, I too believe that if a British company such as "OO" want to seriously compete with the likes of giants like Skywatcher, they (OO) do need to pay particular attention to the "finish" of their products. I think everyone knows that they make superior mirrors, but if a customer receives a scope (for which he/she has paid over the odds), in a condition which takes away that "WOW" factor when they open the box, (and they then have to go through the uncomfortable process of complaining), then the reputation of the company supplying that scope is going to suffer. "Mud" as they say, does stick, and once a company starts receiving a constant trickle of customer complaints, it is the beginning of the writing on the wall for them. It is the "little" things that count - a missalligned screw here, a bit of a rough finish there, poorly packaged goods, or unexplained delays in delivery times - which all add up to reduce or sometimes completely take away the excitement of when one first undoes the packaging to reveal the scope of their dreams!

It does not take much extra effort to put these things right though. I work in an industry where that "extra bit of effort" and "attention to detail" (which often only costs me literally minutes) makes all the difference to the customer getting a quality product and service. (My efforts are reflected in customers commenting positively, on my efforts to give them a good product and service).

This is how it has got to be with British companies - if they want to survive and compete successfully.

As you say David - "will they listen?"

Regards,

philsail1

[philsail1]

Just a Final, Final note to this thread!

I'm afraid I won't be able to conduct a comparison test of the Orion Optics 8" Newt with a Skywatcher 8" Newt, as I have recently let it go (did a deal with "Whippy"), and acquired an "Intes MK66" Maksutov!.

So. The next report you will see, is my evaluation of the Intes 66!

Bye for now!

philsail1

[Nostromo]

Guys I'd suggest that if you are comparing two mirrors on DSO's only it might help getting an idea of performance on planets or the moon and a high power star test at around 50x per inch. I'd suggest several sessions to find stable seeing conditions to really determine which is better. With machine finished mirrors you can often get a lot of scatter and bright objects with low contrast features often show this where DSO's do not. A selection of different EP's would help too. I have found the background contrast can change with FL making it difficult to assess relative brightness. The Televue 3-6mm zoom as a good one because you can choose different FL's and it introduces virtually no scatter. The supermonos are also a good bet. I have an Orion 14" which is absolutely magnificent so I know they can make very good mirrors. Some experienced planetary imagers in the use Orion optics mirrors for this very reason. Having said that, Chinese and Taiwanese companies are catching up rapidly now too... Also I have noticed they are starting to use interferometers to test stuff which gives them better quality control. Nick

[Nostromo]

PS: I put that mirror into my own OTA and the mirror supports are custom...

[FLO]

.... acquired an "Intes MK66" Maksutov!

Excellent choice Phil

The Intes will compliment your 8" Newtonian nicely.

[philsail1]

Ta Steve!

Got to get that clear night now!

Regards,

philsail1

[darditti]

Another post-script: re. the discussion on testing telescopes and the Zygo interferometer, which I say OO use as more of a marketing gimmick than anything else.

Read this page on this site

http://www.oldham-optical.co.uk/

entitled "interferometers" (menu on the left).

I know the Oldham Optics people and they are the top people on telescope optics in the UK - they know what they are talking about, they are optical engineers, not salesmen.

David

[kniclander]

Read this page on this site

http://www.oldham-optical.co.uk/

entitled "interferometers" (menu on the left).

thanks david - that looks like a really interesting site

[philsail1]

Yes, "Oldham Optical's" "Double Pass Null Test" is yet another way of trying to accurately test the manufacturing accuracy of a Newtonian Mirror.

I like the idea of involving the use of the "Mk 1 eyeball" in the test! In my opinion, there is a lot to be said for the ability of someones eyes (if in reasonably good health) being able to tell pretty accurately if something is amiss - and this goes for other things other than telescope mirrors! (like when one is looking at perhaps a picture frame that has just been put on a wall - you can usually tell if it has been hung right, horizontally and vertically).

(They say that "if something looks right, then it is right!").

All these different (and often competing) methods of testing mirrors, is good news for us amateur astronomers - in that it keeps manufacturers on their "toes" in trying to ensure that "their" product (mirror) is top quality (after all, they want to more of their product than their rivals are selling!), and virtually ensures that we are sure of getting a quality product at a competitive price.

(The actual testing doesnt need to mean that much to us in reality - if what we see through our scope looks the business, then it's got to be "AOK!").

Regards,

philsail1

[Nostromo]

Another post-script: re. the discussion on testing telescopes and the Zygo interferometer, which I say OO use as more of a marketing gimmick than anything else.

David

Blimey David, these Zygo interferomter thingies certainly seem expensive for a marketing gimmick Maybe 30-40 K UKP for a good one? What would you choose below?

or perhaps....

I like the 65 stinger...

N

[darditti]

Well, OK, I don't say OO bought it for marketing purposes, I am sure they bought it believing it was a good way of testing astronomical mirrors. But the Zygo has featured quite heavily in their publicity over the years, with an implication it is somehow the "ultimate device" for testing astronomical optics, and many amateur astronomers seem to have become convinced of this as well. The fact is that respected optical engineers dispute this.

David

[Nostromo]

Hi David I can't understand where you're going with this.

You now say OO didn't buy it for marketing purposes good because that's a lot of money to spend on marketing.

But now you say "I am sure they bought it believing it was a good way of testing astronomical mirrors".

Are you now saying OO don't know what they're buying or what it's for?

Just becasue they have invested a substantial amount of money in a Zygo is certainly no reason to cast dispertion or doubt on Orion Optics, in fact I would have thought. It's a matter for congratulations. It sounds like progress to me.

I'm not saying that we shouldn't use theMK1 eyeball either. I have used plenty of hand figured mirrors and Zygo tested ones too at starparties all over the world all of which are stunning to my MK1 Eyeball. What I am saying, is that repeatability and confirmity is important in the optical component industry, and for some companies, the Zygo can be used to obtain repeatable results. Of course an interferometer is set up by a human being and therefore would have to be set up correctly but I think that's a given for any test kit really whether knife edge/null or whatever.

For example have a look here http://www.oldham-optical.co.uk/Cert_Conformity.htm

My question would be - what does this web page with an interferogram of a 12" F5.3 mirror #000 actually say to you, the customer, who is about to part with some hard earned cash?

It seems on the surface to say "our products are consistently tested using scientific methods"

Is this not the very marketing you accuse Orion of?

Is it really wrong for companies to market their wares by stating they are using the best testing kit they can afford?

OO are saying the same thing, but in a different way - they are throwing a Zygo into the mix because it's a powerful tool of the optics industry - just like null, knife edge testing and so-on.

So essentially now you're comparing 2 reports created using different methods.

They use these methods to control quality.

So now you're comparing they way they manufacture, and control quality.

That means you're comparing companies now.

That affects their reputation and therefore livelyhood, so best to get the facts absolutely dead straight.

If we're going to do that, then I'd have questions about how both these systems work and derive the data.

The more I talk to opticians about this stuff, the more I learn. Even to frankly poor understanding, I'd want to know things like:

- How do you arrive at a multi-decimal point Strehl number?

- Are you using actual fringes sampled from the mirror for this data?

- How many actual points are you sampling on the mirror surface?

- Does your testing method take astigmantism and other forms of error into account?

- How many levels of grey can the human eye really distinguish subjectively every time?

- How long would it take to sample a hundred or so points using each method?

- Based on this data, are you using software to create a report by calculation?

- Is this software freeware, or can it be directly linked to the test apparatus to transfer data fast and accurate?

- Did you set up your test kit the same every time?

I am no expert, but I rekon an expert can answer these questions, if they are even the right ones to ask.

Nick

[Astro_Baby]

Well at the risk of pouring petrol on here the fact is with most tests of things be it optical, audio, bit error rate, or anything else most testing methodologies are open to interpretation of the results and a good technical martketing person can throw the best possible light on results no matter how bad OR alternately rip a competitors product to pieces irrespective of their test results.

In fact a good competitive analyst could make a rolled up newspaper seem like the optimum telescope to own ( no collimation required, simple reliable components, easy to use, air based optics provide best possible views free of optical distortion, zero chromotic abberation and coma free design ).

On the other hand a good analysts will make the competition look dreadful ( aluminium tube design can corrode, optical surfaces susceptible to damage, chromatic aberration and coma are possible, requires extensive collimation, huge number of components results in poor MTBF and creates inherent unreliability, expensive).

In a nutshell I dont believe most testing - never bought a hi-fi based on test results, bought it on what my ears like. Never bought a car on test results, buy on what I like and manufacturers reputation for reliability. I know from working in the marketing game everything else, no matter how scientific and objective it may seem, is at the end of the day marketing puff and subject to interpretation.

Besides with a telescope how would I ever know - round here its been non-stop cloudy since I bought the wretched thing and even on the off clear night light pollution would hardly allow any telescope to give its best. Maybe if I were in Arizona and buying a 40" scope I'd pay a bit more attention to test results for mirrors.

[darditti]

Are you now saying OO don't know what they're buying or what it's for?

I can't say why Orion Optics would spend their money in any particular way. They are a quite successful company, it would seem, and must have their own good reasons for any commercial decisions they make.

I am only pointing out, as Nick is as well, that it is a not a bad idea to read up a bit about these testing methods and find out the issues around them, as, in this thread, rather a lot of faith was being placed in the Zygo test.

That' all.

David

[johninderby]

Laser interferometer testing is the ONLY accurate way of testing telescope optics and providing an accurate Strehl number, everything else is just an estimate. One curious fact to note, all the optics manufacturers that rubbish laser interferometer testing don't have the equipment themselves. The equipment is very expensive and requires proper training to use correctly so most of the smaller companies just can't afford it.

Try googling Roland Christen (Astro-Physics) on the subject of laser interferometer testing sometime if you want a technical explanation of why this is so. Cloudy Nights has also had a few threads on this topic. Now I'm not saying that a good optician with plenty of experience can't make a good mirror without laser interferometer testing, just that when it comes to rating the quality they can only produce an estimate of the quality and their mirrors will have more variability between samples due to this factor.

Now when it comes to marketing games isn't it the one selling a mirror with only an estimated Strehl rating versus a confirmed rating that is the one playing games?

John

[brympton]

...rather a lot of faith was being placed in the Zygo test.

I'm guilty of that David, but then again having owned and used an OO scope for a little while I now have more faith in the Zygo test than I did before . I had a read of the Oldham Optical article, then looked at their price list (£1,350 for 16" 1/4 wave mirrors for example) which I have to say makes the big Flextube's and Lightbridge's look like absolute bargains.

Regards

Mark

[kniclander]

Laser interferometer testing is the ONLY accurate way of testing telescope optics and providing an accurate Strehl number, everything else is just an estimate. One curious fact to note, all the optics manufacturers that rubbish laser interferometer testing don't have the equipment themselves.

I don't profess any expertise in optics and I bow to those who clearly do but a couple of John's points jumped out at me -

1. re the "ONLY accurate way", surely any physical process is never 100% "accurate" so to say one way is the only accurate way and all others are (by definition therefore) inaccurate is surely wrong.

2. Even if one way is "more accurate" what does that mean? That still allows that other methods will give more accurate results more of the time, for example if the "more accurate" way is very sensitive to the skills of the tester or the test conditions. My impression was that that was what the Oldham people were saying.

3. It's not curious at all that folk who rubbish laser testing don't have the kit - why would they have it if they're rubbishing it? I rubbish crystal ball gazing and (surprise surprise) I don't have a crystal ball - not cos it's too expensive but just cos I think it's rubbish...

Don't want to cause offence (and John I have certainly appreciated and learnt from many of your other posts), but I thought the comments were a tad dogmatic.

Dan

[johninderby]

Hi

Sorry, didn't mean to cause any offense, but after looking into the whole subject the conclusion of the experts was that inferometer testing was the best testing method available to optics manufracturers. One thing to realise about laser inferometer testing is that it can test 10's of thousands of points on the mirror's surface whereas the other testing methods may only test 10's of points on the mirror's surface, so when you take the average of the test points which one do you think would give a more reliable result?

I would suggest that anyone wanting more information should search various forums etc. or take a look at these links and draw their own conclusions.

http://geogdata.csun.edu/~voltaire/roland/APO_testing.html

http://www.obsessiontelescopes.com/optics/index.html#Quality%20control%20with%20Interferometry

http://www.opticalmechanics.com/telescope_mirrors/optical_testing_service.html

There's lots of info out there on the subject, and take note of which manufacturers are using inferometer testing.

John

[philsail1]

Re Zygo Interferometers being used as a "sales gimmick."

I think "Astrobaby" has hit the nail on the head there! (and that's from someone who's been in "sales."

However, the bottom line must be that we have to have some kind of method(s) for the testing of mirrors.

The more different methods and techniques we have, the better (I would have thought) the result. (as long as these methods support eachother's findings, and don't conflict with eachother).

It's all got to be good news for us (the customer).

Regards,

philsail1

[ChrisEdu]

I've got a simple way to test mirrors. I look in them and if I look my usual stunning self, then I know that they're good and if not I smash them!