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Orion Optics v Skywatcher!

philsail1

By philsail1
in Member Equipment Reviews

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johninderby

johninderby

Posted
Posted

One other very important point that I didn't raise in my previous post is that the eyepieces used have a major effect on showing the differences between different quality mirrors.

Simply put lower priced eyepieces, with their limitations in light transmission and various optical defects, may be the limiting factor in the performance of the better mirror whereas top quality eyepieces such as Televue Naglers etc. will allow the good mirror's qualities to show through unimpeded.

So if you want to compare different scopes then make sure that the eyepiece is good enough so that it doesn't influence the outcome.

John

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DaveGibbons

DaveGibbons

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Very interesting and entertaining thread this one! I am not the greatest OO fan having had issues with an omc140 a few years back that was optically disappointing. However , getting back to the excellent shootout review ,I have no doubt that the mirrors in the OO newt will be smoother and have a better PV than the skywatcher. I've had a dozen or so chinese reflectors over the past few years and currently own a 10" flextube dob which has excellent optics. For the price they are unbeatable and what a lucky lot of astronomers we are. I also owned 2 OO newts and have to say they completely blew me away when viewing ultra tight doubles and the planets (2002/3). You can have a moan about the focusser or the tube rings etc with an OO scope but even I draw the line with the newtonian optics they simply produce some of the best hand finished mirror sets (at a price) that can be found anywhere in the world.

I would go so far to say if I could own only one scope it would be an OO high spec 8" F6 newt. I would of course junk the focusser fit a moonlite unit and not expect the tube to be round :) .

Dave

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philsail1

philsail1

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Johninderby - Yes, I take your point about the possible eyepiece issues with short focal length scopes. I had this conversation with Barry from Orion before I purchased the scope. He asked what eyepieces I had, and told me they should be OK. When I did the first comparison I intitally used a cheap 10mm skywatcher (plossl?) simply because I'd had two supplied with a pair of Astro Engineering Binoviewers I'd bought some months previously. Although I could tell the difference straight away - between the Skywatcher 10mm and an Antares 10mm Plossl, they did suffice to carry out an equal test of each scope. Surprisingly, they managed to produce reasonable images on the night. I also used two 25mm GSO Super Plossls. These did perform well. Also used them with a Celestron 2x Ultima Barlow. The best eyepieces I had were two Vixens - a 5mm Lanthanum, and a 10mm NVL Plossl. The 5mm was at its limit in both scopes on the night I tested them (seeing was only mediocre at best). Both scopes seemed to perform well enough when using the Kelners, Orthoscopics and other various plossls I have - all being low, to averagely priced items. (Although when using these individual eyepieces, it was hard to compare as I kept having to remove the eyepiece and re-insert in the other scope).

Dave. Yes, although I was initially dissapointed with the Orion's perfomance, over the Skywatcher, I would agree that the mirror on the OO scope does seem to perform that little bit better than the Skywatcher. However, I do think that OO need to "tidy up" their attention to mechanical details if they are to capitalise fully on the quality of the optics of their scopes.

People are people, and we do want (and expect) good quality instruments - in all respects - when spending a fair bit of money on the item. I'm sure many of us have experienced the elation of studying different types of scopes for many hours, then finally deciding on what we think is the best one for our particular needs, then eagerly and excitedly (almost like a child waiting for a birthday present to arrive!) awaited its arrival, only to have that anticipated "wow" factor dashed when we find that something is not right with our new scope. When buying a Chinese manufactured scope, although we hope it will be 100% OK (and most times they are!), we don't seem too upset if something is amiss - and even the suppliers of the scopes seem to be prepared (which is comforting) to put things right immediately. When one deliberately seeks out what is advertised (and recommended) as a real "quality" telescope manufacturer, we tend to expect (and should get!) perfection - in every sense of the word. If this is not the case, then the company's "customer satisfaction department" has got to be 100% comitted to going out of their way to put things right - otherwise they are going to lose custom - that's the bottom line. Without mentioning any names, I personally have found the area of "customer satisfaction" to be much most reassuring when dealing with the suppliers of Skywatcher products.

As you (all) know, I'm calling up to OO in Crewe on Thursday, to get my Skywatcher mirror "Zygo" tested, and to have a new "improved" Crayford focuser fitted to my scope - I had to stick two pieces of black insulation tape on the one fitted as it "wobbled" in the inner tube! Not really acceptable in a scope costing over £500 (Tube only). So we will see how we get on with it all. I'll post outcome ASAP.

Thanks for everyone's interest.

Regards,

philsail1

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John

John

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When a mirror is tested, is it just the primary mirror or are both the secondary and primary tested as a pair ?.

I'm asking this because it occurs to me that you could have a very nice primary but the overall performance of the optical system is compromised if you have a mediocre secondary mirror - or is that not the case ?.

John

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GazOC

GazOC

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IMHO a good primary and a half decent secondary still makes a good scope. You can can buy "premium" secondaries but the value of these in terms of views seems to be open to question based on the discussions I've seen on the subject. I guess at the least though a good secondary wouldn't hurt... :undecided:

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ngc2403

ngc2403

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i principle a bad secondary would be a disaster because i would have a must more intense illumination and so small bad bits on it would throw off a lot more light than a bad bit the same size on the primary.

that said they are much easier to make so they should be much high quality than the primary mirror.

hence getting a premium one would not be a huge improvement on the image quality over all.

ally

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John

John

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Thanks Ally & Gaz :undecided:

Thats interesting because it mirrors (no pun intended !) the situation with refractors where the general concensus seems to be that spending a lot on a high quality diagonal is not the best use of money in terms of the performance difference that you see at the eyepiece.

John

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narrowbandpaul

narrowbandpaul

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when I asked john about the combination method of PV errors he said something along the lines of...

if you have a 1/10th wave primary and an 1/8th wave secondary, the result at the focal plane depends on the secondary..ie even though the primary is 1/10th, the secondary scatters this light to 1/8th wave...so the focal plane PV is 1/8th wave.

if you have a 1/8th primary and 1/10th secondary, you are also limited to 1/8th wave.

So you really need a secondary at least as good as your primary to make full advantage of your ptimary accuracy.

But as ally says, secondaries are easier to make as they are flat.

This is my understanding...

before this i thought the following...

1/PV_tot = 1/PV_pri + 1/PV_sec

this appears not to be the case

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Psychobilly

Psychobilly

Posted
Posted

Welsh Spreakers in Wales ... a bit like english speakers in... :undecided:

Wasn't there a move to make Polish an "official" language in Southern Ireland as there were more Polish Speakers than Gaelic Speakers...

It's a funny old world...

Anyway this little diversion whiles away the time whilst we eagerly await the Zygo Results...

Billy...

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