The little voice in my head (Z.S. 66 Triplet APO)

[Stu]

Finally the review I've been waiting for!
http://www.cloudynights.com/item.php?item_id=1212

I do solemnly admit that I am about to spend (what I think is) a lot of money on a big scope. But there's this little voice in my head, that tell's me of what it would be like to own just one really high quality refractor, with a perfect star test, with awesome focuser, that I could take anywhere and use anytime, and know that I could use it as the benchmark that I compare everything else I buy in the future to, and just be really proud of.

I have looked at the TV60, but something just wasn't right (the helical focuser?) and I've seriously considered the ED80, but is it to big? not quite APO?

Finally someone reviewed the W.O. ZenithStar 66 triplet (not the Petzval) and compared it to an ED80:

(stolen from the link above, please goto the link > it's good!)
"The first thing that slightly surprised me was the overall contrast in the little triplet. Looking at the sun, using Baader Astro-solar safety film with both scopes, the background sky in the ZS 66 was almost perfectly black, while it appeared a lighter shade of grey in the 80 ED. The difference in contrast was quite noticeable. The solar image in the bigger refractor also seemed to suffer a little more from some false colour.

(and some time later in the article.....)

This was also confirmed looking at an artificial star at high power with both refractors side-by-side. The overall figure of the 80 ED lens is descent, showing smooth, even and concentric diffraction patterns, with a bright outer ring and no signs of astigmatism. Overall, the spherical correction is not bad, but the ZS is clearly superior.

The excellent control of both chromatic and spherical aberration was definitely noticeable in actual use; whether I was viewing the Moon or Mars, or the leaves on a distant tree, the Zenithstar 66 apo consistently snapped to focus, yielding some of the sharpest views that any instrument of this size, regardless of its price, would be capable of showing. "

The person was not trying to bag the ED80 and did stay the the CA in the 66 was more effected by seeing than the ED80 but, Geez, I have to stop reading these reviews or I am going to go mental before I choose a scope.

[ballaratdragons (Ken)]

Stu, just bring anything to Star Camp! Check out what's there then you might be able to decide a bit easier.

That is a pretty good review though.

[Stu]

Yeh I'll be bringing the AOE80L on AZ3. It was always my intention to use the star camp to find out whether aperture is going to be important to me or not.

[asimov (John)]

Is there any threads here saying whos bringing what to starcamp?? Don't worry Stu!! I went mental yrs ago reading refractor user reviews!

[ballaratdragons (Ken)]

Originally Posted by asimov

Is there any threads here saying whos bringing what to starcamp?? Don't worry Stu!! I went mental yrs ago reading refractor user reviews!

Yep, but I can't find it. It was a new thread only about a week ago!!

[janoskiss (Steve H)]

Stu, as a basis for comparison with other (bigger) scopes, a small apochromat will not work. The reason has to do with the wave nature of light (i.e., diffraction) and the resulting limitations on the resolving power of a scope.

It is easy to see stars as beautifully concentric and very well defined Airy disks on a small aperture scope, because the diameter of the Airy disk will be large (inversely proportional to the aperture of the scope). The smaller the scope the larger the diffraction rings, and hence easier to see, and the less affected by an unsteady atmosphere. You will see textbook perfect Airy disks at relatively low magnifications in a half decent 70mm scope. You will rarely see them in a 300mm, because seeing almost never permits a steady image at the high magnifications required to actually see the diffraction rings.

But these perfect diffraction rings are precisely why you cannot resolve fine details in a small scope. Every point on the true image is replaced by an Airy disk in the image you see through the scope, effectively blurring the image.

Chromatic aberration on my ED80 is non-existent as far as my untrained eyes can tell. I certainly wouldn't want to go smaller in aperture. The tube of the ED80 is oversized (100mm) which might put you off if you want a really compact scope.

You're most welcome to check out my ED80 at Star Camp.

[gbeal]

Stu,
I'm afraid that I side with Steve, nasty as it sounds.
I have a "decent" small refractor, a Zeiss 63/840 Telementor, and while an achromat, it is a darn good one. It gives spectactular views, and has that wonderful star test that everyone wants.
It's bigger brother is even better, (another Zeiss ED80/840) and also gives those elusive stellar images we all desire.
Do I use them? Well yes on the sun, and a little, but only to justify in my own mind the outrageous amount I paid for them. To me it is the warm and fuzzy feeling you get when you use something like this, something that is rare, and expensive.
The most used scope I have is either the MN76, or a homebrew 10" newt/dob.
Sorry.

[Starkler (Geoff)]

I have both a 10 inch gso dob, and an Orion ED80.
The ED80 gets very little use from my suburban light polluted home location as it just doesnt collect enough light to be able to get enough magnification to punch through the light pollution.
After being accustomed to the views I got with the dob, I was dissapointed with what the ED80 could do for me. Its strengths are in wide field viewing and in a dark sky location I would no doubt get more use from it.

[rumples riot]

Stu, I looked at buying the TV before I got the ED80. It had impressive reviews, but the bottom line was that this scope cost a lot more than the ED80 and the ED80 was coping some really good reviews. I have to say I would be more inclined to use the money towards another more expensive scope and buy something like the ED80 which is very good for both viewing and astrophotography. Just my opinion.

[Stu]

Thanks guys. It's good to have consensus, one way or the other. You have helped a lot. I just hope the someone at the Star Camp has a really big dob that completely blows my mind and I'll never have to think about small refractors again.

It has been cloudy the last week (since the luna eclipse) so I have been observing less and surfing the internet more, which is not always a good thing. Can't wait for the weekend!

P.S. The LX90 is still winning...and I think to much...

Stu,

With so much great gear available for us amateurs to buy and use, it's sounds like
your just itching to get something. I think the best advice I have heard in this thread
is wait until you get to Star Camp and check out what going. In the end you will be
much better for it. Sometimes the thing you most want, fails your to impress when
you get to try one.

regards,CS

[janoskiss (Steve H)]

Originally Posted by gbeal

I'm afraid that I side with Steve, nasty as it sounds.

I didn't mean to sound nasty.

[Stu]

Steve, you just told it as you saw it. I really liked your post a lot. I didn't understand the bit about the Airy disk being inversely proportional to the aperture of the scope, but you can explain it at the star camp.

Hey Paul, I might be a bit pretentous or something but I think I don't want an ED80 because everyone else has one, is that bad? I just associate them with Coca Cola or Microsoft (we need a smilie that has tounge in cheek )

(Hey norm, I'd get the 8" because I'm not strong enough to life the 10")

[rumples riot]

Stu not at all. You can have what ever you like so long as it is black!

Seriously, I understand. Get what you like.