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ZAO I vs. ZAO II...?

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#1 Levine

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Posted 05 May 2013 - 12:04 PM

I recently corresponded with a friend overseas. He had bench tested the two generations of ZAO's with a laser interferometer, and found the results to be so dissimilar that he felt that there was hardly basis for comparison.

He much prefers and recommends the I's over the II's

Now, those are his eyes, and all of our eyes are FAR less sensitive than an interferometer.

So the question: given the following conditions -

Dark and steady skies with optimal seeing
An optically perfect telescope
Sample EP's from both batches selected at random
An experienced observer who has worked with "good" orthos for a long period of time

- would any *MEANINGFUL* differences in performance be detected?

Any of you who have had "head to head" experience with these pieces, please tell us about your observations and preference.

:cool:

#2 leonard

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Posted 05 May 2013 - 12:34 PM


Hello ,

>>>>> I recently corresponded with a friend overseas. He had bench tested the two generations of ZAO's with a laser interferometer, and found the results to be so dissimilar that he felt that there was hardly basis for comparison.

He much prefers and recommends the I's over the II's <<<<<

Which brings up the question , what did this test show your friend ????????????????????????
:help:

#3 Levine

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Posted 05 May 2013 - 01:19 PM

Hello ,

>>>>> I recently corresponded with a friend overseas. He had bench tested the two generations of ZAO's with a laser interferometer, and found the results to be so dissimilar that he felt that there was hardly basis for comparison.

He much prefers and recommends the I's over the II's <<<<<

Which brings up the question , what did this test show your friend ????????????????????????
:help:


Only that the resulting diffraction patterns were different.
That's all. :o

#4 leonard

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Posted 05 May 2013 - 02:24 PM

Hello Levine,

IMO , this test your friend did would have no bearing on the optical performance of these two eyepieces . I may be wrong but both the Zeiss 1 an Zeiss 2 are excellent .
The fact this person is basing his judgement on a different pattern says nothing at all.

Leonard

#5 Jeff Morgan

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Posted 05 May 2013 - 02:39 PM

Good question.

Send me a set of each and I'll get back to you in a year. :grin:

#6 Levine

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Posted 05 May 2013 - 02:41 PM

Hello Levine,

IMO , this test your friend did would have no bearing on the optical performance of these two eyepieces . I may be wrong but both the Zeiss 1 an Zeiss 2 are excellent .
The fact this person is basing his judgement on a different pattern says nothing at all.

Leonard


Right...Interferometry, and viewing with one's eye, are two different things: you cannot directly infer or predict "real world" perfomance based solely upon bench testing.

:thinking:

#7 SteveC

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Posted 05 May 2013 - 02:41 PM

I compared both sets and couldn't find any visual differences, other than the fact that ZAO I's were available in 25mm and 34mm (?). I kept the ZAO II's because they were newer and sold off the I's..............except for the 25mm, which I still own.

#8 Levine

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Posted 05 May 2013 - 02:44 PM

I compared both sets and couldn't find any visual differences, other than the fact that ZAO I's were available in 25mm and 34mm (?). I kept the ZAO II's because they were newer and sold off the I's..............except for the 25mm, which I still own.


I have the 34 and 25 ZAO I's, plus the II set.
My eyes, 'scopes, and seeing are all so-so.
Given that, I have found no reson to complain.

:smirk:

#9 johnnyha

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Posted 05 May 2013 - 02:55 PM

The ZAO-IIs are supposed to have better edge correction for faster scopes, down to f4. Whether this makes a difference on axis I dunno since I don't have any ZAO-Is for comparison.

#10 SteveC

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Posted 05 May 2013 - 03:42 PM

I compared both sets and couldn't find any visual differences, other than the fact that ZAO I's were available in 25mm and 34mm (?). I kept the ZAO II's because they were newer and sold off the I's..............except for the 25mm, which I still own.


I have the 34 and 25 ZAO I's, plus the II set.
My eyes, 'scopes, and seeing are all so-so.
Given that, I have found no reson to complain.

:smirk:


You're a lucky guy, that 34mm ZAO is a rare bird. I gave up my search for one a couple of years ago, just too difficult to find.

#11 Levine

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Posted 05 May 2013 - 04:31 PM

I compared both sets and couldn't find any visual differences, other than the fact that ZAO I's were available in 25mm and 34mm (?). I kept the ZAO II's because they were newer and sold off the I's..............except for the 25mm, which I still own.


I have the 34 and 25 ZAO I's, plus the II set.
My eyes, 'scopes, and seeing are all so-so.
Given that, I have found no reson to complain.

:smirk:


You're a lucky guy, that 34mm ZAO is a rare bird. I gave up my search for one a couple of years ago, just too difficult to find.


Pieces like this require determination, to be sure!

Acquisition requires 4 ingredients:

Time
Persistence
Ready cash
LUCK

When one finally came up for auction, I refused to allow it to slip away.

In my experiece, just about any EP you could imagine can eventually had, if you just stick to your guns.

For example, I once assembled a FULL Set of Clave focal lengths, including the 2" pieces.

I did it in 11 months.

10 piece Silvertop set? Two weeks.

Etc...

:tonofbricks:

#12 Paul G

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Posted 06 May 2013 - 05:42 AM

I recently corresponded with a friend overseas. He had bench tested the two generations of ZAO's with a laser interferometer, and found the results to be so dissimilar that he felt that there was hardly basis for comparison.

He much prefers and recommends the I's over the II's

Now, those are his eyes, and all of our eyes are FAR less sensitive than an interferometer.

So the question: given the following conditions -

Dark and steady skies with optimal seeing
An optically perfect telescope
Sample EP's from both batches selected at random
An experienced observer who has worked with "good" orthos for a long period of time

- would any *MEANINGFUL* differences in performance be detected?

Any of you who have had "head to head" experience with these pieces, please tell us about your observations and preference.

:cool:


I've side-by-sided the I's and II's, both mono and binoviewing with the Mk V, in several scopes including the following Astro-Physics refractors and Mak-Cass:

92 mm f4.9
92 mm f6.6
105 mm f5.8
130 mm f6
130 mm f6.3
155 mm f7
175 mm f8
254 mm f14.6

I've seen no noticeable difference between the I's and the II's. It's possible that one might notice a slight difference in edge correction in a fast scope if one were observing in an area with excellent seeing, but that's not where I live. In our seeing here, no difference.

The real gems of the I's were the 25 and 34mm. I was disappointed they didn't include those focal lengths when they brought out the II's.

#13 ManuelJ

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Posted 06 May 2013 - 06:14 AM

ZAO II: less afov, better corrected for fast optics
ZAO I: less eye relief, I like the eyecup of the 16

That's all, folks ;-)

#14 vahe

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Posted 06 May 2013 - 06:40 AM

Two ways to look at this:

1 – Newer is always better, be that an eyepiece, a camera, a car or whatever, if you subscribe to this theory then there is your answer !!!!

2 – I took that question to ap-ug and got an answer from Roland (#61232 & #61241)
According to Roland;

“They are optically the same, mechanically a bit different. The newer ones have smaller field stops because a few picky people complained in the past that the outer part of the field were not sharp in the version 1, so Baader had them made with smaller field stops.”

And for coatings;
“I have both and they look quite similar, I am not sure there was any great improvement. Both types produce very dark fields and both produce the same sharp planet images.

I have three pairs of version 1, 16, 25 & 34mm, with my F/20 Maks the 34mm offers the finest planetary views of any eyepiece, head and shoulder above all else including ZAO-25 and 24mm Brandons which are my only eyepieces that rival Zeiss on planets.

Vahe

#15 Levine

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Posted 06 May 2013 - 06:48 AM

Two ways to look at this:

1 – Newer is always better, be that an eyepiece, a camera, a car or whatever, if you subscribe to this theory then there is your answer !!!!

2 – I took that question to ap-ug and got an answer from Roland (#61232 & #61241)
According to Roland;

“They are optically the same, mechanically a bit different. The newer ones have smaller field stops because a few picky people complained in the past that the outer part of the field were not sharp in the version 1, so Baader had them made with smaller field stops.”

And for coatings;
“I have both and they look quite similar, I am not sure there was any great improvement. Both types produce very dark fields and both produce the same sharp planet images.

I have three pairs of version 1, 16, 25 & 34mm, with my F/20 Maks the 34mm offers the finest planetary views of any eyepiece, head and shoulder above all else including ZAO-25 and 24mm Brandons which are my only eyepieces that rival Zeiss on planets.

Vahe


Great stuff!

:bow:

#16 Scott99

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Posted 06 May 2013 - 09:58 AM

there is one obvious difference.....the dreaded undercut. ZAO I has it and also the sliding eyeguard

#17 Scott99

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Posted 06 May 2013 - 10:02 AM

I have three pairs of version 1, 16, 25 & 34mm, with my F/20 Maks the 34mm offers the finest planetary views of any eyepiece, head and shoulder above all else including ZAO-25 and 24mm Brandons which are my only eyepieces that rival Zeiss on planets.


Interesting, I don't do much planetary with the longer ones but I've heard this before - people also liking the 25mm orthos best for planetary and just using barlows to get to higher magnfication.

Could it be that larger lenses somehow deliver better contrast? Maybe because the light is spread out over a larger area of glass. People have been saying for a long time that you get better contrast with a high quality Barlow + ortho rather than with an eyepiece with a tiny integrated barlow, could be the same effect.

#18 Sarkikos

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Posted 06 May 2013 - 10:05 AM

Take into account that his Mak is an f/20.

:grin:
Mike

#19 Paul G

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Posted 06 May 2013 - 10:12 AM

Obligatory pic:

Posted Image

#20 Sarkikos

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Posted 06 May 2013 - 10:13 AM

Scott,

Could it be that larger lenses somehow deliver better contrast? Maybe because the light is spread out over a larger area of glass. People have been saying for a long time that you get better contrast with a high quality Barlow + ortho rather than with an eyepiece with a tiny integrated barlow, could be the same effect.


FWIW, my XO 5.1 showed more perceived contrast and ease of discerning surface detail than my BGO 5. The XO 5.1 has 5 elements in 3 groups, the BGO has 4 elements in 2 groups. Some observers have said that the XO's are at the same level as the ZAO's.

I think that how well an eyepiece with an integrated Barlow (Smyth lens or whatever) performs might vary quite a bit from eyepiece to eyepiece. I usually avoid separate Barlows except to bring my binoviewer to focus in my Newts.

Mike

#21 SteveC

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Posted 06 May 2013 - 10:15 AM

Take into account that his Mak is an f/20.

:grin:
Mike


That's the reason why I stopped searching for the 34mm ZAO, not enough power even for my f/15 Mak...................that and the cost, I'm retired and on a budget. I'm waiting for my wife to break her budget deal - I need another mount.

#22 vahe

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Posted 06 May 2013 - 11:28 AM

Could it be that larger lenses somehow deliver better contrast? Maybe because the light is spread out over a larger area of glass.



For visual astronomy there are three factors that contribute to a satisfactory performance, scope, eyepiece and the eye. Eyepiece and eye interface and compatibility is one reason why super high quality short focal length and short eye relief eyepieces just do not deliver the same level of performance as the longer focal length eyepieces.
I have tried 4 & 6mm ZAO eyepieces and decided thanks but no thanks, not for my eyes.

Of course with longer focal length eyepieces one will need long focus telescope if high magnification is the goal.
Optically a 4mm and 25mm ZAO may be of equal quality but not when you factor in the limitation imposed by our eyes, or at least my eyes for sure.

Vahe

#23 csrlice12

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Posted 06 May 2013 - 11:46 AM

My only Zeiss lens is the one in my smartphone camera. Therefore, I'm volunteering; send me your losing ZAOs and I'll make sure they're properly diciplined (may take a few years, you know how those ZAOs can be).

#24 Paul G

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Posted 06 May 2013 - 12:19 PM

I have tried 4 & 6mm ZAO eyepieces and decided thanks but no thanks, not for my eyes.


It's interesting how tastes differ. After the ZAO I's sold out and started to come up on the used market, the 4mm seemed the least wanted in the US but in Europe it was the most wanted of the set and commanded the highest prices used.

I used to cut off my eyelashes to use the 4 and 6mm, now I just use an eyepiece with greater eye relief.

#25 Starman81

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Posted 06 May 2013 - 12:55 PM

Obligatory pic:

Posted Image


Obligatory WOW! :bigshock:






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