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FIELD TEST: CARL ZEISS APOCHROMATIC & SHARPEST (CZAS) BINOVIEWER

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#1 BillP

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Posted 24 January 2021 - 01:13 PM

This astronomical binoviewer is offered by Denis Levatić of Croatia (denis0007dl@gmail.com) as an after-market modification of new Zeiss binoviewer bodies. Mr. Levatić's value-added modifications to these Zeiss binoviewer bodies are then offered under the moniker of "The Carl Zeiss Apochromatic & Sharpest Binoviewer".

Click here to view the article
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#2 Astrojensen

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Posted 24 January 2021 - 01:38 PM

Very nice review, Bill! 

 

 

Clear skies!

Thomas, Denmark



#3 Sandy Swede

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Posted 24 January 2021 - 02:01 PM

Excellent article, Bill.  I don't know what more one could want in the way of specifications, findings, and evaluation.



#4 RichA

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Posted 24 January 2021 - 04:17 PM

A very thorough review.  This head is from a Zeiss Axiomat microscope.  The PN is 45 29 07. As far as I know, it's the only mirrored unit they make.  However, one thing;  a lens nowadays is typically incorporated into the binohead not to correct SA or CA, but to shape the light cone that comes from Infinity corrected microscope objectives.  Infinity objectives are now used in microscopes (to facilitate the introduction of various optical devices in the light path after the objectives but before the binohead) whereas in the past, microscope objectives typically had tube lengths of 160mm or 170mm (Leitz) that made it more difficult to incorporate various accessories.  This is why you can't use older 160/170mm microscope objectives on an "infinity corrected" microscope.  Olympus is one company that incorporates a "tube lens" into the bottom of the microscope head.

 

https://www.edmundop...pYaAvzbEALw_wcB



#5 dUbeni

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Posted 24 January 2021 - 05:02 PM

Hi Bill, what a wonderful read. Thank you for taking the time to share your experience, and also for mentioning your observations with the MaxBright-II.

My problem with your reviews is that I keep adding equipment to my Wishlist and my wallet keeps complaining... Lol

 

CS

Bernardo 



#6 BillP

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Posted 24 January 2021 - 05:05 PM

Rich,

 

Thanks for the info as I am not aware of the microscope field.  However, it is my understanding that these correctors are very much also used today to correct for spherochromatism (i.e., defect of image formation in which spherical aberration varies with wavelength) caused by long prism glasspaths.  Thomas Back, Roland Christen, Yuri from TEC have all commented on how any long light path through a prism, bino or diagonal, can induce spherochromatism.  The GPCs from Baader for their binoviewers were designed by Roland specifically for this I understand.  In my testings I can see it as well at high magnifications.  From the Baader website on their GPCs - "A Glaspathcorrector® is primarily intended to correct the prismatic color fringing that occurs on Refractors due to the high amount of glasses used in binocular prisms."

https://www.baader-p...s-and-sc's.html

https://www.baader-p...nd-mark-v).html

 

OCA/GPCs also serve other functions as well such as extending the backfocus of the telescope so they can come to focus with the binoviewer, allowing the use of longer focal length eyepieces for higher magnification so image merging is easier, etc.


Edited by BillP, 24 January 2021 - 05:16 PM.


#7 MarMax

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Posted 24 January 2021 - 07:43 PM

Bill, thank you for the thorough review. Is the telescope side clear aperture of 21mm correct? Just curious as a soon to be owner of these. And the MBII's seemed to be equivalent which is good to know. After more time with both it will be interesting to see if you have a preference between the two. 



#8 Howard Gao

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Posted 24 January 2021 - 08:03 PM

Thank you Bill for the review. Did you have chance to compare it with Mark V and if so how was the result? Thanks.



#9 BillP

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Posted 24 January 2021 - 08:25 PM

Bill, thank you for the thorough review. Is the telescope side clear aperture of 21mm a typo? I've just ordered these and thought that this measurement was larger.

No.  Not a typo.  That restriction is located about 5mm inside where the  light path measure was taken for the binovewer with the ClickLock holders.  My measure for the bino's light path was within 1mm of the manufacture spec so will assume that the manufacturer made a more precise measure and use their number of 138mm.  So 138-5=133mm.  So the 21mm telescope-side clear aperture point is at the 133mm point in the light path.  That means that as long as whatever aperture light cone is going into the bino is smaller than 21mm across at the point 133mm before focus will have no vignetting.  Running the calculations that means as long as the focal ratio of the scope is f/6.3 or longer than that 21mm clear aperture point in the bino will not restrict the light cone.

 

So the CZAS Binoviewer should operate with no issues just fine in any scope with a focal ratio of f/6.3 or more.  I did test it in an f/6.25 and saw no visible vignetting even with a 24mm ES68 under the stars so obviously a little wiggle room depending on exactly where the field stop is located in the eyepiece.  Many 1.25" eyepieces, like Tele Vue, have their field stops 1/4" below the shoulder with shortens the utilized bino light path by 6mm, now making it 133-6=127mm, meaning with those eyepieces it will work fine with scopes as fast as f/6.05.  Using the Baader Helical eyepiece holders that Denis uses, which look shorter than the ClickLocks, will allow the use of even faster focal ratios.  And of course if you use a GPC/OCA/Barlow with it, since these lengthen and slim down the light cone means will work fine with much faster focal ratios when these are utilized.

 

Sorry I neglected to put all this in the review as useful for folks to realize that your refractor needs to me pretty fast for this 21mm clear aperture on the telescope-side to be of any issue.  I always forget a thing or two, that's life and I'm not fighting it lol.gif.  I did however confirm that no vignetting observed when using a 24 ES68 in an f/6.25 scope.  This clear aperture point will be no issue on SCTs with or without the standard Reducer.  And since most Newtonians require a GPC/OCA for them to reach focus, unlikely to be an issue there as well.


Edited by BillP, 24 January 2021 - 09:01 PM.

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#10 BillP

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Posted 24 January 2021 - 08:38 PM

Thank you Bill for the review. Did you have chance to compare it with Mark V and if so how was the result? Thanks.

I do not have a Mark V, just the MB-II and a WO.



#11 Dave Ponder

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Posted 24 January 2021 - 09:04 PM

So, do you feel the CZAS is worth the extra cost over the Maxbright II?



#12 BillP

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Posted 24 January 2021 - 09:16 PM

We all weight the pros and cons of equipment differently, mostly because we each have our own unique likes, dislikes, and specialized needs.  I pretty much these days try to just report what I saw or discovered without making any judgements as they would be personal anyway and not necessarily extensible to other observers. That I publish a review on something at all says that I liked the item and feel it is special in some way relative to what is available in the market.  Up to each reader to decide if its mix of attributes and price point makes it worthwhile for them.

 

For me personally the MB-II was the first really high precision high quality bino I have ever used.  The CZAS is similarly very high precision and quality.  They both have uniquely excellent attributes so am going to leave it up to you decide how you want to weight those various attributes in the mix of what makes you judge "worth" flowerred.gif


Edited by BillP, 24 January 2021 - 09:28 PM.

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#13 denis0007dl

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Posted 25 January 2021 - 05:28 AM

Excellent, very detailed review, Bill!



#14 David I

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Posted 25 January 2021 - 06:20 AM

Thank You Bill,

            Not having to fuss with GPC with the Zeiss bino and get such excellent performance, is HUGE!

In Fig13 , left shortest connection, it looks like you can only use 2 inch filters, is that right?

 

David



#15 krakatoa1883

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Posted 25 January 2021 - 11:35 AM

Fine article, Bill. As far as I know GPC's corrects for aberrations introduced by prisms therefore using a prism-free binoviewer with a standard GPC should make those aberrations visible because are introduced by the GPC itself. One can see this effect, for example, by using of a GPC as if it were a Barlow lens. Have you observed something like this ?



#16 Jeff B

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Posted 25 January 2021 - 05:19 PM

Hi Bill.  I really enjoyed your evaluation and optical review of this viewer.  You-are thorough!  Your experiences with this viewer match well with mine...very sharp and, especially, color free. 

 

I mention this viewer in my thread here:

 

https://www.cloudyni...iewers-in-dpac/

 

Even in the harsh environment of DPAC, its superior color correction, or better yet, lack of error, is clearly seen.

 

Well done.

 

Jeff



#17 BillP

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Posted 25 January 2021 - 05:24 PM

I mention this viewer in my thread here:

 

https://www.cloudyni...iewers-in-dpac/

 

Even in the harsh environment of DPAC, its superior color correction, or better yet, lack of error, is clearly seen.

Impressive waytogo.gif



#18 BillP

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Posted 25 January 2021 - 05:29 PM

Fine article, Bill. As far as I know GPC's corrects for aberrations introduced by prisms therefore using a prism-free binoviewer with a standard GPC should make those aberrations visible because are introduced by the GPC itself. One can see this effect, for example, by using of a GPC as if it were a Barlow lens. Have you observed something like this ?

So your point is since the CZAS Bino is essentially prism-free (given only a cube prims for beam splitting), that using a GPC/OCA that corrects for the spherochromatism of the prisms should now introduce errors.  Makes sense but I have never tried.  While I have GPC/OCAs from Baader and William Optics, more often then not I use a standard Barlow when I am using a bino at high magnification.  So I have not tested to try and see if a GPC/OCA with the CSAZ introduces anything.  Interesting point though.



#19 buddy ny

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Posted 25 January 2021 - 10:29 PM

Nice work bill
Gotta give denise his due
He treds were few will

#20 buddy ny

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Posted 25 January 2021 - 10:30 PM

Dennis,,, auto corrrect

#21 Highburymark

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Posted 30 January 2021 - 12:04 PM

Fine article, Bill. As far as I know GPC's corrects for aberrations introduced by prisms therefore using a prism-free binoviewer with a standard GPC should make those aberrations visible because are introduced by the GPC itself. One can see this effect, for example, by using of a GPC as if it were a Barlow lens. Have you observed something like this ?


This is an interesting point. I was binoviewing the Moon this week with Zeiss apo BV, Delite 18.2 eyepieces, Tak FC-100 and 2.6x GPC - and didn’t notice any aberrations, but I wasn’t looking for them. Next time I’ll compare the GPC views with those through a standard barlow
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#22 Highburymark

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Posted 31 January 2021 - 03:38 PM

Can someone more optically knowledgeable than me chime in on the point raised by krakatoa1883? Ideally, should GPCs only be used with prism binoviewers?

Thanks for a very thorough review Bill.

#23 Jeff B

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Posted 01 February 2021 - 04:01 PM

So your point is since the CZAS Bino is essentially prism-free (given only a cube prims for beam splitting), that using a GPC/OCA that corrects for the spherochromatism of the prisms should now introduce errors.  Makes sense but I have never tried.  While I have GPC/OCAs from Baader and William Optics, more often then not I use a standard Barlow when I am using a bino at high magnification.  So I have not tested to try and see if a GPC/OCA with the CSAZ introduces anything.  Interesting point though.

I have done exactly this with DPAC testing of the 1.25 & 1.70X GPCs and CZAS (both samples) & Zeiss 30mm viewers.  In DPAC, I've seen no SA degradation or improvement with any combination of GPC and viewer which is what I've seen visually as well.  If there are differences, they would appear to undetectable in DPAC and visually.

 

Having said that, I felt the minor color error in the blue side of the spectrum was slightly improved with the 1.7X GPC with the Zeiss 30mm viewer in both DPAC and visually.  My CZAS displays only the slightest bit of blue error (beam splitter?) and it is gone with the 1.7X GPC...but SA correction is unchanged (visually & DPAC).   This is also consistent with what I see (or don't see really) with Denks Power Switch/OCS "Super System".

 

Jeff


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#24 BillP

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Posted 01 February 2021 - 04:09 PM

Yes.  Similar to if you were to use a coma corrector on a main objective without coma that aberrations should then be introduced.  But the grand assumption here is that the particular GPC/OCA is actually doing more than simply amplifying like a Barlow, as some may claim.



#25 BillP

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Posted 02 February 2021 - 04:16 PM

I have done exactly this with DPAC testing of the 1.25 & 1.70X GPCs and CZAS (both samples) & Zeiss 30mm viewers.  In DPAC, I've seen no SA degradation or improvement with any combination of GPC and viewer which is what I've seen visually as well.  If there are differences, they would appear to undetectable in DPAC and visually.

 

Having said that, I felt the minor color error in the blue side of the spectrum was slightly improved with the 1.7X GPC with the Zeiss 30mm viewer in both DPAC and visually.  My CZAS displays only the slightest bit of blue error (beam splitter?) and it is gone with the 1.7X GPC...but SA correction is unchanged (visually & DPAC).   This is also consistent with what I see (or don't see really) with Denks Power Switch/OCS "Super System".

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