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THE BAADER BBHS-SITALL SILVER DIAGONAL

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#1 BillP

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Posted 15 February 2016 - 04:25 PM

The Baader BBHS dielectric protected silver diagonal distinguished itself by pulling in fainter stars, showing minimal scatter, and presenting colorful stars and planetary features more richly colored, with its silver technology besting the defacto standard for high performance dielectric diagonals. Its Clicklock mechanism provided a level of ergonomic ease far surpassing other locking technologies I have used. It clearly demonstrated low levels of perceived scatter, the ability to bring into view the dimmer of stars in clusters than the other diagonals, the ability to make more authoritative double star splits, and the ability to show the faintest extents of nebula. All these attributes were highly welcomed and they clearly enhanced my observations. Most surprising however, was how brightly and vividly the BBHS technology portrayed the colors of stars and of planetary features, showing colors more richly saturated and more beautifully bright than even the best dielectric technology diagonal could muster. The views through the BBHS of brightly colored stars accentuated in familiar clusters, and of a richly colored GRS coursing its way across Jupiter were nothing less than truly memorable.

Click here to view the article
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#2 Derek Wong

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Posted 15 February 2016 - 04:57 PM

Thanks for the report Bill, very interesting.  I have a question then.  If you had to choose one for planetary viewing (in a slow scope so the color aberration is minimal),which would you choose--the BBHS dielectric or one of the Baader/Zeiss prisms?

 

Derek


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#3 Crow Haven

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Posted 15 February 2016 - 05:30 PM

Great report, Bill, and now I want one of these!



#4 BillP

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Posted 15 February 2016 - 07:48 PM

Thanks for the report Bill, very interesting.  I have a question then.  If you had to choose one for planetary viewing (in a slow scope so the color aberration is minimal),which would you choose--the BBHS dielectric or one of the Baader/Zeiss prisms?

 

Derek

 

I'm actually going to have to see about that.  I liked the BBHS just a little better than the 2" Zeiss, but the 1/25" T2 Zeiss is another story.  I did not compare the two during the testing for this article, but certainly plan to because I want to know the answer to your question as well!


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#5 BillP

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Posted 15 February 2016 - 10:15 PM

Great report, Bill, and now I want one of these!

 

:lol:   I gotta say...the color of the GRS on Jupiter was astoundingly different between the BBHS and the MaxBright Dielectric.  It really did shock me when I saw it and kept exchanging the diagonals as I just could not believe it when I first saw it.



#6 Perseus_m45

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Posted 16 February 2016 - 10:01 AM

Great report Bill . Thanks for the info .



#7 astrophile

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Posted 16 February 2016 - 10:57 AM

Bill, thanks for this report.  Any comparison between the BBHS and the Zeiss prism on color rendition?



#8 jrbarnett

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Posted 16 February 2016 - 12:41 PM

Nice report, Bill.

Does this unit have the short nose piece that the Baader Maxbright Click-lock diagonal has? If so it will work in EdgeHD SCTs with no risk of damaging the corrective optics in the OTA.

The other question is this. Were the other diagonals cleaned before testing? Diagonals seem to collect debris rapidly and comparing a dirty diagonal to a clean one might affect results in such critical testing.

- Jim

#9 BillP

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Posted 17 February 2016 - 08:32 AM

Yes, the nose is rather short.  I did not know that the corrective Edge optics could be impacted by a long nose piece!!  They do not have some sort of a metal stop in there for that??  And yes, all diagonals nicely cleaned and inspected. 



#10 BillP

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Posted 17 February 2016 - 08:34 AM

Bill, thanks for this report.  Any comparison between the BBHS and the Zeiss prism on color rendition?

 

The color from the 2" Zeiss prism was also more saturated than what the dielectric was showing, but not quite as bright as the color showed in the BBHS, although satisfyingly close.  I really want to see though how the colors compare between the BBHS and 1.25" T2 Prism; that should be interesting.


Edited by BillP, 17 February 2016 - 08:35 AM.


#11 Paul G

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Posted 17 February 2016 - 09:48 AM

Interesting report, Bill. Since a diagonal is typically considered a visual accessory I wonder what the benefit is of the extended reflectivity far outside the visual spectrum? One benefit of the Astro-Physics Maxbright is that it has a hard cutoff at 700 nm, dropping to less than 1%, so it transmits almost no IR and serves as an extra safety precaution for solar viewing and will protect a Daystar filter from aging.

 

I'm not sure I'd call AP "inconsistent" wrt optical quality of their Maxbright. They say nothing on their website but Roland posted his personal guarantee on the Astro-Physics Users Group, "I personally assemble and test every diagonal under controlled conditions to assure that there is no detectable error of a perfect star image at very high powers. Measurements that I have made using interferometer techniques show that over the clear aperture of an F4.8 telescope, the flatness runs typically 1/40 wave, and I will guarantee at least 1/20 wave." He also posted an interferometer test on a Maxbright mirror (after coating) in the APUG Files section, Strehl 1.000.



#12 BillP

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Posted 17 February 2016 - 12:22 PM

Interesting report, Bill. Since a diagonal is typically considered a visual accessory I wonder what the benefit is of the extended reflectivity far outside the visual spectrum? One benefit of the Astro-Physics Maxbright is that it has a hard cutoff at 700 nm, dropping to less than 1%, so it transmits almost no IR and serves as an extra safety precaution for solar viewing and will protect a Daystar filter from aging.

 

I'm not sure I'd call AP "inconsistent" wrt optical quality of their Maxbright. They say nothing on their website but Roland posted his personal guarantee on the Astro-Physics Users Group, .

 

 

Hi Paul.  From discussions I've had with multiple vendors, seems most all dielectrics drop off fast once outside the visual range.  Not sure extended IR would have any safety issues as that would imply then that unsafe to do solar viewing with telescopes that do not use diagonals.  I think that UV would be more of a potential health issue for the eye, but seems dielectrics and BBHS both cutoff that.  If indeed there is some issue, and not just marketing hype, with non-dielectrics for solar viewing, then would imagine that prisms as well should be an issue as would be scopes that do not employ a diagonal.  This topic is certainly worth more discussion in the forums under solar viewing (something I do very little of).  Not sure what the driver was for having colors be so much more vibrant with planetary and star clusters with the BBHS.  Perhaps it was the extended spectrum.  While the eye does not see out that far, it certainly is sensitive past 700 if that is where the dielectrics cut off.  In any event, the review was of course from the perspective of diagonal use for optimum night time observing. I did not do any solar observing with the BBHS.

 

On the inconsistent thing, the review did not say that the quality was inconsistent, but that the wave front claim was.  So there was no intention to imply inconsistency in quality, nor an any field test determine something like this.  Instead, there is inconsistency between marketing and forum discussions.  Yes I have seen the posts by RC in the discussions.  But as a consumer, these things are best when in the product information as easier then to hold sellers liable.  So hence, I did not see a consistent addressing of wave front accuracy on the product as what is mentioned in casual conversation, vs what is available on the product's website.  As consumers, we need to be aware of this as we are protected when the claim is guaranteed in the product literature/marketing.  I've spoken to lots of vendors and often hear them say things that are not reflected in their marketing.  As a consumer I can only hold them to what is marketed, and cannot hold them to passing discussions.  So I was just pointing that out in the article other than saying what is the fact that there is no claim to accuracy in the product materials that I could get access to. Would be nice if they did put the accuracy claim in their marketing as then it would have legal teeth for all consumers.


Edited by BillP, 17 February 2016 - 02:21 PM.

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#13 Cliff C

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Posted 22 February 2016 - 09:36 AM

Bill,

When will these silver diagonals be available here in the US?

If I remember, the reflectivity of silver drops off dramatically in deep violet.

This might benefit users of achromats to some extent.

Great write-up,

Cliff


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#14 tomjones

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Posted 22 February 2016 - 10:30 AM

They were for sale here, till this article came out.


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#15 BillP

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Posted 22 February 2016 - 11:03 AM

Bill,

When will these silver diagonals be available here in the US?

If I remember, the reflectivity of silver drops off dramatically in deep violet.

This might benefit users of achromats to some extent.

Great write-up,

Cliff

 

 

Thanks.  The violet spectrum is 380–450nm.  Dielectrics tend to fall off at 400 so they cut off a portion of the violet.  The BBHS is advertised to fall off at 400 also.  Alpine Astronomical has them currently, at least it still says in stock for some versions on their site.


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#16 Cliff C

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Posted 22 February 2016 - 12:33 PM

Thanks Bill and Tom.



#17 Starman1

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Posted 25 February 2016 - 04:26 PM

spectra of reflectivity of silver and aluminum:

http://spectrumthinf...ngs-reflective/

http://www.edmundopt...irror-coatings/

 

spectrum of reflectivity of typical dielectric coated mirror (see 3rd graph down):

http://www.photonics....aspx?AID=25501

 

Comparison:

https://www.layertec...metalDielectric


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#18 RichA

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Posted 28 February 2016 - 04:04 PM

So, what are the chances this diagonal will fare better than Lumicon's silvered diagaonals and Meade's MCSO telescopes, both of which saw their silver coatings rot off?



#19 Neptune

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Posted 28 February 2016 - 04:39 PM

So, what are the chances this diagonal will fare better than Lumicon's silvered diagaonals and Meade's MCSO telescopes, both of which saw their silver coatings rot off?

That's the 64,000 dollar question, well maybe the 479 dollar question.  Always looks good up front but what about looong term.



#20 jrbarnett

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Posted 28 February 2016 - 05:06 PM

Yes, the nose is rather short.  I did not know that the corrective Edge optics could be impacted by a long nose piece!!  They do not have some sort of a metal stop in there for that??  And yes, all diagonals nicely cleaned and inspected. 

Hi Bill.

 

The C11, C8 and C14 Edge HD designs all place the corrective optics further inside the baffle (though the placement varies by aperture) than the C9.25 Edge HD.  The C9.25 Edge HD unit's corrective optics, however, are scarcely an inch inside the rear aperture, and there is no stop.  If you use the stock 1.25" VB there's no issue; the Edge HD VB is pretty long.  If you do what I did and swap the stock VB for the A-P 2" VB for the C11 and C14 (one of the differences between the standard and Edge C9.25 is that the Edge version has the same larger rear aperture as the C11 and C14), you will contact the corrective optics with an 2" diagonal with a longer than 1" nosepiece.

 

Thus the shorty noesepieces used on some of the Baader diagonals and also the short-nosepieced "SCT version" of the Televue Everbrite are very desirable.

 

Regards,

 

Jim



#21 Starman1

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Posted 28 February 2016 - 05:42 PM

Alas, TeleVue has discontinued the short nosepiece version of their dielectric star diagonal.



#22 ewave

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Posted 29 February 2016 - 08:13 AM

The Baader T2-19 (2") nosepiece is the one I use when combined with the AP adapter for my C9.25 Edge ota.  It has a total length of 32mm providing just a few mm shy of hitting the corrector.  I like the T2-19 so much that I got a second one to work with my GSO 2" Quartz diagonal. 



#23 BillP

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Posted 29 February 2016 - 08:43 AM

 

So, what are the chances this diagonal will fare better than Lumicon's silvered diagaonals and Meade's MCSO telescopes, both of which saw their silver coatings rot off?

That's the 64,000 dollar question, well maybe the 479 dollar question.  Always looks good up front but what about looong term.

 

 

I believe the vendor is claiming that longevity will be the same as protected aluminum.  They are very well aware of the longevity of Silver using the older protective technologies and processes like the ones you mention.  What they are using now is supposed to overcome all those issues.  So should not be any issues.  Time will be the ultimate teller of the story though.  FWIW, I have zero worries on the issue and am rather enjoying the vibrancy it brings to colors. :D



#24 BillP

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Posted 29 February 2016 - 08:48 AM

 

 C9.25 Edge HD unit's corrective optics, however, are scarcely an inch inside the rear aperture, and there is no stop.

 

Wow.  That's amazing!  Thanks for the info.

 

I have often toyed of getting a 9.25 to replace my 10" Dob as it is a rarely used instrument and I like the smaller form factor of course.  Would be for DSO only.  From what I read little difference off-axis between the Edge and Non-Edge of the 9.25, so would probably go with the non-Edge anyway.



#25 tomjones

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Posted 29 February 2016 - 09:00 AM

The Great Red Spot is really red with the BBHS.




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