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Talk to me about diagonals again

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#1 GOLGO13

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Posted 11 April 2022 - 11:14 PM

OK...I have trouble following all the threads on diagonals for NV. Can we cover this topic again?

 

I have the following diagonals:

2 inch:

1) TeleVue Enhanced Aluminum

2) TeleVue old unknown style (probably enhanced). It's likely from the mid/early 90s.

 

1.25 inch:

1) Baader BBHS prism

2) Tak prism

3) TeleVue Dielectric

4-x) lots of other cheap ones

 

Are these 2 inch ones I have affecting the view? Does this affect nebulas at all? Or just non-nebula stuff?

 

When I observe through a Newt is the secondary of any concern? I have just a normal Orion XT10i and the 6 inch F4 astrograph by Apertura.

 

I know there's been a lot of discussion on this in the past, but I just don't understand most of it.

 

When I use my 8 inch SCT, I use my Baader BBHS prism because I know those are supposed to be the best for NV. I guess I could do a comparison between all those diagonal on some globular clusters.


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#2 RodShea

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Posted 12 April 2022 - 02:18 PM

As soon as I get the sky to do it with, I'll be testing a 2" Astro-Physics dielectric vs my brand new 2" Baader Sitall BBHS (ordered mid 10/2021).  We will have a lot of clouds for a while yet, though.

 

About the secondaries in your Newtonians, the only thing I know is that they can have several different types of aluminized coatings, and/or dielectric ones.  These likely have differing reflectances in the near IR.  The manufacturer may have the data you want.  The aperature and focal length will be confounding variables.  Probably, you will just have to test and see.

 

Rod



#3 GOLGO13

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Posted 12 April 2022 - 02:47 PM

As soon as I get the sky to do it with, I'll be testing a 2" Astro-Physics dielectric vs my brand new 2" Baader Sitall BBHS (ordered mid 10/2021). We will have a lot of clouds for a while yet, though.

About the secondaries in your Newtonians, the only thing I know is that they can have several different types of aluminized coatings, and/or dielectric ones. These likely have differing reflectances in the near IR. The manufacturer may have the data you want. The aperature and focal length will be confounding variables. Probably, you will just have to test and see.

Rod


I'm guessing my newts are fine. But interested in peoples' test results for sure.

#4 Deadlake

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Posted 13 April 2022 - 03:38 PM

The two know performers in the infra-red for NV are the Baader BBHS (prism or mirror) and the ES carbon 2" diagonal.

 

My 2 cent's is the Baader will give you better reds for planetary (Jupiter) and also has a shorter light path.

For instance even with an FT3545 focuser I could not achieve focus with a APM 20 mm XWA with a ES 2" diagonal but could with a 2" Baader BBHS.

 


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#5 Joko

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Posted 14 April 2022 - 12:53 AM

I don't have any but for sure I'll order a BBHS when i have my refractor. It has great reflectivity in the IR and does not stop at 700nm which is perfect for NV (NV goes from 400nm to 1000nm and BBHS goes from 390nm to 2000nm).

All NV users I discussed with and who use it always had positive results with this diagonal.

The only doubt i have is should we have prism or miror as the BBHS is available in these 2 options. What is the best ?


Edited by Joko, 14 April 2022 - 12:58 AM.


#6 Deadlake

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Posted 14 April 2022 - 01:39 AM

I don't have any but for sure I'll order a BBHS when i have my refractor. It has great reflectivity in the IR and does not stop at 700nm which is perfect for NV (NV goes from 400nm to 1000nm and BBHS goes from 390nm to 2000nm).

All NV users I discussed with and who use it always had positive results with this diagonal.

The only doubt i have is should we have prism or miror as the BBHS is available in these 2 options. What is the best ?

Depends on if you need your scopes CA corrected by the prism, see here for a discussion

 

https://www.cloudyni...e/#entry7334377

 

and here 

 

https://www.cloudyni...help-me-decide/
 


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#7 25585

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Posted 15 April 2022 - 03:45 PM

Would the Vernonscope gold diagonal do well for NV?



#8 StarAlert

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Posted 24 May 2022 - 12:09 PM

Two nights ago, I was viewing globulars (M3 and M13) with my NVD and a TV 40mm plossl. The images were fabulous! Last night, after getting my custom RAF adapter, I was trying out the 30mm UFF with the NVD. Unfortunately, I was kind of disappointed with the views. I couldn’t see nearly as much detail (much dimmer stars) as I was seeing with the 40mm. I swapped to the 40mm to compare, and the views didn’t look nearly as good as the prior night. I think the seeing and transparency was just as good as the prior night, but maybe not. 

 

Today, I realized that I was using my 2” AP Maxbright diagonal last night and I was using a Baader BBHS the prior night. Now, I’m thinking the diagonal might be the reason for the difference in brightness. Tonight, I’m going to compare the two diagonals. If there is that much of a difference between diagonals when using NV, I’m going to be surprised. 



#9 chemisted

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Posted 24 May 2022 - 02:19 PM

Two nights ago, I was viewing globulars (M3 and M13) with my NVD and a TV 40mm plossl. The images were fabulous! Last night, after getting my custom RAF adapter, I was trying out the 30mm UFF with the NVD. Unfortunately, I was kind of disappointed with the views. I couldn’t see nearly as much detail (much dimmer stars) as I was seeing with the 40mm. I swapped to the 40mm to compare, and the views didn’t look nearly as good as the prior night. I think the seeing and transparency was just as good as the prior night, but maybe not. 

 

Today, I realized that I was using my 2” AP Maxbright diagonal last night and I was using a Baader BBHS the prior night. Now, I’m thinking the diagonal might be the reason for the difference in brightness. Tonight, I’m going to compare the two diagonals. If there is that much of a difference between diagonals when using NV, I’m going to be surprised. 

Yes there really is that big a difference.  It's clear you haven't read the following thread:  https://www.cloudyni...bular-clusters/



#10 StarAlert

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Posted 24 May 2022 - 03:35 PM

Yes there really is that big a difference.  It's clear you haven't read the following thread:  https://www.cloudyni...bular-clusters/

Thanks. I hope you’re right because the difference was stark. Typically, when I read CN reports about differences between equipment, the differences are subtle. And then when I make the same comparison with my crappy old eyes, I don’t see any difference. 
 

I’ll report back tomorrow what I find. This should be interesting. 

 

I have compared the Maxbright to my two Baader T2 BBHS diagonals (mirror and prism) and didn’t see any difference with a regular eyepiece. 



#11 careysub

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Posted 25 May 2022 - 06:52 PM

I recommend getting the MAX-1S T2 BBHS diagonal over the MAX-2S 2" BBHS. It has a shorter light path reducing focusing issues with some scopes, and it you are using it for prime focus (like me) you don't use the 2" aperture anyway with the 18mm sensor. And its cheaper.




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