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Dual ED Paradigms and binoviewing

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#1 doug mc

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Posted 07 September 2019 - 08:31 PM

Thinking of getting a few pairs of these. I have a TS binoviewer and was wondering if the 25mm ones vignette. Would they be more pleasant to use than plossls?

#2 REC

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Posted 08 September 2019 - 10:32 AM

They are fat! I like a pair of Meade 26mm SP. They bino very well.



#3 MalVeauX

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Posted 08 September 2019 - 10:40 AM

I have some of those (Agena Starguider brands, but same thing). I like them a lot. They're high contrast like a plossl, but 60 degree. Their size doesn't seem to be an issue with the binos and they're not ultra heavy. I haven't noticed any significant vignetting, since these are not long focal length eyepieces. I also use some SWA 20mm 70 degree eyepieces in mine and there's no vignetting either. I think you're good in the 25mm to 32mm range regardless of what you get in that respect with these but I don't have measurements (someone else might).

 

Very best,



#4 Lookitup

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Posted 09 September 2019 - 12:18 AM

Replaced 11mm Delites with ASTRO-TECH 12MM's. Decloaked 11mm's had a little wider FOV, but I prefer the tighter fit of the AT in binoviewers.  



#5 doug mc

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Posted 09 September 2019 - 07:08 PM

Would the 25mm ones vignette in my TS binos? I recently purchased the 2x William optics OCS. It has a larger diameter set of lenses then the 1.6x OCS that I have. Viewing the moon last night and a pair of Celestron 32mm plossls showed almost no vignetting. Much better than the 1.6x unit. I machined a threaded adaptor that allows me to attach the OCS almost directly into the binos body, without having the original nosepiece attached.



#6 Miranda2525

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Posted 11 September 2019 - 06:00 PM

Would the 25mm ones vignette in my TS binos? I recently purchased the 2x William optics OCS. It has a larger diameter set of lenses then the 1.6x OCS that I have. Viewing the moon last night and a pair of Celestron 32mm plossls showed almost no vignetting. Much better than the 1.6x unit. I machined a threaded adaptor that allows me to attach the OCS almost directly into the binos body, without having the original nosepiece attached.

I used to use a pair of 25mm AT Paradigms in a William Optics binoviewer and they vignette a lot. If the clear aperture of your binoviewers are the same as the WO binoviewers, they will vignette and so will the 32mm's.



#7 doug mc

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Posted 11 September 2019 - 11:00 PM

Ok thanks, I will start with the 18mm ones.



#8 roblindau

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Posted 12 September 2019 - 03:35 AM

I've once heard that as a rule of thumb for a WO binoviewer and similar (e.g. TS bino), the product of focal length and apparent field of view of an eyepiece should be smaller than about 1350 to avoid vignetting.
For a paradigm eyepiece with 25mm focal length and an apparent field of view of 60 degrees the product is 25x60 = 1500, so it will significantly vignette.

 



#9 Miranda2525

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Posted 12 September 2019 - 07:11 AM

I've once heard that as a rule of thumb for a WO binoviewer and similar (e.g. TS bino), the product of focal length and apparent field of view of an eyepiece should be smaller than about 1350 to avoid vignetting.
For a paradigm eyepiece with 25mm focal length and an apparent field of view of 60 degrees the product is 25x60 = 1500, so it will significantly vignette.

The importance is the aperture of the field stops in the eyepieces. The WO binoviewers and others that are like them have 20mm of clear aperture. Rule of thumb is to use eyepieces that are no wider than about 23mm, or there will be significant vignetting.



#10 Miranda2525

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Posted 12 September 2019 - 07:16 AM

Ok thanks, I will start with the 18mm ones.

You can use a pair of Svbony 20mm 68 degree eyepieces for your lowest power. They work great in the WO binoviewers.



#11 roblindau

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Posted 12 September 2019 - 12:56 PM

The importance is the aperture of the field stops in the eyepieces. The WO binoviewers and others that are like them have 20mm of clear aperture. Rule of thumb is to use eyepieces that are no wider than about 23mm, or there will be significant vignetting.

That's correct Miranda. But sometimes you do not know the field stop of an eyepiece or cannot evaluate it. Then you can use the other simple rule of thumb.


Edited by roblindau, 13 September 2019 - 01:26 AM.


#12 Miranda2525

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Posted 13 September 2019 - 08:15 AM

That's correct Miranda. But sometimes you do not know the field stop of an eyepiece or cannot evaluate it. Then you can use the other simple rule of thumb.

The field stops in most simple eyepieces, (which are used a lot in binoviewers), are easy to measure. How did you come up with the product of focal length and apparent field of view at the number 1350? I think that's a great little calculator you have there, but exact apparent field of view and focal length cannot always be determined either. 



#13 doug mc

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Posted 13 September 2019 - 06:05 PM

The 18mm EDs are on the way. I have a Siebert 1.25x OCS, 1.6x and 2x William Optics OCS. My plan is to swap out the amplifiers instead of the eyepieces. Easier this way. This will give 166x, 213x, and 266x. A good range for most luna, planetary observations with my CC8. I have a 2x 2inch GSO ED barlow for anything higher. Thanks.



#14 Lookitup

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Posted Yesterday, 10:14 PM

Used the 18mm's in a binotron to replace the Panoptics 19mm and was happy. Great option with the 3x OCS.  Pete 




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