Siebert Optics - 2" Binoviewers

Elite 45mm.(#BK45) The only ones in their class. Call or email for availablity.

Sometimes in astronomy forums other binoviewer sellers and non useers will raise questions about my Elite 45mm. If you see ## before a comment it is to clear up some of the comments that have been made. Also click here to see comments that I have addressed.

## These Self Centering Micro focusers are the best available. They make the unit a pleasure to use. If a binoviewer does not have them regardless of what the seller says it will be sorely missed later. Not only that but why would a modern premium unit be without them?

## It is just bigger in every way(Not heavier) The link below will show that for the binoviewers Clear Aperture size(45mm) it will make the optical path longer(no way around that) but the optical path is perfectly balanced to the CA and will alway illuminate a much larger area even in fast scopes.

Click on links below to read more Reviews on the 2" Black Night Elite Binoviewers

Brass Elite 45mm for those who want a Vintage Binoviewer and the same Brass construction as our 4.3" Observatory series Eyepieces. Add $600 for special order.

Smaller dis-continued 40mm Elite sized up next to one of the biggest and best 1.25" units.

The use of first surface diagonal mirrors will eliminate almost any possibility of reflections that prisms can create and also greatly reduce aberrations. These units have the spec's to out perform any bino in planetary and deepsky use. Try a set of my 2" 35mm or 2" 36mm 70 deg observatory series eyepieces for the ultimate DS view. Low mag correctors in the 1.3x,1.5x and 2.0x sizes are available and also highers power 2.0x, 2.5x and 3.0x range are available.

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## Even though these binoviewers will focus in virtually all SCT/MCT the OCA correctors below will make the binoviewer focus in any Dob/Ref.. So the optical path of the binoviewer is fine for the binoviewers Large Clear Aperture size..

1.3x OCA (#E1.3xOCA) for dobs/refractors 38mm CA: $399 (Full illumination down to 2.9)

2x OCA (#2xOCA) for dobs/refractors (2pc): $399 (Full illumination down to F2.5)

1.3x / 2x OCA (#E1.3/2xOCA) for dobs/refractors 38mm CA: $599 (Full illumination down to 2.9)

SCT Accessories pricing:

.6x-.7x FLR for 45mm Elite unit for SCT's: $199 (#ESCT06)

Multi Mag OCA (#ESCT0625) for SCT's 0.6x, ******1.3x, ****2.0x, *****2.5x OCA for SCT's: $399*

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Lightweight Low Profile Self-centering 2" to 1.25" eyepiece adapters set (#SCSD2125): $60

These eyepieces are from the Observatory series that is now supporting the largest and most historic Observatories in the world. See here

2" 17mm -19mm's Ultra Plus Series Eyepiece (70 deg. fov, 20mm ER): $298 a set

2" 13mm-15mm's Ultra Plus Series Eyepiece (70 deg. fov, 20mm ER): $398 a set

Sometimes in astronomy forums other binoviewer sellers will comment about my Elite 45mm. If you see ## before a comment on this page it is to clear up some of the comments made.

If you see a comment about my units, look to see if the one posting is a vendor. The one posting may have a conflict of interest. Also see if they are a user of the product since you are more likely to get accurate information from someone that is actually using one of the BK 45mm units. Please come here to get clarification if something is said that you do not understand or does not sound right. Below is a list of issues raised vs the reality.

1) The binoviewer is too big. -- You can't have a 2" binoviewer without it being bigger than a 1.25" unit. This is a good thing.

2) The binoviewer is too heavy -- The weight is only 2lb 3oz making it about as heavy as the 1.25" Baader binoviewer. Not bad for a 2" binoviewer.

3) The IPD is too big for people -- The minimum IPD is 57mm(average IPD is 64mm) and can be special ordered down to 54mm. Many 2" EP's made for binoviewers are trim in size as well. So this is no problem

4) The optical path is too long -- It has to be since the clear aperture is larger. But ray tracing shows that it is the best balance of CA vs OP possible for any binoviewer. Also a longer OP is no problem since I make low power focus adaptors for all Dos/Ref that take care of the OP. SCT/MCT are fine. This is not a real issue

5) Mirrors can move -- No one ever has ever reported this and I have only repaired units that have been dropped.

6) Cleaning may scratch optics -- This has never been reported in 15 years of production but if it happened the unit is sealed with optical windows which are easy to replace and are inexpensive. I do this free for 2 years.

7) Beam Splitter type -- It is the same beamsplitter as all binoviewers. All are cemented prisms with a coating in the middle for separating light.

8) Polarization effect. All binoviewer will have this. The Dielectric splitter has the most efficient splitting of the color wave lengths. If you use something else like a metallic surface you will reduce light transmission way too much. It is a minor effect in most binoviewers but it is better than anything else.

For now this is all the comments I have heard and needed clear answers to. Please let me now if you have other questions.