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Orion Linear Binoviewer: Yes or No?

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#76 jprideaux

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Posted 01 March 2024 - 07:03 AM

The following is a picture of the reducer that I successfully use with my linear BV to increase the FOV.

 

i had ordered it straight from Japan.  

 

IMG_0395.jpeg

 

It is possible that other reducers won’t work if this one has optics designed especially for the linear-type BV.  
 

A few years ago I had started this thread with more details on using this reducer with the linear along with some pictures taken through the eyepiece with my iPhone.  

 

https://www.cloudyni...epieces-reducer

 

 

 

 


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#77 Sarkikos

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Posted 01 March 2024 - 10:33 AM

The following is a picture of the reducer that I successfully use with my linear BV to increase the FOV.

 

i had ordered it straight from Japan.  

 

attachicon.gif IMG_0395.jpeg

 

It is possible that other reducers won’t work if this one has optics designed especially for the linear-type BV.  
 

A few years ago I had started this thread with more details on using this reducer with the linear along with some pictures taken through the eyepiece with my iPhone.  

 

https://www.cloudyni...epieces-reducer

Two questions:

 

1) Was the Kasai 0.66x Reducer especially designed for the linear binoviewers?

2) Where is the Kasai 0.66x Reducer actually available in-stock for purchase?  (Link, please.)  Or a differently branded equivalent?  I cannot find this item anywhere.  Is it discontinued?  (That's actually three questions.)

 

Mike


Edited by Sarkikos, 01 March 2024 - 11:01 AM.


#78 Sarkikos

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Posted 01 March 2024 - 11:00 AM

I do have an Antares 0.7x Reducer.  I bought it a while back when I thought I was going to get into Night Vision.  (Still thinking on that.)  

 

It is 2" format, though.  I'd rather have 1.25" that I screw directly onto the neck of the binoviewer.

 

Mike

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#79 Sarkikos

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Posted 01 March 2024 - 11:01 AM

There are plenty of 0.5x 1.25" reducers.   But no 0.66x or 0.7x 1.25" reducers that I can find.

 

Here's a GSO 0.5x 1.25 reducer at ScopeStuff:  https://scopestuff.com/ss_fr1a.htm

 

Mike


Edited by Sarkikos, 01 March 2024 - 11:25 AM.


#80 Sarkikos

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Posted 01 March 2024 - 11:24 AM

Hutech has a 1.25" 0.75x reducer.  On backorder, of course.  https://astrohutech....x-reducer-1-25/

 

Mike



#81 Bintang13

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Posted 01 March 2024 - 02:32 PM

Mike,

 

I would just email Kasai Trading referencing the reducer. They were very helpful and quick to respond. Sorry to have you chase something that maybe hard to find I thought that it was more readily available than just through Japan.

 

Jim


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#82 Bintang13

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Posted 01 March 2024 - 03:17 PM

TS Optics makes reference to a .66 reducer for their own linear branded version but they don’t list the reducer as offered recommended accessories.

 

Jim



#83 kroum

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Posted 01 March 2024 - 04:12 PM

When you scale the clear aperture of the linears by the reduction factor of the focal reducer, you get close to  27mm.

 

I wonder if the focal reducer requires as much additional back focus as a traditional prism binoviewer would without an optical path corrector.


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#84 Bintang13

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Posted 01 March 2024 - 04:50 PM

Hi,

 

I noticed the 27mm correlation too. The linears with reducer come to focus in all our 8”,10” and 12” commercial Dobs.

We have a pair of WO, Maxbright 2, and currently a pair of Binotron 27s ( without power switch ) all need amplified to reach focus in the Dobs. I had the Baader 1.7x but prefer the Siebert 1.3 OCA for Dobs or the WO 2x for binoviewers. I do now prefer the linears for the Dobs mainly using 67 and 80 magnification. The standard binoviewers are preferred over the linears for moon planets and bright double stars in our refractors.

 

Jim


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#85 kroum

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Posted 01 March 2024 - 06:47 PM

Hi,

 

I noticed the 27mm correlation too. The linears with reducer come to focus in all our 8”,10” and 12” commercial Dobs.

We have a pair of WO, Maxbright 2, and currently a pair of Binotron 27s ( without power switch ) all need amplified to reach focus in the Dobs. I had the Baader 1.7x but prefer the Siebert 1.3 OCA for Dobs or the WO 2x for binoviewers. I do now prefer the linears for the Dobs mainly using 67 and 80 magnification. The standard binoviewers are preferred over the linears for moon planets and bright double stars in our refractors.

 

Jim

That’s extremely interesting.

 

It blows my mind that this focal reducer isn’t a standard part of the kit, or at least isn’t marketed as a big selling point in favor for the linear binoviewer and an accessory every linear owner should have.


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#86 Sarkikos

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Posted 01 March 2024 - 07:15 PM

Has anyone tried a 0.5x reducer on their linear binoviewer?  These 0.5x 1.25" reducers are sold nearly everywhere.  The 0.66x reducers are pretty much unobtainium.  

 

Mike



#87 Sarkikos

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Posted 01 March 2024 - 07:31 PM

When you scale the clear aperture of the linears by the reduction factor of the focal reducer, you get close to 27mm.

 

I wonder if the focal reducer requires as much additional back focus as a traditional prism binoviewer would without an optical path corrector.

Assuming 17mm clear aperture, the reduction factor of a 0.66x reducer would yield 28mm.   A 0.6x reducer would yield 27mm.  A 0.5x reducer would yield 26mm.  A 0.7x reducer would yield 29mm.   (All products rounded to nearest millimeter.)

 

Mike



#88 jprideaux

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Posted 02 March 2024 - 12:12 AM

Two questions:

1) Was the Kasai 0.66x Reducer especially designed for the linear binoviewers?
2) Where is the Kasai 0.66x Reducer actually available in-stock for purchase? (Link, please.) Or a differently branded equivalent? I cannot find this item anywhere. Is it discontinued? (That's actually three questions.)

Mike


I don’t know if other reducers besides that .66 will work. Fortunately, they are not all that expensive so it don’t cost a lot to find out. I also don’t know if the .66 was designed especially for this type of binoviewer or not.

If you want to try to get that .66 one you can start at the following link.

https://www-kasai--t...=en&_x_tr_hl=en

I think that is what I did about 3 years ago when I ordered mine. I found a way to send an email to them and at that time they had them in stock and sent me instructions on how to buy using PayPal. They quoted a price in yen and PayPal did the conversion and I received it a few days later. I had also ordered a 45-degree half pentaprism from them as well.


Edited by jprideaux, 02 March 2024 - 12:22 PM.

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#89 Bintang13

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Posted 02 March 2024 - 10:07 AM

When I saw the reference on TS Optics version of the linear I thought that they were packaging the reducer together with  the binoviewer. I don’t want to overstate its effectiveness, like a Barlow it took some fiddling to find the right combinations. I do hope that it is still available because I do find it useful. Thank you jprideaux for attaching the link I had a hard time doing that. It does make a Neanderthal chuckle to see modern society revert to hieroglyphics though.

 

Jim


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#90 Sarkikos

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Posted 02 March 2024 - 10:57 AM

I don’t know if other reducers besides that .66 will work. Fortunately, they are not all that expensive do it don’t cost a lot to find out. I also don’t know if the .66 was designed especially for this type of binoviewer or not.

If you want to try to get that .66 one you can start at the following link.

https://www-kasai--t...=en&_x_tr_hl=en

I think that is what I did about 3 years ago when I ordered mine. I found a way to send an email to them and at that time they had them in stock and sent me instructions on how to buy using PayPal. They quoted a price in yen and PayPal did the conversion and I received it a few days later. I had also ordered a 45-degree half pentaprism from them as well.

I doubt very much that the optics of the 0.66x reducer were designed specifically for the linear binoviewer, except maybe to provide a near equivalence for the maximum field stop possible in a 1.25" eyepiece, which is around 27mm.   It's probably optically no different than the ubiquitous 0.5x reducers.  The only real difference is the reduction factor.

 

First, I'll order one of the 0.5x reducers.   A 0.66x reducer would yield an effective 28mm clear aperture, actually a bit more than 27mm.  A 0.5x reducer would yield 26mm, so it's still a contender.  

 

In the meantime, I'll see about ordering the 0.66x reducer from Kasai.  Too bad they don't seem to be available anywhere else.  

 

Mike


Edited by Sarkikos, 02 March 2024 - 11:00 AM.

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#91 Sarkikos

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Posted 02 March 2024 - 01:21 PM

So far, looks like the Apertura 0.5x reducer at High Point Scientific is the winner for the 0.5x reduction factor.  The price is right, AFAIK the Apertura brand is OK, and HPS is in the next state over from where I live in Maryland.  https://www.highpoin...MBoCLG8QAvD_BwE

 

Mike


Edited by Sarkikos, 02 March 2024 - 01:21 PM.


#92 Sarkikos

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Posted 02 March 2024 - 01:22 PM

I haven't found any 0.66x reducers besides the direct order one at Kasai.   

 

I did find a 1.25" 0.6x reducer at Siebert Optics.  https://www.sieberto...cs-barlows.html   FLR425cel, $99.

 

A 0.6x reducer would yield an effective 27mm clear aperture for the linear binoviewer.   27mm is right at the maximum field stop for 1.25" eyepieces.  Hmm... thinking1.gif   It's almost like Siebert designed this on purpose for the linear binoviewers.  grin.gif

 

Mike

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  • Siebert Reducers.jpg

Edited by Sarkikos, 02 March 2024 - 01:29 PM.

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#93 nof

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Posted 02 March 2024 - 01:27 PM

I have the reducer from Kasai. Inexpensive. It works in my dobs and requires more in- focus than without.
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#94 Bintang13

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Posted 02 March 2024 - 02:28 PM

Hi,

 

I got the 12” Dob especially for globs using the linears. The 10” does resolve the larger globs but I need excellent transparency. I am hoping the 12 Dob will allow more opportunities. It’s a beast to move but I am lucky to have help ( adult kids that visit ). If globs are a target for you with the binoviewers I would very much appreciate any advice and tips such as what eyepieces you use. Also how does everyone deal with rotating the angle of the binoviewers in the focuser so often.

 

Jim


Edited by Bintang13, 02 March 2024 - 02:34 PM.


#95 Sarkikos

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Posted 02 March 2024 - 04:22 PM

Today, I ordered the following:

 

- Apertura 0.5x reducer from HPS

- 0.6x reducer from Siebert (email sent, awaiting instructions)

- 0.66x reducer from Kasai (email sent, awaiting instructions)

 

Mike


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#96 Sarkikos

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Posted 02 March 2024 - 06:18 PM

I just now completed the purchase of the Kasai 0.66x Reducer. 

 

Still awaiting response from Siebert for the 0.6x reducer (I also ordered a 10mm MonoCentric). 

 

Edit:  The Kasai 0.66x Reducer has already shipped!

 

Mike


Edited by Sarkikos, 02 March 2024 - 09:58 PM.

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#97 jprideaux

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Posted 03 March 2024 - 06:50 AM

It will be interesting to find out which of the other ones you end-up getting also work besides the one from Kasai. I also found that it was easy to order from Kasai. They have shipping figured out where airplanes are involved and it doesn’t have to go on a container ship which could end-up taking over a month.
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#98 Bintang13

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Posted 03 March 2024 - 11:32 AM

Glad to see that the reducer is still available. Very interested in seeing if the other reducers work as well. 



#99 Bintang13

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Posted 03 March 2024 - 11:37 AM

Another general question regarding the linears. Does anyone use the linear in a Paracorr if so what settings are chosen. Do you follow the settings for the eyepiece ( D for Delites ) or do you use setting A for all eyepieces? Thanks for any advice.

 

Jim



#100 sanbai

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Posted 03 March 2024 - 06:04 PM

Another general question regarding the linears. Does anyone use the linear in a Paracorr if so what settings are chosen. Do you follow the settings for the eyepiece ( D for Delites ) or do you use setting A for all eyepieces? Thanks for any advice.

Jim

I just tune the Paracorr in mono with an eyepiece of known setting (A, actually). I left the focuser at a fixed position , and every time I put a new eyepiece I tune the paracorr to bring the image to focus. This includes the linear binoviewer with the eyepieces of choice. Since tuning the paracorr rotates the eyepiece/binoviewer, I keep turning the binoviewer to have it in the right position for my eyes.

I may do a very fine tuning with the fine-focus knob of the focuser. At effective f/5.15, the focuser position doesn't need to be very accurate to have a good coma correction, even if using a 110° eyepiece (mono). If eyepieces are parfocal, fine tune knob is the only thing I would move when using the Linear binoviewer.

The weight of the binoviewer in a dob is significant. I"m not thrilled buy them, but sometimes it works better than mono. Other times not. Part of that is just personal, not the fault of the binoviewer.
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