Testing my new binoviewer and 102ED-R

[RobertI]

After agonising over which binoviers to get I finally went for the William Optics which come with some nice 20mm eyepieces and 1.6x barlow nose piece.

This afternoon I had a chance to try them out on a distant rooftop, around 250 feet away, which I don't think quite equates to infinity from a focus point of view. The quick summary is that although I could JUST focus on the rooftop using the provided 1.6x barlow (B in diagram), I don't think I will quite be able to manage it on a star at true infinity.

However I used the 1.3x element from my Baader classic barlow (A in the diagram) and I WAS able to reach focus with 30mm of focus travel left. I worked out (by comparing numbers of bricks visible) that this combination gave me around 175x magnification - probably a bit high for plantary/luna but hopefully should give good results - what do people think?

I didn't think to try the 1.6x barlow screwed in to the Baader Barlow (effectly acting as an extension tube) - I think this would probably give enough backfocus and a magnification of between 60x and 100x (I'm guessing at how much effect the extension will have).

So at least I can reach focus in some form and I can also merge the images nicely, so looking very promising.  

 

 

Edited October 30, 2020 by RobertI

[globular]

Following your journey with binos with interest.  Keep us posted with all the gory details 👍

[Louis D]

Which of your many telescopes were you using the BVs in?

I get 3.0x magnification with the optical nose piece of a vintage Meade 140 2x Barlow screwed onto the front of my Arcturus (similar to OVL) binoviewers.  I have no trouble reaching focus in my limited in-focus Dob with this combo.

[RobertI]

8 minutes ago, Louis D said:

Which of your many telescopes were you using the BVs in?

I get 3.0x magnification with the optical nose piece of a vintage Meade 140 2x Barlow screwed onto the front of my Arcturus (similar to OVL) binoviewers.  I have no trouble reaching focus in my limited in-focus Dob with this combo.

Hi Louis, I was using in the 102ED-R (hiding in the title of the thread! ) - I was particularly interested in trying it on this scope as I was not sure how it would work (I'm confident it will work in the C8). It's good to know you can get focus in your dob, it might be that I can use the binoviewers in my 150PL in that case. Interesting that your 2x barlow becomes 3x, whereas my 1.3x barlow becomes 5x!! I guess all barlows would behave differently in this setup? Never quite got my head around barlows!

[Paz]

It's good news that you can merge the images ok.

I've been using a Baader maxbright II with my 102 ed-r for a while and can focus with a 2.6x and 1.7x glass path correctors, and depending on exactly how far along the optical train I place them I can vary the magnification and back focus a bit.

[ShrewView]

That does sound promising Rob. I use the WO binoviewers in all my scopes including the TS80Ed which is I think the same as the AA80, the smaller brother to yours. The views of the moon the other night were fantastic. Crisp and clear, though I do have to change the 1.6 nosepiece to achieve focus and swap it for a 2x. Should be great in yours!

[Louis D]

44 minutes ago, RobertI said:

Hi Louis, I was using in the 102ED-R (hiding in the title of the thread! ) - I was particularly interested in trying it on this scope as I was not sure how it would work (I'm confident it will work in the C8). It's good to know you can get focus in your dob, it might be that I can use the binoviewers in my 150PL in that case. Interesting that your 2x barlow becomes 3x, whereas my 1.3x barlow becomes 5x!! I guess all barlows would behave differently in this setup? Never quite got my head around barlows!

I figured you mentioned it somewhere, but I wasn't looking in the thread title, just your posts.  It's not the first time I've missed pertinent info mentioned only in the thread title.  🙄

It will definitely work in your C8, but it will requiring moving your mirror forward which will increase the focal length a few hundred millimeters I believe.  It will also induce a bit of spherical aberration by moving the mirror well away from the optimal design position.  It might be visible at high powers or it might not.  Some people are sensitive to it while others are not.

The longer the Barlow is originally, the less effect lengthening the working distance in BV usage has on the magnification.  The Meade is a "mid-length" Barlow like the 2x Tele Vue 1.25" Barlow.  Your Baader Q-Barlow would be classified as a "shorty" Barlow.  I do have a "long" Barlow (6 inches or so), but it does not have a removable optics section.  If it did, it would be terrific for BV work.  I'll have to see if I can swap the optics into a spare Meade 140 nose piece I have someday.  It will all depend on lens diameters and the combined spacer/lens depth of each.

[RobertI]

Thanks @Paz and @ShrewView . Yes I think I may need to invest in the WO 2x and 3x glass path correctors if I want a decent range of mags with that scope/eyepiece combo although it doesn’t look like I can get less than about 60x.

[RobertI]

24 minutes ago, Louis D said:

It will definitely work in your C8, but it will requiring moving your mirror forward which will increase the focal length a few hundred millimeters I believe.  It will also induce a bit of spherical aberration by moving the mirror well away from the optimal design position.  It might be visible at high powers or it might not.  Some people are sensitive to it while others are not.

Oh yes, I’d read about that effect in SCTs but forgotten it, so actually using the BVs without a Barlow would give more than the 100x I was expecting, possibly closer to 110x or 120x? And the the 1.6x might give closer to 200x? 

Thanks for the info on Barlows, very helpful, I now understand the meaning of ‘shorty’! 👍

[globular]

In your SCT:

If you add your WO binos into your usual visual back/diagonal/eyepiece holder then you're adding around 100mm to the light path which is about 310mm extra on your C8's focal length (there is about 3.1x factor in C8s). 
So if you're currently at F/10 it will become a F/11.5.

I don't know what type of C8 you have nor what visual back arrangement you have; but it might have an optical path length of 145mm or more, especially if you've gone 2".
This can be reduced to about 70mm if you select a diagonal with a very short light path.
This saves some optical length so you'll now only add (100-145+70)*3.1 = 77.5mm to your focal length compare to your current visual set-up (if the 150mm guess/assumption is correct).
So now, if you are currently F/10, you will only move out to F/10.4 with binos.
(Although it's more likely you're currently already at F/10.5 (or more) and will, with this short as possible set-up + binos, move to F/11).

If you can arrange your scope so you can look straight though with your binos then things move back down to something much closer to the optimal back focus and F ratio.
If you have the Edge C8 then, with your WO's straight into a visual back (no diagonal), you will be pretty close to the 133.35mm optimal back focus for the scope and be operating at the scope's optimal F/10.5.

Personally I think I'd use the shortest possible good quality prism diagonal I can find and live with operating at F/11 in comfort rather than F/10.5 doing contortions.

Edited October 30, 2020 by globular

[Chris]

Some kind of focus? Check, image merges? check. Sounds very positive Robert   I bet 175x will be fine for Lunar and planetary when the seeing is average or above. I'm looking forward to your BV adventures!

[RobertI]

16 minutes ago, globular said:

In your SCT:

If you add your WO binos into your usual visual back/diagonal/eyepiece holder then you're adding around 100mm to the light path which is about 310mm extra on your C8's focal length (there is about 3.1x factor in C8s). 
So if you're currently at F/10 it will become a F/11.5.

I don't know what type of C8 you have nor what visual back arrangement you have; but it might have an optical path length of 145mm or more, especially if you've gone 2".
This can be reduced to about 70mm if you select a diagonal with a very short light path.
This saves some optical length so you'll now only add (100-145+70)*3.1 = 77.5mm to your focal length compare to your current visual set-up (if the 150mm guess/assumption is correct).
So now, if you are currently F/10, you will only move out to F/10.4 with binos.
(Although it's more likely you're currently already at F/10.5 (or more) and will, with this short as possible set-up + binos, move to F/11).

If you can arrange your scope so you can look straight though with your binos then things move back down to something much closer to the optimal back focus and F ratio.
If you have the Edge C8 then, with your WO's straight into a visual back (no diagonal), you will be pretty close to the 133.35mm optimal back focus for the scope and be operating at the scope's optimal F/10.5.

Personally I think I'd use the shortest possible good quality prism diagonal I can find and live with operating at F/11 in comfort rather than F/10.5 doing contortions.

Thanks Globular, very informative. I'll be using a WO 2" diagonal (see below) which screws directly onto the scope, eliminating the visual back, so hopefully not too bad butlonger than a 1.25" prism diagonal. Actually I do have one of these so could try if the results with the 2" are not so good.

Edited October 30, 2020 by RobertI

[RobertI]

9 minutes ago, Lockie said:

Some kind of focus? Check, image merges? check. Sounds very positive Robert   I bet 175x will be fine for Lunar and planetary when the seeing is average or above. I'm looking forward to your BV adventures!

Thanks Chris, I'm really looking forward to observing Mars and Luna with them.

[jock1958]

Like you @RobertI been dithering around with which bino’s / extenders to buy, I eventually bought a second hand set of WO’s for my Tak FC-100DL, however haven’t had a chance to check them out due to the endless stormy weather. 
As soon as weather clears up will give them a go and see what they are really capable of, barlows & extensions included!! 

[RobertI]

8 minutes ago, jock1958 said:

Like you @RobertI been dithering around with which bino’s / extenders to buy, I eventually bought a second hand set of WO’s for my Tak FC-100DL, however haven’t had a chance to check them out due to the endless stormy weather. 
As soon as weather clears up will give them a go and see what they are really capable of, barlows & extensions included!! 

Look forward to your reports - feel free to add to this thread. 👍

[Don Pensack]

I reviewed these eyepieces and binoviewer a while ago in the context of a small refractor review:

https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-william-optics-zenithstar-80-st-r1390

I encourage owners of them to utilize another brand of OCA to enable the focal plane to extend backwards sufficiently, or to eliminate the OCA entirely

if the scope has enough focuser travel.  And to use other eyepieces.  These do not perform well.

[RobertI]

1 hour ago, Don Pensack said:

I reviewed these eyepieces and binoviewer a while ago in the context of a small refractor review:

https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-william-optics-zenithstar-80-st-r1390

I encourage owners of them to utilize another brand of OCA to enable the focal plane to extend backwards sufficiently, or to eliminate the OCA entirely

if the scope has enough focuser travel.  And to use other eyepieces.  These do not perform well.

Thanks for the link to your review Don, makes interesting reading. It sounds like the binoviewer/eyepiece combo is likely to perform ok in my C8 but may struggle at higher mags in the ED102 which is faster at F7 (more challenging for the supplied eyepieces) and requires a Barlow? I hope to find out if the weather ever settles! 

[Fozzie]

Not I knew from the title this is a thread I shouldn't read, but oh boy I couldn't resist..

It'll be interesting to see how you get on with the BV.  I used them once in my 102f11 frac, the same WO set as you, and came to focus with the baader nose piece from the 2.25x classic Barlow..  I reckon I was about 235x mag which, while the achro was capable on the best nights, was too much most of the time.. 

I found the views when it worked, breath taking, almost 3d like on the moon, and more detail on Jupiter..  I never really caress for them on deep sky tbh..

I've got a tak prism, which is short compared to my 2" diagonal.. that would be my diagonal of choice for BV..

It's on the list to try again..

Interesting to see how you get on, but from my very limited minimal experience, if it works for you, then it WORKS for you!

Ta & CS

Fozzie 

[Surreydocker]

Hi Rob, I'm very interested in this thread as I have the 102 ED. Were you using your 2" diagonal with your binoviewers and 102 ED-R ?

[RobertI]

10 hours ago, Fozzie said:

Interesting to see how you get on, but from my very limited minimal experience, if it works for you, then it WORKS for you!

Thanks Fozzie, I'm desperate to get out there and have a proper session - last night was clear for a couple of hours but sadly the demands of a small boy and Halloween had to come first!

6 hours ago, Surreydocker said:

Hi Rob, I'm very interested in this thread as I have the 102 ED. Were you using your 2" diagonal with your binoviewers and 102 ED-R ?

Yes I was using the 2" diagonal - I do have a 1.25" prism diagonal which I could try - it's a cheapish and oldish celestron, and I'm not sure I trust it to hold too mcuh weight, but worth trying I guess just see whether I can reach focus.

[RobertI]

Well, I finally got to try the bino-viewer with the 102ED-R on Mars and the Moon. To cut a long story short - WOW! Why didn’t I do this years ago? The viewing experience is so much more enjoyable with two eyes, no eye strain, no screwing up the other eye, easier to discern detail, it makes such a difference.

With the 1.3x element from the Baader Barlow screwed directly onto the BV nosepiece I was getting around 175x which I have to say seemed perfect. There was about 25 mm of focuser travel left. 

The seeing was not particularly good, there was a gusty wind and quite a bit atmospheric turbulence. The edge of the Mars’s disc was shimmering but a large amount of detail was visible, including Syrtis Major, the Southern Polar Cap and quite a lot of subtle shading  in the dark band - definitely the best view so far through this scope. One of the key differences is that with this setup I would have been able to draw the subtle features - they were that clear - with cyclops viewing it always seems to be a case of - have I seen it or not? 

Moving on to Luna and it was equally thrilling, such engaging views and relaxed viewing. I think the comfort and relaxed viewing afforded by BVs adds to your ability to discern detail and encourages you to stay at the eyepieces for longer. 

So far, so good, I think I have lucked in on a good combination. Can’t wait to get out for another try! 
 

[JeremyS]

Great report @RobertI

What eyepieces were you using?

[Space Hopper]

@JeremyS they are the standard WO 20mm pair that come with the bino.

 

Lovely looking setup there @RobertI 

Really pleased to hear you are enjoying the views. 

[Space Hopper]

Good advice earlier in the thread with keeping a short lightpath when using binoviewers with Catadioptric scopes.

Less focal length, less central obstruction, optimal contrast, and spherical aberration at a minimum.

I found this old picture from 2014 of my old C8 scope.

The Baader Maxbright in this case  is directly coupled to a short prism diagonal. Instead of using a nosepiece, a special T2 to SCT short adapter (i think it takes up only 15mm of lightpath)

is used that threads straight on to the SCTs rear thread removing the need even for the SCT visual back.

Edited November 2, 2020 by Space Hopper

[John]

Nice report Rob !

I've read a number of reports on binoviewers which reckon that the quality of the eyepieces you use with them is less important than if you are observing in cyclops mode. I guess being able to use two eyes is much more benefit than minor differences in eyepiece performance ?

I just wish that I could get on with the things !

FLO loaned me a pair of the William Optics ones complete with those eyepieces when they loaned me the Skywatcher ED150 to try out and I held onto those for a while and tried them with my 130mm triplet. They worked fine so it must be me