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Equipment Discussions >> Binoviewers

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REC
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WO BV in 10" Dob?
      #6031056 - 08/17/13 02:10 PM

Well I tried out my WO BV with my new A10" Dob last night on the Moon and as I expected I could not get it to focus even with the 1.6x nose-piece that came with it.

Any suggestions?

Thanks,

Bob


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Eddgie
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Re: WO BV in 10" Dob? new [Re: REC]
      #6031113 - 08/17/13 02:36 PM

If you were not able to rack in far enough, the only place where you can get a bit closer could be to ensure that the collimation screws on your mirror cell are near the top end of their travel, pushing the primary as close as possible.

this will likely only buy you a few millimeters, but every millimeter helps.

Otherwise, you will need to Barlow up.


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REC
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Re: WO BV in 10" Dob? new [Re: Eddgie]
      #6031243 - 08/17/13 03:42 PM

Ok, will try a 2x shorty Barlow I have, I don't want to mess with the mirror, thanks!

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Pinbout
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Re: WO BV in 10" Dob? new [Re: REC]
      #6031533 - 08/17/13 06:37 PM

Quote:

don't want to mess with the mirror,




y

you probably should update to beefier springs anyway.

a shorty shouldn't be a problem. looking at the moon will never be the same...


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REC
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Re: WO BV in 10" Dob? new [Re: Pinbout]
      #6032412 - 08/18/13 08:41 AM

I did get the "Tweakers Dream Package" and they added the beefier springs and replaced the front screws of the secondary with knobs that makes alighnment much easier. Also the other good thing in this package is they flocked the tube.

I will try the barlow, but I dis see Orion just brought out a new low profile focuser that looks like have the size of the original and maybe that will allow enough back focus for the BV to work.....but it is expensive, $250!

Yes, the only way to view the Moon!


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REC
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Re: WO BV in 10" Dob? new [Re: Eddgie]
      #6035955 - 08/20/13 07:55 AM

Ed, tried the 2x barlow way in the WO and sill not focus!

Next I tried the Denks with either arm inserted and that would not come to focus.

Now what do you suggest?

Bob


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Eddgie
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Re: WO BV in 10" Dob? new [Re: REC]
      #6035962 - 08/20/13 08:01 AM

How did you try the 2" Barlow?

Did you use a 2"/1.25" reducer to hold the Binoviewer?

If so, were you using a 2" barlow?

If you are using a 1.25" barlow and a 1.25" nose on the binoviewer, try unscrewing the barlow lens alement and screwing it directly into the nose of the binoviewer.

If you were using a 2" / 1.25" adapter and a 2" barlow and your adapter is threaded, again, try unscrewing the barlow element and screwing it directly to the front of the reducer.


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Re: WO BV in 10" Dob? new [Re: Eddgie]
      #6036013 - 08/20/13 08:52 AM

Yes, I had the included 2"/1.24" reducer to hold the WO and was using a Meade 126 2x Barlow. I tried to unscrew the element and it does not fit the nose piece..too wide.

The 1.6 barlow that screws into the nose it 1" long. My shorty barlow ads another 1.5" to the nose.


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Eddgie
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Re: WO BV in 10" Dob? new [Re: REC]
      #6036549 - 08/20/13 01:41 PM

Well, it can be very hit or miss when you are trying to get the focus right on a Dob I think. They generally don't have the same focuser travel as refractors do.

Your result might be because you are using a short barlow, but at this point I can't tell you what will work or what won't work. It is often just trial and error. I was lucky that the 2" AT barlow lens worked. Just one of those things.


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REC
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Re: WO BV in 10" Dob? new [Re: Eddgie]
      #6036572 - 08/20/13 01:54 PM

Ed, thanks for your reply. Well next I will try my 2.5x Powermate and see how that works. BUT, it has a very long length on it and will be sticking out pretty far and somewhat heavy. I thought I would get more feedback from other CN members who are actually using the WO with their Dobs?

As for getting my Denk to work in it, I guess I'll just have to call Russ and get the adapter for it.

Bob


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TomCorbett
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Re: WO BV in 10" Dob? new [Re: REC]
      #6036892 - 08/20/13 04:40 PM

REC...

I am sorry, but I have no suggestions for you--however, I am very interested in your results.

Please hang in there and find a configuration that works.


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REC
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Re: WO BV in 10" Dob? new [Re: TomCorbett]
      #6036923 - 08/20/13 04:58 PM

Tom, ok I will keep you posted. I'm going to send an email to WO and see what they say....stay tuned.

Bob


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pftarch
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Re: WO BV in 10" Dob? new [Re: REC]
      #6037373 - 08/20/13 10:05 PM

Have you tried the filter body extension technique? With my Z10 my best results came from stacking three 1 1/4" filter bodies together (with the actual colored glass removed) and screwing that between the supplied 1.6 corrector and my WO bino's. I believe it resulted in about a 2.1 x Barlow effect and allowed me to reach focus. You may just want to stack three filters together before you take the glass out and see if you can focus on the bright moon.

Peter T


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Messyone
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Re: WO BV in 10" Dob? new [Re: pftarch]
      #6037710 - 08/21/13 04:37 AM

I binoed on a Skywatcher 8" f5 with the standard I.e. not low profile focuser with the 1.6 OCA and WO binos without problem so I'm having trouble understanding what your doing...can you post a photo of the set up? Skywatcher have an awful 2-1.25" adaptor, hi hat style that did a good job of mucking up focusing with a number of eyepieces. A picture would help.
Matt


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REC
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Re: WO BV in 10" Dob? new [Re: Messyone]
      #6037867 - 08/21/13 08:23 AM

Thanks for these two ideas, will try the filter trick and also my 2.5X Powermate.

I tried a 35mm extension tube, but guess it was too long? I spoke to OPT last night and they have a 25mm tube extension that he thought would do the trick, so maybe try that? I'm going to try screwing in the 1.6x and then manually pull the BV out of the focuser to see if there is a just right distance and mark it. Then I will have a better idea how much of an extension I need.

I want to get this fixed by Saturday as we will have a few clear nights for the first time in months and the Moon won't be out, so looking for some of the brighter globs to view in the BV. Anyone have good luck on DSO's with BV?

Thanks again for all your suggestions!

Bob


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Hothersale
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Re: WO BV in 10" Dob? new [Re: REC]
      #6038282 - 08/21/13 12:32 PM

Quote:

I tried a 35mm extension tube, but guess it was too long? I spoke to OPT last night and they have a 25mm tube extension that he thought would do the trick, so maybe try that? I'm going to try screwing in the 1.6x and then manually pull the BV out of the focuser to see if there is a just right distance and mark it. Then I will have a better idea how much of an extension I need.




Have you tried using the nosepiece and NO extension tubes? Assuming you are talking about focuser extension tubes, I don't think you should be using any extension tubes at all.


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REC
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Re: WO BV in 10" Dob? new [Re: Hothersale]
      #6038315 - 08/21/13 01:00 PM

Well yeah, that was my first move, just insert them into the focus and it would not focus. I have sent an email to WO asking them for advise.

Thanks,

Bob


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johnnyha
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Re: WO BV in 10" Dob? new [Re: REC]
      #6038451 - 08/21/13 02:27 PM

I don't know if you are doing this Bob, but the typical "newt mode" for a binoviewer involves an extra long nosepiece with a barlow element attached to the end. The extra long nosepiece mimics the extra long light path of a diagonal. Check the Denkmeier manual to get an idea.

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REC
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Re: WO BV in 10" Dob? new [Re: johnnyha]
      #6038473 - 08/21/13 02:39 PM

Thanks Johnny, wow that is a huge set of tubes sticking out of the BV! Hoped I didn't have to go that long and I see you must use a OCS with all of them.

Seems BV with a SCT is much easier!


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johnnyha
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Re: WO BV in 10" Dob? new [Re: REC]
      #6038495 - 08/21/13 02:50 PM

They look longer because it's 1.25". Its possible to achieve focus with a slightly shorter tube, it all depends on your setup. Generally speaking though the nosepiece needs to be as long as the binoviewer and with a barlow on front to create "negative lightpath".

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pftarch
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Reged: 09/21/07

Re: WO BV in 10" Dob? new [Re: johnnyha]
      #6039106 - 08/21/13 08:32 PM

What eyepieces were you using? I ask this because if you are using a high or even moderate power eyepiece and you are using a 2" Barlow, the final Barlow effect would be more like 5x. If you are using 20 mm eyepieces at 5x you are getting up around 300x on your scope. At those powers conditions may not let you focus even in mono mode.

I will say that I am surprised that the extension tube with the 1.6 Barlow didn't work. For me the longer the extension tube or Barlow power the easier it is to focus. The problem being that the resultant magnification increase makes the views unusable, or extreme limited. I also doubt that a low profile focuser will give you enough back focus.

Peter T


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REC
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Re: WO BV in 10" Dob? new [Re: pftarch]
      #6039718 - 08/22/13 08:30 AM

Hi Peter, I was using the supplied 20mm EP in it. Yes the 1.6x would not come to focus even If I added more extension tubes, which I think is going the wrong way anyway. The 2x barlow was the short type and that did not work either.

I sent this question over to WO and they came back with this reply. Seems they don't have a solution either!

"Many telescopes, especially Newtonian reflectors, do not have sufficient back-focus to achieve focus with such an optically long accessory. By using a barlow, the focal point of the telescope can be extended sufficiently to accommodate the length of the binoviewer.


We recommend first choosing the lowest powered barlow that will allow your scope to reach focus. This will permit the widest possible field of view. In addition, one or more higher powered compensators can be added to give a greater range of magnifications.

You already tried 1.6x and you also can try 2x barlow for Binos.

It would be easier if you check with your telescope maker if the model you have bino friendly or not.

Best regards,

Tim

WO


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REC
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Re: WO BV in 10" Dob? new [Re: REC]
      #6039900 - 08/22/13 10:54 AM

Ok, update...I just spoke to Russ at Denkmier and told him I needed an adapter OCS for my Denk2 and so he is sending me that and the middle spacer for my Dob and that's that I guess. Since I can't get the WO to focus with the Dob even though it a lighter set up, I'm just going to sell the WO and be done with it.

He told me that with my 20mm EP's I would get about 80x as the lowest power, so that sounds good. I'll use the 26SP for lowest power and brighter EP for DSO's

Stay tuned!

Bob


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MaestroMyth
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Re: WO BV in 10" Dob? new [Re: REC]
      #6041058 - 08/23/13 12:17 AM

i had the same problem as you with my WO binoviewer and solved it, thanks to help from this forum. i ordered this from siebert optics:

http://www.siebertoptics.com/Burgess125xto3x.html

i use this with my A12 and my WO binoviewer. works great, and i get three magnification options.


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SkyGibbon
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Re: WO BV in 10" Dob? new [Re: johnnyha]
      #6041121 - 08/23/13 01:32 AM

I was able to achieve focus by Attaching three unused filter cells (with filter glass out of course)to bino nosepiece and screwing on the 2x element of a shorty barlow to the end of filters. When I switched to a low profile focuser, I was able to do the same with the 1.6x corrector that came with the WO viewers. You will have to move mirror up to do it without any correctors.

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REC
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Re: WO BV in 10" Dob? new [Re: MaestroMyth]
      #6041337 - 08/23/13 07:27 AM

Thanks for the tip! As of now, I think I'm just going to see how the Dob setup for my Denk works out before I spend any more money for tubes ect. for the WO BV.

Just to be clear with this Siebert fix, you are using a combination of tubes ans some kind of glass element as well?


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MaestroMyth
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Re: WO BV in 10" Dob? new [Re: REC]
      #6044369 - 08/24/13 10:56 PM

yes, REC, that's correct. i might be reading into your question here somewhat, but if you're concerned about adding all those glass elements to the light path, and any possible image degradation, there is little to no drop off in crispness in my system. i know that sounds impossible, but i've tried it both ways. the siebert OCS is a great fix for our problem.

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Relativist
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Re: WO BV in 10" Dob? new [Re: MaestroMyth]
      #6045471 - 08/25/13 04:22 PM

Same exact setup I use. It even let me use my WO with a Firstscope

http://www.celestron.com/astronomy/series/firstscope-telescope/?cat=4

No kidding.

That said, you also have another BV set to try, and it probably makes sense to only keep one.



Quote:

i had the same problem as you with my WO binoviewer and solved it, thanks to help from this forum. i ordered this from siebert optics:

http://www.siebertoptics.com/Burgess125xto3x.html

i use this with my A12 and my WO binoviewer. works great, and i get three magnification options.




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REC
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Re: WO BV in 10" Dob? new [Re: MaestroMyth]
      #6046511 - 08/26/13 07:53 AM

Ok, than that's what I need then, thanks! So next question to resolve this whole BN business and to get down to observing, is what to keep?

I have been testing a Denk 2 PS with my 8" SCT and trying to determine a basic question, what looks better in the EP? So far I'm have a hard time choosing. Next up is to see how well the Denk performs in my 10" Dob.

Last night I was using M13 as an acid test and the Denk was not doing to well with it. M13 was directly overhead in an area of least LP and I could not resolve stars in it like I can in Mono. If we get another clear night this week, I'll do a side by side with both BV on some of the brighter DSO's


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Eddgie
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Re: WO BV in 10" Dob? new [Re: REC]
      #6046563 - 08/26/13 08:55 AM

If you are configured properly, the difference between binoviewing and non binoviewering for DSOs should be very subtle and hard to see. If there is an obvious difference, then I suspect something is wrong.

Are you using a 2" diagonal?

The problem with using a 2" diagonal with something like a powerswitch (or even without the powerswitcy) is that the system can loose apeture.

When the light path is very long, the primary has to be moved so far forward that the light cone widens so much the baffle on the secondary miorror starts to shave off the outside of the light cone so that aperture is reduced.

The other consequences are that the central obstruction becomes larger by percentage and the excessive back focus induces spherical aberration into the system.

If you are using a 2" diagonal and a typical visual back with 40mm of light path, along with binoviewers, your light path is about 270mm.

This will reduce your apeture to maybe 7.3".

If you are using this configuration with a powerswitch, you add about 18 mm to this, which reduces the apeture another .2".

And when you slide in the powerswitch low power arm, your apeture drops to about 6.7" or so,

I would not avoid using a Binotron or similar system in an SCT because the effect is least when you are in high power mode (double Barlow), but as you can see, there is a compromise.

If you are using a 2" diagonal, you can save qite a bit of back focus by converting your system to work with a short visual back and short light path diagonal.

What I recommend are the Televue Short Visual back and the Baader T2 Prism. These will save you about 60mm of light path, restoring about .6" of apeture to each of the figures above.


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Re: WO BV in 10" Dob? new [Re: Eddgie]
      #6046745 - 08/26/13 10:51 AM

Hi Ed, yeah it's me Bob again and still trying to work out all of this back focus problem and yes, still using the 2" Diagonal and the 32mm OTA with it.

I did not try the reducer arm in it because you had told me that will reduce my aperture even more! Just looking straight through with a pair of 26mm SP. The view was still dim and could not quite resolve any stars in M13.

Next I am going to try the WO BV and see if there is any change and then, use a 1.25" diagonal with the stock OTA that came with the scope. That would be the shortest light path of all at 24mm long.

I am also waiting for the OCA from Russ to use my Denk on my new 10" Dob and hoping that will show a big increase on DSO's.

Bottom line for BN is two fold. One I like the views of the Moon and planets for sure! Two, my right eye is not quite as good as my left eye on DSO's. With my left, I can see a little bit better on faint stars and also it has better contrast and shows a little darker background. I am hoping by using both eyes, this will give me a more pleasing overall view and yes, a lot more comfortable.


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Relativist
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Re: WO BV in 10" Dob? new [Re: REC]
      #6047690 - 08/26/13 08:51 PM

between the WO BV and the Denkmeier 2, the Denk has a larger clear aperture, which will will allow for wider FOV, hence why Siebert has 'supercharge' services for less expensive BVs.

http://www.siebertoptics.com/SiebertOptics-Binoviewer%20Upgrade.html

If you find that you like BVs, then you might want to keep the Denks.


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Epsilon_Lyrae
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Re: WO BV in 10" Dob? new [Re: Relativist]
      #6047868 - 08/26/13 10:37 PM

You used WO binoviewers with a Siebert OCA in a Firstscope mini-dob? How did you manage that - did you only use part of the OCA? I remember trying that when I first bought my binoviewers, but it looked like the OCA would hit the secondary mirror, so I gave up. Maybe I'll have to take another look at that!

Quote:

Same exact setup I use. It even let me use my WO with a Firstscope

http://www.celestron.com/astronomy/series/firstscope-telescope/?cat=4

No kidding.

That said, you also have another BV set to try, and it probably makes sense to only keep one.





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Re: WO BV in 10" Dob? new [Re: Epsilon_Lyrae]
      #6047984 - 08/26/13 11:45 PM

Quote:

You used WO binoviewers with a Siebert OCA in a Firstscope mini-dob? How did you manage that - did you only use part of the OCA? I remember trying that when I first bought my binoviewers, but it looked like the OCA would hit the secondary mirror, so I gave up. Maybe I'll have to take another look at that!




Be very careful if you do, if they touch then you could scrape the OCA lens or coating! I used the 1.25x setup. I was trying to get a large FOV, and I did...

P.S. that's why I didn't post pics or talk about it much, I don't recommend it.


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Epsilon_Lyrae
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Re: WO BV in 10" Dob? new [Re: Relativist]
      #6048010 - 08/27/13 12:11 AM

Ha ha - you're careful not to say much, then mention it in an unrelated thread, and I immediately want to try it! Thanks for warning.

Anyway, I've used the WO binoviewers in a 10" dob, but I had to use the Siebert OCA.

Quote:



Be very careful if you do, if they touch then you could scrape the OCA lens or coating! I used the 1.25x setup. I was trying to get a large FOV, and I did...

P.S. that's why I didn't post pics or talk about it much, I don't recommend it.




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Re: WO BV in 10" Dob? new [Re: Epsilon_Lyrae]
      #6048152 - 08/27/13 02:57 AM

Quote:

Ha ha - you're careful not to say much, then mention it in an unrelated thread, and I immediately want to try it! Thanks for warning.

Anyway, I've used the WO binoviewers in a 10" dob, but I had to use the Siebert OCA.





yea, main point i was trying to make is that the OCA works. The way I did it is racked in the focuser so it was as close to the secondary as I was comfortable with, then focused by racking out slowly. Because damage might happen if someone just racks in, I don't really share the views when I do this.


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