Going grey...

[Silentme]

Good day,

I am sure you have all read this topic, all seen and giggled.

However, my hair is getting greyer as i type.

I currently have an Orion SkyQuest xx12g. Huge, heavy and OMG fantastic.........

I was given Reverlation BinoViewers (1.25mm), as an xmas gift. I also was given two sets of 4/10/23mm Svbony 62deg field of view lenses to use with these viewers.

I finally got a clear evening and i have hit a small issue. I was only able to see anything if i attached my x2 Barlow, when i managed to find starlight, all i saw was a huge reflection of my mirrors, complete with the 4 metal struts holding up my top mirror, very out of focus. I was not able to get this into focus... As soon as i removed the viewer i was able to view as normal.

I am looking for ideas, also a good set of lenses.

Thanks for your time.

SM

[RolandKol]

I never had BinoV, but as I understand you need to get closer to the primary with them...

Not sure if your DOB has an option to shorten the OTA by placing tubes in a different manner. For example, -  Skywatcher Flexitube DOB (which I had) holding tubes have 2 positions, full length and halfway

I guess Skywatcher would get into focus while being halfway.

[John]

Hi and welcome to the forum.

I think you need around 100mm of inwards focuser movement to reach focus with most binoviewers. With the barlow element attached it's less but still possibly more inwards travel than your scope has available.

 

[Ricochet]

Which barlow do you have and are you using it as "normal" with the binoviewer or are you screwing the  barlow lens cell directly onto the nose of the binoviewer?

I have one Astro Engineering "2x" barlow that when screwed onto the nose of my binoviewers gives about 2x, but needs approximately 30mm of in travel compared to monoviewing. I also have another "2x" barlow similar to the following link, but without the filter threads. When I screw its lens cell to the binoviewer it gives about 3x, and requires a touch of out focus. 

https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html

I don't know what difference there is between using that lens cell and this one, sold specifically as a binoviewer gpc:

https://www.teleskop-express.de/shop/product_info.php/info/p5806_TS-Optics-Optics-2-6x-Glass-Path-Corrector-for-binoviewers---full-compensation.html

[Mark at Beaufort]

SM welcome to SGL.

I have used binoviewers with many types of scopes but its only Mak Cass and SCT scopes that don't require a barlow to gain focus. Currently I use William Optics binoviewers on my 6" Newt and 12" Dob but need to screw in a barlow to gain focus. The WO barlows are the 1.5X and 2X to gain different magnifications. One of the best barlows I have found is this one - https://www.firstlightoptics.com/barlows/baader-classic-q-225x-barlow.html

You will also find that magnification is greater than the stated barlow and I have found that using higher powered eyepieces just provide too much magnification. I only use 20mm and 16mm EPs.

[Silentme]

16 hours ago, Ricochet said:

Which barlow do you have and are you using it as "normal" with the binoviewer or are you screwing the  barlow lens cell directly onto the nose of the binoviewer?

I have one Astro Engineering "2x" barlow that when screwed onto the nose of my binoviewers gives about 2x, but needs approximately 30mm of in travel compared to monoviewing. I also have another "2x" barlow similar to the following link, but without the filter threads. When I screw its lens cell to the binoviewer it gives about 3x, and requires a touch of out focus. 

https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html

I don't know what difference there is between using that lens cell and this one, sold specifically as a binoviewer gpc:

https://www.teleskop-express.de/shop/product_info.php/info/p5806_TS-Optics-Optics-2-6x-Glass-Path-Corrector-for-binoviewers---full-compensation.html

Hi Ricochet,

I have a x2 screw in that attaches to the nose.

So i hear that i have to increase the length of my 'nose' which will move the focus point?

I will see if i can find another barlow, maybe longer.

SM

[niallk]

Hi FWIW I use a 2.6x Baader glass path corrector to reach focus with my BVs in my solid tube 250px 10" f/4.7.  I don't know if the Baader GPC range is compatible with your Rev BVs: perhaps try googling their website for pictures and description... they give some guidance on choosing the right one for different scopes. 

[Moonshane]

This is one of the reasons I use the Baaders too