Binoviewer first light and questions

[Size9Hex]

I had a very brief chance last night to test out a new TS binoviewer in the SW 250PX.

Good news on the focussing. The 2.6x GPC brought focus when I used the stock 1.25" eyepiece adapter that comes with the dob.

Better still, the 1.6x brought focus when I removed the stock adapter and replaced it with a simple low profile 2 - 1.25" adapter from a star diagonal. I wasn’t sure whether this combo would work, but am delighted as it opens up the possibility of relatively low power viewing for nebulae.

I started with a pair of 25mm stock Super MA eyepieces and could merge the images with no problem. When I switched to a pair of stock 10mm, I felt I was a long way from merging the images. I rather wish I had an in-between pair to test.

Does this indicate unacceptable misalignment of the optics? Is it just a case of persisting until I can merge the image? Is a 10mm EP just too powerful for binoviewers? What length EP do other users stop at when binoviewing? Bit worried if I can’t use a 10mm (or at least something approaching that), then planetary/lunar high power isn’t going to work out.

Checked out a handful of deep sky. Too short a session and too many variables to form opinion on the performance. That said, by the standards of my viewing site, M42/43 was superb (especially when noting that it was unfiltered) with terrific contrast which seems very promising. I’m really excited to test it further on large faint low contrast objects.

[Moonshane]

It's more like;y you need to adjust the BVs in terms of IPD for different eyepieces. I find sometimes higher powers take some getting used to and sometimes rotating the BVs in the focuser helps too as daft as this sounds. I am not keen on them for DSOs in general though and use them almost exclusively on solar system objects.

[Cosmic Geoff]

I have the Starguider binoviewer. It really works best on bright objects like the Moon, as the amount of light reaching each eye is less than half of what you would get entering the single eye without it.  This seemed to have an accidental benefit on viewing Mars, where the reduction in glare made it easier to see surface detail.

I found that merging was easy with the 30mm eyepiece pair supplied, but I bought a second 20mm Plossl eyepiece so I would have a higher powered pair, and found that merging with these was very difficult. The fact that one Plossl had a security groove and the other did not didn't help.  Since then I have relied on Barlow lenses to increase the magnification. I have never tried the BV on nebulae.

[Ricochet]

7 minutes ago, Cosmic Geoff said:

The fact that one Plossl had a security groove and the other did not didn't help.

If the eyepiece nose design allows the eyepiece to be tilted in the eyepiece clamp then merging the images won't work. In that case you either have to be very careful when clamping the eyepiece to ensure alignment or switch to an eyepiece with a suitable nosepiece. I currently use 25mm Starguiders and 18mm BCOs with my Starguider binoviewer and both types are fine. 

 

1 hour ago, Size9Hex said:

I started with a pair of 25mm stock Super MA eyepieces and could merge the images with no problem. When I switched to a pair of stock 10mm, I felt I was a long way from merging the images. I rather wish I had an in-between pair to test.

Does this indicate unacceptable misalignment of the optics? Is it just a case of persisting until I can merge the image? Is a 10mm EP just too powerful for binoviewers? What length EP do other users stop at when binoviewing? Bit worried if I can’t use a 10mm (or at least something approaching that), then planetary/lunar high power isn’t going to work out

As the 10mm eyepieces are only the cheap MAs given away with scopes it is possible that the manufacturing tolerances aren't tight enough for them to be suitable or that one or both can be tilted. It could also be that you have not correctly positioned your IPD. A 10mm eyepiece will produce a much smaller exit pupil than the 25mm eyepieces and so your positioning has to be that much more accurate.

As with the previous posters I use binoviewers for lunar and planetary rather than DSOs. For bright objects like the Orion Nebula you might get away with it but on dimmer objects I think monoviewing gives better results.

[Stu]

A few things to try I would suggest. Rotating the eyepieces to see whether that helps, also check they are seated properly and that there is no slop in the holders at all. Also play around with the IPD adjustment as I find that I need to change this with higher power, or at least it has to be more accurate.

I tend to use 25mm orthos and barlow to get the magnification I need. I believe this tends to make for easier merging than natively shorter focal length eyepieces. I use mine up to x200 and more with no issues.

[Size9Hex]

Thank you for the replies and advice. A few things I hadn’t thought of trying and didn’t realise might be significant. Will give it another go! ?

[F15Rules]

My binoviewers are unusual in that the IPD is adjusted by sliding the 2 eyepiece holders laterally towards or away from each other. The movement is hydraulic and very smooth..The down side is that with any change of eyepiece pairs (unless they are parfocal pairs) I have to refocus..But on the plus side I can use the marked calibration lines to record what setting I use for each eyepiece pair..For example with my Morpheus 17.5mms I have the setting at 68mm. With the 25mm Parks Gold the best merged view is at 65mm. The total available IPD range available with my bvs is c 55mm-75mm.

I agree that collimation is critical for sharp images and good merging. Frankly, it can be a real faff... but when you get it right, the views can be stunning! 

Practice (and greatly collimation) makes perfect ☺.

I would also say that you DO lose some light transmission versus Cyclops viewing, so some deep sky objects will suffer a bit. For example, I haven't yet managed to see E or F in the Trapezium when binoviewing, whereas both are often seen when Cyclops viewing.. However , when viewing M42 as a whole, the sheer comfort and "naturalness" of the two eye view with binoviewers still makes the overall view captivating, more "3D". It's hard to explain in words, but when you get those moments you will know exactly what I mean.

It is definitely worth persevering?☺..

Dave

[mikeDnight]

Hi Paul,

I've found with my binoviewer that not only is the interoccular distance critical but also the position of the individual diopter. I believe the diopter is supposed to aid in focusing individual eyepieces, as each eye focuses at a slightly different position. It's my belief that at mid to high powers, the engineering is not nearly good enough for this to work properly and even fractional movement of one or both diopters demerges the image. I decided I would not use the diopter movement for focusing, but would simply retract one eyepiece very slightly until both were perfectly sharp. 

I set my locking screws on the inside of my eyepiece holders as shown in the 1st attached pic. By moving one diopter only slightly, as in pic 2, the images are very obviously demerged. The 3rd pic shows one eyepiece slightly retracted to attain sharp focus.  With the diopters set in the first position, my binoviewer remains totally merged even at high powers, with only very minor adjustments to the diopter position as needed. 

Once youve found the exact position for your diopters, keep them set in that position. Don't let other observers alter anything but the separation on the binoviewer or you could spend a good hour trying to remerge the images. Binoviewer don't generally make good companions for group sessions!

 

[jetstream]

It is very hard for most to merge low fl eyepieces as Stu says, but with practise it can get better. I can now easily merge 9mm VT orthos (7's sometimes too)- but most get the mag barlowing lower mag fl's.  So much comes into play using binoviewers...

[Moonshane]

I can merge the images with 8mm TV plossls and my maxbrights but often find the image is a bit dim and generally does not gain much over the 11mm or even the 15mm. I nornally revert to the 20mm view and even the 25mm view for the moon and just gawp in awe.

With my 12" dob and 1.7x GPC the mags are 

8mm = 255x

11mm = 185x

15mm =136x

20mm = 102x

25mm = 82x

[JTEC]

There is some further useful advice here

https://agenaastro.com/choosing-astronomy-eyepieces-for-binoviewers.html#eyepieces

and in Roland Christen’s comments - down the page - here

http://www.darksights.com/Binoviewers.htm

I do agree with the need to get IPD and, of course, independent focus for each eyepiece carefully adjusted. There seems to be a point for each where things snap into place. Because of the different ways we might engage with different eyepieces with varying eye lens sizes, eye relief, curvature, the IPD does seem to need checking for different pairs. I’m not really sure why this should be - think it’s probably as Stu says that generally with shorter fl eyepieces and higher mag it’s more exacting.

I’ve successfully used 8mm TV Plössls and 9mm Tak orthos without any problem, in fact the Taks are a favourite pair for lunar/planetary. I do have the Baader MkV though and that is supposed to be bench tested for collimation at x3000. There is someone who’s name (apologies) I forget using one of these with a pair of Vixen HR 2.4s  That said, note Roland Christen’s advice about getting a lot of the mag done ahead of the prism/viewer. I use the x1.7 GPC which reportedly actually gives about 1.4/5 like this. My most used eyepiece pairs are 11mm TV Plössls, 9 mm Taks orthos, 18mm Tak LEs and Edmund RKE 28mms. 

I can’t imagine ever moving away from binoviewing for lunar and planetary. You just see more.  Nor would I be quick to dismiss it for brighter deep sky: M42 is incredible as are globs and brighter planetaries like M27.

 

[Saganite]

48 minutes ago, jetstream said:

It is very hard for most to merge low fl eyepieces as Stu says, but with practise it can get better. I can now easily merge 9mm VT orthos (7's sometimes too)- but most get the mag barlowing lower mag fl's.  So much comes into play using binoviewers...

I had these problems with my first binoviewer, a well respected unit, and a pair of Zeiss 10mm eyepieces. Thanks to merging problems I turned down the chance to buy them from a friend here on the forum !

Since that time I have bought a Denkmeier bino with which I view using 7 pairs, from 35mm Euduascopic to 6.7mm UWA without a single problem , in each of my scopes. 

[Saganite]

2 hours ago, F15Rules said:

My binoviewers are unusual in that the IPD is adjusted by sliding the 2 eyepiece holders laterally towards or away from each other. The movement is hydraulic and very smooth..The down side is that with any change of eyepiece pairs (unless they are parfocal pairs) I have to refocus..But on the plus side I can use the marked calibration lines to record what setting I use for each eyepiece pair..For example with my Morpheus 17.5mms I have the setting at 68mm. With the 25mm Parks Gold the best merged view is at 65mm. The total available IPD range available with my bvs is c 55mm-75mm.

I agree that collimation is critical for sharp images and good merging. Frankly, it can be a real faff... but when you get it right, the views can be stunning! 

Practice (and greatly collimation) makes perfect ☺.

I would also say that you DO lose some light transmission versus Cyclops viewing, so some deep sky objects will suffer a bit. For example, I haven't yet managed to see E or F in the Trapezium when binoviewing, whereas both are often seen when Cyclops viewing.. However , when viewing M42 as a whole, the sheer comfort and "naturalness" of the two eye view with binoviewers still makes the overall view captivating, more "3D". It's hard to explain in words, but when you get those moments you will know exactly what I mean.

It is definitely worth persevering?☺..

Dave

I agree Dave, 100%. Since my first use of binoviewers, several years ago, I have not used anything else for Lunar observing, so captivating is it.. Apart from M42, globular clusters, particularly M13 are a must see with a binoviewer.

[Saganite]

2 hours ago, mikeDnight said:

Hi Paul,

I've found with my binoviewer that not only is the interoccular distance critical but also the position of the individual diopter. I believe the diopter is supposed to aid in focusing individual eyepieces, as each eye focuses at a slightly different position. It's my belief that at mid to high powers, the engineering is not nearly good enough for this to work properly and even fractional movement of one or both diopters demerges the image. I decided I would not use the diopter movement for focusing, but would simply retract one eyepiece very slightly until both were perfectly sharp. 

I set my locking screws on the inside of my eyepiece holders as shown in the 1st attached pic. By moving one diopter only slightly, as in pic 2, the images are very obviously demerged. The 3rd pic shows one eyepiece slightly retracted to attain sharp focus.  With the diopters set in the first position, my binoviewer remains totally merged even at high powers, with only very minor adjustments to the diopter position as needed. 

Once youve found the exact position for your diopters, keep them set in that position. Don't let other observers alter anything but the separation on the binoviewer or you could spend a good hour trying to remerge the images. Binoviewer don't generally make good companions for group sessions!

 

I am also using a pair of these Mike. Quite superb aren't they

[Stu]

2 hours ago, mikeDnight said:

It's my belief that at mid to high powers, the engineering is not nearly good enough for this to work properly and even fractional movement of one or both diopters demerges the image.

I agree with this too. When extended, there is some play in the dioptre adjustment which is enough to cause problems so, like Mike, I lock mine down. I just carefully adjust the focus by pulling one eyepiece out slightly.

My Baader Zeiss Mark IV is apparently one of the early ones and has a very tight tolerance on the eyepiece holders. Some 1.25" eyepieces don't even fit. They have a single set screw, but there I a no play in them so alignment is very good. The Zeiss orthos I use have a built in dioptre adjustment which makes life easier.

[Stu]

53 minutes ago, JTEC said:

That said, note Roland Christen’s advice about getting a lot of the mag done ahead of the prism/viewer.

That's what I tend to do John. 25mm orthos but with a x2.6 GPC and often anything up to a x4 Barlow ahead of that. For solar and lunar the image at high power is superb. I took years and 4 or 5 pairs of binoviewers to train my brain to see well through them. My floaters mean that it's the only way I enjoy high power in a 4" scope.

[JTEC]

As you say, Stu, they do help a lot to reduce the impact of floaters - presumably because the parts of the field that are being troubled by floaters in one eye have a good chance of being clear in the other, and when you perceive the bundle of data from both eyes the identity of each eye’s contribution is somehow dissolved into the mix. 

Which Barlows are you using up ahead? I’m planning to have a go with the x2 Powermate with the x1.7 in the prism behind. I’m not sure what the interaction will be, but it should give plenty of mag with the advantage of comfortable eyepieces. Perhaps by enabling the use of more accommodating eyepieces this would help with the issues with managing IPD, etc that others have highlighted. 

[mikeDnight]

32 minutes ago, Stu said:

I agree with this too. When extended, there is some play in the dioptre adjustment which is enough to cause problems so, like Mike, I lock mine down. I just carefully adjust the focus by pulling one eyepiece out slightly.

My Baader Zeiss Mark IV is apparently one of the early ones and has a very tight tolerance on the eyepiece holders. Some 1.25" eyepieces don't even fit. They have a single set screw, but there I a no play in them so alignment is very good. The Zeiss orthos I use have a built in dioptre adjustment which makes life easier.

Your mention of the single set screw Stu reminded me of another problem i experienced, and another reason why I placed the screws on the inside holes. I noticed that if the screw is in one of the outer holes, it pushes the eyepiece slightly out of alignment. May be it could have been caused by the undercut or Shaffer on some eyepieces allowing the eyepiece to tilt when the screw pushes against it? I haven't tried seeing if the same thing happens with my Ultima's, which have no undercut. I think its interesting that it appears to be more of an engineering issue that seems to be the reason binoviewers can be a little problematic. 

[mikeDnight]

I used a Tak 1.6X extender Q which gave terrific views. For higher powers I used the Q as well as a 2X SW delux barlow screwed into the binoviewer nose piece, which was stunning.

For most of my binoviewing I now tend to use either a complete SW 2X delux barlow or a Celestron 2X Ultima barlow (which actually amplifies 2.25X). The difference between the two may seem insignificant in normal use, but when fit before the binoviewer the extended light path between the barlow and the eyepiece, the amplifications are approximately X4 for the delux and X5 for the Ultima. Both barlows give exquisite views at high power with no noticeable CA, so i dont feel the need to pay through the nose for expensive "apochromatic" barlows or Power Mates. Just to try and illustrate: a couple of years ago almost, I had opportunity to try a friend's 5mm TMB Super Monocentric eyepiece in my Takahashi FC100DC while viewing the high spring moon. The evening was truly first class seeing! The super mono gave a jaw droppingly sharp view, yet when the binoviewer with 2X delux barlow and 16.8mm Abbe Orthoscopics were used, the jaw dropping views became even better; not by a small amount but with a real wow factor!

 

[Saganite]

1 hour ago, Stu said:

That's what I tend to do John. 25mm orthos but with a x2.6 GPC and often anything up to a x4 Barlow ahead of that. For solar and lunar the image at high power is superb. I took years and 4 or 5 pairs of binoviewers to train my brain to see well through them. My floaters mean that it's the only way I enjoy high power in a 4" scope.

Hi Stu,

I have used binoviewers for about 6 years now and never once thought  about using a barlow in the system as well. I was initially confused by what what you were suggesting but It has just dawned on me, that a binoviewer is after all, an eyepiece, and should work when inserted into a barlow. I will have to try it out. 

 

[jetstream]

26 minutes ago, Saganite said:

Hi Stu,

I am a bit confused by this. What am I missing ? 

In  my Tak FC100, I have a Baader T2 prism diagonal, with the Denk OCS screwed into the telescope side. The bino then has an optical nosepiece giving 1.4X , or a hollow nosepiece giving 2.5X. 

Where does the barlow come into it. Does it go into the eyepiece side of the diagonal before the bino ?

 

The Denks including my Binotron 27's have been well thought out by Russ- thanks Russ! I think that other bino's need a bit of "figuring out" by users.

The bino's in my 15", with 12.5mm Tak orthos in the middle position go roughly 365x sharp and with zero merge issues- Mr Ledermeier also included an extension to focus in the dob, free. This package works in any scope.

Not all binos are this easy to use IMHO so in comes the barlows etc. This is not to say that these binos are inferior by any means.

[Saganite]

3 minutes ago, jetstream said:

The Denks including my Binotron 27's have been well thought out by Russ- thanks Russ! I think that other bino's need a bit of "figuring out" by users.

The bino's in my 15", with 12.5mm Tak orthos in the middle position go roughly 365x sharp and with zero merge issues- Mr Ledermeier also included an extension to focus in the dob, free. This package works in any scope.

Not all binos are this easy to use IMHO so in comes the barlows etc. This is not to say that these binos are inferior by any means.

Hi Gerry,

I had gone back and edited this post because I suddenly realized after typing it, what was meant, so the post is now different. That said, I will give putting a barlow into the diagonal , a go and see what happens.

I certainly have had no issues whatever with merging even at high powers with short focal length eyepieces. 

[Stu]

1 hour ago, Saganite said:

Hi Stu,

I have used binoviewers for about 6 years now and never once thought  about using a barlow in the system as well. I was initially confused by what what you were suggesting but It has just dawned on me, that a binoviewer is after all, an eyepiece, and should work when inserted into a barlow. I will have to try it out. 

 

Yes, that's right, you can just treat it like an eyepiece, although the thing to remember is that the increased optical path means that the Barlow effect is increased. I've never really got to a clear idea of what magnification I'm using, I just know what works.

I use a completely crazy system, but one that I find quite satisfactory. I often have a x1.7 GPC installed in the binoviewer, and then use the optical element from an AP Barcon either attached directly or with one or two extention tubes to vary the magnification. It looks a bit unwieldy but means you don't have to change eyepieces. I use t2 quick changers to add the extensions.

[F15Rules]

I do agree that there is something in the idea that single screw eyepiece holders can slightly tilt an eyepiece, and also that the diopter tolerances can be slightly different - enough to give less than perfect merging. Add to that my own experience whereby my right eye focuses at a different point to my left, this is exactly why I am now using a pair of baader focusing eyepiece holders in my binoviewers.

I am lucky that my bvs don't need an OCS/Barlow and can focus at native magnification , with room to spare (adding in the focusing eyepiece holders does consume a bit of back focus).

However, if you are using an OCS you will probably gain enough back focus to use focusing ep holders, so worth a try. The other benefit is that as I don't have compression rings in my bvs, any marks from the set screws will now hit the eyepiece holder T2-1.25" nosepiece, not those lovely Ultima Japan eyepiece barrels!

See link here which might be of further interest..

If you want a relatively cheap microfocus capability, the Baader 1.25" to T2 microfocusing eyepiece holder is worth trying. 

I've just got a pair for using with my binoviewer..as my eyes have slightly different focus points, I can now focus each eyepiece independently of each other until each eye focuses to the best sharpness I can detect. You can of course use just a single focusing eyepiece holder for cyclops viewing.

As the eyepiece holder has a T2 female thread on one end, you need a T2 male -1.25" nosepiece to attach to the eyepiece holder so that the assembly will accept your eyepiece at one end and fit into your focuser or diagonal at the other..you get c6 mm of fine focus (ideal for high power fine focusing) just by turning the knurled barrel and the bottom screw locks focus in place.

See photos below☺:

Photo 1 shows the T2 female to 1.25" nosepiece (available on eBay - search "1.25" to T2 / 31.7m Eyepiece insertion to M35 Prime Telescope Adapter Black, cost £3.22 each delivered from China!)

Photos 2  and 3 show the Baader focusing eyepiece holder (Baader part #2408195 ) and then threaded into the nosepiece.

Photo 3 show a Parks Gold Series 25mm eyepiece inserted into the focusing eyepiece holder.

It's not an FT or Moonlite dual speed, but it only costs a fraction of either of these - around £34 for the focusing ep holder and around £4 for the nosepiece.

Dave

 

 

[Telescope40]

Hello Dave. 

That looks like a very neat solution. 

May have a Bino’s look into it for my BV set up. My eyes seem to have different focus points of late when binoviewers are in play. 

Old timer syndrome   LOL 

 

regards.  John