New 10mm BCO pair First Light

[F15Rules]

Having been delighted by my new 18mm bco pair in the Maxbright bv I resolved to get a pair of 10mm to go higher in power, to x190 in my 5" F15.

They arrived on Saturday in as new condition looking just like smaller identical versions of the 18mm. I really like the smooth side barrels and wish that more new eyepieces were available without the so called "safety groove" or "undercut", which I loathe..the larger eye lenses also make for very comfortable viewing.

Anyway, the sky cleared tonight so I decided to have a quick peek. Target was M42 which is a great binoview object taking up all of the field.

The thing that struck me first was the contrast..with the 18mm the view was sharp across the field with jet black clouds which clearly obscure other newly forming stars behind them. Popping in the 10s, the view was almost identical but twice as highly magnified- but absolutely as sharp. Not quite parfocal with the 18s but minimal refocusing needed.

The edge of field sharpness is really good all but the last 3-4% which softens slightly..but its great to see "wide" views of ortho quality.

I'm really looking forward to using both these excellent pairs of eps AMD would heartily recommend them.

Dave

[Stu]

Sounds fabulous Dave, great combination with Andromeda.

Slowly getting to grips with binoviewing myself.

Was delighted to see a greenish tint to M42 in the 6" last night, not seen it with that small an aperture before

Enjoy

Stu

[F15Rules]

Cheers Stu:-)

Hope you will be able to do a proper first light for the big Vixen 6" soon (love how you refer to it as "such a small aperture", but I know what you mean:-).

I think a few of us would like such a "small aperture" Semi-apo refractor tbh!

Cheers, Dave

[Stu]

Hi Dave,

My apologies, I was comparing with a 12" Dob which is the only other scope with which I've seen colour in M42. I certainly wasn't belittling either of our lovely scopes [emoji3].

You must also permit me an 'Oi, less of the semi-Apo' too [emoji6][emoji6]. Most CA I see seems to be atmospheric rather than scope related.

Rather most seriously, I do apologise for not doing a more thorough first light report. It will now be a sixth or seventh light I suspect, but actually I really want to get it under some decent skies because mine really aren't very good. I do suspect being between three large reservoirs and near Heathrow plays havoc with the seeing.

Hopefully I'll get it to SGL10 and have some lovely clear skies there.

Anyway, back to you. It sounds like Binoviewing is really working for you which is great. I am finding it does allow the brain to cancel out most of the floaters visible at high powers so gives great results for lunar and planetary work

Cheers,

Stu

[John]

I have a couple of semi-apo's to Stu. I tend to call them ED doublets to avoid contention. Dave is not a nit picker though

I had a look through a Meade triplet 127mm a couple of years back and it showed slightly more CA than my ED120 doublet does

I'll have to give binoviewing another shot sometime. I tried a WO set but could not get them to reach focus with either of my fracs. They would reach focus with the barlow element in place with my 12" dob though but maybe I don't have "bino eyes". I'm not that keen on binoculars generally other than for birding. I must be weird

[YKSE]

Great first light, Dave

I cant fault 10mm BCO for it's constrast and light throughput, it's just as good as 18mm BCOs, and the vocano top is plus to me.

[Stu]

I have a couple of semi-apo's to Stu. I tend to call them ED doublets to avoid contention. Dave is not a nit picker though

I had a look through a Meade triplet 127mm a couple of years back and it showed slightly more CA than my ED120 doublet does

I'll have to give binoviewing another shot sometime. I tried a WO set but could not get them to reach focus with either of my fracs. They would reach focus with the barlow element in place with my 12" dob though but maybe I don't have "bino eyes". I'm not that keen on binoculars generally other than for birding. I must be weird

No, I know John, was being a little tongue in cheek [emoji3]

I'm on my third pair of Binoviewers now, I sold both the previous pairs because I just found them too much hassle and two difficult to get the image merged properly. The Denks I have now seem excellent and are nearly convincing me to continue with them, particularly for planetary use. I have an annoying floater right in the centre of my observing eye which sits right in top of Jupiter. Binoviewing should overcome this, though I haven't tried them in Jupiter yet. I've got my two 25mm orthos and a x2.5 PowerMate which should give me a decent magnification I guess.

[Dude_with_the_tube]

very nice Dave and i am glad to read that binoviewing is working fantastic for you.I am itching to try my new set up out,but its another 4 days before i get home

[F15Rules]

Hi guys

Stu, I totally agree about the apo/semi-apo nonsense... I would dare to say that my F15 scopes show so little CA as to be semi-apo in practice...not my shorter ones of course. I think John's moniker of ED Doublet probably hits the mark but I remember when the Vixen Atlux was launched in the UK at some amazing price (wasn't it around £4k or £5k with or without the mount?) and I'm sure it was marketed as being effectively colour free - a really  desirable beast it was, and it's no less enviable even now .

It will be great to read your impressions of the big Vixen once you get the chance Stu..there are so few of them about and they just look so...well, "right"!

The binoviewer debate is interesting isn't it.. John, I had a couple of pairs as you did, and almost gave up on them, thinking they weren't for me. I think one of the biggest factors that puts people off using them is the need, on many scopes, to use a barlow lens. Due to the nature of binoviewers, ie splitting the light beam, they do lose a bit of light versus cyclops viewing: I've read more than once that this is estimated as being around half a magnitude or so. Add to that the limited field of view that most ordinary priced bv's can deliver, ( I think a 24mm Panoptic is thought to give the widest view possible without vignetting?), so using a x2 barlow effectively makes the 24mm Pan operate as a 12mm cyclops, then the appeal of bv's to those who like wider views starts to diminish rapidly.

So, short of getting an SCT or Mak where a barlow isn't needed, refractor users either have to accept relatively small fields of view and higher than normal minimum magnifications, or they have to bite the bullet and chop down their OTA tube to deliver enough in-focus to use without a barlow being necessary. And that's exactly what I did. To be fair, I had another reason for embracing this solution - with a 1.9m focal length and a tube of similar length, the loss of 130mm (which is what I had taken off my D&G tube) was actually welcome, as it gave me a few inches of height in the viewing position of the scope.

And since I was having the tube cut down, I decided also to go the whole hog and have the tube fitted with new ray traced baffles, flocked from end to end, and resprayed to boot -so I effectively got a new OTA tube. As I still like using 2" eyepieces and some 1.25" eyepieces I bought 2 x 50mm good quality extension tubes with compression rings and twin retaining screws to "give back" the missing length when needed. In fact, I only need one of the tubes with 2" eyepieces: but whichever format of viewing I'm using, it's a matter of seconds to increase or reduce the focal length to the level I need.

The result is that I can use eyepieces at their native focal length. It also means that I can consider using short focal length eyepieces for even higher power, without a barlow. I think that in practice the shortest length eps I could use in my scope while binoviewing will be 7mm to 9mm.  A 7mm pair will give me x272, which is as much as I can usually usefully get away with. The 10mm BCOs give me x190, and on M42 last night I certainly could have gone a fair bit higher whilst retaining a good measure of clarity and sharpness. I do have a single 6mm eyepiece so I might try that in one side of the bv to see if a pair of them would work...I'm aware that the BCO is available in a 6mm and that John, I seem to recall that you raved about the 6mm as being the pick of the BCO bunch? So, might be worth a try with them to complete the set at some point! (6mm would give me x317, definitely within the reach of Andromeda on a good night..).

I appreciate that cutting down the tube is not really practicable for either your Atlux Stu, or your ED John, and in so doing you might also hurt the resale value of your scopes. I don't believe that is the case with my D&G, but time will tell.

All I can say is that I am finding binoviewing very comfortable, and when I am comfortable I see more. I don't get floaters at all in the bvs, and the BCO's eyecups really help reduce the stray light that is around me from neighbours conservatory lights etc. I won't ever give up cyclops viewing, but I hope I will also continue to explore the fascinating world of two-eyed viewing and the three dimensional feeling it gives you when looking at suitable targets. I won't EVER forget the first time I had a proper view of the first quarter moon with the Maxbrights and a pair of 25mm plossls - simply stunning  

Dave

[John]

Thats a great explantation of what and why that makes a lot of sense Dave

The BCO 6mm is excellent. I felt the Baader GO was just a tad better at light scatter control but the BCO was of a very high standard. The only slight downside on my 6mm BCO was a slightly fuzzy field stop. I didn't make any difference in use of course but it niggles me more than it ought to

Quite possibly not typical though. The other BCO examples I have have razor sharp field stops.

[Dude_with_the_tube]

this is very good reading and greatly explained Dave.Also i am really pleased to read that you are enjoying your bino set up

i agree that cutting the tube is a very drastic measure to do,but binoviewing in native focal length makes a lot more sense then using an extra barlow just to achieve focus,still it is perfectly usable and nothing wrong with that.I did try Denks on Atlux but i had to use the OCS to reach focus,still,images where very good,particularly planetary ones.I have now gotten rid of the original 4" focuser and replaced that one with a nice Moonlite 2.5" unit (Mark from Moonraker did the job) and as the 4" unit was so large, i didnt need to do anything to the OTA(wasnt even in my plans to cut the Atlux).With all the measurements done,proper adapter was manufactured for the focuser and now i can reach native focus with binos on Atlux.I have a custom made extension tube for use when i go cyclops mode.Unfortunately,i didnt had the chance to test the rig as i had to leave for business trip,but as soon as i am back in UK,i will test fire everything and will give a proper report here.On top,i have quite a few EP pairs to test so should be an interesting reading material.

Looking forward to your tests Dave if you do decide to go for another pair of 6mm BCOs.i am kind off thrilled to see how high on magnification this can go and if 6mm works,that would be trully awesome.I actually cant think of any reason why it shouldnt.

AS for widest possible field Dave,it is down to your bino prism size.Bigger prisms=lower mag EP can be used.I dont think Maxbrights will work with 24mm 68 deg EP due to prism size,(assuming we are talking native focal length) Denks work fine with them as they have 26mm prisms,MarkV have 28mm and you can use 35mm baader Eudiascopics and they clones what will give you even lower magnifications.I am actually after the Zeiss binoviewer as that one had 30mm prisms )

However,if you want to test the 24mm 68 deg pair,i am more than happy to "loan" them to you for test purpose when i am back home.Could also loan you a pair of 6mm BGO`s if you want

Clear skies!

[F15Rules]

Hi John,

The fuzzy field stop on the 6mm is interesting. Like you, I do like a sharp field stop. Gaidis, how are your 6mm's as regards their field stops, are they sharp, or are they also a bit "soft"?

Regarding the Panoptics and vignetting in the Maxbrights, I will bow to your better knowledge of this...it's unlikely I will be buying a pair any time soon, sadly! . Thanks also for the kind offer ref the loan of your 6mm pair, I might just take you up on that...

One other thing occurred to me about binoviewing...much as I too like wide field views, they don't seem to matter when I'm binoviewing - and I think this is because of using both eyes. This came to me while using a new pair of 8x40 binoculars..I believe the normal apparent field of view range for binoculars is around 50-60 degrees, ie about from Plossl view to up to 10 degrees wider, so not superwide, but nice. And in most modern binoculars from 30-50mm aperture the "view" as supplied seems quite wide, yet it's only about the same, or a bit wider, than a standard plossl field of view. But, because you view with both eyes with binoculars, your eyes relax and it's very comfortable - you can take in the whole field of view, without fatigue, whereas when viewing even a 50 degree scope cyclops field can become tiring if you are looking at the outer third or so of the field of view. I hope that makes sense? So, I am thinking that the binoviewer (when used without a barlow, or with low power eyepieces of 20mm or longer focal length and the lowest barlow that will bring you to clean focus), is doing the same thing, relaxing the eyes, making the most of the available field of view etc etc? Thoughts?

I've also seen some varying reviews on the low to mid range of binoviewers regarding quality. I'm thinking here, for instance, of Maxbrights, William Optics, Teleskop Service, Revelation, Orion, etc etc. At the premium end you have Mark IV/V Baaders, Televue, Denkmeier, Zeiss etc, often pushing a grand or more in cost. In the "real world", for most of us, our binoviewers will cost between about £100 and £200 per pair.

These seem to come from the same factory, with the same basic design but some with better cosmetic finish and connectivity.. What seems very hard to determine is the differences, if any, between optical quality. My Maxbrights, for instance, have nice cosmetic touches, such as three screw eyepiece adjustment for each eyepiece, compression rings, nice quality exterior trim (the WO is very good in this regard too) etc. But the useable aperture of each one seems to be the same, ie 23mm and 21mm and nosepiece and eyepiece ends, and this obviously determines the field of view and types of eyepiece that will work with each bv. But as regards the prism quality internally etc, it seems almost impossible to determine any real differences.. some bv fans are adamant that Revelations at £99 are every bit as good as Maxbrights at £200.

Although I am really pleased with my Maxbrights, to be fair it's only with them that I have been able to use eyepieces without a barlow...I had a WO pair for a short time (bought new), and sent them back, but that was before I had my ota cut down to avoid needing the barlow (I do have to say that I have twice used WO 1.6x barlows and found them useless, although the bvs seemed very well built). So, I can't honestly say that Maxbrights are x percent better or worse than WO or Revelations (the brands I have used). I'd be interested to know what anyone else has found if comparing the low-medium cost brands of binoviewers.

Dave

[Dude_with_the_tube]

sure thing Dave,

i have 2 full sets of BGO`s for binoviewing so any focal length you are interested,let me know and i will get them posted to you for a couple of weeks for you to test them out.

As for your thoughts.As for the field stop,BGO`s are sharp to the edge in cyclops mode.Havent tried them yet in binos as at that time i had to use OCS and 6mm was too much magnification with OCS.As soon as i am home,and weather permitting,i will be trying all focal lengths of BGO`s in my binos.

Yes you are correct,viewing with 2 eyes is more relaxing and surprisingly this fact brings our more detail,despite sometimes you actually use far less magnification as you normally would in cyclops mode.

And again yes you are correct on all "low" budget binos,they do actually come from the same factory but are re-branded depending on company they are going to and finished in the same way as per company they go to request.To be honest,nothing wrong with these binos and they can be used perfectly fine.As i mentioned earlier,for planetary views you dont need large prisms,but you do for low power as at the end of a day,it is not only planetary you want to use your binos on but also for some brighter DSO`s,and thats where premium binos come into play with they larger prisms and ability to accommodate lower power EP`s.Again its a can of worms i dont want to dig into,not forgetting that even the premium ones ,well majority of them are converted microscope heads anyway or still produced in China.To my knowledge only one Zeiss bino was made specially for astronomy use from ground up and had 30mm prisms with the famous Zeiss T coatings.Not that my bino knowledge is huge,just recently started myself lol and had a bit of digging and reading up done.Still,i think Maxbrights are great unit and good value for money to get you started in binoviewing and if you really like it,you do have the option to upgrade to a premium unit later on.Well atleast thats my plan.I have the Denks now,but i do really want something with bigger prisms in like of trying to find the Zeiss unit would be great.(Nothing wrong with Denks!!)

[great_bear]

One other thing occurred to me about binoviewing...much as I too like wide field views, they don't seem to matter when I'm binoviewing...

I've noticed this too. The apparent field-of-view simply feels bigger when binoviewing for some reason...