Best eyepieces for binoviewers

[Prickly]

Evening all,

I am considering getting some binoviewers and was interested in feedback about what would be a good choice of eyepiece / barlow combinations for planetary observation (approx 250 - 350x mag) for my telescope. My scope is a 140mm f5.8 refractor 800mm focal length.

Some points I have gleamed from reading other points.

-Most binoviewers allow a max usable field of 60 degrees
-Mostly binoviewers need a barlow (around 1.6x seems common) to enable focus to be met
-Barlows used in front of the star diagonal (say a 2x barlow) may end up resulting in closer to a 3x barlow effect [maybe not the case with the powermates]
-The effect of using the barlow increases the eyerelief so that 20mm eye relief eyepieces may end up more like 30-40mm depending on barlow used I guess
- The preferred eyepiece range is 10-20mm and less than 10mm can be hard to fuse.
- I dont want to get too heavy with the diagonal, eyepieces and binoviewers which may cause focussing problems.

One thought has been a 8-24 zoom eyepiece with around 12-15mm eye relief (post barlow maybe around 24mm?). Allowing for the barlow effect it might be possible to have a nice range to dial in the right focal length.

Another though would be just a nice high quality fixed focal length eyepiece eg. 5mm ortho or similar with short eye relief that barlowed might increase to around 10-15mm. At present Im thinking this may be the way to go.

So over to everyone. What do you find works well. Appreciate feedback from those of you who have experimented with binoviewers/eyepiece/barlow combos. Im thinking the williams optics unit looks quite a good binoviewer.

Thanks in anticipation.

David

[PhilW]

David/Prickly,
My standard eyepiece set on the binoscope is a pair of 11mm type 6 Naglers. They are great: light, compact, wide field & adequate eye relief. In your scope that would only produce 72x magnification, but you could use a shorty barlow & still have a compact setup.

Phil

[Prickly]

Hi Phil,

Thanks - around the 11mm mark does sound pretty safe and you cant beat those naglers. I have a 4.7mm nagler type 1 which is great too. Was considering maybe another of these but maybe this could be too high powered? To some extent maybe the 82 degree field is a little wasted if the max is around 60 degrees.

Dont know whether you or others have found problems using shorter focal length eyepieces. I think I read that the 3-6mm zoom televue can be used with binoviewers but I do wonder how well this would work with the short focal length.

Cheers
David

[wavelandscott]

While I do not have an over abundance of experience with binoviewing, I am quite fond of my Denkmier 14 mm and 21 mm. I have used them in my 8 inch dob and also in my ED80 to good effect.

They have ample eye relief and 68 degree FOV...there are nice eyepieces and I would highly recommend them (depending on your budget). I consider them to be in the same league as the other "premium" eyepieces I own (compared mono mode only) and I do own and use some Naglers (13 T6 and 16 T5) and Pentax XW (7 and 10 mm) along with an assortment of TV Plossls. I think they are that good.

I have also used TV plossls in my Denkmier Binoviewer which also work well until the eye relief gets a little tight in the shorter focal lengths. When I am going for max magnification I move to my 8 mm TMB Planetary eyepieces...while not as nice as the Denks in terms of overall build quality (my opinion), they are good value for money...no they are not Naglers but they are not priced like Naglers either.

Good Luck!

[gbeal]

I've deviated somewhat from those above, going budget, and longer. My Denk standards have really only seen the pair of old, and not too pretty Celestron 20mm Erfles. They work, and well. The 10" newt and 2" OCS only ups the mag by about 1.3x and I can also use the OCS in a configuration that gives 3x. If I need more, then I use the 5x Powermate.

[Prickly]

Hi,

Thanks for this. I understande the denkmeiers are pretty much top of the line binoviewers. Have you compared them to other binoviewers out there? How do you find them?

Interesting that a standard 20mm works so well with the 3x barlow. The WO binoviewer comes with 2x 20mm eyepieces so maybe barlowing / powermating is the way to go.

Have you ever tried lower power eyepieces in the binoviewers in comparison to the 20mm and barlow? If so did you have any problems merging the images. Guess Im a little sceptical / unclear of the basis for why there should be a problem fusing the images as I have read elsewhere.

Cheers.
David

[astropolak]

Hi
I suppose the cost of Denk binoviewer needs to be kept down to be affordable and I can see many shortcomings in my Big Easy package. I think we spend too much time reading equipment reviews on US web sites.
I find the Denks quite usable but doubt they are a class ahead of binos like WO or Burges.
As mentioned in previous posts the Denk eyepieces are good, so are my 24mm Panoptics (if you ignore slight vignetting ) or my KK Erfles 20mm. You will find that you will spend a lot more time comfortably studying objects so it pays to get eyepieces with a decent eye relief.
I treat the Denks as a stepping stone to my future 14" bino telescope project. (just dreaming for now and reading all literature on the subject).

Personally if I had to do it again I would choose a cheaper brand of binoviewer as the Denk failed to live up to the promise. I am not saying it's a bad product I just do not think it's any better than the rest of them.

Joe

[Prickly]

Hi,

Thanks for that - interesting there doesnt seem to be too much difference between them. Interested to hear about what others think of the cheaper binoviewers. Nothing like practical experience looking through them.

The previous post on using cheaper 20mm eyepieces was along the same lines as my thinking about using some cheaper zoom eyepieces.

Cheers
David

[wavelandscott]

While I have not tried any other binoviewers except the Denk Big Easy package, I am happy with their performance in my different scopes. Of course your mileage may vary :D

[gbeal]

While as I stated my eyepiece selection has been limited to the 20mm Erfles, I wonder how the zooms will work. The focal lengths will have to be exact of the images will suffer, surely?

[Prickly]

Yes, not sure how accurate the focal length are but a number have click stops. They can be adjusted too up and down marginally but that would be messy of course. The meades, televue, vixen and zhumell 8-24 all seem to share a similar design, although the vixen have an additional element and use lanthanum. I think I read somewhere that some of these might be made in Taiwan. Usually televue and vixen are pretty accurate in terms of QC.

Probably a burgess planetary or UO ortho might be safer and better quality wise at around the same price but the zooms get a pretty good rap, have good eye relief, reasonble weight and field and would be handy being able to go in and out to locate objects. So not the perfect eyepiece but might have a couple of handy features in practice - maybe. Have heard rotating zooms can be a pain though because of the helical eyepiece adjusters.

[casstony]

The Chinese binoviewers will do most of what the premium bino's will do, in a similar way that a decent plossl will do most of what a several hundred dollar eyepiece will do. However when pushed to the limit, as you will be doing by observing at 300x, you might run into eyestrain problems with the Chinese units since they are not as well collimated as the Denk's. An exception to this might be the University Optics unit since they are apparently re-collimated before being sold. Even then the prism surface accuracy is greater on the premium Denk's which may(?) be noticeable at high power.

I'd be interested to hear of any experiences with the Chinese bino's at high power - my skies don't allow me to go much over 100x most of the time.

[skies2clear]

I found Joes comments about his Denks interesting, and of course others may have different opinions. For some time I've considered upgrading from the WO BV'er. I have assumed the Denks are better units.

My opinion of the WO unit is it has given me taste of what binoviewing is about, for not too much money. To be really honest and try and put things into perspective for me and my viewing preferences/idiosynchrosies, they have been fun, but not a serious observing tool. They are Ok at lower powers, but when I want high contrast, high magnification and sharp views, I forget about them. I keep reading how great BV'ers are on planets, but with the WO unit, I have to say the performance at high powers is pretty ordinary. I have no trouble merging views, and am using very high quality ancillaries, but they just don't have the resolution at high powers, that mono viewing gives. Planets never really snap in compared with cyclops vision, and the image is noticeably dimmer. The loss of image brightness is a bigger problem though with DSO's.

I find the BV'er is good on the moon though, and gives comfortable views. This is the great advantage with my unit, in that 2 eyed viewing in general has less strain. So, I have been researching into better BV'ers lately, trying to see which ones have higher optical accuracy to satisfy my high power needs.

The supplied 20mm eyepiece pairs do a good job though, but not up to the better premium types. I have a pair of Pentax 14XW's and a pair of Tak LE 7.5's, that are superb in mono viewing, but as I've said, the BV'er holds things back at high powers. I also acquired a Seibert Multimag OCS, which improved things over the WO 1.6X OCA quite noticeably. I don't believe anything is wrong with my WO unit, just isn't up to the optical accuracy I would like.

If I stay around 100X they are fine, but when venturing into 300X or higher territory, it ain't pretty!

So for me, where to from here? I am reluctant to purchase any other afordable BV'er because I feel the improvement will be a waste of time. My shortlist now is Denk II's or the very expensive Baader MkV (I'll be saving for a long time it seems).

Cheers
Nick

[astropolak]

Hmmmm
To be fair, the Denkmeier Big Easy does give me around 200 -250 mag with improved detail when compared to a single eyepiece. It is less sharp by a small margin compared to monocular viewing but the brain processes two eyes with ease and allows me to spend more time viewing with the bino thus allowing to discern more detail...
It may be a good time to clearly state what I do not like about the Denk Big Easy:
Lack of grip (ANY grip) on the body makes it easy to drop...
The OCS uses bright retaining rings for the lenses causing reflections especially in the focal reducer.
It claims the highest clear aperture yet vignettes with the Pan 24's
Bright stars or planets cause reflections from my eyes back into the bino and the bino combines the reflections - this may be a common problem with all binoviewers...
Most recently I have discovered that my new Denk is out of collimation without dropping it or even shaking it. It does not hold collimation and I do not know what is worse - not collimated properly from factory or loosing collimation in use. The unit is only few months old.
The eyepiece locking mechanism is crude and flimsy (but it works).
That is all for now...
I use it on 10" SCT with the 1 /1/4" OCS.

Joe

[casstony]

Joe, what indication is there that your unit is out of collimation?

[astropolak]

Tony, and everyone else listening...
The out of collimation was picked by one of my learned colleagues at our latest star party. He stated that he could not merge the image. Now, I had disagreed with him at that time but took a note of it.
Few nights ago I set up for observing but I was more tired than usual from looking at computer screens all day long. Centered on a single star and guess what... two of them. It turns out that when I am fresh and not tired I can merge just about anything but when my eyes are more lazy than usual I can see that there is a problem, basically we can easily accommodate small horizontal shift but can not tolerate any vertical shift and this is what I've got...
There is no doubt that the bino is out of collimation as I saw it before in binoculars that I had to collimate myself so I know how to test for it..

Joe

[casstony]

Thanks Joe. If you get the time, could you try looking through the bino's at a calender with no eyepieces - try holding them at different distances and see if you can merge the image.

[Prickly]

The Denkmeier would sound the shot if it werent for the collimation issue. One think Im trying to get around is to avoid constantly blinking to even out the tear film with high power viewing and also being generally more relaxed using 2 eyes for viewing.

Nick, have you tried the WO unit without the screw-in barlow using instead a high quality barlow / powermate with your tak eyepieces. Be interested to hear what the outcome was if you have.

Pity to have to jump up to the higher price bracket viewers but perhaps this is not possible with the lower priced bino viewers.

[Satchmo]

Interesting thread.

Theres no magic bullet with binoviewers. Your adding lots of glass and surfaces into the light path which all scatter and abberate the light as well as a long light path which only amplification solves. I've viewed through a $2000 Televue unit a number of times and still find them interesting but not a serious solution to full time binocular viewing. The brain is never really fooled enough into complete action by them IMHO.

I'm getting out a Baader Maxbright unit ( $259 USD )to play with on my 14" Mono-Newt: I'm particularly interested that they are end - user collimatable . For 1.25X amplification I need 92mm in travel so I'll use a larger secondary, shift the primary forward and two Bintel 2" extension tubes stacked into the focusser for Mono viewing.

Neverthless I am still collecting parts feverishly for my 14" F4.5 Bi-Newt, the binoviewer is for fun and education and will always go well for solar viewing on my 6" F8 refracter.
Have also ordered two 14.5" fast cooling Conical shape mirror blanks for another matched binocular optical set for sale.

[Prickly]

Hi Mark,

Keen to hear how the Baader Maxbrights go. I also noticed a new burgess optical binoviewer. This one has 24mm diameter barrel to avoid vignetting on 1.25 inch eyepieces 27mm prisms and 3 screws to centre the eyepeices. Also sells for about $300 US. Havent seen any reviews.

Interested to hear if anyone else has been able to use binoviewers sucessfully for detailed planetary viewing and if so what binoviewer / barlow/eyepiece combination.

The idea of planetary viewing with a binoviewer seems very attractive but its hard to see the point forking out the money if they images arent too great. Agree minimising optical surfaces would have to be a key factor. Some ortho eyepieces might go some way to achieving this and use of a high quality barlow?

Cheers
David

[astropolak]

Tony, I will try this as soon as it clears up here..

Mark, could you perhaps share a bit more detail with us on your Bi-Newtonian?
Why F4.5, do you intend to use coma correctors, what size secondaries, what diameter focusers and how are you going to allow for interpupillary adjustment....and what is a "fast cooling conical mirror" ?

Joe

[Daniel Beringer]

The Big easy performs at it's optimal with Denk eyepieces. I'm not surprised that the Pan 24mm vignet a little. This is not a problem with the binoviewer, in fact if you were to use the pan 24mm in another binoviewer system they would vignet more, For this reason I always recommend Denk 21mm for the Denk binoviewer. The Denk Binoviewers has a larger clear aperture which will give you a lower power and wider angle view then what can be achieved with any other binoviewer with out vigentting, This plus the Big easy package works on just about any telescope and has better multi-coatings providing better contrast is what sets the big easy apart from other binoviewers.

The eyepiece locking mechanism is designed to lock the eyepiece in the centre of the barrel, binoviewers that use set screws on the side push the eyepiece to the side of the barrel, and there for they are not centre, merging would be a lot harder. In my experience I have found them to work better than the other alternatives.

[Satchmo]

I'll check out the Burgess too, thanks. The Baader is 23mm clear aperture.

If you are serious about visual planetary observing then best to buy a patch for one eye to give more relaxed viewing in a mono scope or use a real binocular.

Binoviewers contain beamsplitting prisms, mirrors and optical windows which all degrade the optical path.T Theres just no way around that.

Regards

[Satchmo]

Frontieroptics:
The Panoptioc 24 gets vignetted because of the insufficient aperture of the binoviewer, and the long light path. No 20mm eyepiece will show vignetting in these units because the field stop is smaller ( Panoptic 19mm is the low power eypiece of choice for Binoviewing ) . Can you point to any special feature of the Denk 21mm that makes them specially suitable ?

Regards
Mark

[Satchmo]

Hi Joe

My 14" will follow on same design as Paul Shopis's 12" but more lightweighted so no surprises accept I'm going for pushbutton electric collimation using dc servo motors and bits and pieces from Jaycar. You'll want to follow Omaroos progress too, he is building a 12" F5.

The 14.5" Conicals I'm inspired by as Anthony Wesley is getting such good results. My version will use a new rear mirror attache=ment design and there'll be no perforation in the front face. No flotation cell required so another weight saving there

http://acquerra.com.au/astro/equipment/13/

Regards

[Daniel Beringer]

Hi Mark, Thanks for your question.

There are several reasons why the Denkmeier 21mm eyepiece set it the better option for Denkmeier biniviewers.

As you have said, Denkmeier binoviewers have a clear aperture of 26mm, The Denkmeier 21mm eyepieces have a field stop of 24mm. This allows the field to be fully illuminated to the edge without any distortions.

The Denkmeier eyepieces are manufactured with binoviewing in mine. They are shipped as a fully matched pair. The tolerances in the machining of the housings are tight and one or both eyepieces won't be off centre when used in a binoviewer. Eyepieces that are not matched could have slightly different tolerances to each other in their housings. This means the images will not merge correctly and will give the user eyestrain.

The eyepieces are light weight, anyone who uses binoviewer will want to try to keep the weight down at the eyepiece end.

The 21mm eyepieces have a 20mm eye relief allowing the user to comfortably place their eyes over the centre of each eyepiece.

The Denkmeier eyepiece use rotating L-shaped rubber eyecups. This features eliminates stary light entering in through the side of the eyes when viewing.

If you look at the 24mm Panoptic, The housing tappers up to the eyecup. Depending on the user, this feature can make it difficult for them to position their eyes correctly over the centre of the eyepiece. The Denk 21mm eyepiece have a straight housing where this won't be a problem.

[dannat]

Frontier,
I really enjoyed your responses (apart from the fact we are namesakes), you appear to have given your honest opinion, someone was not quite so sure why, politely disagreeing and you have had right of reply - excellent. this is how a forum should be

[Satchmo]

Hi Frontier

The Denk 21's sound like they have some good features for binoviewers.



Binoviewers have a conical light cone through them not a parallel one so there is always significant vignetting from the nosepiece, but if it can be kept at least 70% lighting at the edge of the eyepiece then cosmetically it is acceptable in the sense that the vignetting will not be obvious to the casual observer.

A quick `thumbnail' calculation suggests that putting for example an F10 cone ( either native F10 or an F5 scope with 2X OCS ) througha 26mm aperture binoviewer with a typical path length of 115mm yields a *fully illuminated field of around 15mm diameter* at the focal plane. Clearly the edge illumination must be better than 70% if you are not seeing any vignetting with a 20mm eyepiece.

Regards

[Satchmo]

For those interested in the technicalities of the issue heres a focal plane vignetting plot of an F10 cone through a 26mm aperture ( ie Denkemeir binoviewer ) with a 114 mm pathlength. It shows why a 24mm Panoptics shows vignetting at the edge and not a typical 20mm eyepiece

If you trace the semi-aperture at the fieldstop of Denk 21mm eyepiece ( about 11mm ) the light transmission is about 70% at the edge, which is on the margin of casual detectability for the human eye. A 24mm of 14mm semi-aperture indicates 45 % illumination which will be obviously appear vignetted to the human eye.

There lies the dillema of binoviewers. The long internal pathlength demands a slow F ratio to get acceptaable off axis lighting which means a narrow field of view compared to a true Newtonian binocular. Astronomy like life is full of compromises if you want to take a shortcut :).

[astropolak]

Thank you Mark and Frontier (Daniel) you both have given us very informed and totally satisfying responses.

Mark
There is substantial light path length in Newtonians as well as there is a need for diagonal and focuser as well as the need to have steeper light cone at F4-F6. In my limited understanding of the optics this would require larger secondary than normal as well as something like 3" aperture focuser...
All this to fully illuminate a 24 Pan with field stop of ~ 27mm...

RGDS Joe

[skies2clear]

Joe, thanks for your thoughts about this very intriging question of planetary peformance. I'm looking for a better understanding of what is going on and what can be expected. Sounds to me like your Denks perform better than my WO, but I still do enjoy using the WO and the comfort of binoviewing. Just wish it was better!

Cheers
Nick

[skies2clear]

David,
I don't have a powermate and the best barlow I have is a Celestron 2X Ultima (1.25"). At one stage I almost upgraded to something better (unfortunately used a Zeiss Abbe barlow to compare), but decided the best barlow was no barlow! Nevertheless, the Celestron is a reasonably good barlow, and I did try it early on when I couldn't get much use from the WO 1.6X OCA ( I don't own an SCT). I managed to get the barlow to work, but the magnification was very high and I estimate it gave me around 4.5X !!! Makes me think to try it again though, but it will have to be with the original WO 20mm eyepiece pairs, otherwise the magnification will be way too high with my other eyepiece pairs.

I purchased the Seibert Multimag, which gives 1.25X, 2X and 3.5X. At the time I thought this was a much better solution, not only because it works in all my telescopes, and has great flexibility, but optically was superior to a barlow in this application, being a true OCS (see Seiberts website for more info). But I will try it again and report back, just to be sure.

And it is a great pity to have to be considering stepping up to something more expensive. I'm starting to think along the lines of Marks comments though, that there are no free lunches, and the extra glass, prisms, beam splitters, get in the way. What I'm unsure of though is to what degree can a really premium BV'er satisfy my needs. Either will have to eventually look through one at a star party or spend the money to answer this question.

On the other astro site that's cloudy, I have continually read how these affordable chinese binoviewers do almost everything, including change your diaper, when you lose control of bodily functions because the views are so marvellous. :lol: Somehow, I don't think so! :(

For me, the BV'er experience is tantalising, but also frustrating! With time, this may change (I hope).

Cheers
Nick

[Satchmo]

Hi Joe

The point with focal plane illumination is that you don't need 100% lighting to the edge, 70% is fine with low power. Also faster mirrors have much more gradual drop of than slow systems ( such as F10 SCT ). The typical figure for 100% illumination area used on large modern truss Dobsonians is around 6mm to 12mm diameter at the field center . At a figure of 70% illumination, light loss is not really noticeable but stellar magnitude loss is about 0.5 magnitude.

My 14" design uses 3.1" diagonals ( 22% obstruction) and 2" low profile focusers ( GSO ) and with a 6mm fully illuminated field I can acheive lighting to 70% at the edge of a Panoptic 24mm. I may well grind the mirrors to F4.75 to get better off-axis performance, although I don't find F4.5 really too objectionable coma wise . At F4.5 I would be able to keep my feet on the ground 95% of the time which is quite important. For a larger instrument I would employ F4 mirrors and Baader coma correctors.

I believe central obstruction is one of the more overated issues in telescope construction( compared to other issues of figure quality ) . As long as you keep it under 25% there will be little penalty ( most SCT's are about 38% measured at the secondary baffle).

Theres a great Java program By Eric Rohr called Binewt designer which allows you to play with all the design parameters and come up with the best solutions for adequate lighting and minimum central obstruction.

Hope this helps.

Regards

[casstony]

Joe (and everyone),
on the subject of collimation, I pointed a laser collimator through my Denk II's, projecting the beam out through the eyepiece holders onto a wall 6.3 metres away. I didn't have a very accurate measuring system set up, but the two red dots were within a few millimetres of where they should be vertically and horizontally, which I guess is a reasonable result over a 6.3m distance. It occurred to me that you might be able to use such a setup to collimate the bino's at home, though I'm not familiar with the adjusting mechanism of the prisms.

With regard to merging calendar images through the bino (calendar about 6 feet away) with no eyepieces, my Denks will merge the image whereas my previous Stellarvues would not, even though they performed just fine in the scope at around 100x. I imagine this means the collimation is tighter on the Denks and they could be taken to higher power without running into merging difficulties.

Any criticism of my half-baked theory is welcome :)

[Prickly]

Hi Nick,

Like you it is tricky reconciling the glowing reports of the binoviewers elsewhere with the possible reality that they dont cut it in practice. I accept that there are likely to be problems with light scatter etc, but I can see that monocular viewing also presents limitations. Another thing is that the Chinese gear is improving all the time. In fact I wonder how much Japanese gear originates in Taiwan / China. Im careful therefore to not discount Chinese gear without looking into it. Also mindful of the earlier post questioning whether it would be been better to go with a budget binoviewer rather than the Denkmeier.

The Burgess 24 looks interesting - it has self-centring eyepiece holders and might be more suitable for deep sky with 24mm clear aperture. A little more expensive at $300 US. Spec wise while not perhaps quite up there with the most expensive models practically it might give them a good run perhaps. Interestingly however for planets it seems that even 18 to 20mm would be ok. The silvered prism coated prism might also make a difference of course (mind you the images get fused in the end - hopefully). I still wonder whether a cheaper budget variety would be that different for planets. Hence the call for further feedback from anyone satisfied with viewing even around 200-250x or so.

Interested that you get a good barlow effect with such a low barlow. Most people already own a 2x barlow (I have a very nice 1.8x televue barlow hence the interest). With a 2x barlow and my setup that would be a fairly acceptable 180x for planets. Thanks also for the reference to the optics of the OCS - worth a read.

Thanks also to Dan from Frontier too for the feedback on the Denkmeier eyepieces. I guess it is great if you can take pot luck in getting similar focal ratios out of the equation.

Cheers
David

[skies2clear]

Hi David,

the 1.8X Televue is indeed a nice barlow. I haven't had much of a chance to try my barlow again, as the skies have been very hazy lately, due to bushfires on Kangaroo Island, unfortunately for the people, animals, and plantlife that live there too.

If I was to revisit the "which BV'er to buy?" question, and didn't want to spend heaps, I'd get the Burgess 24, without a doubt. Probably the best bang for the buck.

By the way, when I said I was frustrated, things need to be taken in context. It's still lot's of fun, so I don't want to put you off trying it. The great thing about our wonderful hobby is how much you learn along the way and make progress,

Cheers
Nick

[ausastronomer]

Just to add something to this thread. I have used both the 14mm and 21mm Denkmeier eyepieces in both cyclops mode and in denk binoviewers. They are an outstanding eyepiece in every respect and consistent with the quality of Televue or Pentax eyepieces and so they should be at the price. Notwithstanding the vignetting issues between the 21mm Denk and the 24mm Panoptic, be rest assured that both the 14mm and 21mm Denks are excellent choices for both binoviewer work and in cyclops mode.

Cheers,
John B

[Prickly]

Hi Nick.

Hope the fires settle down soon (for everyone!). Hang in there with the experimentation - the WO unit was awarded best binoviewer in a test by sky at night so they must be pretty good. Interested to hear how you get on.

From the feedback so far it seems that the detail is no better through a binoviewer than in "cyclops" mode (certainly not by a drastic margin). Maybe more relaxing though with binoviewers with good units.

I think perhaps burgess 24 is a good option. Another slightly cheaper option might be the stellarvue BV3 which has self-centring collets with helical diopter focusing and apparently comes with pretty good 23mm eyepiecese - clear aperture is less though. You could almost buy yourself a new scope for the price of the televues / Denkmeiers but they are no doubt a bit better I guess (as is usually the way).

Cheers
David

[astropolak]

Hi
Received some notes from Daniel (Frontier Optics) how to check calibration of a the Denk Binoviewer.
All checks passed with flying colours, so I must have been in a really bad shape if I could not merge images the other night.

As for real life observing...in a word perfect, I could not fail the Denk. I do not think I've ever seen the M42 trap and its 6 stars with such clarity and separation. This is at ~250 magnification.

I would say my complaining about the unit being out of collimation was full of s..t.:mad2:

Merry Christmas everyone.:hi:
Joe

[casstony]

Could you post how to do the calibration checks here? My methods are only what I've dreamed up myself.

[wavelandscott]

Glad things worked out Joe, I've been happy enough with my Denks so I'm glad that your's worked well at 250X...

I'd be interested in the collimation checks too just for ready reference...

Cheers!