Yes, thanks Mark, I saw this today after a lead from Mike Lockwood's site. Printed out the whole story to read very closely and see exactly what he has done. I gotta have a bionewt some day - but portable.
A 12" bino is certainly not a grab n'go. Its quite a handful - probably on par with a 20" scope portability wise.
I have been thinking about putting together a couple of GSO 10" F4 imaging Newts one day into a cradle to see how easy it would be to turn into a working binocular.
Interesting. I was thinking the same, Mark. Get a matching OTA for my current 8" f5 GSO and make up a solid support, a bit like JMI's reverse binocular RB-10. It needs to dismantle into two OTAs and a compact cradle/pier for portability. Not thinking of encoders/Argo/tracking etc. Keep it simple, I think - targets being the Moon/bright globs/bright nebulae and open star clusters (and the occasional great comet)! I suspect the focal lengths of the two primaries don't need to be as close as some suggest. Then, I just need to be able to translate the mirror end of one OTA in the Alt/Az directions for image merge. I'm thinking of a very simple two screw translation mechanism pushing the OTA against a spring (like GSO finderscope adjustment) But only people with my IPD need apply for a look . Adjustable IPD is too difficult, but I guess I could try regular focussers plus diagonals plus 2" helical focussers above that and push the primaries well up the tubes - but that's getting a bit over the top with equipment, then, at the focusser! I've been picking up some cheap matched eyepiece pairs, so am starting to be serious.
Just put the rotate the tubes in a set of individual tube rings for setting IPD by rotating the tubes, and then you don't need helical s in the diagonals. I'm not sure why Arie used helicals- its no problem to just rough focus first then set your IPD then do a fine focus which won't noticeable effect IPD.
Theres no point in building a set that only you can look through properly
if you are serious I can give you some ideas about how to achieve co-collimation ( merge ) without doing anything to too radical structurally.
Quote:
Originally Posted by erick
Interesting. I was thinking the same, Mark. Get a matching OTA for my current 8" f5 GSO and make up a solid support, a bit like JMI's reverse binocular RB-10. It needs to dismantle into two OTAs and a compact cradle/pier for portability. Not thinking of encoders/Argo/tracking etc. Keep it simple, I think - targets being the Moon/bright globs/bright nebulae and open star clusters (and the occasional great comet)! I suspect the focal lengths of the two primaries don't need to be as close as some suggest. Then, I just need to be able to translate the mirror end of one OTA in the Alt/Az directions for image merge. I'm thinking of a very simple two screw translation mechanism pushing the OTA against a spring (like GSO finderscope adjustment) But only people with my IPD need apply for a look . Adjustable IPD is too difficult, but I guess I could try regular focussers plus diagonals plus 2" helical focussers above that and push the primaries well up the tubes - but that's getting a bit over the top with equipment, then, at the focusser! I've been picking up some cheap matched eyepiece pairs, so am starting to be serious.
Chris , thanks for asking - The 14" project is now officially redundant ..
I spent a night at SPSP looking through a nice pair of 14" F5's so there will be no adventure in building another one...
As I have pretty much decided that the 24" bino project for which I bought glass for is impracticable given I can't permanently locate them I've decided that I need to make a pair that will tick the boxes for as much aperture as I can have along with good portability and feet on the ground.
I have also been spoilt by looking through a 17mm Ethos eyepiece so if I am to build a system that will take 2" EP's I think its going to be the first and last for me.
the obstacle for large aperture /feet on ground was that a standard Paracor is impractical- it would have to go above the star diagonal and teemed with the Ethos would be very 'wrong'
With the release of the 95mm back focus Baader Rowe Coma corrector I can now build a tertiary mirror assembly that has the coma corrector on the entrance to the tertiary mirror and the Ethos on the other side.
So now an F4 to F3.5 is practical. My plan at the moment is to get some 18" plate glass balnks I've got only 29mm thick slumped to a meniscus in the USA to F3.5. So with a fL of 63" , I'll have feet always on the ground and the 17mm Ethos would give a 4.8mm pupil with a whopping 1.1 degree 100 degree apparent field at 95X and pinpoint to the edge
The whole thing would also be built in the featherweight class - I'm looking closely at the Hubble Optics tubes for ideas.
Well thats the current status of the project - and I sold one of the 14" primaries the other week to ensure I didn't change my mind
One thing I always wondered about these bino scopes, wouldn't the observer's body heat ruin the view at higher powers and it seems their head might block a small portion of the light path
One thing I always wondered about these bino scopes, wouldn't the observer's body heat ruin the view at higher powers and it seems their head might block a small portion of the light path
Obviously I've seen Binoscopes before but it is rather funny that my very first thought like you, on seeing the photo at the top of the page was thermals from the observers head. Why had that thought never occured to me all the other times I looked at photo's of Binoscopes?
I wonder is it the guys bald head??
Maybe thinking about all the mods I have done/plan to do on my scope has conditioned me to think in Pro's/Con's. Pro - Bald head minimises obstruction of the lightpath. Con - No insulation and heat thermals from head wafting into lightpath.
In terms of whether the thermals are a big problem, I think maybe its not a big deal. I presume Binoscoping is aimed more at the DSO observer and are used primarily at Medium to Low powers. Thermals would only really become annoying for high power viewing of Globs and Planetaries. For those brighter DSO's and planets a binoviewer is probably the better option where the light loss is not as much of a problem
Well I'm sure he can pop on a beanie and a coat...
No thermals don't seem to be a problem. Arie built some over the top hoods to investigate ( check his final page ) and said that he could only see a slight improvement on the Moon,
I think the issue of how much currents effect the view is dependent on a lot of variables. Is there wind if so what direction, what altitude are you looking , is the instrument cooled, what is the seeing like anyway and what clothes are you wearing etc etc.
The 12" binocular I am commissioning at the moment has no limitations- I got the best views of the moon I have ever had not that long ago, and it is very comfortable studying small globular and planetaries with 10mm eyepieces . I don't believe Binewts are limited in any tangible way. The only criticisms I hear are from people who haven't used true binocular scopes- those that have are usually rendered too speechless
Interesting to hear that, because Im sure an entire body standing directly infront of the light path would no doubt have some detrimental effect on the view. You hear of people blasting unshrouded truss scopes because the observers's body heat can ruin the view when he's sitting to the side, let alone directly infront of the aperture. Maybe these guys are using only low to moderate magnification?
The advantages of true binocular vision with individual optical systems for each eye far outweigh any technical points of difference ( which seem to only be the preoccupation of those that have never used one ) . Once you have a session with a binoscope of reasonable aperture it spoils you for life- the contrast is something that a monocular can't come close too.
The feeling of `presence' ( which doesn't really occur for me with a binoviewer - the brain is just never fooled by them ) , is palpable - just two eyes, your brain benefiting from millions of years of evolution in binocular image processing, and the Universe. Here endeth the sermon
You hear of people blasting unshrouded truss scopes because the observers's body heat can ruin the view when he's sitting to the side, let alone directly infront of the aperture. Maybe these guys are using only low to moderate magnification?
Read my previous post again- there are a lot of variables that determine how much heat currents might effect the view on any given night.
I couldn't agree with Mark more, it has to be experienced to be believed.
Quote:
Originally Posted by Satchmo
The advantages of true binocular vision with individual optical systems for each eye far outweigh any technical points of difference ( which seem to only be the preoccupation of those that have never used one ) . Once you have a session with a binoscope of reasonable aperture it spoils you for life- the contrast is something that a monocular can't come close too.
The feeling of `presence' ( which doesn't really occur for me with a binoviewer - the brain is just never fooled by them ) , is palpable - just two eyes, your brain benefiting from millions of years of evolution in binocular image processing, and the Universe. Here endeth the sermon
Good to see some interest in the binocular Newtonian concept.
fwiw) I have had a brief bit of correspondence with Ron (of Moonlight focuser fame) with respect to making a dedicated focuser assembly designed specifically for binocular Newtonians. What I proposed was a 2" crayford with a permanently installed Rowe corrector with a custom diagonal holder machined as part of the assembly, obviously one that was trimmed so IPD could be set down to 60mm or so.
Here is his response:
Quote:
Hi Clive,
Sorry- I don't have a working proto type of a bino focuser at this time, but
did draw one up years back for my own use. Never manufactured it however.
Maybe I should take another look at it?
it would be awhile as we are booked 3 months out on our CNC machines
production load.
Ron
MooNlite
Now personally, I think if Ron actually had enough people requesting such a device, he would no doubt put it on his product list. Something like that becoming an off the shelf item would be a game changer. imho)
My experience with the 20's is that they are capable of absolutely jaw dropping planetary views under the right conditions.
I'll relate one observing session that really changed the way I look at designing and building scopes. On this particular night, the wind was really strong... I mean so strong I elected not to use the shroud(s) so the scope was basically open frame. Where I was set up was somewhat protected by trees which cut down the general force of the wind, but still resulted in cyclical intermittent gusts from the vortexes generated by the wind brake. Essentially, the local conditions went from no-wind to medium wind to strong wind and back again over a period of a few seconds.
With no wind, the seeing was poor... normally I would have put that down to just a crap night, and thought no more of it.
With medium wind, no change... still crap in both eyepieces. Now here is an important lesson, if the seeing conditions were ONLY the result of body heat, the wind would have preferentially pushed the plume to affect just one of the OTA's. There was no discernable difference between either OTA.
With strong wind... The image sharpness just locked down to perfect. I can say without a shadow of a doubt that I have never before (or since) seen astronomical views remotely as good as that through any scope ... period.
The lesson here is that 90% of what I had thought of as bad seeing could be traced to the boundary layer.... that pesky plume of heated air 1 inch in front of the primary. Therefore, thermal management should be prioritized pretty much above all else.
For some interesting reading on how the pro's do it, Wilson is a pretty good place to start. It has been a while since I read it, but from memory he advocates an airstream flowing at 2.5m/s (or was it 1.5? I forget) and curiously, suggests blowing horizontally across the optic is better than having your fan aligned to blow vertically up or down.
I guess the other point to note here is that whatever issues are associated with a loss of accuracy in an optic's figure due to temperature gradients, any loss of image sharpness pales in comparison to the convective plume in the optical path.
2c
~c
Last edited by clive milne; 30-05-2011 at 04:16 PM.
Hello,
I'm new to this forum, but I am on the binewt list. This list may seem without activity because we are just a few binoscope builders. But if ask a question on the list, you will certainly get some answers from people with a lot of knowledge about binoscopes.
The image sharpness just locked down to perfect. I can say without a shadow of a doubt that I have never before (or since) seen astronomical views remotely as good as that through any scope ... period.
