Binoscope Project

[philj]

Inspired by Peter Drews post on his ED80 bins I picked his brain (thanks Peter) at Kelling and had a go myself.

 

Ive had observational bins in the past and never really was a fan of the mags available plus if I wanted decent glass I would have to pay quite alot, so when I saw Peters thread I thought I would have a go.

 

So 2 SW ED80s dual speed later and some ali plate, bar, screws and broken hacksaw blades, blunted lathe and milling tools later I present my Mk1 version mounted on my Berlebach and Giro11.

 

Just sorted collimation today and its all working. Ive got a few bits of tidying up to do like beef up the prism and eyepiece clamping arrangement, make OTA 1 collimation tool less (needs allen keys at the moment), sort a pan and tilt handle and a carry handle out.

 

Its fitted with 2 off 8-24mm Vixen LV zoom eyepieces and these are working nicely having tried the rig out on some apple trees about 80 yards away. Collimation wanders a little when zooming due to some play in the eyepiece and prism clamp arrangements but thats next on my agenda to fix.

Not had chance for first light on astro yet but on terrestrial it performs nicely.

 

 

 

 

 

[nightfisher]

Phil me ole mate, you did it, and well done, once you have it fettled im sure you will love it, you have done a great job

[philj]

Cheers mate. Its been a long time coming but Ive got there. Its workable as it is but just needs a bit of refinement now. I may even take it to the nature reserve and give it a go spotting birdies

 

[Stu]

Excellent project Phil.

Just out of interest, which prisms or mirrors did you decide to use and how did you fix them together?

It has always intrigued me how the images end up being the same orientation having gone through three diagonals in opposite directions. Does it just ‘work’?

Look forward to hearing how it works for astro first light.

[philj]

I used Peters idea of 2 prism diagonals in rhomboid configuration Stu, as the InterPupillary Distance  prisms then a bog standard mirror diagonal on the end, it gives correct orientation.

The prisms are araldited together. They are the Celestron 1.25" ones but the mirror diagonals are just generic but I may treat myself to a decent pair if it looks good.

 

 

[Stu]

Thanks very much Phil. Sorry, one more question. Do you use prisms tomorrow the light path as short as possible?

[mark81]

They look amazing! It's something i never thought about or even considered been done.  

I look forward to your first light with them ?

[JamesF]

Very impressive.

James

[Alfian]

Great stuff Phil, thats a magnificent achievement. Takes some courage and committment, let alone the financial outlay of two of everything, to embark on such a project. Respect. 

[philj]

36 minutes ago, Stu said:

Thanks very much Phil. Sorry, one more question. Do you use prisms tomorrow the light path as short as possible?

Yep, prisms for shorter lightpath

 

16 minutes ago, Alfian said:

Great stuff Phil, thats a magnificent achievement. Takes some courage and committment, let alone the financial outlay of two of everything, to embark on such a project. Respect. 

I already had 1 ed80, vixen zoom , 2 prisms and 2 mirror diagonals so it was just about obtaining a second scope and ep plus 2 more prisms. The nerve wracking bit is actually cutting 60mm of 2 perfectly good scopes. Ive cut lots of tubes down in my time but it always makes me nervous.

[Stormbringer]

very nice mate ?

[philj]

I managed a very brief and rushed 1st light on the bins last night. The moon was high and almost full, the sky was misty thus all but the brightest stars were washed out, not the best conditions for testing. Got home from an early Christmas meal with some business friends and chucked everything outside quickly to have a look at the moon, I was dog tired so this was going to be quick.

After a quick collimation on the moon I managed to get binocular vision at 24mm (24x) on the vixens and hey, the moon was really 3d. Set off even more by a background star just off the limb.

I upped the mag to 8mm on the vixens (75x) and collimation shifted, (must sort the clamps out) Recollimated in seconds and was rewarded with an even nicer 3d effect particulary on the craters on the terminator. The moon looked like a globe instead of a disc.

Keeping at 75x I shifted to Albireo then Polaris, ( doubles are the main target I will be using this on). Even more 3d effect, particularly on Polaris, fascinating.

I tried for a couple of dsos but they were wsshed out by the moon and conditions.

A very brief test on astro targets but enough to show it works and Im on the right track.

Now for some tweaking.

[Peter Drew]

I tried a Nagler zoom set at 3mm on mine which showed that it would take 200x. Or it would if I had a pair of Nagler zooms!    ?

[philj]

Sounds promising, collimation will need to be bang on at 200x. Im seeing why quick no tools collimation is preferrable on these

[Peter Drew]

28 minutes ago, philj said:

Sounds promising, collimation will need to be bang on at 200x. Im seeing why quick no tools collimation is preferrable on these

Exactly.  It's ironic though, that self built binoscopes seem to incorporate easy owner adjustable collimation whereas many high end commercial units do not. Purchasers of the latter often spend extra to have them "super" collimated for high powers. My experience has been that what appears collimated often varies with different users.  ?

[Stormbringer]

sounds really promising so far

[philj]

Managed about 30 minutes in between clouds to try out the bins under darkish skies before the weather moved in again.

The aim of this exercise was to see what DSOs looked like in the bins and also to get used to the handling and collimation.

 

Collimation

Even though I collimated the tubes I found the two FOV circles were off  resulting in the object to be viewed being in different parts of each scope FOV, this was not right and I traced it down to the mirror diagonal clamps on each prism. Thus tube collimation wasnt shifting which was good but the movement in the clamps meant the eyepiece angles were not the same and this was throwing things out. This was evident in that I could collimate to get good binocular vision at 75x but when wound down to 24x it would be out again. The other week it wasnt doing this, I could collimate at 75x and collimation would stay on whatever mags I used, so I know it can do it.

 

OK so thats the next area to concentrate on ironing out and beefing up.

 

 

 

Handling,

 with the pan and tilt handle, handling was OK but it felt a little odd at first because the bins are offset from the mount, this was no problem with alt and az locks off but if I put a bit of friction on them it felt odd. I think this is just a matter of getting used to it.

 

I fitted a RA finder to help with finding stuff at the zenith but I had the tripod set a bit too high initially so using the finder was a bit fiddly. I lowered the tripod slightly and rotated the finder to a different position and things were a bit more comfortable.

 

Performance.

Collimated on Mars at 75x and this was a nice view. Mars was small but a definite gibbous shape could be seen and the background stars were good. No detail as at 75x it was a bit small plus the atmospherics were turbulent to say the least. I was glad I was in the lee of the house.

 

M45 at 24x. Yep, lovely colour, depth and really bright. The Vixen zooms are not the widest FOV around, I havent built this scope for wide FOV but the cluster fitted just nicely in view. The brighter stars seemed to stand forward of the fainter ones giving a 3d effect.

 

M31. This surprised me because normally this is just an elongated blob in an 80mm in these skies but I was really surprised at it being brighter than expected with 32 and 110 standing out nicely. In the  fuzzy elongated shape of 31 was a clearly identified darker area corresponding to the darker dust lanes, no detail just the indication that this was a dark patch.

 

Double cluster. Found it easily with the finder then had a look through the vixens and was underwhelmed, then looked  up to see a blanket of cloud, I was trying to look through quite a thick layer. I waited for it to disperse then had another look..... Woah!!!! Talk about 3d.

Because the clusters were at the zenith I set a small stool alongside the scope and the eyepieces were at a perfect height for me to just sit and drink the view in. The colours for a start, yellows and the odd hint of orange. Next, just like with M45 the brighter stars stood right out, I just sat there for 10 minutes drinking the view in until it disappeared behind thick cloud. I looked up to see not a single star visible in the sky, game over due to complete cloud cover.

 

OK it was only a short test but I was buzzing, this scope, despite the few snags that still need ironing out is starting to perform. I am really looking forward to testing this properly now. When I have ironed out the reliability side and get a good nights observing I will post a proper first light on the full set up section of the forum.

 

Oh just forgot to mention, the views are far brighter than a single ED80 with binoviewer. I know its an obvious point but when committing to a project like this there is always a little niggle in the back of the mind.

 

 

Edited December 1, 2018 by philj

[Stu]

Sounding really promising Phil! A few little tweaks and I can see it will be a really enjoyable bit of kit.

[Peter Drew]

Progressing nicely, if it was easy to do, everyone would do it! No reason why your binoscope should perform differently to mine as they both have the same optics, I've been very pleased with mine and have just knocked up a parallelogram mount for it.   ?

[philj]

On 01/12/2018 at 17:16, Peter Drew said:

Progressing nicely, if it was easy to do, everyone would do it! No reason why your binoscope should perform differently to mine as they both have the same optics, I've been very pleased with mine and have just knocked up a parallelogram mount for it.   ?

Thanks Peter

Its not difficult in principal but its fun in practice.

Making one telescope is a cinch but trying to get 2 scopes to optically match can make you scratch your head a few times.

My first problem was the IPD prisms didnt match, traced to my not taking enough off a coupling step ring on one of them resulting in one prism not seating correctly which threw the collimation out. Getting firm and concentric clamping on the prisms, diagonals and eyepieces is fun. I am using 2-1.25" Self centreing adapters in the focusers to reduce the movement and seriously thinking about making something on similar lines for the diagonals and eyepiece clamps now, this may be slightly beyond my current lathe skills though ?

[Peter Drew]

Trial parallelogram mount for my 80ED binoscope prior to making a heavy duty one for my 6" F5 achro binoscope.   ?

[Stormbringer]

Very nice ?

[philj]

That looks a useful piece of kit Peter.

I see theres a Vixen binoscope in the background as well.

 

Are your OTAs staggered, (one further forward than the other) or is it the angle in the photograph

[Peter Drew]

2 hours ago, philj said:

That looks a useful piece of kit Peter.

I see theres a Vixen binoscope in the background as well.

 

Are your OTAs staggered, (one further forward than the other) or is it the angle in the photograph

The 80ED's are not exactly equal in length but it's the photo that makes them look staggered. The binoscope in the background is my 6" F5 achro made from Skywatcher OTA's.    ?

[philj]

Ah right, its the colour scheme that fooled me, now I look closer I recognise the SW Cells