What type of eyepiece is this?

[markse68]

No- not the wrong category as it’s a bino ep

Took my newly acquired ancient Ross binos eps apart tonight to give them a clean as they seemed hazy. Alas it wasn’t dirt that i was seeing (although they did need cleaning) but one of the doublets has been “repaired” and it looks like they used a scourer  to remove the old balsam 🤦‍♂️

Anyway back to the point of the post- what type of ep design is this? 🤔 It doesn’t seem to match any on the ep evolution charts i’ve seen. It has a plano convex eye lens with the flat to the eye followed by a concave convex cemented doublet followed by a field stop and then another plano-convex element with the flat side towards the objective. Any idea? 

Given the separation of the objective already noted and now this poorly re-cemented ep lens and how much i like them as a design I think i might have a go at re-cementing them myself- what could possibly go wrong? 😳

[John]

A form of Konig ?:

 

[Louis D]

You could check with Martin Pond over on CN.  He loves to take apart vintage binocular eyepieces and create new, home-brew eyepieces from the lenses.

[markse68]

10 minutes ago, John said:

A form of Konig ?:

 

Thanks John, that’s exactly what it looks like but according to that chart a Konig has one fewer element?  Where did you get that image- is it yours?

[John]

13 minutes ago, markse68 said:

Thanks John, that’s exactly what it looks like but according to that chart a Konig has one fewer element?  Where did you get that image- is it yours?

If you click on the image it takes you to a flickr page by Simon Spiers, who knows a bit about binoculars.

 

[DaveL59]

am wondering if they repaired the doublet or if it's just separated and left as-was? If there's balsam residue and they are apart, then hot water will soften it and you'd be able to gently scrape it away with a soft-edged tool. Will be a fun exercise being they are small lenses and in hot water so be careful 😮 

You could get some new modern cement (balsam isn't available any more) which would need UV to cure, but you'd need to be very precise with placement of the lenses since once cured you won't be able to part them if you find things out of true. Alternatively you might find that not adhering the 2 lenses will give reasonable results while leaving you the option to glue them later on if you really felt the need.

[markse68]

8 minutes ago, DaveL59 said:

am wondering if they repaired the doublet or if it's just separated and left as-was? If there's balsam residue and they are apart, then hot water will soften it and you'd be able to gently scrape it away with a soft-edged tool. Will be a fun exercise being they are small lenses and in hot water so be careful 😮 

You could get some new modern cement (balsam isn't available any more) which would need UV to cure, but you'd need to be very precise with placement of the lenses since once cured you won't be able to part them if you find things out of true. Alternatively you might find that not adhering the 2 lenses will give reasonable results while leaving you the option to glue them later on if you really felt the need.

Bit pricey but seems you can still get it Dave- they use it for microscope slides apparently.

https://www.supremepaint.co.uk/products/canada-balsam-100ml

I do like the idea of it not being permanent  the more i’m thinking about it the more i’m tempted- it would be a fun restoration job and if it works worth it as they’re a very nice binocular potentially.

No it’s definitely been repaired Dave- it’s one piece stuck together but when you catch the light it’s hazy with tiny bubbles and clear cleaning marks from removing the old cement. hopefully they didn’t use araldite! 

This is the back of the objective which looks to be smaller diameter than the front element which will make alignment a bit hit and miss. then there’s the collimation after 😬

I was thinking of painting the inside with black 3 but actually i like they way it looks now even if it’s not ideal so i’ll leave it

Mark

[johninderby]

Very pricy but there is Norland optical adhesive range which is a more modern adhesive

https://www.edmundoptics.co.uk/f/norland-optical-adhesives/11818/

Edited August 4, 2020 by johninderby

[markse68]

7 hours ago, John said:

If you click on the image it takes you to a flickr page by Simon Spiers, who knows a bit about binoculars.

 

What’s in a name? Well apparently very little- Konig was enormously prolific whilst working for Zeiss with a long list of patents but according to this, most modern “Konig” eps were indeed 1-2-1 like this so these ep evolution charts seem a bit inaccurate! 

http://home.europa.com/~telscope/koenig.txt

Interestingly Ross had close relations with  to Zeiss before the war so likely got to share some of his wisdom.

He sounds like a bit of a legendary designer alongside his boss Abbe!

 

[PeterW]

Heat will soften epoxy, though it’d be a pain to get the residue off to the bare glass. Norland UV adhesives are popular, but as said, once stuck-always stuck. Hopefully you can get the muck out and get some better index matching stuff in there, hopefully make the scratches less visible.

Peter

[DaveL59]

Handy find Mark, not too bad a price given it should do what you want and be removable in the future should that be necessary. We do seem to like these little projects and challenges huh 😄 

Fingers crossed that they've not wrecked the lenses in the past and you are able to get it sorted, will watch with interest for sure. Luckily I've not had lenses separating in the ones I've bought but never say never... and I did after all have a big heart-sinking moment when I messed up one large lens not so long ago on the vintage scope. Am lucky that still performs well and wasn't a total loss.

Internally those do look in good order, blacked prisms too? Wonder if that was OEM or someone did that later on to improve contrast?

[markse68]

1 hour ago, DaveL59 said:

Internally those do look in good order, blacked prisms too? Wonder if that was OEM or someone did that later on to improve contrast?

Not sure Dave- they have a close fitting metal plate under the spring clip (which looks like phosphor bronze- nice ) but i don’t know if the prisms are blacked? Is that a good idea or necessary? the prisms should totally internally reflect surely? i guess painting the flat side nearest the objective could help minimise scatter from  the objective? 🤔 Maybe i should paint it all inside with black 3...

Edited August 4, 2020 by markse68

[DaveL59]

I've some that have a black metal cap over the prism which I guess is to improve light shielding/leakage. None I've opened so far have blacked prisms but have read of others doing the sides as mods which may reduce stray light in the chambers. Same for blacking the lens edges. I expect the intent is to improve overall contrast tho I've generally not bothered on most of mine as they work fine as-is. Be careful of painting the reflecting surfaces however as that may not go as expected and cause image issues, but no harm doing the ground edges - which is what it looked like in the pic but maybe that was just reflecting the blacked interior and tricked my eye 🙂 A black sharpie pen would do rather than paint if you went that route. You'll likely disturb the collimation tho if you remove the prisms, not sure if these had eccentric rings for adjustment or used shims/prism-tilt screws.

I noted that the 0.965 diagonal I opened recently was a prism rather than a mirror and it had a black card insert on the long edge, perhaps with the same goal, to cull stray light and improve internal reflection. Mind you, as much I expect too to protect the prism from the shiny metal spring clip that sits between the prism and the cover plate so as not to marr the reflecting surface.

[markse68]

4 minutes ago, DaveL59 said:

You'll likely disturb the collimation tho if you remove the prisms, not sure if these had eccentric rings for adjustment or used shims/prism-tilt screws.

I think i’ll most definitely disturb the collimation if I remove and re-glue the objective Dave  It’s eccentric adjustment. I’ll have to read up on what’s involved in readjusting then before going too far- I guess they used an optical bench in the factory for precision but i wonder if it’s possible without or if it’s plausible to jerry-rig something? 

[DaveL59]

ah ok, well with the objective cells out you'll likely have to reset the alignment unless you can screw them back in exactly the same as before. Adjusting is fiddly but can be done but you won't have true collimation afterwards. On a couple pairs here (Chinon roof was one IIRC) I marked the relative positions with a marker pen so I knew where the eccentric rings sat relative to each other and the body so I could replace them in close to the correct position on reassembly. Then it was just minor tweaks to true things up for my IPD, a bit of a cheat but it worked fairly well 😉 

Here's a pic of the Chinon 10x40 roof, objective end. It's an oddity tho with only the one eccentric ring. Fun bit is keeping it in the desired place while tightening the lens ring...

I expect yours may have 2 rings below the locking ring which I think is the more usual arrangement.

Edited August 4, 2020 by DaveL59

[markse68]

It’s done! 🤦‍♂️ no turning back now 😂

So what’s the goal of collimation? Presumably it’s to adjust so that the entrance and exit beams are parallel? If I use a laser cross projected  through each side of the binos and adjust the objectives to align the crosses with correctly spaced marks on a distant wall ?

Mark

[DaveL59]

nice find and a good price I'd think 🙂

The aim of collimation is to have the two sides operating parallel to each other with regard the central axis so that as you pivot through the IPD range the two sides remain aligned. You're unlikely to get it accurate without the right jig and equipment tho there are some other methods that have been used making a jig to hold the bino and using the sun and projecting the image to check/adjust.

https://www.birdforum.net/showthread.php?t=184856 which references the below

https://sites.google.com/site/rchamon/home/sun-images-method-for-collimation-of-binoculars

Should hopefully do what you need if you care to make up that rig 🙂 

Might be interested in the source for the balsam too, hit buy on a TAL 6x30 finder that looks to have objective separation so may give a go at splitting the elements and use them air spaced or try to re-fix them later. At the price I figure useful for spares or as a spare or maybe even mod to be a RA finder with a suitable diagonal.

Doesn't come with the bracket so I'd have to sort something if I want to use it with the vintage scope as it's a larger barrel than the Prinz one that it came with.

[markse68]

ooh you found an honest ebay seller! Interesting patterns there- I have a couple of “perfect” (🤦‍♂️) tal plossls that are separating too - this could become a handy skill to have! 

I found it on ebay Dave- hope it’s decent quality.

Ill do some reading up on the collimation thing- thanks

[DaveL59]

heh yeah, like how he warned it could be fungus too, so very honest in the description. Also says view isn't affected which I'd believe especially after my adventures with the vintage scope lens 😉 I know the TAL finders are good, I've 2 already after all and even as parts it'll be useful since the TAL-1 doesn't have the dew shield or caps, but I also won't feel quite so bad if I then decide to shorten the tube to build one as an RA finder.

Did a quick search on the bay and found the one you showed, might hold off to hear your results tho just in case 😄 I'm sure it'll be ok tho, just needs care in placement and hopefully you'll return that lens to its old glory.

I've often thought about making a solar jig, just never got around to doing it, lack of materials and space being part of that. Luckily most of the binos I have only needed slight tweaks, the ones that are bad aren't worth the time so are just spares really so potential experimentation fodder too when required...