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markse68

Question about bino collimation

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I’ve had a few pairs of old boot fair binos for ages but never really had a use for them until now that i’m discovering their usefulness for astro. But all of them have a similar feature- or rather defect? Either side of focus on a bright star they all show astigmatism rather than the clean diffraction pattern you’d get with quality scope optics. Does this indicate they all have issues with collimation or something? Or is it normal for the folded optical path in binos?

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hmmm must say I've not checked for that. Collimation would give you double stars if it was out rather than an odd shape to a single image.

Are they Porro or roof type?

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all old style porro prism type and all pretty ancient so quite likely not factory fresh collimation wise but the 2 images merge ok on them.

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Could just be a feature of the lenses used or the eyepiece design, prisms I'd hope should be ok as they'd be made with good plain surfaces for the image to be folded accurately.

I'll have to try that next time I'm out with a few and see how they fair but I don't recall any odd star shapes but then to be fair I wasn't really looking for them, just shifted focus to get to pin sharp 🙂 

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I just remembered it was Jupiter i was noticing it on- a very bright star ;) 

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cloud permitting I'll try have a look tonight and report back, I've a few older pairs and a more recent minolta pair as well as a few roof type to test with.

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If you move jupiter about round the edges of the field of view in many bins (especially wide old Porro), you’ll find it goes off elongated bird shapes, highlights that the edges are for your peripheral vision. Move the bins not your eyes, unlike with a telescope. Must say I’ve not tried looking through focus, I could try and see what my reasonable, collimated ones do.

If you get a single view of a bright star in the centre of the field then the collimation isn’t far off.

 

peter

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Posted (edited)

I guess it could be my eyes- they’re quite old now. I do notice some issues with long fl eps in my scope too...

Mark

Edited by markse68

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heh so know that feeling Mark 😉 I certainly notice mine getting tired after doing a lot of small fiddly works.

As Peter said, if you get a single point star then collimation is probably OK, good to know I'm not the only one not to have noticed, like Peter I just get focus and carry on. Sounds like you'll get a couple feedbacks on testing which is nice.

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Many focused star misshapes as opposed to collimation issues are caused by strains in the objectives due to the cementing of the lens components.  Notably in the cheaper models.   🙂

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Posted (edited)
1 hour ago, Peter Drew said:

Many focused star misshapes as opposed to collimation issues are caused by strains in the objectives due to the cementing of the lens components.  Notably in the cheaper models.   🙂

It’s not so much the focussed shapes Peter- I find getting eyes in right place seems to resolve quite nice round stars and planets (though rarely perfect) but defocusing it’s not going to nice round blur but weird seagull shapes like you get with astigmatism.

Edited by markse68

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If the central stars present oval stars when defocused and the major axis of the ovals reverses inside and outside of focus that is astigmatism of the objective/s and also caused by cementing strain.  If the effect is round only the edge of the view that is astigmatism caused by the inability of the eyepiece to cope with the fast focal ratio of the objectives, typically F4 or less.   🙂

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gave a brief test just now but cloud covering the moon part way so used bright stars as alternate. So far the Porro's I tested all bar one showed round fuzzy moon/jupiter/stars, even the HR/5 with the spalled prism which I half expected might show an abberant on the RH side.

Bino's I tried were:

Swift Audubon 8.5x44 HR/5
Swift Audubon 8.5x44 MK2
Old japanese 10x50 JB86/JE54
Old japanese micro/skeleton type 15x50 (well, a LARGE miniature bino lol)
Minolta 10x50 modern
Nikon Micro 7x15 modern model
Old Tasco plastic body 8x30
Halina Sightsetter 8x30

The one that didn't and showed more oval was a pair of Regent compact 10x50 wide angle Empire made. These are shorter 10x50 body (objective tubes that is) so more compromised optically than a regular 10x50 I expect.

 

Edited by DaveL59
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Thanks very much for doing that Dave- I guess that narrows it down to one of two things then- either all of my binos are faulty or probably more likely it’s my eyes 😞 I should probably get them checked I guess...

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ahh can't claim great eyes these days myself, for sure if tired I've a feeling my eyes go out of collimation, vertically to a small degree, which makes bino use "interesting". As Peter says tho, could just the be objectives as binos are fast F4. What makes are you looking at when you checked?

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one thing you could try... focus on the target then shift the dioptre so only one side is defocused and ideally you should get the two concentric, bright central dot and fuzzy aura around it. If offset them collimation could be slightly out but close enough not to notice once well focused.

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2 hours ago, DaveL59 said:

ahh can't claim great eyes these days myself, for sure if tired I've a feeling my eyes go out of collimation, vertically to a small degree, which makes bino use "interesting". As Peter says tho, could just the be objectives as binos are fast F4. What makes are you looking at when you checked?

I think it is the binos not my eyes- i swapped eps on the same eye and the directions of the astigmatic defocus changes and swapping the same ep between both eyes it stays the same. Maybe i’m just being too fussy but it does make getting sharp focus a bit tricky. They’re all old market finds/ebay bargains and none especially good. A couple of russians that are are about the best but not quite right either, optolyths which are not too bad, Jenoptems which aren’t good at all and some really old Ross which have a separated objective which doesn’t help. Maybe I should buy something decent ;) Actually one of the russians arrived today- BNU4s which are very similar to the Jenoptems. Mechanically they’re not as nice feeling but optically they seem better

Getting back to Peters point I wonder if air spaced objective models would fair better?

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The russian ones tend to be good optically but more agricultural mechanically, but then they work better in extreme low temps I believe. For the Ross if feeling brave you could separate the objective using boiling water immersion to soften the balsam and then clean them up, can be done from what I've read. You can then reassemble  without a bonding agent or use a modern UV glue to recement them. Downside of the new glue is you won't be able to split them again, where no glue can give moire fringe patterns but do work well. Peter may have experience of doing this, I can only say what I've read so far.

Sounds like me not winning on a couple of old CZJ's was a good thing if you find them not good, tho I have considered going after some BNU's in the 12x40 range.

edit:
I should caveat the above by saying don't drop the lens into boiling water as the thermal shock could prove fatal for it. I have read though that putting them in a steel mesh carrier (chip pan basket or steamer maybe) and immersing in cool water then bringing that to the boil so the lens gradually heats up should work. It takes a while and you can tease the lens sections from each other using a soft tool like a spatula to slide them apart.

Edited by DaveL59

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3 hours ago, DaveL59 said:

Sounds like me not winning on a couple of old CZJ's was a good thing if you find them not good,

Oh i’d never diss CZJ Dave 😳 No no no! Only that comparing my particular example against some of the others i have they have more of this issue but they’re 40-+ years old and probably been dropped a few times etc. They’re the 2nd nicest mechanically and way nicer than the russians in “quality feel” though the older BNU4s are quite nice actually. The Ross have the nicest focus feel by far. I think the Tento 8x40 are probably the best for what I want them for- sharp and bright and light. But they’re the nastiest cheapest feeling and they really stink. The Ross are the worst performing- 7x30 uncoated 80 odd year old damaged optics, but they’re the ones I want to use cos they feel the nicest ;) 🤦‍♂️The Optolyths are v nice- V light for 10x50 but that’s too unsteady for handheld in my hands. I should look for some Audubon’s like the ones you’re fixing but they’re a bit heavy too I think? Maybe some Zeiss West 8x30 as they’re air spaced and maybe less likely to have this issue if Peter’s right?  Gonna keep an eye out for some later coated Ross in better condition too ;) 

PS I don’t think i’m brave enough to try fixing the separated lens in the Ross- the glass has deep scratches too so not really worth the bother. I had the obj cell out already and the rear element is smaller diameter than the front by the looks of it so it would be nigh on impossible to realign them and using them glueless wouldn’t work i think. I do plan to open and clean the eps though as they’re a bit hazy. They have a lovely wide easy view but they’re dimmer and suffer way more flare and reflections being uncoated and the separated side is worse obvs.

E404C557-68AD-45D2-8600-28119C788ADB.jpeg

Edited by markse68

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ahh ok, I did wonder as the CZJ's seem to race to silly prices, it's not like they're rare after all. I'd wanted some as a benchmark glass more than anything really but have held off so far. Missed a nice older Leitz Porro too as while I looked up the details on that model someone else hit the buy button, doh! I'd read that some of the russian ones can pong a bit, the case being the prime culprit IIRC, thankfully the Foton 7x35 roof's didn't suffer from that and are solid and very nice to use.

The Audubon HR/5 aren't particularly heavy tho the older larger model 804's are quite a chunk. Having small-ish hands I do find the HR/5 easier to use and a better fit for me. Very nice if you can find a pair at a good price, tho they also climb the price ladder pretty fast. 

I know what you mean re uncoated lenses, but how's the internal baffling and damping in the tubes on the Ross pair? I've an old just post-war Hensoldt Wetzlar Jagd dialyt 6x42 that I got for a song a while back. Paint mostly gone and corrosion, on prism chipped, uncoated lenses so I guess they never got returned to factory for the free update, probably as they'd come to the UK and no longer in Germany to take advantage of that offer. I've refurbed them and blacked the prism chip (didn't affect the view anyway but for completeness) and while they were nice, bright light in the general observing direction would cause internal flare losing contrast. So I popped some flocking inside the objective tubes, wow what a difference! Sharpened up the image beautifully and even aiming close to the sun or at the full moon these now give great views. Worth considering for the Ross pair, perhaps.

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3 minutes ago, DaveL59 said:

Worth considering for the Ross pair, perhaps.

That’s a very good idea Dave- I’ll use them as an experiment and see if they can be improved. The Leitz porros are meant to be lovely as you’d expect- shame you missed them!

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5 minutes ago, markse68 said:

That’s a very good idea Dave- I’ll use them as an experiment and see if they can be improved. The Leitz porros are meant to be lovely as you’d expect- shame you missed them!

certainly worth a try, I didn't stick the flock, just rolled it with the backing still on and inserted in the tube. Up-side is the flock can then be easily removed if needed later on. Best I could achieve since I still haven't managed to get the objectives out on the Dialyt's. Didn't want to wreck the tubes so I fixed the lens rattle by using some black wax melted into the edges which worked well too 😉 

Was a shame on the Leitz but heck, I'd not long gotten the dialyt's for the princely sum of £14 so can't really complain 😄 

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