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wookie1965

Maybe Collimation issue

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Posted (edited)

I bought a pair of Revelation 8 x 42 SF Waterproof Roof Prism Binoculars a couple of nights ago thought I would look at Jupiter it was clear. I could not see any moons and Jupiter did not look round just would not focus.

I have looked at Jupiter many times and know exactly where it is I was not confused with Antares. When I use them through the day they seem fine I have tried them 3 times now no luck any help appreciated. I used to have a really cheap pair of Prinz 12 X 50 which showed all four moons but I gave them to my grandson and bought these so they would be easier to handle.

Edited by wookie1965

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Usually, collimation with binoculars refers to if the tubes are parallel, which is needed for both images to merge as one. It doesn't sound like that's what you mean.

If you had really bad seeing, the view through both tubes would be equally bad. You might get that if you're observing through a column of hot air rising from the neighbours' barbecue.

If there is an optical problem inside the binoculars, it would be rare that the problem existed to the same extent in both tubes, unless something is wrong with the mechanism that moves the focussing lenses in the tubes. Maybe the whole mechanism is crooked, or the focussing lenses are loose.

Roof-Prism-Design.gif source: see bottom of image

At least the focussing mechanism is shared by both tubes.

The other parts are independent of their counterparts in the other tube. If for instance there is a chance of 1 in 30 that an optical part in one tube is mounted poorly, then the chance is 1 in 900 that both tubes have a poorly mounted optical part.

So My guess is: the neighbours had a barbecue, or something is wrong with the focussing mechanism.

 

 

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Cheers for that I will have to check the focusing mechanism or try again on a different night.

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Can you try a different pair of binos? This might be a bit left of field, but if they seem OK during the day but are "out of focus" on points of light during the night, perhaps it's your eyes, might have developed astigmatism?

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Following on from what Ruud and MarsG76 said, perhaps you could have a look at Jupiter again but compare the image in each half of the binocular?  I.e close one eye at a time and then try to focus that barrel.  If you can get sharp images, but not at the same focus, then the dioptre is not adjusted correctly. If you can only get a sharp image in one barrel then the other has an issue (loose element?). You should be able to get a sharp image in each barrel but if the two images won't combine you have a collimation error. Easy test for this is to look at a distant object like a telegraph pole in the daytime. Close one eye at a time and see if the image shifts eye to eye. With well collimated binoculars you should be able to move the binos several inches away from your eyes and still hold the object in each field as you alternate between eyes, even if not both perfectly centered. Astronomical objects like stars and planets with extreme contrast in the field are much more demanding on the optics of both the binos and your eyes/brain - especially with regards to collimation -  than terrestrial daytime viewing. Good luck in sorting it out.

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3 hours ago, MarsG76 said:

Can you try a different pair of binos? This might be a bit left of field, but if they seem OK during the day but are "out of focus" on points of light during the night, perhaps it's your eyes, might have developed astigmatism?

I don't have a spare pair now after giving my grandson the prinz 12 x 50s

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Just now, wookie1965 said:

I don't have a spare pair now after giving my grandson the prinz 12 x 50s

Ask to borrow them for a night?

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2 hours ago, MarsG76 said:

Ask to borrow them for a night?

He is too far away only see him maybe 4 times a year bit of bad luck really.

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