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PostPosted: Tue Feb 12, 2019 10:38 pm 
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Hello to all.
I recently had to do some work on the trinocular head of my Reichert Jung 120.
When I had finished everything seemed ok, the image seemed clear and sharp, but I then noticed that the right eye tube had a distinct red tinge compared to the left, which was much more blueish. Swapping the eyepieces made no difference.
I then checked my other scope (same model) and there seemed to be some difference in that one too, although to a lesser degree. I have been using that one happily for several months, so luckily the brain seems able to ignore the colour difference.
But is this common, or normal, or are both my scopes suffering from some age related problem? Prism misalignment?
Any thoughts or suggestions would be welcome.
Tim


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PostPosted: Tue Feb 12, 2019 11:05 pm 
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Location: NorthWest England
Tim,

May I suggest that, as a first step, you take some photographs [or use a colour temperature meter, if you have one] to confirm that this is indeed a physical characteristic of the binoculars.

It is possible that you are seeing a difference in your eyes ... This was very noticeable when I had my first cataract done.

MichaelG.

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PostPosted: Wed Feb 13, 2019 1:15 am 
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Tip the microscope down on it's side and have a look with the ocular tubes/eyes reversed . That will tell you if the colour difference is physiological.


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PostPosted: Wed Feb 13, 2019 8:53 am 
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Hi, could it be that you're using polarizers?


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PostPosted: Wed Feb 13, 2019 1:19 pm 
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Thanks for the replies.
The difference doesn't seem so great this morning, probably not worth mentioning (tired eyes yesterday I suppose), but it is still there.
Abednego - I did have a polarizer, I've now removed it. Maybe that helped, I'm not sure.
I've take some photos as I thought that would be the surest way. I can certainly use the scopes, it's not a problem when using both eyepieces, but still it seems odd.
What do you think? The photos should be labeled left or right, first pair are the old scope, second pair are the repaired scope. (I had to re-cement a prism which had come loose.)
There are slight differences in focus between left/right, because the head is not fully assembled yet.


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PostPosted: Wed Feb 13, 2019 3:16 pm 
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Thanks for sharing the photos ... It certainly looks like there is a physical issue with the binocular.

Whether it's worth worrying about depends on how much it irritates you.

If your repair has put new cement into one light path, then that may be enough to cause the shift in colour-balance ... especially if you are using LED illumination rather than tungsten.

All very interesting ... I think a few more details about the repair work and the illuminator would probably help.

MichaelG.

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PostPosted: Wed Feb 13, 2019 3:31 pm 
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Hi Tim,

to me the difference between left and right seems to be about the same with both heads.
So it might be typical for this model.
Of cause a broken cement layer or the re-cementing could have an influence.
I have had bino tubes with colour difference, but remember it to be less visible.
Apart from the cement layers there is little you could influence - you can use it as it is or try to find a better one. Have you cleaned all surfaces? A nice old nikotin layer could cause this effect.
I don't know this model of microscope - is it part of a system so you could choose a different typ of bino tube?

Bob


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PostPosted: Wed Feb 13, 2019 5:50 pm 
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MichaelG - The repair work was cementing a prism which had come loose. The scope was sold as 'not working', so I bought it mainly for spares. I was disappointed to find the loose prism, but luckily it appeared not to be damaged and the cement was still there so I decided that with a bit of luck I could get it back in just the same position. I think it's probably 'near enough'. There's no obvious distortion or doubling of the image, etc. The illuminator is original, using a 100W halogen bulb. The photos I posted aren't good but they were taken quickly, just to show the colours.
But as MicroBob says, the difference looks about the same in both scopes so I wonder if it is just an extra layer of optical cement or something in one eyepiece which colours sllightly with age? Is that possible?
Anyway, as I said I've been using the first scope happily for several months with no concerns, and have been very impressed with the clarity and sharpness of the images. I expect soon I'll forget all about this.
Interesting that you've experienced the same thing, MicroBob. Maybe it's fairly common. I would probably never have noticed if I hadn't been checking carefully.
I'll give the prisms a clean before I put it all back together, but unfortunately there are a couple of faces I don't think I can reach without risking further damage. I suppose nicotine could collect in an inaccessible spot over the years, and that might have affected both my scopes similarly.
If I notice any difference when complete I'll post photos again.
Cheers, Tim


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PostPosted: Wed Feb 13, 2019 6:30 pm 
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Location: NorthWest England
Timor wrote:
MichaelG - The repair work was cementing a prism which had come loose. The scope was sold as 'not working', so I bought it mainly for spares. I was disappointed to find the loose prism, but luckily it appeared not to be damaged and the cement was still there so I decided that with a bit of luck I could get it back in just the same position. I think it's probably 'near enough'. There's no obvious distortion or doubling of the image, etc. The illuminator is original, using a 100W halogen bulb. The photos I posted aren't good but they were taken quickly, just to show the colours.
But as MicroBob says, the difference looks about the same in both scopes so I wonder if it is just an extra layer of optical cement or something in one eyepiece which colours sllightly with age? Is that possible?

Thanks for the clarification, Tim ... it appears that you have only cemented an existing prism back in place ... I initially thought that you had re-cemented the optical faces of a built-up prism.

Also thanks for confirming Tungsten lighting.

As for the 'extra layer' of coloured cement ... Yes, I think that likely but; as I don't know the optical path in this binocular, it's currently only a guess.

MichaelG.

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PostPosted: Wed Feb 13, 2019 7:25 pm 
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Location: Santa Cruz, CA
I've seen significant differences between left and right, with a polarizer, in an older ergo type head. Lots of glass in the optical path -- and apparently not strain free.


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PostPosted: Wed Feb 13, 2019 8:05 pm 
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The colour difference might come from different amount or thickness of cemented surfaces but I think it is probably just the glass itself. Left and right have different light pathes and there is a lot of glass in a binocular tube.

Glass can suffer from discolouration, but it is unlikely in this case. From about 1940 to 1970 special glasses with lanthanum were used of especially bright camera lenses. They contained radioactive ingredients and turned yellow over the decades. This yellow cast is said to be removable by sunlight. Among others Pentax had some lenses of this type (old 35mm1:2,0 and fast 50s) and some Kodak Aero Ektars had the problem too. Not dangerous in normal use.

Bob


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PostPosted: Wed Feb 13, 2019 8:57 pm 
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Glad you have ruled out your orbs. AO got into some cement problems with the Seidentopf heads for the 100 series. The right hand, or straight through beam should have more colouration from cement failure in the beamsplitting prism , than the left or reflected beam.

The failures I have seen do seem a little like nicotine staining, so the right side being more orange then the left would be the result of a cement failure in that prism.


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PostPosted: Wed Feb 13, 2019 9:38 pm 
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Thanks to all for the ideas. As always, a lot of interesting information.
Apochronaut, I suppose if the cement in the light path fails over time, there's nothing to do to prevent it?
Just hope it lasts longer than me I suppose! At least now I've got a spare.
I've been using it again tonight and it's surprising how in normal use I'm never aware of it at all. But I suppose our eyes do that all the time, merging two slightly different views (or slightly different colours in this case).
Maybe this is one reason an image taken via a camera is never quite as good as when we look through the eyepieces!
Cheers, Tim


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