<p>You'd also need a really transparent oil to avoid path length differences changing the colour of the objects. As it is the reflections that appear further out are dimmer because of mirror losses, and it's these that would be affected most. We now have such oils, but they have a cost, and they're not traditional so there's little incentive to use them. In a kaleidoscope stored on end, the objects would sink in a thick layer of oil, and not redistribute very well.</p>
<p>But a layer with a bit of thickness might work, as the eye has a certain depth of field in which items are fairly well focussed. This depth of field is greater in bright light, as the pupil contracts. So you can have a thicker layer of objects with brighter illumination. But it would still be a fairly small fraction of the distance from the eye to the objects.</p>
<p>However depth perception is largely from binocular vision, which a normal single-eye kaleidoscope lacks. With only one eye, depth perception comes from expectations of the size of familiar objects (not applicable here), seing what is in front of what, and loss of focus. So the effect wouldn't be as interesting as you think.</p>

CC BY-SA 4.0
2023-09-01T16:39:15.303Z
I really appreciate your insight.  There is an effect of walking through snowflakes on a still day which I really enjoy.  I think it might be just as enjoyable with an eye patch.  But I'm also recognizing the reasons why that is not possible.
Library Seph
CC BY-SA 4.0
2023-09-01T17:10:01.080Z
I think I understand about the snowflakes, and maybe most of them being defocussed is part of the effect. But then snowflakes don't appear sharp anyway
Chris H
CC BY-SA 4.0
2023-08-31T06:58:31.857Z
2023-08-31T06:58:31.857Z
Chris H
<p>The optics of a kaleidoscope are based on the multiple reflections from the mirrors within. One can focus on the tube end containing the objects while maintaining appropriate focus for the reflections generated.</p>
<p>With objects enclosed in the entire tube, the reflections and the objects will be at various levels, requiring the viewer to change focus for each object (and associated reflection) floating within. I also believe that the results would be more cluttered or require far fewer objects if such clutter is to be avoided.</p>
<p>One could conceivably fill the tube with an optical matching liquid, but without adding objects. This adds weight, cost and the higher risk of a very messy leak. An inappropriate liquid would make the viewing worse.</p>

CC BY-SA 4.0
2023-08-31T00:52:54.703Z
Thank you.  This does a great job of answering my question.  Part of what I don't like about kaleidoscopes is how flat they look.  At the same time, I now understand there is a limited range in which everything can be in focus.  I suspect I'll have to experiment some to understand what the limits are.
Library Seph
CC BY-SA 4.0
2023-08-31T12:23:56.873Z
@LibrarySeph The term you want to look for if you want to research those limits more is ‘depth of field’ or ‘depth of focus’. All kinds of things have an impact on it, including any other optics (such as lenses or prisms) involved and the exact viewing conditions, and it gets really complicated with human vision (as opposed to things like cameras) because our brain does some really crazy stuff at times to try and help us see better.
Austin Hemmelgarn
CC BY-SA 4.0
2023-09-01T16:03:34.827Z
Plus things closer than the end of the tube would not have as many reflections, perhaps none at all since it needs the length of the tube to generate the complex patterns
rebusB
CC BY-SA 4.0
2023-08-31T00:13:06.393Z
2023-08-31T08:01:53.500Z
2023-08-31T08:01:53.500Z
fred_dot_u
<p>I'm outlining a class on building oil kaleidoscopes, and one of the things I find strangely consistent is that they all hold the oil and items at the end.</p>
<p>Why not have the oil and items fill the entire tube?</p>
<p>Will submerging the mirrors in oil mess with the reflections negatively?</p>

<untagged>
Why do oil kaleidoscopes only have floating items at the end?
Library Seph
# Why do oil kaleidoscopes only have floating items at the end?

(Asked by: username_0 on 2023-08-30)

I'm outlining a class on building oil kaleidoscopes, and one of the things I find strangely consistent is that they all hold the oil and items at the end.

Why not have the oil and items fill the entire tube?

Will submerging the mirrors in oil mess with the reflections negatively?

**Tags:** untagged


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## 2 answers

### Answer by username_2 on 2023-08-31. Score: 5 | Accepted answer

The optics of a kaleidoscope are based on the multiple reflections from the mirrors within. One can focus on the tube end containing the objects while maintaining appropriate focus for the reflections generated.

With objects enclosed in the entire tube, the reflections and the objects will be at various levels, requiring the viewer to change focus for each object (and associated reflection) floating within. I also believe that the results would be more cluttered or require far fewer objects if such clutter is to be avoided.

One could conceivably fill the tube with an optical matching liquid, but without adding objects. This adds weight, cost and the higher risk of a very messy leak. An inappropriate liquid would make the viewing worse.

> **Comments:**
> **username_0**: Thank you.  This does a great job of answering my question.  Part of what I don't like about kaleidoscopes is how flat they look.  At the same time, I now understand there is a limited range in which everything can be in focus.  I suspect I'll have to experiment some to understand what the limits are.  
> **username_3**: @username_0 The term you want to look for if you want to research those limits more is ‘depth of field’ or ‘depth of focus’. All kinds of things have an impact on it, including any other optics (such as lenses or prisms) involved and the exact viewing conditions, and it gets really complicated with human vision (as opposed to things like cameras) because our brain does some really crazy stuff at times to try and help us see better.  
> **username_4**: Plus things closer than the end of the tube would not have as many reflections, perhaps none at all since it needs the length of the tube to generate the complex patterns  

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### Answer by username_1 on 2023-08-31. Score: 2

You'd also need a really transparent oil to avoid path length differences changing the colour of the objects. As it is the reflections that appear further out are dimmer because of mirror losses, and it's these that would be affected most. We now have such oils, but they have a cost, and they're not traditional so there's little incentive to use them. In a kaleidoscope stored on end, the objects would sink in a thick layer of oil, and not redistribute very well.

But a layer with a bit of thickness might work, as the eye has a certain depth of field in which items are fairly well focussed. This depth of field is greater in bright light, as the pupil contracts. So you can have a thicker layer of objects with brighter illumination. But it would still be a fairly small fraction of the distance from the eye to the objects.

However depth perception is largely from binocular vision, which a normal single-eye kaleidoscope lacks. With only one eye, depth perception comes from expectations of the size of familiar objects (not applicable here), seing what is in front of what, and loss of focus. So the effect wouldn't be as interesting as you think.

> **Comments:**
> **username_0**: I really appreciate your insight.  There is an effect of walking through snowflakes on a still day which I really enjoy.  I think it might be just as enjoyable with an eye patch.  But I'm also recognizing the reasons why that is not possible.  
> **username_1**: I think I understand about the snowflakes, and maybe most of them being defocussed is part of the effect. But then snowflakes don't appear sharp anyway  

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