Porro Prism restore (1 Viewer)

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bruno28

Well-known member

• Oct 31, 2019

• #1

Porro Prism Chipped/Cracked

Hello

I was given a micro binocular and wanted to restore it as it's lost paint and had some specs of dirt inside.

One side is not focusing far, but focuses close very well. The other focuses far perfectly.

Upon looking at it I noticed a small darkness on one corner of the left eye piece. I opened it up carefully and noticed the porro prism as a small chip/crack that is able to fit back into its location as its 90% in one piece. Is it possible to repair this? Glue it back or get a new prism?

I want to make this binoculars work again.

Thanks for any advice.

 

Last edited: Oct 31, 2019

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Binastro

Well-known member

• Oct 31, 2019

• #2

It is probably better to leave the 90% prism as is.
I don't think you could get the 10% piece perfectly aligned unless the break is such that it has an exact position when attached to the 90%.
This binocular was probably dropped.

I had a 10x70 Ross monocular that I dropped on ice covered granite.
Only 2/3rds of the view remained because of a badly damaged prism, but I used the monocular like this for years.

B.

 

Last edited: Oct 31, 2019

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bruno28

Well-known member

• Oct 31, 2019

• #3

I will try to glue with Loctite Glass Glue.
I managed to sort the focusing issue on it. Its almost perfect with exception of the prism. Someone did play with it as the objective was incorrect direction. I flipped it and it worked perfectly.
Some other signs of it being tempered with.

Sent from my SM-G960F using Tapatalk

 

WJC

Well-known member

• Oct 31, 2019

• #4

bruno28 said:

I will try to glue with Loctite Glass Glue.
I managed to sort the focusing issue on it. Its almost perfect with exception of the prism. Someone did play with it as the objective was incorrect direction. I flipped it and it worked perfectly.
Some other signs of it being tempered with.

Sent from my SM-G960F using Tapatalk

Click to expand...

I agree with Binastro. But three things to consider.

1. Those prisms are not that hard to find.
2. If you are going to use the original prism, blacken the chip with paint or two coats of a thick black marker.
3. How do you propose to get it aligned? :cat:

Bill

 

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richard866945

Bino repair man

• Nov 1, 2019

• #5

If you measure the prism carefully, length; breadth and height, I might have a replacement for you.

 

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bruno28

Well-known member

• Nov 2, 2019

• #6

Where can I find those prisms? I would be interested in swapping them if possible.

Sent from my SM-G960F using Tapatalk

 

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bruno28

Well-known member

• Nov 2, 2019

• #7

richard866945 said:

If you measure the prism carefully, length; breadth and height, I might have a replacement for you.

Click to expand...

Ill have to measure once I settle down as I'm in middle of moving places. Then I can let you know.
Are these prisms easy to find? Where could I find them? Is there a specific website?


Thanks.

Sent from my SM-G960F using Tapatalk

 

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bruno28

Well-known member

• Nov 18, 2019

• #8

richard866945 said:

If you measure the prism carefully, length; breadth and height, I might have a replacement for you.

Click to expand...

I measured the prism to be: 28x11.5x15mm

 

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richard866945

Bino repair man

• Nov 19, 2019

• #9

I have one that is close.
28x11.6x13.5
Do oyu want to try it?
Cost of post to you only

 

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bruno28

Well-known member

• Nov 22, 2019

• #10

richard866945 said:

I have one that is close.
28x11.6x13.5
Do oyu want to try it?
Cost of post to you only

Click to expand...

Thanks Richard,
that would be great. But since one is not the exact same size as the other, does it mean i would need to change both sides (left and right) or just changing one prism shouldn't affect?