Repairing Tento 10X50 Binoculars Image Alignment Psuedo Collimation Aka Conditional Alignment Repair Guide

Difficulty

Moderate

Steps

Time Required

Suggest a time??

Sections

Repairing Tento 10x50 binoculars Image alignment (psuedo-collimation aka conditional alignment)
8 steps

Flags

Member-Contributed Guide

An awesome member of our community made this guide. It is not managed by iFixit staff.

BackBinocular
Full Screen
Options
History
Save to Favorites
Download PDF
Edit
Translate
Get Shareable Link
Embed This Guide
Notify Me of Changes
Stop Notifications

Introduction

Better binoculars than these, have adjustment screws at the sides, and adjustable objective (big front) lenses. This is not “true” collimation. Having said all that, this is what I did to get them usable again. Perhaps this might help with fixing other binoculars, too.

What you need

Step 1

              Remove the hinge cover screw.

Turn cross head screwdriver anti-clockwise.

Turn cross head screwdriver anti-clockwise.

1024

Step 2

              Remove tiny locking screw

Turn CR-V 1.0 screw bit anti-clockwise. Because this screw is so small, it may help to magnitise your screw bit by brushing it with a magnetic screwdriver first. This will make the screw stick to the screw bit. Have a dish handy to keep the tiny screw in.

Turn CR-V 1.0 screw bit anti-clockwise. Because this screw is so small, it may help to magnitise your screw bit by brushing it with a magnetic screwdriver first. This will make the screw stick to the screw bit. Have a dish handy to keep the tiny screw in.

Step 3

              Remove eyepiece locknut.

Insert pointy-nose pliers into both holes. Turn anticlockwise.

Insert pointy-nose pliers into both holes. Turn anticlockwise.

Step 4

              Remove right then left eyepieces

Remove silver washer.
Remove right eyepiece.
Remove another silver washer.
Remove left eyepiece.

Remove silver washer.

Remove right eyepiece.

Remove another silver washer.

Remove left eyepiece.

Step 5

              Remove barrel dust cover

There are no screws holding the dust cover on but you will need to unscrew and remove each eyepiece barrel (not shown in photo). The cover should then lift off fairly easily. If not then work around it with a screwdriver. Eventually it will come off.

There are no screws holding the dust cover on but you will need to unscrew and remove each eyepiece barrel (not shown in photo). The cover should then lift off fairly easily. If not then work around it with a screwdriver. Eventually it will come off.

Step 6

              Replace both eyepieces

Now you can see the prism, which is likely the part that needs adjusting.
Replace the left eyepiece, observing the fitting point (arrowed).
Replace washer.
Replace right eyepiece.
Replace washer.
Replace locknut.

Now you can see the prism, which is likely the part that needs adjusting.

Replace the left eyepiece, observing the fitting point (arrowed).

Replace washer.

Replace right eyepiece.

Replace locknut.

Step 7

              Adjust the prism

Using a flat bladed screwdriver, fit it into the open area around the exposed prism, with the blade laying along side the prism. Try to position the screwdriver’s blade so that when you twist the screwdriver you cause the prism to shift position slightly.
Look for a couple of other places around the prism where you can insert the screwdriver, and by twisting it, slide the prism. These will be your adjustment points. Thank you dannewberry of http://practicalrifler.fr.yuku.com/topic… for this tip.
Play with moving the prism until the image looks immediately clear when you bring the binoculars up to your eyes. Remember that your eyes will have a natural tendency to align themselves with the misaligned binoculars if you stare too long (and get eyestrain).
Close your right eye and check that the image is clear on the left, then close your left eye and focus the right occular, then look away at an object (without the binocs) so that your eyes are in normal convergence – and then look quickly into the binocs to see if the collimation is good.
The night sky is more prone to double-image because there is less information in the image for your brain to work with.

Using a flat bladed screwdriver, fit it into the open area around the exposed prism, with the blade laying along side the prism. Try to position the screwdriver’s blade so that when you twist the screwdriver you cause the prism to shift position slightly.

Look for a couple of other places around the prism where you can insert the screwdriver, and by twisting it, slide the prism. These will be your adjustment points. Thank you dannewberry of http://practicalrifler.fr.yuku.com/topic… for this tip.

Play with moving the prism until the image looks immediately clear when you bring the binoculars up to your eyes. Remember that your eyes will have a natural tendency to align themselves with the misaligned binoculars if you stare too long (and get eyestrain).

Close your right eye and check that the image is clear on the left, then close your left eye and focus the right occular, then look away at an object (without the binocs) so that your eyes are in normal convergence – and then look quickly into the binocs to see if the collimation is good.

The night sky is more prone to double-image because there is less information in the image for your brain to work with.

Step 8

              The arms-length test

Look through the binocs at a distant object.
Keep your eyes focused on the distance, while moving the binocs away to arms-length. Or if you have something to fix the binocs to, move your head away straight back.
If the binocs are out of alignment, the centre images won’t overlap. When you look straight ’through’, the centre image should be just like looking through a tunnel. If so, congrats, the binoculars are aligned - for you!
Please note that someone else, whose eyes are a different width apart than yours, may still notice an error. This is because the “knock” - and your correction - might not be along the axis of the hinge.

Look through the binocs at a distant object.

Keep your eyes focused on the distance, while moving the binocs away to arms-length. Or if you have something to fix the binocs to, move your head away straight back.

If the binocs are out of alignment, the centre images won’t overlap. When you look straight ’through’, the centre image should be just like looking through a tunnel. If so, congrats, the binoculars are aligned - for you!

Please note that someone else, whose eyes are a different width apart than yours, may still notice an error. This is because the “knock” - and your correction - might not be along the axis of the hinge.

Remove the eyepieces again, then follow steps 1-5 in reverse order.

Cancel: I did not complete this guide.

                                                                                      4 other people completed this guide.

Author

                                      with 5 other contributors

                    Phil Jones

Member since: 01/11/2015

155 Reputation

                                      1 Guide authored                  



                       Badges:
                       5







                                                        +2 more badges

Mark Harris - Nov 1, 2020

Great piece of advise and good, clear instructions phil. I have 4 sets of russian bins and mons, so this will come in very handy!

Many thanks.

Mark

Peter Gudden - Jan 9, 2022

Binoculars are usually collimated by turning a front lens. You have to make a simple tool to untighten these but from there on it is not difficult. I am not sure the method above is advisable. Sliding a prism out of place by brute force is unlikely to produce a predictable result, except maybe damage.

Member-Contributed Guide#

Introduction#

What you need#

Member-Contributed Guide

Introduction

What you need