Question about Optics

1 Answer

Out of focus

I have a pair of montgomery wards 7x35 with i think are porro prisims and i know how to shut down the right tube and focus with the center knob and then close the left tube and focus with the right eye piece . after i do this and try to focus with both lenses the binocs will not go into focus. according to what i have read so far it sounds like the collimation is not correct. what can i do? the binocs are very clean for such an old pair. thanks for any help. lance a.

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that gotĀ 5 achievements.

    Sniper:

    An expert who has posted more than 50 answers, of which 90% or more were rated as helpful.

    Governor:

    An expert whose answer gotĀ voted for 20 times.

  • Expert
  • 73 Answers

Assuming you are focussing correctly. When binoculars are out of collimation the most usual effect is double vision as the optical axis do not line up. The only thing you can do is to take them to a binocular repairer. The problem is the cost. Proper repair need the use of a device known as a collimator and it is a laborious task to do it properly. Your binoculars do not carry a high monetary value and a proper repair will cost more than a new binocular of similar specs. Porro prism binoculars mostly have the objective lenses set further apart than the eyepieces. This holds true except for reverse porro prisms which are the other way round. Roof prisms have both the front and rear lenses inline.
Make sure when you focus that the first eye you use to focus with is the one where the eyepiece does not have its own focus ring (dioptre). The dioptre adjustment is on either the left or the right depending on the brand. That eyepiece should be left alone until you have focused using the center ring. Then leave the center ring alone and focus the eyepiece that has the adjustment ring.

Posted on Aug 02, 2009

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

I see double image unless I take the lens as close as the binoculars can go


thats how binoculars are. Yours in this case is really strong. the closer you are to something, looking at it, the more magiflyed you going to be. try view things far a distance, really far away. no more double right?
Everything you need to know to become an expert:
on this website: http://www.chuckhawks.com/binocular_basics.htm
It is surprising how many people do not know how to focus binoculars correctly. There are two common focusing systems used in binoculars.
The first is individual eyepiece focus. This system is simple to understand, and easy to manufacture. It also lends itself well to sealed optical tubes, and thus is usually the focusing system used for waterproof binoculars. Individual eyepiece focus means that to focus the binoculars to your eyes, you simply focus the left eyepiece to your left eye and the right eyepiece to your right eye. There is no centrally located focusing mechanism. It is done like this. Look at something in the distance. Close the right eye (or cover the front of the right binocular), and focus the left eyepiece to your left eye. Close the left eye (or cover the front of the left binocular), and focus the right eyepiece to your right eye. You are finished, until you need to look at something at a different distance, in which case you need to repeat the process.
Because individual eyepiece focus is time-consuming, center focus is more common. Unfortunately, very few people understand how to correctly use center focus binoculars. Here is how it is done. Aim your binoculars at something in the distance. Close the right eye (or cover the front of the right tube), and focus the left side of the binocular to your left eye using the center focus control, which is concentric with the pivot shaft between the binoculars. (Note: the left eyepiece itself does not focus on center focus binoculars.) Next, close your left eye (or cover the front of the left tube), and focus the right eyepiece to your right eye. DO NOT touch the center focus control while you are focusing the right eyepiece to your right eye. Now you are finished. What you have just done is adjust the binoculars for your individual eyes. (Practically everybody's left and right eyes are different.) From now on, you only need to adjust the center focus control when you look at things at different distances. Center focus is faster and easier to use than individual eyepiece focus, once you have initially set the binoculars for your eyes.
Binoculars are commonly described by using a pair of numbers, as in "7x50" or "8x25." The first of these numbers refers to the magnification offered by the binocular. Magnification is why most people buy a pair of binoculars. In the examples above, "7x" means the binocular makes whatever you look at appear seven times closer than it does to the unaided human eye. "8x" means the binocular makes whatever you look at eight times closer than the unaided human eye. "10x" makes things look ten times closer, and so on. The first number used to describe binoculars always refers to their magnification. Common binocular magnifications are 6x, 7x, 8x, 9x, and 10x.
There are also variable power (zoom) binoculars, such as 7-21x50. These almost always perform much better at the low power setting than they do at the higher settings. This is natural, since the front objective cannot enlarge to let in more light as the power is increased, so the view gets dimmer. At 7x, the 50mm front objective provides a 7.1mm exit pupil, but at 21x, the same front objective provides only a 2.38mm exit pupil. Also, the optical quality of a zoom binocular at any given power is inferior to that of a fixed power binocular of that power. In general, zoom binoculars are not the bargain they seem to be.
Remember that everything (including movement) is magnified when you look through a pair of binoculars, especially your own shakes and tremors. So the higher the power, the harder it seems to hold the binoculars steady. 6, 7, or 8 power binoculars are easier for most people, even those with very steady hands, to hold reasonably still. The higher powers sound like a good deal, but often result in jiggly, blurred views. This is why 7x binoculars are chosen by so many experts, including the military.
Power affects brightness. Other things being equal, the higher the power, the dimmer the view. And power also affects the field of view of the binoculars. Again, everything being equal, the higher the power, the smaller the field of view. So, as you can see, power must be balanced against other desirable characteristics when choosing binoculars.

May 09, 2011 | Bushnell 240842 Binocular

1 Answer

After several years use without accidents or damage, cannot focus to one image any longer and left eye will not focus to clear any longer. They are Barska, 8x42 reverse porro prism.


I fear these have suffered damage without your knowledge. The collimation has gone bad, hence the two images instead of one. As the left side doesn't focus properly, I would guess that one of the prisms in that side has shifted position, which would account for both defects. This can be fixed by a skilled and knowledgable person, or made worse by someone who does not know what they are doing, but in the end, it may be too expensive to have them put right by an expert, as very good binoculars are available quite cheaply today.

Nov 16, 2010 | Barska Optics Optics

1 Answer

B/L ZEPHYR 7X35 HARD TO ROTATE CENTER KNOB FOCUS?


Over time the grease in the central pivot shaft hardens to restric the rotation of the focusing wheel. Heat from a hair dryer combined with a little WD-40 can ustally re-soften the grease permitting the wheel to turn slightly. Working the wheel back and forth over a short period of time should get it to work again easily.

Aug 06, 2010 | Bausch and Lomb Legacy 12-1056 Binocular

1 Answer

Eyecup part for Tasco binocular - 7x35


Eyepiece cushions for binoculars, telescopes, microscopes ... are all about the same size (Because our eyes are all about the same size!), and can be easily made from bicycle inner-tube material of the appropriate diameter. Measure the outside diameter of the eyepiece and ask a bike shop for the right tube inside diameter; a few mm smaller. Cut a section about twice the "depth" of the cushion you wish to have, roll the section over itself and stretch it around the eyepiece with the uncut (rolled) edge uppermost.

Sep 19, 2009 | Tasco Rams 7X35 Binocular, Black

1 Answer

I bought these for my husband. In trying them


Difficult to answer specifically without knowing the model. But binoculars are designed to view objects in the distance. They all have a limit as to how close they will focus based on the magnification and design. Objective lenses that are far apart such as on a porro prism binocular will not focus very close. The nature of the design of having the objectives further apart than the eyepieces doesn't allow it. When trying to focus too close the image will appear blurred and double. That is the nature of the design. 9 feet or 3 metres is considered quite close to focus a binocular and is usually for a model designed to do this such as a roof prism where the objective lens and the eye lenses are inline. A specialty binocular such as the Pentax Papilo will close focus to 50 centimeters. It has been designed so that the objective (large lenses) lenses converge.

Take into account when focusing that binoculars are also designed to compensate for differences in each eye. One of the eyepieces either right or left will adjust seperately. For binoculars with a center focus ring. First focus using the center ring with one eye covered. The eye that should be covered is the one that doesn't have the adjusting eyepiece. When the image is clear close the eye you have just used and leave the center focus alone. Focusing on the same spot look through the eyepiece that adjusts and turn the eyepiece ring until the image is clear. Now all you have to do is focus using the center ring only as the binoculars are adjusted for each eye.

Some binoculars do not have a center focus and each eye will adjust seperately.

Jul 29, 2009 | Optics

1 Answer

I have a Swift model 802, 7X35 binocular. The


at the bottom hindge there is a nut you can remove . then take a long thin screwdriver and take off the screw that holds the eyepiece focus shaft. turn center wheel till eyepiece xbars come off body,carefull not to touch lenses. gl larry@reichinstruments.com

Jun 23, 2009 | Swift Audubon 804ED BWCF Binocular

2 Answers

Unable to focus my Bushnell 7x35 insta-vision binoculars


insta-vision bino's are self focusing no adjustments.

Jun 05, 2009 | Bushnell "Insta-Focus" Binoculars

1 Answer

Condensation on several lenses in left tube of 10/42!!wow


I live in Florida and my binocs frequently get wet.I put them out in the direct sun for a couple of hours and it cooks the moisture out of them. I have had a pair of Pentax 12x50s for about 30 years.I've probably dried them out a dozen times or so.Good Luck

Mar 13, 2009 | Swarovski Optik (58026S) Binocular

1 Answer

Steiner Commander Compass not working - possibly low of fluid?


Check this post for lens covers.

http://www.bluewaterweb.com/MarineHardware/Hardware.asp?

Feb 15, 2009 | Steiner Military/Marine 7x35

2 Answers

Missing Minolta Binocular eyecup


LOST LEFT EYECUP FOR MINOLTA 7X35 WP.FP CONTACT ME GEORGE COLE AT gcole@san.rr.com THANK YOU VERY MUCH

Oct 09, 2008 | Optics

Not finding what you are looking for?
Optics Logo

Related Topics:

383 people viewed this question

Ask a Question

Usually answered in minutes!

Top Optics Experts

Joe Lalumia aka...
Joe Lalumia aka...

Level 3 Expert

3185 Answers

kakima

Level 3 Expert

98879 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17129 Answers

Are you an Optic Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...