Double image 7x50 binoculars. Again.

[actionoptics]

We don't seem able to make a pair of binoculars last very long. Time and again they get 'double vision' with 2 images side by side. We have tended to buy the cheaper variety and tried both fixed and adjustable focus types.

So often it is luck whether a bumped bino will go out of alignment or not.
I have had one customer whose bino fell off a coffee table onto carpet and went out whilst another stood on the top of his landrover to check livestock but left the bino on the roof as he climbed down. The bino overtook him at the first bend and continued to the bottom of the hill. Only a few scratches. Russian 7x50.



The debate I'm having, is will I be better served by a more expensive pair? For 3 or 4 times the cost of the cheaper ones, will they last 3 or 4 times longer (or preferably, even longer)?

Steiner, Zeiss, Leitz, Nikon and Swarovski costing very many hundreds still go out if dropped but not so easily or as often as Aldi £19.99.



Would it be worth the extra for an inbuilt compass, as well?

Probably not apart from the fun of still making a single position fix using the compass bearing and distance-off tables.

Nearly all binoculars have four prisms inside and the factories use different methods to secure them. Most are strapped and glued but when jarred, the glue can crack. After resetting and aligning, this glue should be renewed or the slightest bump in future will upset the alignment.
Many models have four small grub screws, one pushing on each prism for adjustment. Some screws are locked with thread adhesive so wont move easily at first.
Some models have eccentric rings around the object glass.
Some waterproof marine models have plugged holes in the top plate to allow access to vertical screws which alter the position of inner plates on which the prisms are secured.

You can get a shockproof MIL STD 810 8x30 for £179 or the same spec 7x50 for £189.

Current reset and align costs around £50 plus return postage

 

[PetiteFleur]

My Pentax 7x50 bins got dropped by a crewmember about 4 yrs ago, sent them to a small outfit I found on line, it cost £50 and they were perfect when returned. I only take them on board when on a long trip relying on an ancient Russian 7x50's bought from a street market in Moscow years ago during Glastnost. These stay on board and still work ok but the rubber eyepieces have deteriorated and held on with masking tape!

 

[johnalison]

My Pentax 7x50 bins got dropped by a crewmember about 4 yrs ago, sent them to a small outfit I found on line, it cost £50 and they were perfect when returned. I only take them on board when on a long trip relying on an ancient Russian 7x50's bought from a street market in Moscow years ago during Glastnost. These stay on board and still work ok but the rubber eyepieces have deteriorated and held on with masking tape!

That's the whole point. You don't actually need especially good binoculars on a sailing boat since almost any pair will be a zillion times better than your eyes, or at least 7 anyway. For many of us the next question is whether we want to fork out for a stabilised pair. I have had great pleasure from mine but I'm not sure that they have often made a critical difference, whereas my old 7x50s have, by virtue of their light-gathering.

 

[greeny]

Yipee, just fixed an old "favourite" pair that were my dad's before he passed away. I dropped them last year and they suffered the double image problem. I fixed them by tweaking the screws until they looked good again. Probably not optically perfect but very usable and my eyes can't tell the difference.

 

[johnalison]

Yipee, just fixed an old "favourite" pair that were my dad's before he passed away. I dropped them last year and they suffered the double image problem. I fixed them by tweaking the screws until they looked good again. Probably not optically perfect but very usable and my eyes can't tell the difference.

I think that fewer than 60% of people have true binocular vision, so that as long as your binoculars give a single image for your eyes, that is all they need to do. It is possible that they only need to be within a certain range for your eyes to adapt, just so long as you don't lend them to someone else.

 

[mjcoon]

I think that fewer than 60% of people have true binocular vision, so that as long as your binoculars give a single image for your eyes, that is all they need to do. It is possible that they only need to be within a certain range for your eyes to adapt, just so long as you don't lend them to someone else.

Maybe so long as you don't indulge in long PI surveillance stints so the effort gives you a headache!

Mike.

 

[Ruffles]

I think that fewer than 60% of people have true binocular vision, so that as long as your binoculars give a single image for your eyes, that is all they need to do. It is possible that they only need to be within a certain range for your eyes to adapt, just so long as you don't lend them to someone else.

Though it may also be true that the accuracy of alignment needed is greater on a moving boat than when you're in the shop trying them out. I have two identical pairs. The one I use on the boat has better alignment.

 

[actionoptics]

Though it may also be true that the accuracy of alignment needed is greater on a moving boat than when you're in the shop trying them out. I have two identical pairs. The one I use on the boat has better alignment.

and horizontal mis-alignment is easier for your brain to compensate although may still give a headache.
Vertical mis-alignment is instantly tiring even painful.

 

[scud63]

Would somebody kindly help me out with locating the infamous prism screws on my Marine TASCO binos. I have a slight double-image issue that I'd like to fix and I hate go searching for those tiny screws without a clue. Somebody says they are usually concealed underneath the rubber grip and thus you need to peel that off first but that was a by and large comment referring to many different models.

Thanx
Scud

 

[Praxinoscope]

The problem you describe is collimation getting the optical axis of the left and right optical components in line with each other. I spent half an hour on a stand at one boat show when looking for a new pair of binoculars and at least 50% of the new ones I tried were not collimated correctly (two images).
An earlier post has indicated how to correct this, you only need to adjust the front optics on one side, usually the left optic, which is in an eccentric mounting, but this may vary according to manufacturer.
The adjustment should be made on a distant vertical object (tower or similar) to make it easier to see the affect.

 

[scud63]

Thanks

the problem is that I ain't that familiar with the specific mechanics of the TASCO MARINE binocular and besides the method and actual algorithm I may use for collimating (that would be the next problem) I need to locate the adjusting screws.

 

[Praxinoscope]

Thanks

the problem is that I ain't that familiar with the specific mechanics of the TASCO MARINE binocular and besides the method and actual algorithm I may use for collimating (that would be the next problem) I need to locate the adjusting screws.

I’m not familiar with Tasso binoculars but normally prisms are fixed an adjustments are made on the Objective glass which is the big one at the front.

 

[NPMR]

Thanks

the problem is that I ain't that familiar with the specific mechanics of the TASCO MARINE binocular and besides the method and actual algorithm I may use for collimating (that would be the next problem) I need to locate the adjusting screws.

You'll probably find the screws easily but only after you've stripped the 'rubbery' (probably) stuff on the main body of the binoculars. Only need to do one side (I did the left side). The two small screws become very obvious once cover is off.

I held the bins to my eyes and twiddled slowly one screw and then another, watching until the image lined up. I used a jewellers screwdriver.

I replaced the cover on the bin with superglue round the edges but not before I had punched a hole over where the screw showed, so that when covered, you could readjust the bins 'next time' without removing the cover. I am happy taking the risk that the screw might corrode from salt water ingress at some point - as I have a few spare binoculars in the cupboard now!