"fixed focus" v adjustable focus binoculars- how easy to focus?

PaulR

PaulR

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Our boat binoculars are fixed focus 7x50's which I have always found easy to use whether I am wearing glasses or contact lenses and others on board seem to have found them easy to use too - BUT- the original pair having over a period of several years become dull (as suddenly seemed obvious last year when I tried a new pair in a chandlers) persuaded me to buy a new pair again of inexpensive fixed focus 7x50's.

Sadly that new pair have in the first year failed in that they are no longer in focus (double image ) which I gather is not an uncommon problem with cheap binoculars when prisms can go out of alignment easily .

Am going to boat show this week so might get a new pair there and wondering how easy it is to set up and adjust for individual users traditional adjustable focus binoculars or whether we are best to stick with fixed focus ones ?

Any recommendations for reasonably robust 7x50's??

Thanks
 
I think the problem may be that fixed focus binoculars are not generally of a quality that will guarantee that they will maintain their adjustment or be easily repairable. I quite like the idea, though I don't have such a pair myself. For marine use, almost all objects are as near as dammit at infinity, whereas for bird-watching you will need to focus.
 
PaulR said:
Our boat binoculars are fixed focus 7x50's which I have always found easy to use whether I am wearing glasses or contact lenses and others on board seem to have found them easy to use too - BUT- the original pair having over a period of several years become dull (as suddenly seemed obvious last year when I tried a new pair in a chandlers) persuaded me to buy a new pair again of inexpensive fixed focus 7x50's.

Sadly that new pair have in the first year failed in that they are no longer in focus (double image ) which I gather is not an uncommon problem with cheap binoculars when prisms can go out of alignment easily .

Am going to boat show this week so might get a new pair there and wondering how easy it is to set up and adjust for individual users traditional adjustable focus binoculars or whether we are best to stick with fixed focus ones ?

Any recommendations for reasonably robust 7x50's??

Thanks
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My Plastimo fixed focus 7x50 binoculars are still great after, as far as i can recall, 12 years. I do not believe that missalignment faults are a function of fixed or variable focus, just robustness. I did once fix an old pair of binoculars by realigning the two parts to restore single vision by some brute force (i had nothing to loose if they broke). While looking through them, flex the two parts to see which direction you need to distort them to correct the missalignment then apply extra load by whatever means in that direction then look through again to check better or worse.

I find fixed focus perfectly ok for boat use but if using them for longer periods for, say, bird watching, i can feel my eyes straining, unlike variable focus ones.

Www.solocoastalsailing.co.uk
 
Not so good for older folk like me with relatively poor eyesight.

IIRC there is some comment about them on Action optics website.
 
I prefer the adjustable focus type - I've tried the fixed focus type but don't like them. I have a Pentax and an old Russian pair which are getting a bit crochety now. The Pentax was dropped by a crew member about three yrs ago but found someone online who fixed them for reasonable cost.
 
Bought these Danubia ones with compass two years ago and am using them every day when sailing (and anchoring). I wanted adjustable focus ones so I could also look up the mast to admire my rigging. The central focus wheel spins easily and after some practice focusing just happens without thinking about it.

They're waterproof, don't fog, came with lens covers, a bag, floaty strap and battery for the red compass light. Pretty pleased with them.
 
I've had a pair of fixed focus 7 x 50 for decades and when one of the internal bits went squint I sawed it in half and now have a fully functional fixed focus monocular. But on the basis that, once on the wrong side of young, one's pupils don't get the full benefit of the light gathered by 7 x 50 I got an posh 8 x 40 and have to say that they are marvellous. The 8 gives better magnification without being too difficult to hold steady and the 40 means they are not too bulky.
 
I've had a cheap Plastimo type fixed focus pair for a few years. Good enough but not great, and a bit fragile, the eyepiece fell off a previous pair, which were replaced foc.

Tried out a pair of waterproof 7x50 fixed focus at the show last Friday. Much clearer than my current ones and more robust. Also tried some other waterproof ones with conventional centre focusing. These seemed a little sharper and I bought them. Same price as the fixed at £89.99. Had a good depth of field too so wasn't essential to refocus them for my wife, although her eyesight is quite different.

The ones I bought were Visionary Stormforce2 from a small specialist stand near the road entrance into the main show area. Chinese made.

You'd probably find a slightly better deal on the Internet but the personal help from the people on the stand was worth any extra.
 
Plum said:
My Plastimo fixed focus 7x50 binoculars are still great after, as far as i can recall, 12 years. I do not believe that missalignment faults are a function of fixed or variable focus, just robustness. I did once fix an old pair of binoculars by realigning the two parts to restore single vision by some brute force (i had nothing to loose if they broke). While looking through them, flex the two parts to see which direction you need to distort them to correct the missalignment then apply extra load by whatever means in that direction then look through again to check better or worse.

I find fixed focus perfectly ok for boat use but if using them for longer periods for, say, bird watching, i can feel my eyes straining, unlike variable focus ones.

Www.solocoastalsailing.co.uk
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+1 for the Plastimo's... I think mine cost £35 and I couldn't be happier, because I don't worry when I take them into the cockpit.
 
At night I find being able to tweak the focus works for me.
Sharpens up those nav lights.
I prefer to take my glasses off.
I have a cheap monocular that is pocket sized.
It can be better to have your own rather than messing with the focus of the ship's bino's on somebody else's boat.
 
We've just recently changed to fixed focus, on easy to just pick up and use, we both have very different glass prescriptions and the old focus pair were a real pain each time either of us picked them up to use. Now does not matter with glasses or without just use as you need. Only paid £34 so not worried if they only last the year before t so far so good.
 
I bought a pair of these..
https://www.gaelforcemarine.co.uk/e...ing-Waterproof-Binoculars-wCompass/m-511.aspx
last winter and used them extensively this summer.
They've been bashed about, dropped, but I have yet to test that they float. They are certainly able to withstand a drenching from saltwater when taking some green over the bows, and heavy rain.

My son (main crew) and I have different eyes focussing without glasses, and we've memorised the settings, to make a minor change between us, but found them excellent.
They have limits on how close they will focus, but the fixed focus aspect for normal things in the distance is great.

They seem to be available from many sources, just with changed branding.
 
I have some Bynolyt Searanger 3. They are marine, fixed focus 7x50s. As I understand it, marine binoculars should be fixed focus, the reason being that having a variable focus means having a moving mechanism, with an external wheel. Marine bins should be nitrogen filled, which means being completely sealed, which prevents having a variable focus, because having an external focus wheel prevents being gas tight. Being gas filled means they won't steam up!

These Searangers are astonishingly good. The quality of the image is way beyond anything I have ever experienced with binoculars before. I would encourage anyone to get them, well worth the money, and in the marine world they are not the most expensive thing around!
 
Daverw said:
We've just recently changed to fixed focus, on easy to just pick up and use, we both have very different glass prescriptions and the old focus pair were a real pain each time either of us picked them up to use. Now does not matter with glasses or without just use as you need. Only paid £34 so not worried if they only last the year before t so far so good.
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I don't understand what's going on optically. With adjustable bins you had to adjust the focus each time because you had different eye prescriptions but with fixed focus everything's fine both with and without spectacles.
 
The OP seems to be a bit confused between focus to get a clear image and alignment to get the 2 images to overlap correctly. A common failure of alignment is not so much the prisms moving but the big end away from the eye being displaced by being dropped. These have a very fine thread and often unscrewing and carefully screwing back will get the alignment correct. Of course also when apart he may be able to clean lens etc. olewill
 
William_H said:
The OP seems to be a bit confused between focus to get a clear image and alignment to get the 2 images to overlap correctly. A common failure of alignment is not so much the prisms moving but the big end away from the eye being displaced by being dropped. These have a very fine thread and often unscrewing and carefully screwing back will get the alignment correct. Of course also when apart he may be able to clean lens etc. olewill
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Had to adjust +\- for eye balance each time, not always very quick when moving about or without with glasses, with fixed focus don't have to do either
 
I know some people like fixed focus bins but I have over the years tried quite a few pairs, and have yet to find one I can get good results with - mostly I just can't see clearly. I am now substantially long-sighted, wearing glasses since about mid-40s. As a result I use traditional focussing ones.

Current favourites car-boot-sale £10 Russian 7x50s - very sharp, just don't drop them on your toe as they are very heavy. Also a mid-range Japanese Greenkat 8x40 which I reckon is also a good size/power on board. I can't honestly say the 7x50s are much brighter in poor light than the 8x40s for my quite ancient eyes.

About the same time I had to start wearing glasses I gave up on a cheap Ebbco plastic sextant and bought a used (older than me) metal one to get a better quality telescope.
 
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