cant focus...

[Andy 5312]

I own a pair of visionary 12 x 50 binos. Had them now well over 12 months. And they frustrate the life out of my.. ( Been a member of sgl around 3 months and only just noticed this binos topic ....doh !) Day time viewing is fine whilst using them , although when focused the image is only clear in the centre of the view. The edges do seem slightly out of focus. Eg while looking at a bird pearched on an ariel. The bird is in good focus but if i look to the edges of the view its slightly out of focus. Is this normal ? But my main concern and frustration is whilst trying to observe stars and the like i can never seem to get them focused at all. Always blurred and never pin point. The moon does come i to view but then again never as clear as i would expect , as views through my scope provide. Is it because they are of lower end binos or is there an actual issue with them. Many thanks for any response

[OscarTheGrouch]

Is there anywhere local you can go to "try out" some different binos?  I've never found a pair of binos I could get on with, which is why I stick solely to my scope now, but perhaps if you give some different ones a try you will find something that's more suited to your needs.

[Andy 5312]

Unfortunately there isnt. Only really got them for a grab and go to have a quick scan when getting scope out was too much hastle. But never been able to make use of them

[Mukv]

Greetings

one thing for you to check is the movement of the focus action as in do the eye pieces stay perpendicular to the body of the binoculars as you move focus? if there is any drag during the action of focusing the binoculars the eyepieces may not be square to the barrel of either left or right prism, gently pull on the eyepiece one at a time to check for any movement also if there is movement dose it return to the same position square to the barrel.

Andy

[Andy 5312]

Everything seems fine . No movement and all feels really sucure. Nothing rattling around . Loooks all squared up and good to go. Just cant get a clear sharp image when using for astronomy. Pain in the butt. Thanks for replies guys .

[Mukv]

It maybe just down to economic coatings on the glass used,

Andy

[Alfian]

Hi Andy, I rekindled my interest in astronomy with some Visionary 12x60s bought originally for general use. The desciption of your problem sounded a bit familiar. Like yourself I found them perfectly OK for watching wildlife but increasingly frustrating for astronomy. I mounted them to avoid shake which will improve matters using almost any binocular. Viewing the moon was OK but Jupiter for example was clearly not a star and the Galilean moons were tiny specs but Jupiter itself was always flared. No matter how I focussed it was the same.  Seeing conditions make a difference but I think, having checked collimation, I realised that the optics and coatings were not as good as my expectations. Moving on I have since bought better (at over twice the price) binos and the difference is, I am pleased to say, a dramatically better experience.

Incidentally, most binoculars, even expensive ones, are rarely sharp edge to edge and tend to have a reduced area that is sharp before things start to fall away. That said, this generally gets better the more you pay - good optics cost.

[BinocularSky]

Andy,

when focused the image is only clear in the centre of the view. The edges do seem slightly out of focus. Eg while looking at a bird pearched on an ariel. The bird is in good focus but if i look to the edges of the view its slightly out of focus. Is this normal ?

This is field curvature. It is "normal" in the sense that it will be present to some extent in all refractor systems that do not have field flattening included, and is generally more apparent in budget binoculars. It is generally most noticeable in wide-field binoculars.

But my main concern and frustration is whilst trying to observe stars and the like i can never seem to get them focused at all. Always blurred and never pin point. The moon does come i to view but then again never as clear as i would expect , as views through my scope provide. Is it because they are of lower end binos or is there an actual issue with them. Many thanks for any response

Again, this is a "feature" of budget binoculars. Some BSO (*) manufacturers try to get around it by internally masking the aperture (usually at the entry to the prism housing), which gives a sharper but dimmer image.

* Binocular-Shaped Object (courtesy Oortrageous)