Focusing IF binoculars, diiference between both eyes? (1 Viewer)

Maljunulo said:

Maybe you are accommodating instead of doing your focusing with the glasses, so you have to go back and readjust after your eyes relax.

Just guessing.

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WJC said:

Hey, Rich, stop guessing and put a number on it and make it more ... scientific! There's a 99.3762582% chance that the problem is in ACCOMMODATION. :cat:

Bill

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Eric.TB said:

Hello Bill. Could you please provide some tips on what method is best for focusing IF binos?

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WJC said:

Learn to STARE so your eyes are at rest while focusing; it’s very important—at least if you want the best possible image.

Bill

PS Welcome to our little band of misfits!

From Vignette 10, page 23

... Frequently, those new to binocular observing will focus on a target quickly and expect the instrument to remain focused—at least at the given distance. However, let’s say you have an accommodation range of 4 diopters and stop focusing the instant you have an adequate image. As time goes on, observing may become problematic because your natural (relaxed at that distance) focus setting should be (for example) -1.5 diopters. That means being in a hurry has placed your focus at an accommodatable, but strained, setting. Then, as fatigue sets in, you may fiddle unnecessarily with the focus or suppose there’s something wrong with your eyes or the binocular when neither is true. In addition, as this “fiddling” takes place the observer will more than likely repeat the hurried technique that got him into trouble in the first place, leaving him once again with an imprecise focus. Perhaps your mother taught you never to stare. Nevertheless, if you want a crisp image, you had better forget that advice.

Vignette 10, page 25

A Digression on Focusing

... Some observers have been led to believe they have to focus their binocular by placing a hand over one objective, then the other. For others, even that isn’t good enough. They think they must place the lens cap over one objective, then do the same with the other side.

I have never understood why one technique is more desirable than the other, especially since the person who has learned to stare—a task that should be learned anyway—never has to worry about the problem. Likewise, they never have to worry about the subject that drove, pedaled, ran, flew, or swam away while they were seeking the ever-elusive perfect focus. Do you derive pleasure from observing or focusing?

[Anyway, precise focus changes with each change in distance. Some of those teaching newbies how to focus leave that valuable piece of information ... out.]

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Eric.TB said:

Great, thanks for the information.

What is your take on leaving both eyes open, and concentrating only on one eye and focusing, then doing the same with the other? Is this not a good practice?

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WJC said:

Over time, you may develop that ability. Right now, GENTLY closing one eye at a time may be your best answer. Your brain wants to out-think you (involuntary accommodation); Don’t let it.

There are two more things to consider:

1) The IPD needs to be accurate.

2) Collimation needs to be good. I’ve had any number of people tell me their binocular was “perfectly collimated” when the collimator told a very different story. Again, accommodation (spatial) was at work. But accommodation cannot be sustained without some degree of eyestrain. As in removing the bino from your eyes and looking at the stars directly. :cat:

Bill

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Eric.TB said:

I've done the defocused star test several times, the star from the left barrel is dead center, as well as using telephone wires at a distance, and backing my eyes away from the eyepieces and looking at the level of the wires. I'm certain the collimation is good. Plus it's a Celestron Echelon, a halfway decent instrument.

Thank you for your advice. I will certainly use it.

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