A quirky advantage of using the NL Forehead Rest in horrid light conditions. (1 Viewer)

[Owlbarred]

In an earlier thread, Tehri 'opened my eyes' to the advantages of using the Forehead Rest (FR) with the eyepieces set to 0 (fully retracted).

Yesterday, I discovered a quirky additional advantage of doing so. Merely by rotating the FR (expanding its length) allows one to rapidly change the distance between the eyes and both eyepieces simultaneously -- adjusting for glare in either barrel as needed while scanning. No, the FR wheel does not rotate buttery-smooth, but it works and works relatively quickly.

For me, this is crucial because rapid glare adjustment is needed to cope with intractably horrid late-afternoon light conditions (and changing side glare) while scanning a large area when facing westward -- the only option -- while searching for meandering harriers coming to a ground roost.

In sum: the scanning arc at the site is roughly 35° on either side of the low sun, thus creating changing glare depending on the azimuth of the binoculars. Rotating the wheel on the FR allows rapidly adjusts the distance between the eyes and the eyepieces, allowing for glare adjustment while scanning,

Revised for clarity thanks to Maljunulo comments below.

 

[Maljunulo]

If the problem is stray light getting in around the oculars, and I’m not sure what you mean by “side glare” I don’t understand why you just don’t leave the eyecups out all the time.

What am I missing here?

 

[Owlbarred]

Good question. That’s what I would’ve said to someone making that same suggestion, That seems like the logical answer, but it’s not. At the Harrier site, because of the horrid light conditions over the arc of the scanned area, there is no eyepiece setting that works for all azimuths. If I used the old method of adjusting both eyepieces, I’d have to pull the binoculars away from my face, adjust each eyepiece, and then resume scanning only to have to readjust as azimuths changed. By turning the forehead rest as needed to rapidly change the distance between the eyes and the eyepieces lenses, it allows one to control glare in whatever barrel it occurs. The eyecups never touch the face, and the Forehead Rest is used for sole support, which as Tehri noted, works well. The method I described is absolutely not necessary for the other sites I visit but has proved a panacea at the harrier roost. It provides a rapid means to control glare in either barrel in severe lighting conditions. I never have to touch the eyepieces to adjust for glare.

Revised for clarity thanks to Maljunulo comments.

 

[Maljunulo]

I guess I’ll have to remain forever confused here.

I do not understand what makes it necessary for you to run your eyecups in and out as you change azimuth.

If I miss it this time, I’ll give up.

 

[Owlbarred]

I guess I’ll have to remain forever confused here.

I do not understand what makes it necessary for you to run your eyecups in and out as you change azimuth.

If I miss it this time, I’ll give up.

Glare conditions change over the arc of the large surveyed area. With eyepieces fully retracted, by turning the Forehead Rest wheel, I can control the distance between the eyes and the eyepiece lenses, in effect controlling glare while scanning over entire the arc of the large area being surveyed. No need to worry about eyecup adjustments.

Despite its warts, this method works for the specialized situation described in the earlier post.

Revised for clarity thanks to Maljunulo's inquries.

 

[Maljunulo]

I give up.

Thank you for your patience.

 

[Owlbarred]

Wish I could do better. One last try, I wish you were here, so I could demonstrate. All that’s happening is that the distance between the both eyes and each eyepiece is being changed/controlled as needed by rotating the forehead Rest wheel when side glare appears in one of the barrels as the azimuth changes. Simply said, it allows glare control while scanning during horrid, later-afternoon lighting conditions at the harrier roost.

Revised for clarity thanks to Maljunulo comments.

 

[Maljunulo]

You are not changing the eye relief, you are changing the distance from your eyeballs to the occular lenses.

Why you feel compelled to do that is what is beyond my ability to understand. I see what you are doing, but I do not follow the reasoning.

 

[Owlbarred]

Wish I could do better. One last try, I wish you were here, so I could demonstrate. All that’s happening is thateye relief is being changed/controlled as needed by the forehead rest when side glare appears in one of the barrels as the azimuth changes. Simply said, it’s proven effective in the horrid lighting conditions at the harrier roost

You are not changing the eye relief, you are changing the distance from your eyeballs to the occular lenses.

Why you feel compelled to do that is what is beyond my ability to understand. I see what you are doing, but I do not follow the reasoning.sorry for the misuse of the term and resulting confusion. By moving the wheel on the headrest you change the distance of the eye from the eyepiece lens

Oh boy, my bad, I used the wrong term. Thanks for the correction. I accordingly, revised the earlier posts.

I think reading the underlined text in the final paragraph will clarify things.

For persons reading only this post, the problem is that no single eyecup adjustment setting works to fully prevent glare across the entire ~ 70° arc of a large, repetitively-scanned area in horrid, west-facing, late afternoon light conditions (see post #1). Edge glare (or none whatsoever depending on azimuth) may appear in either objective lens as the area is scanned.

Note: The NLs have worked spectacularly in other settings. No need for the following:

A clarified revised version
Move the eyecups to their minimum position (closest to eyepiece lenses). Solely use the Forehead Rest for support -- when fully retracted, the eyecups do not (or need to) contact my face (I don't wear glasses). The distance between the eyes and both eyepiece lenses changes when you rotate the clunky wheel of the Forehead Rest, the exact thing that happens when one carefully adjusts the 6-position eyecups to minimize glare. But the method above is rapid, with no need to stop and adjust the eyecups as glare conditions change over a wide arc. This 'Glare Control on the Go' method allows for prolonged, continuous scanning for distant meandering harriers over a large area without interruption.

It's really as simple and effective as that, though I guess hard to envision.

 

[Maljunulo]

Well, thank you.

I certainly had no clue.

 

[Owene]

Thanks. Will try this