Nixterdemus,
You are evidently trying to make a mountain out of a molehill here or maybe you don't get what is going on.
When curious I prefer going to the source & it is your review. I've formed no conclusions that indicated you erred.
I stated that the magnification was 8x. I determined that by shining a light through the ocular and measuring the diameter of the light circle through the binocular. It was 42 mm and the exit pupil is 5.25 mm.
I refer you to Henry's post #26 & 31.
You are talking about resolution.
Resolution, but at maximum distance w/o magnification X whatevah power should evah so roughly also be able to be resolved.
It does not matter enough to matter if you or I or somebody else can read 1/16" on a yellow Stanley tape closer or further away than somebody else can.
Out of context. I merely used a known quality, Stanley tape, at a specific maximum distance unaided view, not excluding corrective lens if required, X 10 due to example of a 10X bin.
If a binocular has a specified fov of 8* or 420' at 1,000 yards you need to be able to see about 50.5 inches of tape. 50 inches is 417' and 51 inches is 425'. That last half inch is easy enough to see even if if the binocular is slightly out of focus, which due to edge distortions and field curvature, it probably will be. If the binocular falls close to those outer limits, my take, as I have stated previously, is close enough. Yes over the whole series of production runs there will be some sample variation in magnification as well as with fov. In my experience it is rare for one of these to get out of whack by over the design specified QC spread. Again I am not too concerned with a couple of tenths magnification or with a couple of tenths of fov variance.
So, anything you can see whilst mounted to the bins is fov & if you cannot read the 1/16" you rely on 1/8" &/or perhaps a bit o' estimation. If the couple of tenths become a half or even more that would be significant.
How clearly the binocular reads the small gradations across the view of the tape is useful in determining size of sweet spot. Resolution is determined in the center field of the binocular.
You do have to strain or screw your eyes to actually getting a reading at the edge of the field. Typically the fov is the same with one barrel vs both. Yes there can be differences if specifications from ones side to the other. When two sides differ enough to exceed the ability of the users eye to accommodate there will be issues with apparent focus and some eye strain or lack of depth of field.
I don't know what I was thinking when I suggested that one barrel doubled would equal the bins fov. I was curious of possible extra fov from not forming a perfect circle w/both barrels. Plausible especially w/fat E.P.
Also if you have properly set the focus for the binocular it seems you are dealing with corrected vision.
It seems Steve Ingraham used some small spots on dollar bills to use for vision acuity, but he was talking about resolution in those reviews.
Also Nixterdemus please note the 8*/420 feet was just an example, not a reference to the fov I measured in the Toric.
Some folks require corrective lens to view through bins, but even if they do not the diopter adjustment w/focus could be considered corrected vision.
My use of 'corrected vision' is not of the latter.
I just found it peculiar that you referenced your example of 8*/420' w/377' of the listed spec for the reviewed bin instead of your 7.8*/404' determination.
I suggest you can screw your eye balls around the fov all you want.
That's a childish approach at best. I wondered if you stayed mounted looking to the sides for fov & if you could see more unmounted looking across the field stops.
I cannot hardly view at any deviation L-R w/o vision blacking out. Possibly if I backed away from the mount though I cannot stand not being buried in the eyecups. I can look sideways across the field stop unmounted one eyed for more fov & in one case the other day, at the same time, it brought the previously out of focus far edge into sharp focus. I could see fine detail of the small red berries that grow from an ivy type vine. I know what's up w/that, how 'bout you?
This method has been discussed here in discussions of how to measure fov. It works for my purposes.
You do have to screw the eye somewhat to actually read the tape at the edge. There can be some issues with the two barrels differing too much from each other.
I never speculated that you invented the method, nor do I doubt that it works accurately enough if indeed the magnification is as stated. You have no problem dismissing spec sheet fov/close focus, yet you do not question magnification to the point of testing.
Closer than spec minimum focus combined w/larger than spec fov would seem to suggest that perhaps the spec'd magnification is lagging a wee bit on the low side. Doesn't have to, but it could. Also, if lower than 8X it doesn't have to be to the point of 377'. Instead of the whole 27' it might only account for around half putting the bin at a very respectable 390'.
Because of blackouts when straying very much from center view wide fov means little to me. I can see fov w/peripheral though devoid of sharp detail. However, I note it seems to be a big item for birders in the lower, <12X, magnifications. The higher magnification, even if considered wide fov, are narrow enough for me to see the entire fov sharply.
Is it possible that bias for large fov prevents some from digging any deeper when they run across a much larger fov and/or significantly shorter miniumum focus than spec'd?
I enjoy reading your reviews. Not quite as much fun as analyzing various possibilities for the abundent fov. I love a good argument though do not care to argue.
JGRaider came up w/similar results. For whatevah reason the fov appears to hover around 400' suggesting a pattern in at least a sample of two.
Thanks for your replies I appreciate your explanations and the time it took to present them unto me.
I think my next book will be—
Hey swabbie how 'bout sharing that w/Cloudy Nights crew?
Oh, R-I-G-H-T
nevermind ...