-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Which sub-alpha bino (2 Viewers)
- Thread starter oxygen
- Start date
james holdsworth
Consulting Biologist
Complete and utter rabbit hole.
I'm pretty sure, Dennis, you know what you are trying to perpetuate simply cannot exist - but yet you pursue it.
perterra
Well-known member
I'm not sure after you reach mid 40's that 4% is a perceptible difference for the normal human eye.
Pinewood
New York correspondent
Hello Perterra,
I doubt that a young man could perceive such a difference. This is what Bill Cook likes to point out: some folks obsessively pursue improvements which they cannot perceive. It may be measured but that does not mean that it is useful.
I would grant that for astronomical use, assuming clear skies, one might perceive a 4% improvement but in terrestrial diurnal use, I think not.
Happy bird watching,
Arthur
WJC
Well-known member
Now, Gerry:
Don’t you realize that if we removed all the posts relating to differences in optical performance that are demonstrably below the average observer’s ability to perceive, the forum would shrink to vapor? :cat:
Bill
ACTUALLY...the allbinos transmission % data is:
Conquest HD 10X42- 93.1%
MHG- 88.3%
SLC- 93.4%
House of Outdoors data:
Conquest HD 8X42- 92.5%
SLC 8X42- 90.1%
Shouldn't be any difference with any 8X binocular. I don't notice a difference. As Lee mentioned, the fast focus of the Conquest HD may amplify this perception.
If one desires more DOF...get a 7X42...
WJC
Well-known member
Sorry, Arthur,
I was working on mine while you were working on yours.
In the vein of stacking BBs, I have designed telescopes in which all visible wavelengths—at the edge of a 1.5-degree field—would fit in the Airy disc and look like a pea in the middle of a platter. My BB stacking was for the purpose of learning. But ...
Neither hands nor machine could produce the optics to spec, changes in temperature and humidity would keep the performance in flux, a dove flapping its wings 50 feet away could destroy the best interferometric testing, and NO HUMAN EVER BORN could discern the difference between that telescope and one in which those rays got even close to the EDGES of that platter (Airy disc). Furthermore, there are folks who have bragged about their 3-quarter wave mirror as if it were made by God or Zambuto.
We all have such varied differences in perceptions. If you took the smoothest lens or mirror surface ever produced, and magnified it enough, it would look like an aerial view of a rock quarry! (Note Herbert Highstone’s excellent article in The Best of Amateur Telescope Making Journal, Vol. 2). And before anyone gets their knickers in a twist because I am promoting an article in the book, all should know I don’t get a dime from them. :cat:
Bill
Last edited:
I am curious why Upland observed it. I don't think I did when I had my Conquest's. You can't say it doesn't exist because all our eyes are different. I am sure Upland observed what he did. Some people see different things through the same binoculars. For example, some see glare through the SV 8x32 and some don't. Some see CA and some don't. I think DOF is more complicated than it seems on the surface."Depth of field refers to the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. In principle, only the image on which the binoculars are focused is really clear and sharp. However, since people are fortunately able to see slightly blurred images as sharp, phenomena like depth of field occurs. The consequence of this is that the depth of field is not easy to determine. One person may think that a particular image is sharp and crisp whereas another person may find this same image unacceptably poor in quality." I think everybody differs in what they feel is sharp so Upland may be more critical than some other people in what he feels is sharp hence he feels the DOF of the Conquest is poor while others who are less critical would think it satisfactory.
Last edited:
Sometimes I do question Allbino's data when they get 88.3% transmission on the Conquest HD 8x32 and they get 93.1% on the Conquest HD 10x42. Too much difference in my opinion for the same binoculars even if they are different formats.
dries1
Member
I got my laughs tonight from these two, I call this humor with a twist.
"Don’t you realize that if we removed all the posts relating to differences in optical performance that are demonstrably below the average observer’s ability to perceive, the forum would shrink to vapor? "
"Occasionally I read a post here which states that two instruments are "essentially the same" or "do not differ significantly" and I am tempted to suggest a trip to the ophthalmologist, or at least an optometrist.
So far I think I have resisted this impulse".
Andy W.
"Don’t you realize that if we removed all the posts relating to differences in optical performance that are demonstrably below the average observer’s ability to perceive, the forum would shrink to vapor? "
"Occasionally I read a post here which states that two instruments are "essentially the same" or "do not differ significantly" and I am tempted to suggest a trip to the ophthalmologist, or at least an optometrist.
So far I think I have resisted this impulse".
Andy W.
WJC
Well-known member
Sorry, Richard:
Neither doctor could help because so many of the questionable contributors don’t relate well to reality, in that they cannot do so and still have a sturdy soapbox under themselves. In the Navy, we just fixed and collimated the stuff. In the civilian world, it’s a realm for conversation. And while accuracy is helpful, it’s not essential.
I once saw a question on a writer’s forum about how many spaces should be used after a period. The answers included: what “I’ve always used …,” what “I think looks best …,” what “I always heard …,” and what “my 8th-grade teacher said ....”
With this having gone on post after post, I took pity and butted in. Please remember, these were people who presented themselves as professional writers.
I offered references from the Chicago Manual of Style, with additional information from the Associated Press Style Guide. Yet when I walked away from the forum for the last time there had been over 50 more responses. There was more of: what “I’ve always used …,” what “I think looks best …,” etc.
It seemed clear to me those people weren’t really looking for the helpful information they claimed; that certainly wouldn’t have taken days of discussion. I’m confident they just wanted to chat and circulate their own opinions. Being right or wrong had little place in the issue. The same can be said about binocular forums. An important question might be answered by someone quoting a renowned authority in the pertinent field only to have the quote ignored so the questioner can get swiftly back to the opinions of well-read, armchair speculators. :cat:
Bill
Last edited:
james holdsworth
Consulting Biologist
Dennis,
I'm sure that what Upland is experiencing is the fast focus effect of the Conquest, which can suggest lesser DOF. We know that DOF is fixed by magnification.
Also, Dennis, you mention less contrast in the Conquest - I suggest you go back and review what you said when you briefly owned the 8x32 HD - ''great contrast'', even compared to the 8x32 SV....have your later samples been noticeably different?
I assume transmission values are photometrically weighted, assuming they are going to be used in the daytime. Also technically any measurement without some form of associated uncertainty is invalid. For instance I can eyeball binocular transmission values to arbitrary precision..... but with a “healthy” 20% or so uncertainty (expressed at the 95% confidence level).
I’ll get off my box now. I happen to enjoy the views through my sub-sub-alpha-beta binoculars, some of them were alphas once.
PEter
I’ll get off my box now. I happen to enjoy the views through my sub-sub-alpha-beta binoculars, some of them were alphas once.
PEter
James: if you are sure that what I experienced was the fast focus effect please explain this to me: I would get many objects at varying distances in perfect focus and then look at nearby objects both fore and aft. These objects would be out of focus. I was not touching the focus wheel after I got the initial object in focus. As I said this happened at all distances near and far. I don’t get that with my other glasses.
james holdsworth
Consulting Biologist
No idea, I only know that the optics experts here - far more expert than me - assert that DOF is determined by magnification. Your perception of that, however, is going to be personal...and apparently variable.
If you think about DOF it is subjective just like a lot of other parameters when viewing with binoculars. When you focus on something really only that object is truly in sharp focus and objects nearer and farther from that object are going to be slightly out of focus no matter how good you might think a binoculars DOF is. It is subject to your own eyes and personal opinion of how sharp those other objects are. The binocular is performing the same it is just that your perception is different from others.
Last edited:
Similar threads
