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Always used 10x but thinking about switching to 8x (1 Viewer)

pshute, post 87,
The effect of magnification on image quality of handhold binoculars is very well investigated by Russian scientists and by Zeiss scientists, I have published some graphs and references on Birdforum some time ago, but if one is interested I could repeat it. One graph can be found in a review of published literature I have published on the WEB-site of House of Outdoor entitled "Color vision, brightness, resolution and contrast in binocular images" figure 39 (the paper is in English). You may be surprised by this graph, since it indicates that at magnifictions of 6-7x and more resolution rapidly declines when handhold. The Russian investigators reach the same conclusions.
Gijs van Ginkel

Here is the graph to which Gijs refers, the gap between the two curves represents the detail lost by hand-holding instead of using supported binos:

Lee
 

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For me when I started birding the answer to this was obvious. Binos are to bring things closer, 10x brings things closer than 8x, therefore 10x is better.

For many years now I have preferred 8x as a well-balanced compromise between magnification, field of view, depth of field and hand tremble.

But I use a 10x in special places.

Lee

Sums it up for me too.
 
Here is the graph to which Gijs refers, the gap between the two curves represents the detail lost by hand-holding instead of using supported binos:

Lee
That graph is "efficiency" vs magnification. What's "efficiency"?

It shows a steady increase with magnification both hand held and supported, which doesn't match what Gijs said: "at magnifications 6-7x and more resolution rapidly declines when handheld". Is this the right graph?
 
Your comments please Gijs? Thank you!

Here is all the relevant text I can find in a fairly quick reading:

Within the article:
"The resolution is also diminished when binoculars are used handheld. Handheld binoculars with 8x magnification may perform 20-30% less due to muscular tremble or shake than supported binoculars and this difference grows with increasing magnification. This muscular tremble does affect the visual resolution."

The figure caption:
Figure 39
"Visual resolution for handheld binoculars is lower than for supported binoculars and this effect increases with increasing magnification."

It appears that the y axis shows "effective resolution". Steadied this is always equal to the nominal figure: with 8x it is 8x. Handheld it is always (in the range shown) less than that: 8x delivers the degree of detail conveyed by a steadied 5.5x approx., 10x delivers at approx. 6.5x.

I may be mistaken but it seems to me from my experience that in actual nature watching the differences in the typical x ranges we use are not quite that dramatic. I would think that for a typical user in the field the difference in 10x supported vs 10x handheld is striking but 8x supported vs 8x handheld is not so easily seen.
 
That graph is "efficiency" vs magnification. What's "efficiency"?

It shows a steady increase with magnification both hand held and supported, which doesn't match what Gijs said: "at magnifications 6-7x and more resolution rapidly declines when handheld". Is this the right graph?

Unfortunately without the experimental details and data points we can't be sure what that plot is telling us. I suppose it's meant to illustrate the relative level of detail observer on a tripod and hand held. We just have to calculate the "efficiency" ourselves. Just reading off the screen as best I can
4x 82%
6x 75%
8x 71%
10x 66%
12x 63%

I've done this kind of comparison a few times with different binoculars I have around at the moment. Usually just 3 to 5 at a time when I think one or another feels steadier or shakier in the hand than usual. My results don't sit on a smooth line like that. The binoculars have different weights, lengths, balance points and grip comfort which all appear to affect the results. On one occasion I experimented with just adding weight to a a few of my binoculars and got improvements of up to 10%.

Last time I did a comparison was when I had a 12x50 for review.
7x 65%
8x 52%
10x 70%
12x 60%
You should spot that the 8x looks particularly out of line with the others. I've had that model for a while. At my IPD I find the grip particularly awkward. I think it is hand tension that makes the view particularly jittery. I've had better results with other 8x binoculars. The 7x is only 620g (22 oz). It was one of the those where I tried extra weight in the experiment I mentioned, and got an 8% improvement. The 10x is my most used. The weight, dimensions and other characteristics just seem to suite me.

Obviously everyone has different physical attributes and will get different results with different models. I sure it's no surprise to anyone that magnification alone is not the only factor in stability. Things like weight, balance and grip tension are going to make a difference. I'm guessing that to get a smooth curve like the one shown in that plot they would either have to standardise some of the binocular's physical metrics, or otherwise average a considerable number of binocular models and user data points.

David
 
So it is better handheld and far better supported.....but it is always better ! :)



No, I don't think so. The further away the hand-held curve gets from the supported curve, the worse is the detail seen. So the best is 4x because the gap between the two curves is the smallest and 10x is worse than 8x because the gap at the 10x point is bigger than for 8x.

Lee
 
Dear all,
If everything goes as planned you will find figure 1 from the publication "Effect of hand tremor on observation efficiency in binoculars"written by L.P. Osipova and V.V. Potikhonova in Sov. J. Opt. Technol. vol. 58 (9), sept. 1991, pages 542-544.
The graph is similar to the one shown and discussed here and published by Zeiss.
I hope that clarifies everything.
Gijs van Ginkel
 

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For those who are interested in the experimental conditions of the test results: -
Test charts were viewed in daylight with an illuminance of about 10 to the power 4 lux. Test charts were mounted against a natural landscape background of 50-110 m. About 70 trained obeservers aged 18-20 took part in the experiment. Furtheron they alsodescribe the use of auxiliary test targets and test conditions, but you have to read all that yourself. The tests have been performed with great precision and utmost care.
Gijs van Ginkel
 
Gijs,

Do you have the definition for the alpha prime value on the y-axis?

David

PS. What are groups 1 and 2? I think the plot might make more sense if the lower line was the tripod mounted result.
 
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While waiting for clarification on the new graph (from some source):

- This thread (linked here) in another forum should be of interest.

- My comments above refer only to a model/s which provide the steadiest view for an individual. Certainly not for "near-worst-case scenarios" such as David has encountered when he went to the trouble of quantitative testing!

- Here is what I have written in another thread (link) (in two posts, the latter a response on one type of use):

"To me (as an individual user) there is no gain in mounting an 8x. There is some steadying but at the distance at which this makes a visible difference the subject is too far for an 8x image to convey more useful detail. With 10x mounted versus 10x handheld, however, there is a significant difference in image detail. There is a further improvement with 12x mounted over 10x mounted..."

"Among those who can hold a 8x steady enough but not a 10x, or a 10x but not 12x, in ordinary bird watching, many will find that they can use the higher power or powers for observing a distant raptor in flight, well enough even to make out finer points in ID, or I assume, an aircraft flying across. I think this is because the binocular is anyway being moved, smoothly, as it follows the subject, and then shake does not occur or does not affect this, and also it is being held more vertically."
 
adhoc, post 111,
I have given the reference of the publication of the graph I showed in post 108, so if you search for the journal you will be able to find it.
The graph in post 108 is obtained from many measured data collected form 70 trained observers age 18-20, as I have written before, there were a number of different test objects and different observation distances. Test charts used : two dimensional patterns in accordance with a mentioned standards: Landol rings, Snellen symbols and alphabetic tests not on a white background but a background of a greyish pattern as one would find in nature.
They also refer to smilar tests done and published by Brunnckow, Reeger and Siedentopf published in Z. Instrumentk. No 64, 86 (1944). The graph in the post by Lee, from my review paper is essentially from these authors.
For those interested: the handbook by König und Köhler, "Die Fernrohre und Entfernungsmesser", third edition1959, published a table on page 101, which show the same results as both publications mentioned here.
Their conclusion is: "Man sieht dass man mit aufgelegtem Feldstecher ein Fernrohrleistung erreicht, die im besten Falle rund 90% der Fernrohrenvergrösserung beträgt. Diese 90%, der sogenannte Nutzunsgrad des Fernrohres, nehmen bei zunehmende Vergrösserung sehr ab.Man sieht ferner, dass der Nutzungsgrad, besonders bei freihändiger Beobachtung, wesentlich niedriger liegt und das er besonders bei Vergrösserungen über 8 fach bei freihandiger Beobachtung kleiner als 60% wird".
That is all in accordance with the Russian paper and with the Zeiss data in the graph, which Lee-Troubadour took from my review paper.
Gijs van Ginkel
 
The graph in post 101, which Lee took from my review paper, can be found, for those who have difficulty reading German, on page 53 of the "Field guide to Binoculars and Scopes" by Paul R Yoder, Jr. and Daniel Vukobratovitch, Spie press 2011. This graph is in full accordance with the data from the papers I mentioned in my post 112.
Gijs van Ginkel

P.S. There are more Russian papers devoted to this subject, but I think that the data I referred to are convincing enough.
 
Gijs,
Thank you very much for the information.
The first thing I did on reading your post #108 and viewing its graph was indeed to search (Google) for the text of the publication, in order to try to understand the graph. But I am still unable to find it.
For now could you please say what the values on the y axis represent? Thanks!
I did not separately thank you for your outstanding paper because I think I have done that some time back!
Adhoc
 
adhoc, post 115,
Apologies, I understand where your question is about. I think added figure 2 is much better to understand, as a plot of real resolution against magnification whereas the figure I showed before may have not been quite clear. Moreover the figure 2 also contains a plot of a German study showing exactly the same pattern, so it may be more helpful for comparison.
Gijs van Ginkel
 

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Gijs, Adhoc,

Rather than resolution, I think the y-axis of the #108 plot might be better understood as apparent visual acuity. I am unsure if the value is as simple as the visual limit multiplied by the magnification. That would mean that the unaided visual acuity of the test group is a little better than 70 arcseconds which sounds unlikely, even for 20 year olds. I thought there might be some other mathematical adjustment?

The plot in #117 puzzles me. How can the lines be parallel? At a magnification of 1x don't the lines have to converge? The label at the bottom says 1- Test Results and 2- data of Ref. 9. Is the plot compilation of two entirely different experiments?

David
 
David,post 118,
One plot is from the Russian investigators and the other one is from German investigators. The point is that both investigations show the same pattern: with increasing magnification handhold binoculars perform worse than stabilised (tripod or something similar) binoculars and all mention a sort of optimal boundary for a steady handhold image at a magnification around 8x.
That is probably also the reason that the infantry used mainly 6x30 and on ships 7x50 although the last one has some other advantages as well for that purpose. That is not the point of this thread where the discussion is: 8x or 10x?? The experimental data indicate that for handheld binoculars 8x yields a better view with regard to a steady image than 10x.
Gijs van Ginkel
 
Gijs,

I'm certainly not denying that magnification is a primary factor limiting apparent visual acuity, just that it is the only one.

I hope you would understand that any experimental result only applies within the limits of experimental design. When you present simple line plots without an adequate explaination I think anyone is entitled to wonder what it means and whether it has any relevance to them.

I've not seen the original work, but if the study used 1940's uncoated, heavy military binoculars, and only used young military trained men selected for the excellent acuity, wouldn't you question how applicable it might be to you? I'm not a fighting fit 20 year old either, and I wouldn't generally use 75 year old military binoculars.

I'm only one of many on the forum that point out that weight balance and grip also matter and I've found examples where I experience less visual loss through shake with a particular 10x than a quite different 8x. It's a complex matter and one size does not fit all.

David
 
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