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- Magnification and move vision: (1 Viewer)

Rico70

Well-known member
To better understand the issue, we should first try to understand what are the foundations that govern this topic.
Let's start by saying that magnification means magnifying the visible detail and that the cause of a blurred or shaky vision observable through the binoculars used freehand, it cannot and must never be attributed to the greater magnification.
Therefore, there is in fact no magnification value which due to itself is the limiting factor of the observed or observable detail.
The causes are fundamentally attributable to the user (who in no case will remain rigid as a block of granite), but also to the limits of visibility through the atmosphere (when this enters into question, generally for long-range observations) and others causes such as the disparity of ergonomics and optical quality, between the binoculars in comparison (but these disparities are subjective and therefore useless causes in the general objective discourse).

Let's try to clear the mind, to make room for the principle that any magnification value assigned to optical observation instruments, such as magnifying glasses, microscopes, telescopes, telescopes, sights, aiming optics, rangefinders, eyepieces, eyeglasses, eyeglasses, binoculars, etc., it always refers to the vision with the naked eye. This, in fact, is the absolute reference, and is equivalent to the value of 1x (that is, 1 magnification).

The magnification of each binoculars, indicates how many times larger we will see the objects, compared to the apparent dimensions observed with the naked eye. So, for example, each 10x binocular increases the apparent linear measurements of objects by 10 times, such as the diameter of the disk of the full Moon, which will appear 10 times greater than that visible to the naked eye. And this also means a proportional increase in visible detail, equal to 10 times as much, similarly to having increased the optical resolution of our visual system by 10 times.
The math is not an opinion!

Since the resolution of the observed details is directly proportional to the magnification value, it will be logical that in order to detect certain details in normal lighting conditions, a very specific minimum magnification is needed, which is appropriate for the purpose.
And the question is clearly mathematical, as it all depends on the actual size and observation distance of the object.
But, with the same observation conditions and of course also the quality of the binoculars used, the precise value of the magnification necessary to read certain details, will depend substantially on the individual value of the visual acuity of each observer (where, the visual acuity is in in this case the value equivalent to what the optical resolution is for all optical observation instruments, such as binoculars).

Visual acuity values ​​between normal individuals can vary by a maximum of 2x, from 10 tenths to 20 tenths. But 60% of the population has on average a maximum visual acuity of 14 tenths, which is the middle way between the normal value 10/10 and the maximum value 20/10. Thus, the most common differential factors will be between 1.2x and 1.8x. And just to give an example, the same detail that user A (with 12 tenths) can detect using 10x binoculars, user B (with 18 tenths) could detect it using binoculars of just about 7x (all things being equal, quality , ergonomics, etc.).
This immediately suggests that no golden rule can ever indicate a unique, good and right magnification value, which is ideal for everyone.
But on the contrary, that the choice of magnification will be absolutely a completely personal matter, and that it will be determined by so many other factors that I struggle to list them all, among which we will find the very important needs for use and therefore, the various individual needs.

-------------------------

Having said that, however, there is also a general line at the basis of the geometric rules on optical resolution, which is valid for anyone and which establishes that in order to discriminate-separate-resolve at a minimum level the details barely perceptible with the eye vision naked (to the limit of individual possibilities), the magnification must be increased by at least 3 times as much (that is, at least 3 times the starting optical resolution).
That is, in order to effectively separate-discriminate two adjacent light points (like two nearby stars) or two consecutive white lines in a test with alternating black and white lines, at least three retinal photoreceptors are required. A similar example is given by the spatial resolution of digital cameras, based on the quantity of pixels needed to be able to discriminate the same test with alternating black and white lines. And in fact, the results of the research on the estimation of the radial movement of the focus (FRM - Journal of Vision August 2016, Vol. 16, 12. doi: 10.1167 / 16.2.12), indicate that [...] The standard deviation the Gaussian RF profile is one third of the distance between the centers of two consecutive RF [...] confirming in part a similarity between the functioning of the photographic sensor and the functioning of the ocular retina (analogy between eye and camera).
And since the magnification directly describes the increase in optical resolution compared to viewing with the naked eye (1x), a 2x binoculars which doubles the resolution, doubling the size of the objects and its details, will not be able to solve at a minimum level sufficient, that detail barely perceptible to the naked eye. But you will need to use at least 3x binoculars instead.

Again for geometric reasons, a passage of 3.24x (given by the power of the factor 1.8x) represents that minimum reliable step, in order to arrive in a certain way to the higher level of detail visibility. And then starting from the 1x reference of the naked eye vision, the subsequent magnification values, with minimum steps of useful resolution (3.24x), will be indicated in a rounded way, such as: 3.3x 10x 34x 110x 360x ... etc. These represent the basic values, but also essential to obtain at each subsequent step, that minimum increase of detail necessary to solve the previous level. The intermediate levels to these (that is, in steps of 1.8x), become mostly useless, although they are still usable or preferable in place of other values ​​that are too close together. And they can be rounded to: 2x 6x 20x 60x 200x 640x ... etc.

Raising the minimum factor 3.24x (3.24^2) to power, the visibility of the detail reaches a higher plane, made with steps of approximately 10.5x.
This corresponds to the increase necessary, in order to be able to adequately resolve what is absolutely not possible to solve or even perceive, with the naked eye (1x). Where the various plans will be translated with the enlargement steps rounded to: 10x 110x 1200x ... etc.

Magnification scale, in steps of 1.8x (rounded values): 1x 2x 3.3x 6x 10x 20x 34x 60x 110x 200x 360x 640x 1200x ... etc.


From all this, it is easy to see that the 10x magnification is in practice the minimum necessary to be able "to enter the binocular high definition", since it is the first of the scale able to show us what is normally impossible even just to glimpse with the naked eye . That is, the 10x binoculars manages to bring directly to attention, that detail that would like to solve our ocular fovea, in careful observation (the fovea is that central retinal area where the maximum density of diurnal receptors resides, and of average amplitude between 4 ° and 6 ° of the visual field).
Thus, while the 12x is able to increase the detail in a more evident way than the 10x, the 8x is unable to adequately enlarge the details barely perceptible with the naked eye vision. And for this reason, instruments with magnifications lower than 10x will be preferable at smaller distances and to take advantage of the greater amplitude of the visual field (when possible), while magnifications greater than 10x will be proportionally suitable for observing smaller and smaller objects and / or further away, or where more details are required (typically in ornithological, safari, astronomy, etc.). This is also the main reason for the topic under discussion: the visibility of the blur (moved-stir).


Often it is unjustly attributed to magnification, the fault of a blurred and shaky vision. And this also leads to believe in an illusory way, that freehand management has a maximum magnification value. While everything depends exclusively on the user and his inability to stabilize binoculars (not only by improving physical support, but also by using eye stabilization).
So for some users, the larger magnification means being able to look further and aim for a sharper detail, addressing the higher values ​​(useful for any sightings and recognitions) aware of having to improve the stability of the binoculars and their vision, with training and devising functional solutions or accepting any compromises.
While for other users it seems to be more a question of making the blur they themselves produce invisible, reducing the magnification at all costs, until everything appears "stable" to their sight (which is actually impossible!). And so far there is nothing wrong. A choice like this may also be justified, but the important thing is that then it does not lead to believe, or worse, to want to argue, that in doing so it is possible to see better and more detailed, since it would be only a mere illusion from incompetent.

The purpose of the binoculars is undoubtedly to enlarge the details, and it is clear that this will also proportionally highlight any hand shake, which could disturb the observation. But the blur of the hand is precisely the blur of the user, and not of the binoculars or its magnification. Therefore, the user's blur will in any case always be present, regardless of the magnification used, be it 6x or 12x (for example). With the only difference that the blur will appear doubly visible in the 12x binoculars compared to the one visible in the 6x (as per physical laws). And that is, both the detail and the blur visible, will be equally proportionate to the value of the magnification used.

But understanding this irrefutable fact is very important. Since, one must also be aware that:

1 - the less magnified vision may appear even firmer and thus be more restful, but that same vision will certainly (and also mathematically) be equally less detailed. And for this, useless for the purpose of detecting more details.
2 - the cause of any loss of detail due to instability or blur is to be attributed only and exclusively to the limited capacity of the users and not to the possible greater enlargement of the binoculars. On the contrary, on the contrary, it is always preferable to be able to increase the magnification.
3 - it is not by reducing the magnification that the binoculars stabilize. In doing so, only detail is lost.
4 - the maximum limit of detail observed with a particular binocular, exclusively and once again dictates it, the user, with his ability or inability to static stabilization (kineticism) and with any biopsychic abilities or difficulties of his vision binocular.
5 - to increase the visible detail it is understandably necessary to have to increase the magnification, but it will also be essential to learn to better stabilize your hands and especially your binoculars, also training your vision to follow the moving images.

Unfortunately, stable vision through binoculars is the consequence of various individual factors that cannot be generalized. Even many of us have difficulties in binocular observation alone: ​​Cit. [...] the majority of subjects, albeit asymptomatic, have problems concerning binocular vision (Heterophoria and Fixation Disparity) and therefore compromise their daily lives, from the simplest things like playing sports, to activities that require greater attention and visual commitment, such as reading or studying [...] or for example, observing in binoculars.
Of course, it is possible to say that as the magnifications increase, the user-generated shake will become increasingly visible to the eye.
And so, while the vision with binoculars up to 6x still appears fairly stable and "without" visible shake, the vision with values ​​greater than 9x, will be more often visibly shake. But binoculars with magnification up to 6x, appear easier to handle freehand, because it is easier for anyone to hide their instability from use. While, the typical shake with very fine structure present at 10x, will be concretely visible by anyone (especially in the observation of the starry sky, in the way of fixing a single point).

The eye has automatic image stabilization capabilities, capable of hiding part of the blur, using the saccadic and tracking movements and also with the tricks of its perceptive system. But this system becomes more efficient by increasing the blur magnification. And so, with magnifications much greater than 10x, where the shake will have a much larger size, the eye will be gradually facilitated to stabilize the images almost automatically. Of course, training and habit will help improve the results obtained, which will also become useful for the use of lower magnification binoculars. Of course the stabilization of the eye works more in daytime terrestrial observations, compared to night vision, but in practice it will be paradoxically easier to hold 100x binoculars freehand rather than 10x. Since, at 100x, the shake becomes so "large" that there is no longer a shake, but only a wide movement, which is certainly easier to manage and "absorb" for the eye, compared to the "too fine" shake of the 10x. And in fact, using 100x freehand binoculars, it will be possible to see all those fine details that are impossible to see, both at 10x but also at 30x, even if these binoculars were stabilized on a tripod.
The same criterion is valid in a lesser way also for 25x and 34x magnifications so that, having the subjects at the right distance and a sufficient field of view, it will also be possible to easily attach and follow many subjects in rapid movement, as can be done with low magnification binoculars. Unfortunately, not everyone has the same ability to exploit these bio-psychic and kinetic possibilities. And for some users, 10x binoculars already appear difficult to manage, although in practice most of the binoculars users have never seriously tried to use the 12x to 25x tools. Often, also because few light and good quality binoculars are sold, with magnifications greater than 15x.



I firmly believe that everyone must judge the various binoculars trying every magnification, using their own eyes and hands, with an open mind, without being conditioned by the commonplaces of others. And rather trying to understand with intelligence, how to improve the stability of the observations and obtain the detail sought. Knowing in advance that ergonomics, weight balance, ease of controls and precise optical adaptation of the instrument are all very important, if not fundamental, factors that will influence stability management, always improving the quality of our observations . So much so that at the same magnification, the ergonomic differences of the various models could lead to a particular binocular being even "much more stable" than another. But only in this case, will it really be possible to talk about the merits or demerits of the instrument. And for this reason, it is always better to try binoculars in person and be able to make many direct comparisons between the various models, finding the differences, evident or perhaps substantial, regarding ergonomics and good management of free-hand stability.
 
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Alexis Powell

Natural history enthusiast
United States
A fine treatise on (primarily) binocular magnification. Some of your points match my practical experience, but overall, I don't think magnification is itself a very important consideration for birding binoculars. I own a lot of binoculars and I engage in a lot of types of birding, so I appreciate the merits of different specifications and designs for different practical purposes, even for the same user. Nevertheless, when it comes to birding, I think all-in-all, the biggest challenge for a multi-purpose (overall excellent) birding bin is to have the capability to get on the bird as quickly as possible. Many otherwise fine binoculars fail as overall birding binoculars on that measure. Getting on the bird quickly is important, for example, for efficiently sorting through mixed flocks flitting through trees or brush, getting diagnostic views of flybys, detecting and identifying diving birds as they briefly surface, or sorting through waterfowl as they come into view as they trade positions with one another at the perimeter of a mixed-species raft. The properties that allow for rapid target acquisition are good handling/fit to eyes, FOV, DOF, rapid precise focus control, and optical "transparency" (e.g. lack of CA, strong color casts, momentarily disorienting distortion, glare/ flare) including a sharp (high resolution, astigmatism free) view across the field so that once detected by darting eyes, a bird can at the same time be identified, without need for even momentary delay for it to be centered to be seen clearly. For me, magnification takes a back seat to all of the above, and thus I end up with a 7 to 8.5x (the difference between them inconsequential) almost always in selecting a bin to get the other specs. Except in cases of e.g. scanning distant mud flats, lake, or ocean watching, almost all birds in the course of active birding are detected at short enough distances that they can be identified at 6x or even less. On rare occasion, for a day of dedicated long-range birding, I might be tempted by 10x, but even in that instance, the benefits of a tiny increase in magnification are so small that I generally don't bother to get them out (or own them in the first place). In those cases, it's a nice wide-field 30x scope that does the job. If, on very rare occasion I need more (which occurs with long-distance ID and photo documentation of turtles, not birds), it's a wide-field 40-96x that I use (and pretty much at 40x or 96x, not bothering with anything in-between).

In summary, my thesis is that birders should not pick bins based on their magnification.

--AP
 
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Rico70

Well-known member
Thanks for the intervention. I tried to explain the topic, hoping that it will serve anyone, on any occasion (not just birders).
I don't think magnification is itself a very important consideration for birding binoculars.
I am not a birders, so I collect gladly and accept your expert word.

In my general experiences with binoculars, I have noticed that different events will occur, so magnification also becomes important.
For example, in my first experience with an 8x20 monocle, after a few days I had already noticed that I would have preferred the use of 10x25 binoculars for greater efficiency (even at short range). I still use it daily, but in other situations (even with birds) I gladly use the 25x (unfortunately, heavier).

Of course, the magnification values that I wrote above, are referred exaggeratedly to 1200x, just to give some numeric examples. But when I tried to look at a pigeon at 90 m distance with the 100x binocular, I was very amazed at the amount of detail visible compared to the 10x and 25x.
 

Troubador

Moderator
Staff member
Supporter
An excellent discussion Rico.

In my experience, binocular-shake is not a constant invariable factor. It changes according to circumstances, so for example my own bino-shake can be made worse by carrying a backpack which tires my shoulders, by pounding heartbeat following climbing a steep slope or rocks to get to an observation position or in strong but varying wind that adds 'tremble' to my arms. All of these and probably other circumstances can make my bino tremble worse by variable amounts. And certainly in the worst circumstances, the bino-shake is more distracting, and the observations less useful, when the bino has a higher magnification.

So for example, when we are on one of the islands off the west of Scotland with winds coming off the Atlantic ocean, if the wind is strong and gusting (i mean pulsing with a quickly varying speed) I do not take out a 10x bino because the bino-shake is too distracting making observation unpleasant. It is often the case that an 8x or 7x can give useful and enjoyable observations when 10x will not.

But I agree with Alexis that magnification is only one of a suite of characteristics that will determine my choice of bino on any one day and in any specific habitat and when seeking a specific target whether a bird, a dragonfly or a seal. Sometimes field of view will be very important whereas at other times a fast focusing speed might be desirable, and so on.

Lee
 

typo

Well-known member
Rico,

In your short time on the forum you have caused serious offence to many, including those with considerably greater technical knowledge and observation skills and experiece than obviously you do. I do recognise in your more recent post you have been trying to modify your behaviour, and I do appreciate the difference.

With regards to this thread, I think the introduction and conclusion sections make quite a reasonable start to opening a discussion of the subject of binocular shake. Unfortunately the more technical middle section, once again, contains major scientific errors which undermine your logic, interpretation and conclusions. I need to advise everyone to ignore it.

I did have a look at that scientific paper. It's horribly written, and to save anyone else the pain of attempting to read it, I should point out if contains almost nothing of relevance to this discussion.

David
 
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Binastro

Well-known member
I wasn't going to comment, but I'll give practical thoughts.

Firstly naked eye vision is not always 1x.
If people wear glasses it is perhaps between 0.85x and 1.18x. An eye specialist might advise.
Each eye may have slightly different magnification.

Secondly, while observing sunspots with correct filters, the smallest penumbral spots I could see were 38 arcseconds across.
But supporting my head against a lamp post this was reduced to 34 arcseconds, better than 10% improvement.

Thirdly, the reason newcomers give up astronomy, and their telescopes end up unloved in the attic is primarily because the tripod is so poor that the telescope movement destroys the will to observe.

Fourthly, as a planetary observer, a step of 1.8x is usually just too big to see finer detail.
My standard magnification with a fine 12.5 inch planetary scope was 265x.
For finer detail 400x.
To observe planetary moons 600x.
So normally 1.5 times steps.

For Mars, finer detail was seen at 500x, so I might in this case go from 265x to 500x. But Mars is bright.

With a 3 inch refractor it was 80x, 106x, 120x. Rather small steps.

So any theory, as far as I am concerned is redundant.
It is empirical results that interest me.

As to high power binoculars being light weight. Often I found heavier binoculars steadier.
Sometimes short binoculars were steadier, sometimes longer binoculars were steadier.

B.
 
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JerryLogan

Well-known member
You’ve obviously put a lot of thought and certainly effort into your post so that is to be applauded. However, (isn’t there almost always a however) as just a starter, you begin with at least two unfounded and incorrect assumptions. First, magnification is a property of a lens system and, as such, an increase in magnification does not always result in an increase in detail, much less a proportional increase in detail.

Second, magnification is not relative to the human eye, it is a ratio between the angles a subject subtends at the front objective point and at the rear focal plane of a lens system. The eye has nothing to do with the definition of magnification although magnification may have an impact on what the eye observes.

Are the implications clear? If not, more later.

Best,
Jerry
 

WJC

Well-known member
Mark Twain asked his publisher why there was so much erroneous material in print. The publisher responded:

"Because paper never shuns ink." — W.D. Howells

120 years later, Bill Cook responded that more people are interested in being loved by a few than being willing to stand up for the technical accuracy that would help the MANY.
 
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jan van daalen

Well-known member
Mark Twain asked his publisher why there was so much erroneous material in print. The publisher responded:

"Because paper never shuns ink." — W.D. Howells

90 years later, Bill Cook responded that more people are interested in being loved by a few than being willing to stand up for the technical accuracy that would help the MANY.

Mmmmmm Bill,

"Because paper never shuns ink".....

Reading your posts.........B :)

Cheers bro.

Jan
 

Omid

Well-known member
United States
Brilliant thread! :t: The OP probably had a topic in mind but it seems that he forgot what it was that he wanted to say as he started writing yet continued his writing tirelessly in hopes that somewhere down the road he might remember or come up with a topic... The result is a verbose and incoherent post that seamlessly blends the aesthetics of an out-of-focus lens with the curving lines of a vignetting aperture. An example of modern mixed-media conceptual art... Andy Warhol blended with Hunter S Thompson...
 

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Rico70

Well-known member
Hi Lee, I think there may be some translation errors in the opening post. Maybe even several. Too many words in one go.
If you want and can correct, I will be happy to help you.

For the rest I see that there are some interventions to which it is preferable not to respond even, in order to avoid breaking the porcelains. If you can, pay attention to my abrupt movements.

Thank you!


Questo mi ha confuso.
... All of these and probably other circumstances can make my bino tremble worse by variable amounts. And certainly in the worst circumstances, the bino-shake is more distracting, and the observations less useful, when the bino has a higher magnification.
Reading as you wrote it, this circumstance that you describe, more than anything else seems to indicate a paradox: "the greater the magnification and the worse you will see the details".
When not even physically this is possible and not only in my experiences.

There is something in the air that leads to misalign two parallel lines!

Or did you mean something different?
 
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Binastro

Well-known member
Since about 1960 the classic focal lengths of astro telescope eyepieces has been.

4mm, 6mm, 9mm, 12mm, 18mm, 25mm and 40mm.

This suggests to me that the step for providing increasing magnification is about 1.5x not 1.8x.

I happen to have about 9 other focal length eyepieces to meet my needs, but still recognise the value of 1.5x steps.

Before 1960 the Imperial eyepiece focal lengths were 1/4 inch, 3/8 inch, 1/2 inch, 5/8 inch, 3/4 inch, 1 inch and 1 1/2 inch.
This a bit less, maybe 1.3x steps, but certainly less than 1.8x.

B.
 

Rico70

Well-known member
Since about 1960 the classic focal lengths of astro telescope eyepieces has been.

4mm, 6mm, 9mm, 12mm, 18mm, 25mm and 40mm.

This suggests to me that the step for providing increasing magnification is about 1.5x not 1.8x.
Hi Bin, 3x (or 3,24x) not 1,8x.
You are talking about something else. Always inherent in magnification but of what perhaps you have found most useful.
I'll give you an example: according to 3.24x as a minimum level step, I should prefer and use 10x and 34x. I tried (34x), but that in the absence of a wide (very large) field of view, it becomes difficult to use that binoculars easily freehand. And I have seen that with a normal field of view it is possible for me to use 24x-28x max. But this does not cancel out the meaning of 34x.
 

Rico70

Well-known member
naked eye vision is not always 1x.
If people wear glasses it is perhaps between 0.85x and 1.18x. An eye specialist might advise.
But of course the vision with the naked eye is always 1x, because it is according to your condition. And without going to ask the ophthalmologist.
 

Rico70

Well-known member
the smallest penumbral spots I could see were 38 arcseconds across.
But supporting my head against a lamp post this was reduced to 34 arcseconds, better than 10% improvement.
I'm not sure what you mean by this 10%, but if you see 34 arcosec, you have a visual acuity of about 18/10. Very good! Mine is 14/10.
 

Binastro

Well-known member
A very short sighted or far sighted person won't see much without glasses.

Wearing glasses alters the magnification.

Wearing glasses using a binocular alters the marked magnification of the binocular.

I use a binocular without glasses.
However, if I wear glasses I increase the magnification of the binocular by varying amounts, depending which glasses I use. I.e. distance or reading glasses.

In addition, if I hold the distance glasses about 20cm in front of my eyes, not only do I get a 2x magnification, I get much improved stereo vision.

B.
 

Rico70

Well-known member
Wearing glasses using a binocular alters the marked magnification of the binocular.
But why do you have to get to say such a thing?
If the magnification of the binoculars is 2x, it means that it will double the size of all observed objects. Regardless of who uses that binoculars.

Or am I wrong?

if I hold the distance glasses about 20cm in front of my eyes, not only do I get a 2x magnification, I get much improved stereo vision.
But so you are altering the optical pattern of your eyes!
What the hell are you doing?
 
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Alexis Powell

Natural history enthusiast
United States
Rico70,

One of the points that you seem to be trying to make (Perhaps it is even your main point?) is that because magnification provides more detail (so long as the resolution of the bin is beyond human vision, which most are), it isn't the case that high magnifications will show less detail than low magnifications, even when the image is shaky. High mags will, instead, show _more_ detail, even if shaky. In a manner of speaking, that can be true, but in practice it is not, or at least it reaches a practical trade-off limit very quickly for (nearly) everyone except (so you claim) you. The brain can't make sense of a shaking image that is magnified enough that the relevant details appear to be rapidly moving in the apparent view. That's one reason why a 7-10x binocular can often be used to easily see and identify birds that one can't make sense of through a shaky 30x view. The _apparently_ (but not really) more stable 8x view allows the brain, among other things, to composite information obtained over a second or two (or more) of viewing.

--AP
 

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