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Sharpness and sharpness impression, details and contrast (1 Viewer)

Jessie-66

Germany
Sharpness and sharpness impression, details and contrast

First, let's imagine a cat in close proximity. The cat ruffles its fur. The "edges" of the cat's body appear washed out, somewhat unsharp, out of focus, due to the visibly ruffled hair. Now we imagine the same cat at a much greater distance, no detail of the hair is visible. The cat's body appears sharp. Are we really judging the sharpness of binoculars correctly?

A short part from the German Wikipedia to shapness in photography:
"The subjective impression of sharpness[edit | edit source].
This sharpness assessment dominates our daily viewing habit. Depending on the specific circumstances (media resolution, image size, viewing distance and time, image message and own expectation) an individual sharpness measure is created.
Example:
...
Sharpness pattern 4: In the center, two versions of a face can be seen. Most viewers describe the right photo as sharper (because it has more contrast).
In the enlargements (outside), it is clear that the left image contains more sharpness. Sharpness and impression of sharpness are two different things.
This kind of sharpness assessment is influenced by a great many subjective things - hence the name subjective sharpness impression."
Sharpness pattern 4: https://de.wikipedia.org/wiki/Schärfe_(Fotografie)#/media/Datei:Schärfemuster4.jpg
Which eye has more "hairs", which eye is sharper? Our impressions (or errors) in somewhat greater distance?

Link with "sharp" pictures and short text in English:

How often are strong contrasts mistaken for excellent sharpness? Strong contrasts are often the enemy of details. Have fun thinking about why low magnification (6x, 7x) binoculars are often perceived to be "very sharp". But sharper (more details) than those with higher magnification?

And good luck for generally valid results within the further discussion whether the Nikon Monarch HG (> 800 Euro/dollars bins) is sharp or not, especially with consideration of the fact that most aberrations occur at the edge of the field of view, affecting light "rays" distant from the optical axis. Many people perceive old soviet porros (BPC5 from KOMC, 30 euro/dollars in ebay, new ~ 80 Deutsche Mark, Made in USSR) very sharp in the sweet spot. Nikon MHGs are > 800 Euro/dollars bins. I'll go get some popcorn ... without mesurement technology (for instance MTF) it's a "dispute over emperor's beard".
I think this is true for many mid-range and upper-range binoculars that have been publicly evaluated for different center sharpness only with eyes of reviewers.
Jessie
 
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tenex

reality-based
Macro- vs micro-contrast, resolution, "sharpness", etc have all been discussed before, but it seems to make more sense to explore such details in still photography where you can dissect a captured image ad libitum (and may need to enlarge it further) than for binoculars which are almost exclusively used in front of eyes, so "subjective impression of sharpness" is really all that matters (and yes, those who can be satisfied with a modest center area of sharpness can get by more cheaply). It's clear that some observers can find the sharpness of (early?) MHGs wanting while others don't, and that's a question of both acuity and taste. Even I form an impression fairly quickly of satisfaction with an optical instrument, and I'm not taking measurements. Whether contrast or resolution matters more depends also on the situation. So can you be more specific about where you'd like this conversation to go?
 
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Jessie-66

Germany
So can you be more specific about where you'd like this conversation to go?
I have now written my well-founded little "warning" against probably frequent errors in the subjective but public, i.e. intended for others, assessment of the sharpness of binoculars. I find your drafted photographic method very good, one can compare so different photos by several binoculars objectively, so to speak on each photo the number of ruffled hairs of my cat count. Automated algorithms for signal and image processing are provided by stochastics, an important and interesting part of mathematics.

Since most members and readers don't have measurement equipment available, for the thread to be informative, I suggest we talk about the most objective and simple DIY methods possible for evaluating and comparing the sharpness of binoculars. I read along with interest ...
 
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YuShan

Well-known member
I just look at the overall picture, which is a combination of both sharpness, contrast, colours, vibrance, brightness etc. When I bought my alpha binoculars (Swarovision EL 8.5x42), what really convinced me was when I looked at a grey concrete wall during an overcast day with the cheaper (but decent) binoculars and then with the alpha. With the alpha could see so much more texture and detail in that otherwise grey wall. I don't know if it was sharper, I could just see more detail and rich textures.
 

dries1

Member
But it's only your brain and your definition, your sharpness impression. Some people write for other people ...

The intelligent folks here, really only care how it is viewed to them, I am one, so to me the conversation is mute.

Andy W.
 

Jessie-66

Germany
dries1, post #7:
You and "liker" Conndomat also thought well what this statement implies for all the public reviewers also popular in this forum???
Si tacuisses, philosophus mansisses. Boethius
;-)
 
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Conndomat

United States of Europe
Europe
The intelligent folks here, really only care how it is viewed to them, I am one, so to me the conversation is mute.
Andy, too bad I can only give 1 "Like" ... I want also popcorn and a popcorn eating picture.

Andreas
 

NDhunter

Experienced observer
United States
dries1, post #7:
You and "liker" Conndomat also thought well what this statement implies for all the public reviewers also popular in this forum???
Si tacuisses, philosophus mansisses. Boethius
;-)
Yes, that is correct, we all have our opinions, and some so-called expert reviewers are just that.

We all have our own eyes that are unique, and what we find liking in a binocular.
It is just as simple as that.

Jerry
 

Jessie-66

Germany
I'm not disputing that in the end, the individual perception of binocular users is important, that is a matter of course. Many potential buyers do not have a collection of binoculars, at least currently can not compare binoculars even in specialty stores. Therefore, the most objective reviews and binocular advice in forums are important for these people. Hence the thread and its concreteness. I like to learn.
Happy new year to all readers. Best wishes. Jessie
 

Jessie-66

Germany
I have now looked again at several comparisons of binoculars from Dr. Merlitz. Dr. Merlitz always writes something about central image sharpness (often he finds it to be similarly very good). In his ratings, he only compares the "image (edge) sharpness". In more recent comparison tests, he explicitly adds the word "edge". I strongly suspect that there are very good reasons for this.
Examples:
So Dr. Merlitz checks representation of point light sources (stars). A good DIY test: Simple and comprehensible for others. Thank you, Mr. Dr. Merlitz!
Please back to the topic: As simple and objective DIY tests (with detail representation in daylight) for comparisons of center sharpness as possible, with results usable for other people in reviews and recommendations - because comprehensible, therefore at least halfway objective. ;-)
Thanks to all, in particular to @tenex and @YuShan.

I hope that @Canip will briefly describe his methodology for public ratings for central image sharpness and contrast (rating "++" = very good for all three Nikon MHG).
Thanks in advance.

For better understanding of my posts in this thread read my short stories: https://www.birdforum.net/threads/lets-talk-porros.403094/page-7#post-4124927

Jessie
 
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Patudo

Well-known member
First, let's imagine a cat in close proximity. The cat ruffles its fur. The "edges" of the cat's body appear washed out, somewhat unsharp, out of focus, due to the visibly ruffled hair. Now we imagine the same cat at a much greater distance, no detail of the hair is visible. The cat's body appears sharp. Are we really judging the sharpness of binoculars correctly?

Ah... but the judgement of how sharp a binocular is, if one had a cat in close proximity as a test subject, would be how well it shows you the fine details of fur texture, down to individual hairs and whiskers.

I do appreciate there can be a difference between apparent and actual sharpness and that factors such as contrast can influence the former. For me the impression of sharpness and detail is good enough - if when using a binocular I think it is sharp and shows me good detail, I'm happy to be happy with it.

Having said that, I would agree that it would be both interesting and useful for binocular resolution to be assessed against more objective tests/standards. Even though I cannot disagree with Henry Link when he remarks that "Virtually all good binoculars have more detail in the image than you can see", if brand X (or L, N, S, Z) were able to state that 100 out of 100 samples tested reached (or all examples leaving the factory were tested against a standard of) x arc seconds resolution, it would probably impress me to some extent.
 

Jessie-66

Germany
I have intended and knowingly not mentioned the resolution of low-magnification hand-held binoculars, since the human eye, with a best resolving power of 1 angular minute under ideal conditions (illumination, black-white contrasts), represents the "bottleneck" in the system binoculars-eye-brain. Even old cheap Soviet porros BPC5/BPZ5 8x30 (manufacturer KOMC/KOMZ from Kazan, Tataristan) have a tested resolving power of better (smaller) 6 angular seconds, which is presented to the eye with 8 * 6 = 48 angular seconds. On Ebay, sellers sometimes photograph test certificates, so I know that. Higher magnification Soviet binoculars have correspondingly better numbers in the photographed test certificates. Threfore Henry link is using a booster (imho 2x to 3x is good) for his evaluations. The old Soviet bins have low transmission values (78% in daytime) therefore with low color saturation and appearent low contrasts under grey overcast skies: Many little observation objects are not "emphasised" enough against background in this ambient light, for instance medium brown birds against dark green foliage.

I have seen transmission curves from our Gijs van Ginkel, if I stumble across them again on Ebay, I will submit pictures of Soviet test certificates with resolution numbers. It might be interesting for some readers (John A. Roberts?). Tento's and Kronos' and Sotem's bins are also Soviet bins, imho only trading labels.
 
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chris6

Well-known member
In #4 I take it that YuShan appreciates sharpness extending well towards the edges, but surely central sharpness is something else. When observing something like a distant bird, or plumage at close range, the attention is upon the latter, smaller, area. Incidentally this can make more economical binoculars seem quite ok, provided that they are sharp in this more usual sense.

I use a watercolour picture in on the wall at about 25ft, which features a tiny building with tall Elisabethan chimneys, for the vertical, a hedge, which is closer but has more texture, for the horizontal, and a row of wheatsheaves in a field for more texture. In another picture a waterbird has an inditinct patch in the painting of its neck and a rather vague signature at the bottom. In dim interior lighting these features have proved to be useful tests for all the main feature: brightness, contrast, colour, and field size of the overall view, to include the picture frames and wallpaper.

Familiar things like this have proved fine for comparison while this involves no technical denomination, but of course such tests would carry little authority in a description! As the target, if the cat were to become equally familiar, if the lighting could be kept the same, and if the cat would stay in exactly the same position, I reckon it would also serve very well...

In the field, I find that the intensity of lighting has dramatic effects, particularly upon colour but also upon sharpness according to the amount of light which a binocular can cope. Sharpness only seems to go off at dusk, while colour disappears long before that, and brighter sunlight is needed to exclude a slightly unnatural colour cast.
 
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Jessie-66

Germany
Familiar things like this have proved fine for comparison while this involves no technical denomination, but of course such tests would carry little authority in a description! As the target, if the cat were to become equally familiar, if the lighting could be kept the same, and if the cat would stay in exactly the same position, I reckon it would also serve very well...
Well, if you use it to make a comparison between 2 binoculars, it would already have significance, since all other conditions (observer, observation object, illumination, etc.) are constant.
YuShan with post #4 suggests so. The description of your beautiful watercolour picture (aquarell?) makes curious, can you show us a photo?
 

Jessie-66

Germany
I have intended and knowingly not mentioned the resolution of low-magnification hand-held binoculars, since the human eye, with a best resolving power of 1 angular minute under ideal conditions (illumination, black-white contrasts), represents the "bottleneck" in the system binoculars-eye-brain. Even old cheap Soviet porros BPC5/BPZ5 8x30 (manufacturer KOMC/KOMZ from Kazan, Tataristan) have a tested resolving power of better (smaller) 6 angular seconds, which is presented to the eye with 8 * 6 = 48 angular seconds. On Ebay, sellers sometimes photograph test certificates, so I know that. Higher magnification Soviet binoculars have correspondingly better numbers in the photographed test certificates. Threfore Henry link is using a booster (imho 2x to 3x is good) for his evaluations. The old Soviet bins have low transmission values (78% in daytime) therefore with low color saturation and appearent low contrasts under grey overcast skies: Many little observation objects are not "emphasised" enough against background in this ambient light, for instance medium brown birds against dark green foliage.

I have seen transmission curves from our Gijs van Ginkel, if I stumble across them again on Ebay, I will submit pictures of Soviet test certificates with resolution numbers. It might be interesting for some readers (John A. Roberts?). Tento's and Kronos' and Sotem's bins are also Soviet bins, imho only trading labels.
To explain the text below:
In several posts by members of the forum I read that people try to judge the resolution of binoculars with the naked eye. This will not work without a booster and a tripod!
International standards exist for testing and possibly naming the resolution of binoculars:
Prices for downloads are around $80.
Most standards are not a law, i.e. they can be used by manufacturers - but they do not have to be. For instance, apparent field of view data is provided by most manufacturers using the simple formula (real field of view * magnification), not ISO formula:
I have yet to find verified (worst=largest) resolutions of binoculars on any manufacturer's website. In the following text and pictures I would like to show that on the one hand even a comparison of resolutions with the naked eye is not possible, on the other hand it is also unnecessary. The images are at least a strong indication that resolutions of even simple, inexpensive binoculars are good enough for the human eye.

The 2nd photo shows the test certificate of a Soviet binocular BPC4 or BPZ4 8x30, manufactured in the year 1979 which was sold in Europe (Germany and UK) in masses (mail order trade) for about 80 'Deutsche Mark'. The certified, and hopefully at least randomly tested worst (largest) resolution is 6.6 angular seconds presented to the eye at 52.8 angular seconds. Under ideal conditions, the human eye has a resolution of 60 angular seconds! I saw also certificates of the successor BPC5 or BPZ5 with only 6 angular seconds. This instrument is still sold today:


4A4506E9-4BEF-41EA-9B72-40DF6ADD7938.jpeg
16254CD3-A780-4419-9A8D-584185A2AFD2.jpeg

D5BEEA57-D6D9-49C3-B728-E69AEFCE5B1D.jpeg
25746D92-C849-4B0F-9DF5-AF1F33012D30.jpeg
4BF7738E-6F93-4DFC-AAE3-0284245862FC.jpeg
The BPZ 20x60 binoculars are tested at least randomly for better resolution than a maximum of 3 angular seconds, which is shown to the eye at a maximum of 60 angular seconds.

Comparisons are, of course, inappropriate for defective or/and $20 binoculars.

Edit: Sources of pictures were actual Ebay-offers (15.01.2021).
 
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Tringa45

Well-known member
Europe
Now that the discussion has turned to resolution measurements I would have hoped that "typo" would have posted, as he has done a lot of work on this. Hope all is well with him.

We corresponded a couple of years ago, as I was interested in measuring the resolution of my 65 mm Swarovski and 88 mm Kowa scopes. I had purchased a 1951 USAF glass slide from Edmund Optics with a range of Group 0, Element 1 (1 line pair/mm) to Group 3, Element 6 (14,3 line pairs/mm). The slide has to be strongly backlit, as exit pupils are rather small at the high magnifications required. I used a 3,5 mm Televue Nagler with astro adapters on the scopes for around 130x and 140x respectively on the Swaro and Kowa.

Ideally, measurements should be carried out at longer distances and mine were at a mere 23 m, but that is still about 50x the focal length of the scopes so shouldn't degrade their performance significantly. With the Swaro I could see separation at Group 2.3 (5,04 lp/mm) and with the Kowa, Group 2.5 (6,35 lp/mm).

These correspond to 1,78 arcseconds and 1,41 arcseconds, i.e. the Dawes limit for the Swaro. The Kowa might have made the Dawes limit of 1,32" if I had moved a little forward for the next element.

Resolution measurements of binoculars will also require a tripod and a doubler or tripler. Their fast focal ratios will normally result in spherical aberration but this is not an issue in normal use as under strong ambient lighting where the eyes' resolution is best and the pupils only 2-2,5 mm, one is only using something like the central 20 mm of the objectives.

My old eyes let me down in my attempts at resolution measurements of my binoculars but typo has carried out measurements with the objectives stopped down and is of the opinion that if a binocular can get near the Dawes limit for 20 or 25 mm with its objectives stopped down accordingly, it will be very sharp subjectively.

John
 

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