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Old Thursday 9th October 2008, 06:11   #51
Kevin Purcell
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Quote:
Originally Posted by APSmith View Post
Kevin has I think touched on what I have seen before and am concerned about here - it is mostly "veiling flare". From general recollection, it seems to often accompany the "substandard contrast" (to which Alexis refers), at least in non-ideal light situations. If memory serves me well, the Conquests are guilty of both, as well as the symmetrical circle phenom you and Kevin seem to be describing. It does seem that bins which have a glare/flare/stray-light problem often have more than one of the manifestations. I've typically attributed it to coatings; however commentary here suggests that there are other major contributors.
Two things:

1. I now have FrankD's 8x30 Conquests (and I really like them). I saw no examples of this "ring" when testing in the same environment that I saw the ring with the Discovery.

2. This ring effect is different from veiling glare. I tried to make this clear in the post above. This "ring" effect is precisely that a ring in the FOV centered on the center of the FOV. Inside and outside the (relatively thin) ring the view is unaffected (as far as I can see). This is different from veiling glare where the section of the view affected a "circular chord" across the FOV i.e. a circle intersecting the FOV circle but not concentric with it though in the workst case it might consume the whole fo the FOV. That is it is not a ring around the center of the FOV but a portion of the FOV.

We really need a standard definition of these effects (I have ranted about this before )

For me glare, flare are three different effects.

0. stray light: the generic name for all problems associated with light going where it shouldn't. Like stray color (e.g. not all stray or false color is chromatic aberration in the lense some of it, especially in roof prism bins, is dispersion in the prism).

1. Glare aka veiling glare. The loss of contrast across part or whole of the FOV due to stray light usually off-axis light. This is also used for on-axis light scattered in the lenses. I'm happy to agree to any usage for glare that involves loss of contrast from non-discrete images

2. Flare aka ghosts: discrete false images of bright sources generating on-axis rays. You know the stuff they put into computer animation to make it more like a real camer (those circles the other side of the image to the sun.

And there is even a third effect that I call "glints" i.e. a discrete reflections off a metallic part either at the objective or the ocular. Really the Promaster suffers from these too. Not seen them in other bins. Who would put a non-matte-black part on a bin in those locations? It looks a bit like a flare with a starburst or diffraction effects (out of focus).

Once you get to this point (with the nomenclature) you can see that these effects have two different origins: one is on-axis (i.e. lens and coating related) and the other is off-axis (and more related to good baffling and keeping off-axis light off the objectives.

The former (ghost image/flare) problem is essentially solved with good current multilayer AR coatings. I noticed yesterday that the Diamondback can show ghosts (I'd not seen them before) but my other (better) bins don't show ghost images.

The latter problem (off axis light reducing the contrast) is a baffling problem and I think comes down to careful design and testing.

Stray light is one of the last issues to get fixed in a bin because it doesn't appear on the spec sheet. So without hands on experience (or feedback from a good reviewer like Frank) you don't know about the problem until you are in a marsh on a fall day at 5:30pm looking into the sun and seeing a whiteout not shorebirds. When the designers of bins like the Promaster ED or the Hawke ED take this seriously (and from comments here I think they're already doing that though they may compromise on the wrong side of the stray light/FOV line for some of us) then the alpha bin guys will have to get worried because all they'll have is their brand.

Last edited by Kevin Purcell : Thursday 9th October 2008 at 06:30.
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Old Thursday 9th October 2008, 06:56   #52
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I wonder whether the two are related(contrast/stray light), and how so, if they are.
Don't know if this will add anything to the discussion or not, but it's something that I've been curious about from a cause/effect standpoint.

I have three very similar binoculars. The Browning 8x32, which my dad actually has now, the Pentax DCF SP 8x32, and the Pentax DCF ED 8x32. Specs are almost identical for all three, and aside from some cosmetics, the only real difference between them is their coatings and the claimed use of some ED glass element in the SP, more in the ED.

Viewing in darkness with a streetlight just outside the FOV, and ~200yds. distant(the only consistent stray light inducing condition in which I have or can easily check all my binoculars):

The Browning suffers from stray light in much the same way it does glare in low angle sunlight, often dimly curtaining the width of the image.

The SP shows it as a circular reflection in the opposite side of the FOV from the light source. It has noticeably better contrast than the Browning.

The ED shows the light scattered across the FOV, radiating out and away from the light source. A starburst is the only way I can describe it. It has noticeably better contrast than the SP.
The ED presumably has the best coatings, and glass.
It handles stray light differently than the SP, but because it interferes with the image more, I don't consider the way it handles it "better".
The differences I see seem to be strictly related to the different coatings.

I found a few articles about related issues, but am not able to digest all the included information, since all of this is new to me.
Page 1 of this pdf offers some causes and descriptions of stray light:
http://boojum.as.arizona.edu/~jill/M...ight_paper.pdf

HTML version:
http://74.125.45.104/search?q=cache:...lnk&cd=5&gl=us
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Old Thursday 9th October 2008, 13:42   #53
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Tero: Did you ever see any of these phenom in the Conquests? If not, I doubt any of this makes any sense.
Yes, there was some, but because of the open eye cups, I think part of the experience was from light at that end, not from the objective. Hard to remember.
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Old Thursday 9th October 2008, 17:06   #54
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Thanks for the Stray Light clarification, gentlemen. I suppose Ill never know until I see a pair of Frontiers. May I be so bold as to ask another question....has anyone compared the 8x43 Frontier ED to a pair of EL 8x32s? Im just wondering if the former are significantly brighter, give the 11mm of extra objective lens.
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Old Thursday 9th October 2008, 17:48   #55
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Kevin,
Thanks for the reply. I agree that "we really need a standard definition of these effects". I can't recall ever having seen the (thin)"ring" effect that you describe in #2. If I have, it didn't register as a real problem. Perhaps that's a very good sign for the Hawkes. BTW I like the term "glints". It sounds exactly like what it is. I wish all the manifestations/combinations of stray light were that easy to describe and/or understand.

Sancho,
I think FrankD decided against both the 8x32 and the 8.5x42 ELs after examining the Promaster EDs. (I believe it was on one of the Promaster threads.) That says alot in my mind.

APS
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Old Thursday 9th October 2008, 18:24   #56
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That's a very good paper. I missed out a couple of mechanisms including the most obvious (and the one I hope the get rid of first: "straight shots".

I suspect most of the issues we're talking about are multiple scatter problems and the correct sizing and plcement of baffles.

The test you describe using darkness and a bright light source is the most sensitive test for stray light but you need to calibrate that test with an excellent bin (an alpha bin) to see how well they do.

It is useful for sorting bins into order on how well they deal with stray light. It was a after a test like this that I sent a Vortex Hurricane back as it clearly had stray light problems (you could see them in normal use but the "moon at night" test showed how bad they were compared to some other bins).

Quote:
Originally Posted by OwenM View Post
I have three very similar binoculars. The Browning 8x32, which my dad actually has now, the Pentax DCF SP 8x32, and the Pentax DCF ED 8x32. Specs are almost identical for all three, and aside from some cosmetics, the only real difference between them is their coatings and the claimed use of some ED glass element in the SP, more in the ED.
That's an unsupported assumption.

They similar in the sense that they have two barrels and are about the same size with the same sized objectives

They almost certainly have different designs of multilayer coatings and phase-compensating coatings but those coatings are similar in more ways than they differ. The real test for AR coating (to differentiate them is to look for direct ghosts (specular reflections between the lens elements) and even that depends a bit on optical design.

They do differ in optical design. Even though you can't see it from the outside.

AFAIK the Browning (Bushnell Legend clone) doesn't have an aspherical elements in the eyepiece but the two Pentax designs do (the SP introduced them, IIRC). So the eyepiece designs are probably different. They may also differ in their overall optical design in some ways: number of groups, number of elements, focuser design, number of elements in objective, eyepiece and focuser. It seems in this case though they have the same number of elements (5) int he same number of groups (3) in the eyepieces.

And they certainly differ in the fine optical design (you can get the similar specs in many different ways). When you put ED glass in a bin you don't just add ED (though I think Swift did in the 820/820ED) but you optimize the whole design to minimize stay color (not just longitudinal CA (objective) and transverse CA (eyepeice) but dispersion in the prism too. That might mean going to a more complex eyepiece design. Pentax design style is rather different from Bushnell design style (in their other bins) especially over field of view and field curvature (a narrow FOV and flat field is what makes a Pentax a Pentax, IMHO). I suspect under the skin you'd see some of that in these superficially similar bins.

And then there's the interior tube design (coating and shaping), eyepiece lens edge blackening, baffling and positioning of field stops which differ in each design and contribute most to controlling off-axis stray light in test you describe.

It's a problem for us "optical hobbyists" that this stuff is not better revealed to use. Bins are unfortunately mostly "black boxes" for us.

Last edited by Kevin Purcell : Thursday 9th October 2008 at 18:41.
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Old Thursday 9th October 2008, 18:33   #57
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Sancho,
I think FrankD decided against both the 8x32 and the 8.5x42 ELs after examining the Promaster EDs. (I believe it was on one of the Promaster threads.) That says alot in my mind.

APS
Thanks APS!
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Old Thursday 9th October 2008, 18:49   #58
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They do differ in optical design. Even though you can't see it from the outside.
Crap. I even knew all that, and still screwed that post up! See what happens when I post in my sleep?
Thanks for the corrections.
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Old Thursday 9th October 2008, 19:04   #59
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But even in your sleep you did post a link to a very good paper

I all interested in stray light should read it.

Perhaps we can come up with a series of simple (standardized) tests for stray light? It might help us compare results.
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Old Thursday 9th October 2008, 19:59   #60
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found where

Ok Frank...so where did you find the Hawke Frontier ED at $425. Google and I can't find any at that price?

Thanks for the report on these.
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Old Thursday 9th October 2008, 21:28   #61
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From Hawke online. That was their original price.

They increased the price by 11% ($50) just after the review was posted.

Read the thread to see the comments on this.

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Old Friday 10th October 2008, 00:46   #62
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Again I am surprised by the great series of posts since I last visited this thread. I only get to hit birdforum once a day because of an internet filtering program at work.

Quote:
Note to self: avoid light bulbs when birding.
Tero, I genuinely laughed out loud at this comment. I will be sure to take note of that. :)

After all of the discussion on stray light and forms of reflections, etc... I want to again clarify what I am seeing with the Frontier EDs. The stray light is in the form of somewhat bright, circular "ring" around the outside of the field stop. The more I use the binocular the more I "feel" this is the result of poor baffling somewhere in the eyepiece or possibly close to the objective. Call that "instinct" rather than experience. If I had the internal binocular knowledge and experience of someone like Henry then maybe I could clarify further. The only other bin that I have owned and that I remember seeing it in was the Bushnell Discoverer 7x42.

Speaking of which, Kevin, if you see what I am describing in the Discoverer then you know what I mean when I try to describe it in the Frontier ED.

I do not notice any flare or glare but maybe an occasional "glint" when using the Frontier EDs. I have been toting them around daily at home and at work. I will be taking them out in the woods over the next few days.

tjej,

Yes, Kevin hit the nail on the head about the price increase. Still they are $21 under $500. My glass is half full.

Sancho,

I should have the Swaro EL 32s back in my possession shortly. I will compare the two directly and report more of my observations. I never compared the 32 mm EL with the Frontier ED but rather the Promaster ED model. My choice to sell both of the ELs was due to the fact that the optical performance of the Promaster was on par with the ELs (the sweet spot wasn't as large but the centerfield apparent sharpness was better). Brightness favored the Promaster EDs as did the lower level of color fringing. When comparing the 32 mm EL to the 42 mm EL I noted a higher level of color fringing and a slightly dimmer image. With that thought in mind I expect the Frontier ED to be noticeably brighter and sharper with less color fringing and a more neutral color tone in comparison to the 32 mm EL. The only characteristic I expect the EL to beat the Frontier ED in is the size of the sweet spot.

Also keep in mind that the full sized 42 mm Frontier ED actually has a 6 foot wider field of view in comparison to the 32 mm EL. Not significant in and of itself but when you consider we are comparing a 32 versue a 42 mm then I consider it significant as you then couple it with the larger exit pupil and brighter image for a very high comfort level.

Last edited by FrankD : Friday 10th October 2008 at 00:49.
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Old Friday 10th October 2008, 21:31   #63
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Frank, sincerest thanks for that. Youve spent a lot of time both testing the bins and explaining these issues to less-technical folk like me, and I really do appreciate your time, skill and patience. Have a great weekend!
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Old Saturday 11th October 2008, 03:07   #64
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Sancho, you got one? To join the others on the shelf? I thought you were a faithful one binocular man. Plus image stabilized toys.
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Old Saturday 11th October 2008, 10:21   #65
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Sancho, you got one? To join the others on the shelf? I thought you were a faithful one binocular man. Plus image stabilized toys.
No, not yet. I'm just intrigued by them. If Santa brings them, and I like them, I'll get rid of my EL's. And I'm trying to clear that shelf.....
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Old Saturday 11th October 2008, 15:02   #66
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Huang - congratulations on producing what are clearly superb binoculars at a very competitive price; had I not recently purchased a pair of Zeiss 8x42s, I would be taking a very close look at your products for my 'primary' binoculars. Congratulations too on the excellence of your English and thanks for taking the time to post your comments here.

Since I am thinking getting binoculars for my wife which would also serve as a 'back-up' pair for myself, please allow me to comment on the preferred options for smaller binoculars. Although they may be popular in the USA I doubt whether 7x32 would be popular amongst British/European birdwatchers. Personally, I'd love to see a good quality 9x36 but only if it was closer to 32 models, rather than 42mm ones, in weight. I feel this unusual specification would make it 'stand out from the crowd'. In addition for many of us birdwatchers who dither between x8 or x10 maginification and 32mm or 40+mm objectives, it would be an ideal compromise. However, it might be debateable whether it would fit comfortably within your current line up so a 8x32 model might be a safer option for you. In conclusion, I add that it'd be good to see a good quality ED 50mm telescope to rival the Nikon 50ED in quality and better it on a similar margin on price. With more birdwatchers travelling and airlines getting ever more fussy about hand baggage this may be a growth area for a go ahead optics company,

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Old Saturday 11th October 2008, 17:31   #67
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John,

Though not a 50 mm Promaster does make a Elite ELX ED 65 mm scope. It was only reviewed once so far over on 24 hour campfire. I believe I am on the list of reviewers at some point.
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Old Saturday 11th October 2008, 18:26   #68
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John,

Though not a 50 mm Promaster does make a Elite ELX ED 65 mm scope. It was only reviewed once so far over on 24 hour campfire. I believe I am on the list of reviewers at some point.
Thanks for the tip, Frank - good review of the Hawke binoculars incidentally. As it happens I was already aware of this scope you mention, it's just that the Nikon scope seems to have the quality small (i.e. under 60mm) scope market sew up,

John
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Old Sunday 12th October 2008, 18:03   #69
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Thank you John.

I seem to remember Bushnell coming out with a new ED scope recently but I honestly don't remember what the objective diameter was. I do know it was very compact because of the folded light path design. Something to consider.

Sancho,

I received the Swaro EL 32 mm yesterday afternoon and took it outside today to compare it directly to the Frontier ED. My previous comments were pretty much confirmed. The Swaro 32 definitely has the edge on the Frontier ED in terms of the size of the sweet spot and, therefore, the overall comfort level of the image. Comparing the two really highighted the one area where the Frontier ED is a bit weak optically.
However, the Frontier ED is noticeably brighter, sharper and has better contrast. The colors in the Frontier ED might even be a bit more vivid. Even during daylight hours the difference was noticeable.

My advice would then be, unless you are someone that is sensitive to the size of a bin's sweet spot (ie, you prefer a large one over most other optical characteristics), then the Frontier ED bests the Swaro EL 32 mm in terms of image quality.

As for physical comfort...this is a no-brainer. The 32 mm Swaro EL is easily the most ergonomic bin on the planet...at least for my hands. The Frontier ED is very good in this area in that it combines a well balanced design with a very reasonable weight (26 ounces) for a full-sized, high image quality binocular. So my suggestion would be that if you are considering a high quality full-sized addition to the 32 mm EL already in your stable then the 42 mm Frontier ED should be at the head of your list...especially if you value high end image quality.
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Old Sunday 12th October 2008, 21:20   #70
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Thanks for that, Frank...I was out this morning with my EL 8x32 and was thinking just how much I love the size and feel of them in the hand, and how that will never be "bested". In any case, the rumour here is that Santa is from Iceland, and will be on the Dole by Christmas.....
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Old Monday 13th October 2008, 01:12   #71
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I spent a great deal of time with the Frontier ED yesterday and today. After extended use in slightly different conditions than what I was previously testing them in I have found that they do indeed display field curvature through a good percentage of the outer portion of the image. Why this was not immediately apparent to me in my previous applications took a bit of thought. In my previous usage of this bin I had been pretty much limiting myself to observing specific objects. Doesn't sound too unusual right? Well when you pick out an object to view and then point the bin at the object you leave out an important part of binocular usage...panning.

Even comparing the 32 mm EL to the 42 mm Frontier ED earlier today and yesterday I seldom really did much more with them other than picking out various objects at different locations to focus each binocular on. I rolled the focus in and out to see how sharply each one popped into focus. I tried to induce flare and other lighting issues with each binocular. I even tried some tricky situations which would really highlight color fringing. But, in no circumstance did I really try to pan with the Frontier ED until today. What I noticed was fairly moderate levels of field curvature. This forced my eye to the center of the image on just about every occasion. I am guessing I noticed it more this time also because I was using the Meopta Meostar yesterday quite a bit too. One very good thing about that bin, at least from my perspective, is that the sweet spot is very large and the image is very flat (field flattener element if I remember correctly). Panning large areas is a breeze with that binocular. Switching from it to the Frontier ED really made me notice the field curvature level that the Frontier ED displays.

I do not remember seeing it much in the Promaster ED though the Promaster's field of view is narrower. I now wonder whether the increased field of view on the Frontier ED is what is showing more field curvature or if the optical designs in each model are actually quite different. Maybe Huan can comment on this if he happens to pop into the thread again.

Last edited by FrankD : Monday 13th October 2008 at 01:19.
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Old Monday 13th October 2008, 12:30   #72
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Thanks for the tip, Frank - good review of the Hawke binoculars incidentally. As it happens I was already aware of this scope you mention, it's just that the Nikon scope seems to have the quality small (i.e. under 60mm) scope market sew up,

John
John,

What about the Opticron MM2 ED?

Paul
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Old Tuesday 14th October 2008, 01:01   #73
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2. This ring effect is different from veiling glare. I tried to make this clear in the post above. This "ring" effect is precisely that a ring in the FOV centered on the center of the FOV. Inside and outside the (relatively thin) ring the view is unaffected (as far as I can see). This is different from veiling glare where the section of the view affected a "circular chord" across the FOV i.e. a circle intersecting the FOV circle but not concentric with it though in the workst case it might consume the whole fo the FOV. That is it is not a ring around the center of the FOV but a portion of the FOV.
After some more experimentation during the weekend I'm now sure this "ring in the FOV" or "lumpiness in the field" is due to reflection between my eye and my birding eyeglasses (that don't have AR coating).

I got into two situations where I could reproduce the effect with two different bins. And in both cases the effect disapeared when I took off my eyeglasses.
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Old Tuesday 14th October 2008, 23:54   #74
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After some more experimentation during the weekend I'm now sure this "ring in the FOV" or "lumpiness in the field" is due to reflection between my eye and my birding eyeglasses (that don't have AR coating).

I got into two situations where I could reproduce the effect with two different bins. And in both cases the effect disapeared when I took off my eyeglasses.

I feel better now (about having never seen such). Something tells me I will in not too many more years.

APS
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Old Wednesday 15th October 2008, 00:37   #75
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I think even I can avoid it AP.

These glasses don't have AR coating due to a manufacturing mistake but they also have a low bifocal height and a very solid stainless stell frame so they make good birding glasses.

That missing AR is the biggest problem for stray light. Of course there is a certain irony in worrying about the quality of AR coatings in bins only to have an uncoated lens just in front of the eye

Unless you develop astigmatism (which most people don't) you shouldn't need glasses to bird. To look at the birds in the field guide is another matter, though. I didn't used to use them with bins but I realized (with better bins) that correcting my astigmatism was a big help in improving the view.
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