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Kowa BDII 6.5x32 XD first day (1 Viewer)

galazie1

Well-known member
Got this pair of binos in the morning. Here's my impression after day 1. For my eyes, my taste, and my particular sample.

Positive:

- 10 degree TFOV is GREAT. This strucks you immediately
- simple but beautifully looking binos.
- "Made in China" is printed on the body. Thanks Kowa for the openess
- CA nothing to worry about
- perfect collimation

Neutral:

- almost everything says "China". the play in the focuser. the sloppy eye cups. and the image! hard to describe. but it's the feel. central sharpness, edge sharpness (or the lack of it), the smoothness of the image, the overall aesthetics of the image, are unevenly distributed across the FOV. having extensive experience with budget Chinese optics, I noticed this immediately. Any old Zeiss or Leica or Swarovski will be superior in this aesthetic aspect, no matter how bleak their images are.

Negative:

- edge sharpness. more than I expected. about 2/3 of the FOV from center when it becomes blurry. Worst is that, the blur is more on the right and at the bottom than in the other directions (to be fair I have seen things like this in other superwidefield binos such as the Komz 6x24 and Bushnell Rangemaster 7x35). I know it is 10 degree FOV and any complaint on edge sharpness should be reasonable, but it is still a bit much to me. I did not notice this in the first few minutes, when I was still overwhelmed by the wide FOV. But once I noticed it, it can't be ignored.

So conclusion:

- Thanks Kowa for offering this. I hope this is a push towards an alpha 6x30 some day
- it is an interesting pair of binos. but quality is no more than 400USD price. its quality is not a bargain for the price. optics-wise, i think $300 is more reasonable.
- if you have to have a 6-7x wide-field pair of binos, then you might get it. But if you can live with 8x, get a Nikon E2 8x30. For less than $100 more (at least for where I live), the Nikon E2 is much much better: the look, the built, the feel, the image. it is the ultimate small and wide-field binos in my opinion.

In the photo are the Kowa and my 1908 CZJ Telex 6x.
 

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typo

Well-known member
Hello Galazie,

Welcome to the forum.

An interesting first post! I'd seen pre-production samples of the BDII XD and despite a couple of reservations, rather liked the 6.5x32 overall. Your sample sounds unacceptably poor and certainly cause for caution. Thanks for letting us know.

David
 

galazie1

Well-known member
Thanks, David.

Night time use:

The Kowa 6.5x32 appeared to me to be better at night than at day. Somehow its short-comings are not so distracting at night compared to daytime use.

Image is bright, clear, vivid in colour, and reasonably clean.

Huge spikes on street lights. Lots of internal reflection near bright light sources. But I don't mind this.

Looking up the sky, star images are quite OK. 10deg FOV gives a lot of context to what you are looking at. Stars at edges of FOV, surprisingly, are not bad.

However, night time use confirmed observations during day time.

1/ the circle of sweet spot and circle of FOV are not concentric (first photo)

2/ within the sweet spot, sharpness is not evenly distributed. putting a star at the center of the FOV, then moving it towards the outer edge. sometimes you see it sharp, then slightly blur, then sharp again, then really blur when reaching near the edge. It is slight, but it is there. (second photo) And this happens with most Chinese optics that I know.

These binoculars are all about the 10 deg FOV. But it is ordinary Chinese optics.

I got this pair for a discount price of $350. I think that is a fair price point. $300 would be spot on.

But it is a very good-looking binoculars. very beautiful. better to look at than to look through.
 

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typo

Well-known member
Galazie,

It seems quite clear that your sample is faulty. Seems like it might be a component alignment issue of some sort, which can happen to any binocular in transportation. Faulty, I'd suggest it's worth nothing. The relevant question is how would the value of an undamaged sample compare to others in the price range. That seems to be a very open question at the moment.

Just a comment on the pattern of uneven radiating sharpness. Is it present in both barrels? This is probably more common pattern than you might imagine, particularly amongst field flattened designs. In it's simplest form it is caused by fluctuating focal distance, though other aberrations can be involved. Few viewing the natural world, without flat surfaces, seem to notice, but I personally dislike it. The original Swarovski EL Swarovision was pretty notorious, though it has improved over the years. It is still very common in cheaper models, though most users seem untroubled by it. I can't say I noticed it in my brief time with it at Birdfair, but given the view from the optics marquee, perhaps excusable.

David
 

Canip

Well-known member
.....
.....

1/ the circle of sweet spot and circle of FOV are not concentric (first photo)

2/ within the sweet spot, sharpness is not evenly distributed. putting a star at the center of the FOV, then moving it towards the outer edge. sometimes you see it sharp, then slightly blur, then sharp again, then really blur when reaching near the edge. It is slight, but it is there. (second photo) And this happens with most Chinese optics that I know.
.....
.....

galazie1:

your observations 1/ and 2/ are spot-on, very precisely observed indeed!!

I also concur with most of your other remarks.

Of course, this does not render these nice and very well finished binoculars useless. It just puts things a bit in perspective; after all, these are middle class binoculars, and Kowa has priced them accordingly. They still fill a vacant spot (low mag widefield binos).

I like them and enjoy them for what they are - well designed lightweight all-purpose 6.5x widefield binoculars. For me, I will mostly use them during the day (at night, I prefer instrument sizes that go deeper).

Canip
 

henry link

Well-known member
It would be helpful to know the cause of these observations. I agree with David's first suggestion, but I don't have much experience with the second, which I assume refers to the "notorious" Absam Ring in the Swarovisions. I'll suggest what I think are the two most likely potential causes I've seen before. Galazie may have already eliminated both, but if not they are easy to test for.

The first is misalignment of the optical train (in transit as David suggested or possibly during collimation). This would cause a centered star to be comatic, but that might not be easily visible at 6.5X. This would be a random sample defect, so unlikely to be identical or even present in both sides. If this is the problem using the binoculars upside down would reverse the direction of the sweet spot offset. A high magnification star test using an auxiliary scope behind the eyepiece would confirm the coma of a centered star image which should be aligned with the direction of the shifted sweet spot. If this is the problem the binocular is defective and should be returned.

If the first possibility is eliminated a second one would be vignetting of the outer part of the field (possibly from undersized prisms). That can cause both an impression of an off-center sweet spot in certain directions as well as variations in sharpness at different off-axis angles when combined with small inadvertent shifts in the alignment of the eye's pupil with the exit pupil as the eyeball rotates toward the field edge. If this is the cause there will be no change in the direction of the offset when the binoculars are used upside down.

To add to the confusion both of these could be present together, or perhaps there is some other cause that a high magnification star test might reveal.
 
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galazie1

Well-known member
Canip: thank you. it's good to know it's not only me who saw these

David & [email protected]: it's not that bad. I tried to be clear for the sake of description. the issues are there to note, but they are not big issues. except the blur. i don't feel like i want to call them defective.

Henry: as you suggested, i used the binoculars up side down. there seemed to be no change in the sweet spot offset. the lower right area of the FOV is still blurriest. but the offset appeared to be less apparent. looks like there is slightly less blur. haha
 

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galazie1

Well-known member
The first is misalignment of the optical train (in transit as David suggested or possibly during collimation). This would cause a centered star to be comatic, but that might not be easily visible at 6.5X. This would be a random sample defect, so unlikely to be identical or even present in both sides. If this is the problem using the binoculars upside down would reverse the direction of the sweet spot offset. A high magnification star test using an auxiliary scope behind the eyepiece would confirm the coma of a centered star image which should be aligned with the direction of the shifted sweet spot. If this is the problem the binocular is defective and should be returned.

If the first possibility is eliminated a second one would be vignetting of the outer part of the field (possibly from undersized prisms). That can cause both an impression of an off-center sweet spot in certain directions as well as variations in sharpness at different off-axis angles when combined with small inadvertent shifts in the alignment of the eye's pupil with the exit pupil as the eyeball rotates toward the field edge. If this is the cause there will be no change in the direction of the offset when the binoculars are used upside down.

To add to the confusion both of these could be present together, or perhaps there is some other cause that a high magnification star test might reveal.

Henry now I just keep using the binoculars up side down haha. So far it is definitely better with less blur. Now it might be what I expected it to be. Thank you very much for this idea.
 
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henry link

Well-known member
Galazie,

I'm not sure I'm following you. Are you saying that the worst off-axis sharpness appears to be in the same lower right quadrant of the FOV whether you use the binoculars right side up or upside down? Also, is the offset of the sweet spot the same in both sides?

I would suggest one more quick test. Repeat what you've done but use only one eye at a time while capping the objective lens of the other side.

Henry
 

justabirdwatcher

Well-known member
and the image! hard to describe. but it's the feel. central sharpness, edge sharpness (or the lack of it), the smoothness of the image, the overall aesthetics of the image, are unevenly distributed across the FOV.

Galazie1 - thank you for articulating what I've been trying to express about chinese optics for several years now. I have found that what you describe is the NORM and not the exception, with chinese binoculars and scopes. I cannot explain well what it is I see - but your description is the closest I've seen so far.

A few exceptions to this norm I've seen so far are my wife's Bushnell Legend M's, most Nikon products I've seen, and my newly acquired, but older, original Bushnell Legend's, that have outstanding sharpness and clarity with no noticeable distortion. I'm not sure what Bushnell is doing or has done to avoid this problem, but I've seen the distortion you describe in Kowa, Hawke, Meopta, Zeiss and other brands who have models made in China. So far, Bushnell (for the most part) and Nikon are the only two companies that seem to be able to have some of their line made in china without the strange, wonky view.
 
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18000bph

Well-known member
My 8x33 Kowa Genesis behave exactly as Galazie1 describes in the two hand drawn sketches. It's worse with my left eye, but is present in both. If I hold upside down or right side up with a single barrel over the opposite eye the view is unchanged. I complained on here a little bit when I first received them.

Overall the Genesis are still excellent binoculars, so I don't worry about it. They are super sharp in the center and exceptional at controlling CA, glare and stray light. They are my favorite star gazing binoculars despite the small objectives--the stars are noticeably tighter points than I've ever experienced with other binoculars.
 

galazie1

Well-known member
Galazie1 - thank you for articulating what I've been trying to express about chinese optics for several years now. I have found that what you describe is the NORM and not the exception, with chinese binoculars and scopes. I cannot explain well what it is I see - but your description is the closest I've seen so far.

Thank you. Like you it took me long time to figure out how to say about it
 

galazie1

Well-known member
Galazie,

I'm not sure I'm following you. Are you saying that the worst off-axis sharpness appears to be in the same lower right quadrant of the FOV whether you use the binoculars right side up or upside down? Also, is the offset of the sweet spot the same in both sides?

I would suggest one more quick test. Repeat what you've done but use only one eye at a time while capping the objective lens of the other side.

Henry

Your 1st question: Yes

Your 2nd question: yes. It is not that clear but i think so

I did the test you suggest. Result: same offset on both barrels but more obvious in the right one. When i turn the binos up side down: same result. It is always more obvious on the right side (although when i turn the binos up side down of course i swap the sides)

So is it the binos or is there anything to do with my eyes/brain
 

henry link

Well-known member
Galazie,

I'd say your results eliminate misalignment of the binocular optics as the cause of what you see.

Observations of asymmetrical off-axis sharpness like yours have come up here before. What needs to be recognized is that movements of the eyeball are not symmetrical in every direction and the pattern of the asymmetry is probably different in different individuals. That affects our evaluation of off-axis sharpness in different directions by introducing more or less vignetting of the off-axis exit pupil in different directions. More vignetting in one direction sharpens the image by stopping down the exit pupil compared to directions that leave the exit pupil more open.

In short I think this does have to do with your eyes (not so much your brain) or rather how you rotate your eyeballs when looking in different directions. In my case I find that rotating my eyeball down toward the 6:00 position of the FOV gives me the least vignetted exit pupil near the field edge. If I want to see what the 3, 12 or 9:00 positions look like I use one eye and rotate the binocular while continuing to look at the 6:00 position.

Henry
 
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galazie1

Well-known member
Henry, thanks. I learnt new things.

why does it happen to these specific binoculars?

i saw this (sweet spot offset), in different shapes and directions, also in the Komz 6x24, and Rangemaster 7x35 (but not in the 12degree Trinovid 6x24). All are super wide field.

not in any binoculars with 9 degree or less

I assume it happens for very wide field only?
 

Canip

Well-known member
Galazie,

I'd say your results eliminate misalignment of the binocular optics as the cause of what you see.

Observations of asymmetrical off-axis sharpness like yours have come up here before. What needs to be recognized is that movements of the eyeball are not symmetrical in every direction and the pattern of the asymmetry is probably different in different individuals. That affects our evaluation of off-axis sharpness in different directions by introducing more or less vignetting of the off-axis exit pupil in different directions. More vignetting in one direction sharpens the image by stopping down the exit pupil compared to directions that leave the exit pupil more open.

In short I think this does have to do with your eyes (not so much your brain) or rather how you rotate your eyeballs when looking in different directions. In my case I find that rotating my eyeball down toward the 6:00 position of the FOV gives me the least vignetted exit pupil near the field edge. If I want to see what the 3, 12 or 9:00 positions look like I use one eye and rotate the binocular while continuing to look at the 6:00 position.

Henry

Thanks, Henry.
This now raises a number of questions for me, since I had a similar experience as galazie1 with the Kowa.
If the effect is caused by brain/eyes and especially in widefield binoculars, it would have to occur also on other widefield binos, esp. those where edge blur or „Absam“ rings are no issue (Nikon WX), right?
 

Canip

Well-known member
And just quick follow-up:

Testing with the WX, I cannot see any of the blurriness patterns that I see with the Kowa. Whether or not that excludes my eyes as the cause of the patterns, I don't know, but:

off-axis blurriness in the Kowa is clearly worst in the left tube at 3 o'clock, worse than at any other angle and also worse than in the right tube. Using the bino upside down, the worst blur occurs now at 9 'clock in the right tube. So in my experience, the Kowa clearly exhibits some (well, actually quite some) asymmetrical off-axis sharpness patterns.

Or am I making a mistake here ?

Canip
 

henry link

Well-known member
And just quick follow-up:

Testing with the WX, I cannot see any of the blurriness patterns that I see with the Kowa. Whether or not that excludes my eyes as the cause of the patterns, I don't know, but:

off-axis blurriness in the Kowa is clearly worst in the left tube at 3 o'clock, worse than at any other angle and also worse than in the right tube. Using the bino upside down, the worst blur occurs now at 9 'clock in the right tube. So in my experience, the Kowa clearly exhibits some (well, actually quite some) asymmetrical off-axis sharpness patterns.

Or am I making a mistake here ?

Canip

Hi Canip,

Sounds like your binocular is defective. A high magnification star test should reveal what's going on, but I think it's likely that a focused star will show the first diffraction ring much brighter in one direction and dimmer to absent in the opposite direction. A little in-focus should show what ought to be a central spot relocated somewhere off-center out among the bull's eye of 3 or 4 refraction rings.

There is an easy way to evaluate off-axis vignetting using an artificial or real star. For an artificial one focus the binocular at infinity, but observe the de-focused star point close up so that it looks like an evenly illuminated disc. That's an image of the objective lens or your own eye's pupil, whichever is smaller. Move it toward the field edge in different directions and watch it turn into a vignetted cat's eye shape and then a slit at the very edge. For a real star change the focus to the closest focus setting and observe the de-focused star at infinity in the same way. The first method shows vignetting as seen in daylight (or any other light level you choose) with the eye's pupil stopped down and the second method shows vignetting in nearly complete darkness with the eye fully dilated.

Henry
 
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Canip

Well-known member
Thank you, Henry.

I will try this.

A question: when you write „sounds like your binocular is defective“, this would imply that

- it could be repaired
- things would be different when inspecting another sample

Right?

I have other binoculars which exhibit asymmetrical blur patterns, so I think this is not that unusual in low to mid price instruments.
 
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ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia

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