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Old Tuesday 17th March 2015, 19:53   #26
Leviticus Plews
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Thanks much for the explanations of the differences, this is valuable information for me.
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Old Tuesday 17th March 2015, 20:03   #27
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Is the term "CA insensitive" a construct of bird forum members? Or is their academic research to support the condition in humans? I assume anyone can see CA (assuming their visual acuity is sufficient and conditions are conducive to it).
Although we are normally unaware of it, chromatic aberration is part of the normal optics of the eye. It does vary significantly between individuals with the aberrations of the cornea and lens, symmetry of the cornea and pupil diameter. We don't see it because of the neural filtering in the higher visual system removes it from the concious visual experience. So the brains of some individuals need to do more correction than others. I've not been able to track down if and how this ties in with the range of sensitivity to supplementary CA from binoculars etc. but from many, many reports on the forum such differences exist.

The most striking example I've witnessed was went I was trying out various binoculars alongside two first time buyers. I tried a 12x50 which was probably faulty and had the worst CA I've ever seen. A leafless bush in the view was just awash with high intensity fringing. The sales person had just been trying to explain ED glass and CA to the novices so I handed the binocular to them to try. The first just went "Wow! What's with the neon light display" the other guy spent the next ten minutes trying to find it, and failed. It convinced me!

Hope that helps.

David
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Old Tuesday 17th March 2015, 20:55   #28
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The first just went "Wow! What's with the neon light display" the other guy spent the next ten minutes trying to find it, and failed. It convinced me!
It could have been due to a number of other factors: eye positioning, viewing the target off-center, or even just poor eyesight by the one viewer.

Even reviews by birdforum members must be taken with a grain of salt. There is opinion wheat here, but also opinion chaff.

I think to be a good optics reviewer, one must be highly observant, meticulous, have good eyesight, have access to optics which are comparable, and strive to reduce personal biases. Few people meet all those points.
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Old Tuesday 17th March 2015, 21:33   #29
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It could have been due to a number of other factors: eye positioning, viewing the target off-center, or even just poor eyesight by the one viewer.
I've checked out several hundred binoculars and that had the worst CA I've ever seen.

The full story was rather interesting, it turned out that the first guy also noticed differences in effective resolution, field curvature, pincushion distortion, astigmatism, contrast and colour rendition between different models as well, though he expressed it in different terms. Pretty remarkable for a novice I reckon. The other guy couldn't spot any of those differences. It seems a reasonable representation of the range of binocular users perceptive skills.

Quote:
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Even reviews by birdforum members must be taken with a grain of salt. There is opinion wheat here, but also opinion chaff.

I think to be a good optics reviewer, one must be highly observant, meticulous, have good eyesight, have access to optics which are comparable, and strive to reduce personal biases. Few people meet all those points.
Totally agree. That first guy probably had the makings of an excellent reviewer. What ever the other guy thought probably wasn't worth reading. Not so different from the forum.

David

Last edited by typo : Tuesday 17th March 2015 at 22:04.
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Old Thursday 26th March 2015, 00:59   #30
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CA reared its ugly head today with the Kowa's. I was looking at a white rope clothes line that went diagonal and away from me against a dark background, and the CA was very noticeable.

At the symphony on Sunday, it wasn't an issue.
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Old Wednesday 15th April 2015, 05:34   #31
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Totally agree. That first guy probably had the makings of an excellent reviewer. What ever the other guy thought probably wasn't worth reading. Not so different from the forum.

David
So which one would be the happier user?
Not necessarily the more critical one.
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Old Wednesday 15th April 2015, 16:40   #32
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So which one would be the happier user?
Not necessarily the more critical one.
True, but at the time he was getting pretty annoyed that he couldn't see the characteristics his buddy was describing, specially reading the small print on a sign about 70m away.

David
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Old Sunday 3rd May 2015, 01:59   #33
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I'm still liking my Kowa BD Prominar 8x42 XD.

The field of view is the same as the Sightron Blue Sky II 8x32 (7.5 degrees), but the sweet spot extends farther to the edge of the field.

Glare control is not as good as the Blue Sky, but it's still good.

I like the ergonomics.

I can notice an ever-so-slight difference in focus as I approach in-focus from far vs. near. There must be a bit of slop in the focus system that affects one barrel differently.

I would like to compare a Celestron Granite ED 8x42 against the Kowa.
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Old Monday 4th May 2015, 19:47   #34
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I'm still liking my Kowa BD Prominar 8x42 XD.

The field of view is the same as the Sightron Blue Sky II 8x32 (7.5 degrees), but the sweet spot extends farther to the edge of the field.

Glare control is not as good as the Blue Sky, but it's still good.

I like the ergonomics.

I can notice an ever-so-slight difference in focus as I approach in-focus from far vs. near. There must be a bit of slop in the focus system that affects one barrel differently.

I would like to compare a Celestron Granite ED 8x42 against the Kowa.
Is there ring on the right eyepiece for individual focusing have ratchet mechanism or smoothly on your binoculars?
Celestron Granite ED 8x42 worse than Kowa.

Last edited by alexbino : Monday 4th May 2015 at 19:49.
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Old Tuesday 5th May 2015, 01:14   #35
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The diopter adjustment works smoothly.

The slop that I mentioned in the focusing from different directions is extremely small.
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Old Tuesday 5th May 2015, 20:17   #36
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The diopter adjustment works smoothly.

The slop that I mentioned in the focusing from different directions is extremely small.
If binocular diopter adjustment is smooth, then the serial number starts with 1300500. When the serial number is from 130000 to 1300499, the diopter adjustment works ratchet. There are no slops in the focusing from different directions in such binoculars. The serial numbers can be small deviations.
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Old Wednesday 6th May 2015, 00:46   #37
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There are no slops in the focusing from different directions in such binoculars.
A geared, mechanical system without tolerances? That would be quite a feat!
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Old Wednesday 13th May 2015, 20:18   #38
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Hi praise indeed, Alex. I'll have to try to see one of these.

Here's something I can't figure. I have attached a photo of the 8x42 to the left of the 10x42. Look at the difference in the eyepieces! And the 10x42 has LESS eye relief than the 8x42. I can't imagine the 10x42 would work with glasses, so why did Kowa do it? Or have they revised it?

Anybody know?
Not only that the eye lenses of 10x42 are smaller, they are more(way too much) recessed than the eye lenses of 8x42 model. Really bad design. The picture in it self is enough to show that you can forget eyeglasses use with it.
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Old Friday 5th June 2015, 19:20   #39
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If binocular diopter adjustment is smooth, then the serial number starts with 1300500. When the serial number is from 130000 to 1300499, the diopter adjustment works ratchet. There are no slops in the focusing from different directions in such binoculars. The serial numbers can be small deviations.
Do you have any more details about the history of diopter changes in the model? They must have had issues that forced a redesign? The serial number of my 8x42 is 13008xx.

Regarding use with glasses, I don't wear glasses, so I don't know.
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Old Sunday 2nd August 2015, 19:21   #40
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My quick comments on the 10x42: no blackouts without glasses, and the only bin that I can use with the eyecups not fully twisted out but no idea if the set is suitable for those wearing glasses. The bin is usable but not a keeper for a pretentious user: CA even in the sweet spot, visible astigmatism, the eyecups are huge and made of hard rubber and hence rather uncomfortable, and the two copies that I tested had a lot of grease inside the barrels.
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