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Meopta Meostar's lens (1 Viewer)

gwsudiro

Well-known member
Indonesia
hello... ^_^

do Meopta Meostar line up equipped with ED-elements ??

for your kind help, many thanks before... ^_^

best regards

Galih
 
No.

Meopta bins currently have neither ED objectives nor dielectric mirror coating on the roof prisms.

I suspect they do have anomalous dispersion objectives and LaK in the eyepiece (they control lateral CA well).

That said the Meostar 8x32 I have gives a very neutral view.
 
I cannot understand the preoccupation with ED or HD glass for binoculars.
A German birding magazine has done a 3 part test on 10x42s (the final part with Nikon, Pentax, Swarovski and Zeiss is still to come and I will then try to offer a synopsis) and the Meopta Meostar was judged to have almost indiscernable CA.
There was an interesting report on "Cloudy Nights" recently on an f/15 Fraunhofer. Despite some CA it was not without its advantages compared to faster ED or fluorite apochromats.

John
 
Perhaps because it makes a difference? It does to me.

All my ED/Fl bins have better perceived sharpness from the small clean up in CA (stuff that wouldn't see normally as color fringing). There are good non-ED bins (all using anomalous dispersion glass that are decent) but I can see the difference.

Astro guys have a different requirements for color accuracy and fine color detail than birders. That one area where birders stress their optics more than astro guys do.

Same goes for photographers who love their ED glassed lenses too.

I don't think I'll be carrying any f/15 bins in the near future ;)
 
I cannot understand the preoccupation with ED or HD glass for binoculars.
A German birding magazine has done a 3 part test on 10x42s (the final part with Nikon, Pentax, Swarovski and Zeiss is still to come and I will then try to offer a synopsis) and the Meopta Meostar was judged to have almost indiscernable CA.
There was an interesting report on "Cloudy Nights" recently on an f/15 Fraunhofer. Despite some CA it was not without its advantages compared to faster ED or fluorite apochromats.

John

John:

I would agree with you here, ED glass really has seemed to be the latest thing for some here. Recently, the Swaro. rep. pointed out that just a lens or 2 with
HD glass does not make an optic. It is the sum of its parts, the quality of the glass, the coatings and all the rest. ;)

As far as CA goes, it is not a big thing for many users, and so just go ahead and judge each optic as it comes.

Jerry
 
I wonder how much difference it would make if it were used in the Nikon SE's? If it already isn't in them. Could the average user discern a difference? Would the view be even more spectacular?

Bob
 
An f/15 binocular is not as preposterous as it sounds. If your eye closes to 2mm in bright sunlight like mine, then a 7x50 effectively becomes a 7x14. If the objective focal length is 200mm that makes the effective focal ratio f/14.3, pretty close.
 
John:

I would agree with you here, ED glass really has seemed to be the latest thing for some here.

IMO, it is the fixation on dielectric prism coating in roofs that has me puzzled. There is so much more that can go wrong in their application that can adversly affect the views while their postive influence is quite limited and virtually imperceptible to most.

On the otherhand, with cost differences to plain crown/flint now minimized, there are no optical "gotchas" to using ED glass for the objective lenses. On the contrary, doing so allows more freedom in the eyepiece design. And one only needs to look a flock of snowy white birds on a sunny day to easily see the benefits ED brings, even at relatively low magnifications.

Rick
 
I cannot understand the preoccupation with ED or HD glass for binoculars.
A German birding magazine has done a 3 part test on 10x42s (the final part with Nikon, Pentax, Swarovski and Zeiss is still to come and I will then try to offer a synopsis) and the Meopta Meostar was judged to have almost indiscernable CA.
There was an interesting report on "Cloudy Nights" recently on an f/15 Fraunhofer. Despite some CA it was not without its advantages compared to faster ED or fluorite apochromats.

John


John, Kevin and Henry:

You all commented on the "F" number and how it may translate over from
camera lens usage, but can you explain, further how it relates to the optics
we are using.

I am familiar with the F stop, as in the past I was quite interested in my SLR's,
but not as much now.

I have a Nikkor, 50mm 1.8, connected to my Nikon FE II, and I should run
a few rolls of film through it, although I just grab the digital, sound familiar
anyone?

Lesson, please.

Jerry
 
IMO, it is the fixation on dielectric prism coating in roofs that has me puzzled. There is so much more that can go wrong in their application that can adversly affect the views while their postive influence is quite limited and virtually imperceptible to most.

On the otherhand, with cost differences to plain crown/flint now minimized, there are no optical "gotchas" to using ED glass for the objective lenses. On the contrary, doing so allows more freedom in the eyepiece design. And one only needs to look a flock of snowy white birds on a sunny day to easily see the benefits ED brings, even at relatively low magnifications.

Rick

Rick:

Get a chance and view the thread on the Meopta 8x32 vs. Nikon EII, where
Holger Merlitz has a nice explanation on the dielectric coatings issue. These coatings have a great influence on color and brightness, and are commonplace on the mid to upper optics. Many of the mid to upper optics do not need ED glass to achieve great results. ;)

It seems Holger as a professor and scientist does a very good job with reviews
and his summaries are very well done. :t:

Jerry
 
John, Kevin and Henry:

You all commented on the "F" number and how it may translate over from
camera lens usage, but can you explain, further how it relates to the optics
we are using.
Lesson, please.

Jerry

Jerry,

I was hoping Henry might chime in here, but I'll have a go.

As you are aware, the f number is the ratio of opening to focal length, so a 65 mm scope with a focal length of 460 mm is f/7.
With a camera you choose a focal length to give yourself the desired viewing angle and if light is at a minimum a "fast" f/1,4 lens fully open will admit four times as much light to film or sensor as a f/2.8 lens, enabling you to use a much faster shutter speed.

With binoculars and telescopes we are interested in magnifications (the ratio of objective to eyepiece focal length) and for a specific objective diameter the longer focal length will have less chromatic and spherical aberration and less field curvature. This is assuming similar types of lens design. The "slow" f number allows simple constructions, which show better contrast than more complicated designs but the disadvantage of course is the overall length.

Fraunhofer telescopes are air-spaced doublets using traditional crown and flint glass pairings and are usually f/10 or "slower." A 100 mm f/15 scope would theortically allow a 3,8° field of view and should be usable down to a magnification of 15x or less. However, for this it would require an eyepiece of 100 mm focal length and AFIK nothing of this sort is available.

John
 
I'll only add one thing to John's post, which may also clarify my earlier post about f/14.3 7x50's.

In daylight the effective focal ratio of the objective lenses in binoculars is subject to constant change from the changing pupil size of the eye. The eye closing in bright light reduces the effective objective aperture very much like the iris stops down a camera lens. So, the effective speed of the objective lens of an 8x30 and an 8x56 in bright light is quite different even though both may be stopped down by the eye to the same 20mm effective aperture. If both have f/4 objectives then the 8x30 changes to f/6 in sunlight and the 8x56 changes to f/11.2 with lower aberrations.
 
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Hi Henry;

I am going to offer a different take on this than you. I agree that the image illumination will be limited by the pupil diameter. I also agree that the edge performance will be increased, but for reasons of vignetting, not stopping down the aperture or changing f numbers.

Some useful diagrams pertaining to the following at http://electron9.phys.utk.edu/optics421/modules/m3/Stops.htm

The aperture stop of the systems sets the light cone for the system. The exit pupil is only an image of the aperture stop and remains constant. The system f number is the ratio of the aperture stop to focal length and only changes by physically changing its diameter, an iris, to change the light cone. I believe stops apply as encountered in the direction of wave front travel. Also, even if the eye generated its own entrance pupil, and then it would only be at the binoculars exit pupil image, that aperture would only apply to the eyes focal length

If the exit pupil is a constant diameter and the eye pupil is smaller, then only the central portion of the wave front, or central rays, enters the eye. This explains the light portion and also explains the decreased aberrations, the rays, or portion of the wave front, from the outer edges are falling outside the pupil diameter. The eye is not modifying the binocular optics, it is just not accepting all the information furnished to it.

In an attempt to verify some of this, and as part of my ongoing DOF experiments, I tried to see any difference in DOF with changing f-numbers and could not see any. To my eyes the DOF remains pretty constant regardless of my pupil diameter. Any changes in f-number would alter the longitudinal-lateral relationships or magnification.

For discussion at a future date concerning larger exit pupils, try this. Take a pair of 8x20s or similar and turn them around. You now have a 2.5 mm aperture, 20mm exit pupil and a 50 degree true field of view. Move your eyes from side to side and toward and away from the binos while watching the FOV and apparent brightness. Give some thought to what this means.

Anyway, an alternative opinion.
 
Agreed Henry. Maybe more about definitions than practical differences.

Have a good day.

Ron
 
I have compared by EL to a pair of Swarovision EL loaned to me from a friend. The SV does exhibit much better CA control than the EL I have. For CA, the SV is about same as ED2, both are better than EL. But the flat field of SV is just amazing. I have never seen anything like that before. The SV has both ED(HD) glass and dielectric coatings.
 
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