Can a Non-Fluorite lens binocular compete with a Fluorite lens binocular? (1 Viewer)

Yes Lief, I guess that makes more sense on the whole, faster objectives are notorious for more false color at astronomical magifications. I still also believe that if more light comes through more CA will show in a given system. If only those William's APO bins were phase coated. Imagine a three element APO Ultravid, Leica are you listening?

jwillson said:

Keep in mind that the eye's response to light is logarithmic, so a 10% difference in light transmission is actually very small in terms of perceived brightness. I'm not certain it would even be detectable. You may have known this, of course, but I wouldn't want someone looking at a 90% transmission vs. a 95% transmission and thinking, "Gosh, that's a pretty big difference in brightness!"

- Jared

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I've spent more idle hours than I would care to admit comparing the "brightness" of every kind of optical thing; binoculars, scopes, eyepieces, diagonal prisms and mirrors, etc. Sometimes I've been helped by actual light transmission measurements like the excellent eyepiece light transmission tests from apm-telescopes and the occasional manufacturer's figures. Using those I've found that my threshhold for being able to see any difference at all is 2-3%. 5% is easy, but not very large. 10% is quite easy and significant. Of course things can be complicated by factors like the shape of the transmission curves in different optics and whether there is more or less scattered light influencing contrast as well as perceived brightness.

Leif said:

Yes I am told that the Victory has more CA than average. However I don't believe there is any connection between CA and light transmission. It might be that because the AK prisms are long compared with SP ones, Zeiss use faster objectives to keep the length manageable (though still long compared with others). That means more CA unless improved objectives are used c.f the FL. However, IMO the FL do have less CA than competing instruments, so on that front they are not merely catching up with the competition.

Leif

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I expect you've got it right. If you look at the light path for AK prisms, they don't "fold" the light back on itself like the typical roof prism, so the binoculars must be quite a bit larger physically for a particular focal length. The only way to keep the binoculars similar in length to other roof prisms is to make faster objectives... This makes virtually all aberrations more visible--including chromatic aberration. That would push Zeiss into using exotic high index/low dispersion glass. It's the trade off for the higher light transmission vs. a traditional, aluminized roof prism.

- Jared

henry link said:

I've spent more idle hours than I would care to admit comparing the "brightness" of every kind of optical thing; binoculars, scopes, eyepieces, diagonal prisms and mirrors, etc. Sometimes I've been helped by actual light transmission measurements like the excellent eyepiece light transmission tests from apm-telescopes and the occasional manufacturer's figures. Using those I've found that my threshhold for being able to see any difference at all is 2-3%. 5% is easy, but not very large. 10% is quite easy and significant. Of course things can be complicated by factors like the shape of the transmission curves in different optics and whether there is more or less scattered light influencing contrast as well as perceived brightness.

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Very interesting results--and slightly different from what I was taught in a college optics class. In that class, we were told that 10% was about the lowest change in brightness that was detectable to the human eye, and I was relying on that number.

I wouldn't tend to trust the manufacturer's numbers (except where comparing between products within the same manufacturer) since each manufacturer probably comes up with its own testing "standards", but if you have done real-world, measured testing that's probably a very reliable result.

Thanks for the information.

- Jared

henry link said:

I've spent more idle hours than I would care to admit comparing the "brightness" of every kind of optical thing; binoculars, scopes, eyepieces, diagonal prisms and mirrors, etc. Sometimes I've been helped by actual light transmission measurements like the excellent eyepiece light transmission tests from apm-telescopes and the occasional manufacturer's figures. Using those I've found that my threshhold for being able to see any difference at all is 2-3%. 5% is easy, but not very large. 10% is quite easy and significant. Of course things can be complicated by factors like the shape of the transmission curves in different optics and whether there is more or less scattered light influencing contrast as well as perceived brightness.

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Henry: Although I cannot see small differences in brightness, I don't doubt what you say. I can only assume that you have trained your eye to see these small differences. I have never noticed vignetting in binoculars, where the brightness variation is larger than 10%, whereas others see it.

Leif

Brightness is not very important. Sometimes I'm surprised by all the in-depth discussion of it, as the actual application of a pair that transmits 85% as oppsed to another that transmits 95% might not be that significant with all other factors considered.

I'm not very knowledgable about these facts and statistics, but I have tried various binoculars during moonless nights, and I would rather have more magnification than brightness...

In one case, my testing of the Zeiss 7x42 and 10x40 Classics, I noted the 7x42 were approximately the same in terms of clarity, sharpness and resolvable definition. Even though the 7x42 were noticably brighter, the 10x could still make out more detail, even under brush in the shadows of night. With the naked eye, much of what appeared black could easily be seen with both binoculars. There was no point to where one pair could see something the other could not. Areas that were just too dark to view were just that, and were far enough away that the 10x could resolve viewable objects alongside the unviewable areas farther, albiet a bit dimmer.

I've done some pretty intesive side by side testing between the SLCs, Ultravids and Classics during the day and night, and my perceptions are my own obviously. I haven't been fortunate to try many other high end bins, but I've compared dozens of models, and this is just my relative experience in the subject.

Leif said:

Henry: Although I cannot see small differences in brightness, I don't doubt what you say. I can only assume that you have trained your eye to see these small differences. I have never noticed vignetting in binoculars, where the brightness variation is larger than 10%, whereas others see it.

Leif

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Here are some figures from variable stars observers :
For very beginners, the minimum perceptible difference in brightness between too stars is 0.3 magnitude. That means that a star must be 32% brighter than another to be perceived as brighter.
On the other hand, for very experimented observers, the threshold difference is about 0.04 magnitude, representing only 3.75% in brightness difference.
So, it depends highly on people.

Jean-Charles

Here is my admittedly obsessive method for detecting small differences in light transmission among binoculars. Anybody can do it, but you must not be bored by lots of repetition. Compare only two things at once and switch very rapidly and repeatedly between the two. This may be as simple as holding a binocular in each hand. I don't think it is possible to remember the exact brightness of an image for more than a few seconds, so I try to set up a situation which allows me to make the switch in about one second. I look at a particular target with one binocular until its image brightness is firmly established, perhaps 10-20 seconds, then switch as quickly as possible. I repeat the procedure many times using different targets and returning to the same ones. I vary the order of the switch and even which hand holds each binocular. Most of the time I do this in daylight, and I prefer bright sun so exit pupil is not a factor. In my experience very high light transmission gives the optical image a vivid transparency, even in bright light when of course it is not really needed to see detail. Lower transmission optics, certainly 10% lower, look a bit dead in comparison.

The Zeiss 8x42 and 8x32FL are interesting to compare. They have the same coatings and the same number of glass to air surfaces. The 8x42 uses an AK prism and the 8x32 uses a Schmidt-Pechan with dielectric mirror coating. According to Zeiss there is about 2% lower light transmission in the 8x32 compared to the 8x42.

The florite Glass does improve light gathering and better views in the dusk hours Leica is just out now with their New HD binoculars with Florite Glass lenses a Leica Ultravid HD 8x42 goes for $1,999 another choice besides the Zeiss and Leica is the Leupold Gold ring HD 8x42 for around $1,395 the Leupolds optics are florite glass and are the same as the Leica in performance but at much lower cost they are very high quality but a bit heavy at 33 oz. Many Leica fans or Zeiss fans despise these Leupolds probably because they overpaid on their purchase people who compared the Swarovski 8.5x42 EL to the Leupold Gold ring HD 8x42 found the image just as good or better and would buy the Leupolds if you want to save over $500 in your pocket check out the Leupold Gold ring HD if you have money to burn you can buy anything you want of course I have a 8x32 kowa Great binoculars and quality glass and build I need a 8x42 for cloudy days and late use near dusk a 42mm is best for this so I am saving now for the Leupold Gold ring HD 8x42 a lot of money but still better in price than a Leica Ultravid I will save $599 with the same quality Florite optics and performance without paying the extra for import fees and the name Leica Leipold has a Lifetime warranty as well you can not go wrong with Leupold customer service it is great just some thought.

After reading through this interesting old thread, I would have to say the use of FL-type glass in binoculars has proven to be more than a gimmick. Almost every brand has moved whole-heartedly into the use of FL/HD/ED glass of some sort in many models.

And, it was a great reason to charge more money to cure a problem [CA] that most people didn't know existed!

james holdsworth said:

After reading through this interesting old thread, I would have to say the use of FL-type glass in binoculars has proven to be more than a gimmick. Almost every brand has moved whole-heartedly into the use of FL/HD/ED glass of some sort in many models.

And, it was a great reason to charge more money to cure a problem [CA] that most people didn't know existed!

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Opticron ED-X and die laughing !!