Twilight test

sheephunter said:
I was just hoping that as you used the term that you'd be able to put some context to it. Even a simple explanation will suffice.
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Direct field is what you would see with the naked eye, looking down an empty tube.
Start with a short and fat tube as the optimal and add everything required, make it as small and light as possible.
Sooner or later you will end up with a tube similar to what scope manufacturers use now.
If we only used scopes for benchrest, they would/should look completely different.
 
bearkilr said:
I just don't understand what your point was in stating it in the first place. If you're a physics major or an aspiring astronomer, then this is probably the wrong forum to boast.
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Actually, I'm an old/miserable semi-retired Engineering Tech. (see my avatar).
Blind, deaf, and usually constipated.
(I work at a hospital on instrumentation.)
 
cet said:
Direct field is what you would see with the naked eye, looking down an empty tube.
Start with a short and fat tube as the optimal and add everything required, make it as small and light as possible.
Sooner or later you will end up with a tube similar to what scope manufacturers use now.
If we only used scopes for benchrest, they would/should look completely different.
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I fail to see how rifle scope tube size would influence that as we are looking through lenses....not empty tubes. Scope tube size is more a function of the amount of internal mechanics required to achieve desired zoom range or MOA adjustment....and often just country of origin. It matters not for light transmission.
 
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bearkilr said:
Nonsense. AR coatings reduce reflection which in turn boosts light transmission. Not sure where you're coming from with your statement.
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Perhaps from the twilight zone.

Judging from his statements about light transmission, I am starting to believe his comment about being blind.:p
 
Quick addition as I got addressed, all opinions my own and not that of Nikon.

The biggest issue I see is the variance in terms and industry accepted terms. Light transmission versus light capture. The fact we as an industry have very little in the way of "industry standards" in regards to testing etc. As far as light transmission goes, a ton of of stuff goes into it. However a few points; the addition of coatings aids light passing through glass. Someone posted above non-coated would be brighter. This is wrong, glass on its own (take your scotch tumbler in your hand, hold it up to the light) will reflect about 10% of light automatically. Its just the nature of glass. However by adding coatings we can actually increase the amount of light passing through. That being said each companies coatings and number of layers is trade secret. However I work for a company that makes some of the worlds best camera, microscope and eyeglass lenses. All we do is research this stuff. Keep in mind however your riflescope/ bino etc has anywhere from 10-12 pieces of glass in a row lined up inside. Add a focus piece or prism in the case of binoculars and a whole lot of other stuff comes into play. Top of my head without rolling out my training slideshow, lol, alignment, quality of the physical glass, aberrations, whether the coatings are only on the surface to air glass or each individual piece, the quality of the coatings on the prism/ focus piece. All glass is poured and is sharpest in the middle and fading going out, the quality of manufacture will determine if you have sharp edges, flat field of vision, no chroma noise (purple fringing when colors overlap). This is ignoring eye relief, exit pupil and the simple eyeball test (does it work for my eyes/ brain).

I stress in my presentations that light transmission should be based on light reaching your eye, Nikon does not officially print our numbers because there is no industry standard test. A lot of times on CGN I see we defer to the birding community for binoculars as they take the time to do these tests on their own. There is merit in that. I'd happily put our scopes up against comparably priced optics in any of these tests. Can you guys get all the other manufacturers to agree? :)

Again, happy to chime in but please understand I will only discuss my knowledge and not that of other brands terminology or claims.
 
Hi Travis,

First, let me thank you for responding, it's great to have a reputable manufacturer representative on CGN.
Nikon will do well with the exposure and personal touch you provide.

Second, let me thank you again for skirting the "old fool" comment like the rest. Very professional.

This thread started with the OP comparing scopes at dawn/dusk, I made several comments about
coatings.

My above stated position, is that coatings are essential.
However, if using a scope at dawn only (for example), you could reduce the number of coatings to only a few necessary ones
and increase the light available to the lenses thus increasing the ability to see in low light conditions.

Using a cheap Tasco with very few coatings, if any, would not be ideal for normal use, but in low light conditions it
will be "brighter". (may have numerous other problems, but will appear brighter)

About all they do in cheap scopes is reduce reflectivity.

Please let me know what you think.

Note: Can you please tell me why manufacturers are not increasing the size of tubes?
 
Missing the point

"Valid"? You are completely missing the point.

It wasn't intended to be a scientific or even a fair test to determine which manufacturer makes the best twilight scope....the ambition of the test was much more modest and personal...I just wanted to compare in dimming light the few specific scopes (all relatively small lightweight low-power hunting scopes) that I actually own and use on a regular basis. I did not intend to compare all scopes or even similar or "equal" scopes. And of course the results would be different if I used different scopes...but these are the scopes I own and use...for all sorts of reasons, and not just for shooting at dawn and dusk....get it?



gunrunner8 said:
Rob, for that test to be valid the "exit pupil" on all those scopes neeed to be equal as well.
For instance Nikon having EP=5mm (20mm:4x) is at disadvantage to Meopta (with larger internal glass as well) with EP=6mm (24mm:4x).
I bet you that if you compared your Meopta to say Bushnell 6500 1-6,5x24mm and Sightron SIII 1-7x24mm the end result of your experiment could be quite different....
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cet said:
Hi Travis,

First, let me thank you for responding, it's great to have a reputable manufacturer representative on CGN.
Nikon will do well with the exposure and personal touch you provide.

Second, let me thank you again for skirting the "old fool" comment like the rest. Very professional.

This thread started with the OP comparing scopes at dawn/dusk, I made several comments about
coatings.

My above stated position, is that coatings are essential.
However, if using a scope at dawn only (for example), you could reduce the number of coatings to only a few necessary ones
and increase the light available to the lenses thus increasing the ability to see in low light conditions.

Using a cheap Tasco with very few coatings, if any, would not be ideal for normal use, but in low light conditions it
will be "brighter". (may have numerous other problems, but will appear brighter)

About all they do in cheap scopes is reduce reflectivity.

Please let me know what you think.

Note: Can you please tell me why manufacturers are not increasing the size of tubes?
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Appreciate the kind comments, in regards to coatings however you're still a little off. Anti-reflective or glare coatings are not the only thing that go into brightness. Aligning the color spectrum into a single point will make the scope seem brighter. Concentrating on color waves the human eye can see will make the scope seem brighter. Darkening the inside of the tube itself to prevent refraction will make the scope brighter (this is really key in binos and is rarely talked about). However even the physical quality of the glass itself, sans coatings, will make a huge difference. As an analogy, think of going to an antique store and picking up an old vase and how cloudy the glass is versus walk into the Dollar Store and grab one off the shelf today. Glass today is just better. However (quick Nikon plug coming) we are one of the only manufacturers sub $1000 that still makes our own glass. Its not farmed out or brought in from a 3rd party. So although adding extra layers of coatings sounds like it would dim the glass, in reality it won't. Pretty much anything added is meant to brighten or sharpen the image which will help our eyes see. My only exception would be the awesome Ruby Red coating you see on some $19.99 blister pack bino's at big box stores, this is just to make them look cool. Lol.

As for tube size, I'd say two fold. Industry standard is the 1 inch and 30mm tube sizes. Most companies don't make optics and rings and bases etc. So to move the industry or do your own one off is risky and expensive. Secondly and my personal opinion; it doesn't matter that much. I know some guys swear by 30mm tubes but if you sit down and do the math we are talking about slight percentages in light transmission. I'm one of those lucky guys with really good eyes, to me it barely makes any difference. However if you're doing competition shooting and that extra few lumens of light make the difference. Well there's that option for you. :)
 
machinistbutler said:
Rob, how do you like the R2 so far? I have read nothing but good things on that scope.
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I've used a quite variety of hunting scopes in the last 4 decades, including (off the top of my head) various Zeiss, East German Jena Zeiss, Swarovski, Burris, Nikon, Bushnell, Leupold, Redfield, Hubertus, Weaver and other Meopta among others and I'd say the Meopta Meostar R2 1-6X24 is the best hunting scope I've ever owned. (I do tend to prefer lower power hunting scopes.) So I guess I like it quite a bit so far.

Its temporarily on a Husqvarna right now. I intend to install it on my Sako 85 FS (away having the woodwork "slimmed") and my only concern is that it just might be a tad too heavy for this rifle. It all depends on how much the weight and balance of the rifle has changed with the re-filing of the stock. I'll have it back in a few weeks and then I'll find out.
 
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Nikon Travis M. said:
Appreciate the kind comments, in regards to coatings however you're still a little off. Anti-reflective or glare coatings are not the only thing that go into brightness. Aligning the color spectrum into a single point will make the scope seem brighter. Concentrating on color waves the human eye can see will make the scope seem brighter. Darkening the inside of the tube itself to prevent refraction will make the scope brighter (this is really key in binos and is rarely talked about). However even the physical quality of the glass itself, sans coatings, will make a huge difference. As an analogy, think of going to an antique store and picking up an old vase and how cloudy the glass is versus walk into the Dollar Store and grab one off the shelf today. Glass today is just better. However (quick Nikon plug coming) we are one of the only manufacturers sub $1000 that still makes our own glass. Its not farmed out or brought in from a 3rd party. So although adding extra layers of coatings sounds like it would dim the glass, in reality it won't. Pretty much anything added is meant to brighten or sharpen the image which will help our eyes see. My only exception would be the awesome Ruby Red coating you see on some $19.99 blister pack bino's at big box stores, this is just to make them look cool. Lol.

As for tube size, I'd say two fold. Industry standard is the 1 inch and 30mm tube sizes. Most companies don't make optics and rings and bases etc. So to move the industry or do your own one off is risky and expensive. Secondly and my personal opinion; it doesn't matter that much. I know some guys swear by 30mm tubes but if you sit down and do the math we are talking about slight percentages in light transmission. I'm one of those lucky guys with really good eyes, to me it barely makes any difference. However if you're doing competition shooting and that extra few lumens of light make the difference. Well there's that option for you. :)
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Aligning the color spectrum into a single point will make the scope seem brighter. Concentrating on color waves the human eye can see will make the scope seem brighter
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Yes ... very important distinction - I recall a scope manufacturer employing a photographic light meter to compare competing manufacturers scopes and proclaiming that the meter clearly demonstrated that their scope was best and "transmitted the most light" - they didn't bother to mention that their particular light meter (a Gossen) was sensitive to wavelengths that the human eye/brain could not register/perceive and that their results were irrelevant to a hunter and misleading.

Darkening the inside of the tube itself to prevent refraction will make the scope brighter (this is really key in binos and is rarely talked about)
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yes ... but as much as I admire/own and use many Nikon products with great satisfaction ... the Ell 8x,30 could be improved here.

Anti-reflective or glare coatings are not the only thing that go into brightness
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... certainly for glare/flare a simple lense hood (with proper matte black non-reflecting interior surfaces) is extremely effective and would be a useful provision on some scopes. And the rubber eye shield that was included with the older Zeiss Jena scopes for ZKK rifles was an added bonus in side and back lit situations.


BUT I am not sure I would dismiss CET's comments too quickly and I wonder if "modern" glass designs (and optical systems) could now be developed that reduced the need for coatings (while increasing light transmission) under certain conditions????? I have an older 2 3/4X "Dialyt" with no coatings and (according to some sources) apochromatically corrected lenses that is extraordinarily bright/sharp and contrasty with beautiful colour - in many light conditions!

Of course there is a broad range of "coatings" available (although not always to the general public) that run the range from Steiner's "ruby red" coatings to exceptional coatings available from Questar (and some others)
 
Rob said:
a Meopta Meostar R2 1-6X24 (the only 30mm, all the rest are 1 in.).
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In all fairness this test should been conducted with all 1 inch tube scopes or all 30 mm tube scopes it is well know tfoor at least 20 yrs know that the larger diameter tube scopes out perform the the smaller ones in low light conditions.
 
Savage said:
In all fairness this test should been conducted with all 1 inch tube scopes or all 30 mm tube scopes it is well know tfoor at least 20 yrs know that the larger diameter tube scopes out perform the the smaller ones in low light conditions.
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How do they do that?
 
sheephunter said:
What math?
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If you took the difference between a 1 inch 50mm objective versus a 30mm 50mm objective as it gathered light at the bell, passed through each layer of glass back through your tube to the rear exiting to your eye you should see some brightness gains by having a larger tube allowing larger glass, meaning the benefits of hopefully sharper center points get more light to your eye. Again in my opinion this would be fairly negligible, I'm also nowhere near smart enough to sit down and do that much algebra. :)

All the above, light gathering at the bell will still outweigh the tube size quite substantially I would assume. If the light can't get in, doesn't matter what you're looking through.
 
So you'd think but it's not what a couple of the top European optic engineers have explained to me and if anyone had an agenda for pushing 30mm tubes it would be them. According to them there is zero difference. Objective size, glass quality and coatings are what matter. Big tubes are just there to accommodate more internal mechanics like additional MOA adjustment or increased zoom range or just because of country of origin.
 
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