Sometimes you need to find things out for yourself....I wanted to know about the relative twilight brightness of the five hunting scopes that I actually regularly use...all have more or less the same reticle: variations on the German #4. Three are low-power variables and two are 4X, so I set them all on 4X. I put them on a box aimed at the same buildings and trees in the distance as the sun went down behind me. The Japanese Bushnell Scopechief VI 1.5-4.5X "went out" first, followed by a Zeiss Diatal-C 4X, then aNikon Monarch 1-4X, then my old favorite Swarovski Habicht 4X32 A 4X, then a Meopta Meostar R2 1-6X24 (the only 30mm, all the rest are 1 in.). The Swarovski has been my go-to standard for many years, with what I thought was great color and resolution at dawn and dusk (at least compared to the 4X Leupolds I once used) and it hung in with the Meopta for quite awhile as it grew dark but it also finally "went out", the image dimming and blurring while the Meopta was still bright with a very clear sharp image. This test proves little about the relative brightness of other scopes made by these various brands, just the relative twilight brightness of my specific scopes, and thats what I wanted to know.
Twilight test
- Thread starter Rob
- Start date
I am really enjoying the Meopta scopes. I have a 7x56 rd with an illuminated#4C ret that is very good in low light, compares very favourably to my Schmidt & Bender Zenith .
I just received a meostar zd 4-16x44 that has some amazing glass in it as well. The mil dot reticle is very fine, but it has a very nice illuminated cross that should work good for low light as well.
For less than half the price of a Schmidt they are very impressive.
I just received a meostar zd 4-16x44 that has some amazing glass in it as well. The mil dot reticle is very fine, but it has a very nice illuminated cross that should work good for low light as well.
For less than half the price of a Schmidt they are very impressive.
gunrunner8
CGN Ultra frequent flyer
- Location
- Kamloops, B.C.
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....
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....
One thing I can tell you, is that coatings on a scope to increase/decrease color rendition, contrast, glare, etc,
will reduce the amount of light available.
A cheap scope with less coatings or none at all, will have more available light at dusk/dawn.
Keep in mind that a cheap scope may have numerous other problems associated with it.
Some scopes even give you the specs on available light in percentage, usually the more expensive scopes will have lower numbers.
For good, reliable rendition under most/extreme conditions, coatings are essential.
will reduce the amount of light available.
A cheap scope with less coatings or none at all, will have more available light at dusk/dawn.
Keep in mind that a cheap scope may have numerous other problems associated with it.
Some scopes even give you the specs on available light in percentage, usually the more expensive scopes will have lower numbers.
For good, reliable rendition under most/extreme conditions, coatings are essential.
Curious to know, What were the times relative to sunset that each scope faded out? The difference in performance would come in handy on those days when it is cloudy and overcast and the light fades out well before legal shooting times end.
BeaverMeat
CGN Ultra frequent flyer
- Location
- Nanaimo, B.C.
This.
It should also be noted when scopes claim light transmission numbers, there are no standards by which to measure it. Some measure after it passes through the first lens...some do it after it passes through all lenses. Buyer be educated.
Contact a reputable manufacturer and ask them.
The same challenges are faced with Binos, microscopes and all coated lenses, even vision glasses.
Light transmission is a factor of lens quality (among other things), any coating applied will reduce it, some more than others.
As I mentioned above, cheap scopes will have OTHER problems associated with them, such as reflections, refraction, focus etc. that will reduce usability.
It's a compromise between glass, tube diameter, lens diameter and coatings (and coating quality of course)
BeaverMeat
CGN Ultra frequent flyer
- Location
- Nanaimo, B.C.
Actually, a shorter and fatter (larger diameter) tube has huge advantages over a long and narrow one.
(it also increases direct field)
Another aspect of coatings I should have mentioned above, is the ability to block/change certain wavelengths.
For example, if you drive at night with yellow lenses, everything looks brighter, even if the (amount) of light reaching
your eyes has been reduced.
Th
bearkilr
CGN Ultra frequent flyer
- Location
- Nowhere, ......just past the middle
Why Choose an Anti-Reflection Coating?
As light passes through an uncoated glass substrate, approximately 4% will be reflected at each interface. This results in a total transmission of only 92% of the incident light. Applying an AR coating on each surface will increase the throughput of the system and reduce hazards caused by reflections traveling backwards through the system (ghost images). Anti-reflection coatings are especially important if the system contains many transmitting optical elements. Also, many low-light systems incorporate AR coated optics to allow for efficient use of light. Figure 1 demonstrates the difference between an uncoated and coated single surface BK7 substrate. The coating used is a ¼ wave of MgF2 centered at 550nm.
http://www.edmundoptics.com/technical-resources-center/optics/anti-reflection-coatings
Why do you need AR coatings?
Between 4-16% of light is reflected back (lost) by a lens, depending on the material and it's refractive index. The higher the index the more light s reflected and the more noticeable an improvement you get from the AR coating. By adding an AR coating the overall transmission of the lens can be increased by almost 3.5-1.5.5%.
(again depending on the lens material ( substrate)
http://www.foresightoptical.com/coatings4.htm
Don't we have a Nikon rep that frequents CGN ? He may be able to tech us all a few things.
Yes, of course IR coatings are used, especially with high refractive glass or substrates (layers of glass).
Every layer of glass you add can produce reflective ghosting (just a surface reflection).
Ever get those nasty reflections on your corrective eye glasses? or safety glasses?
We were talking about the ability to transmit light, as I said, coated lenses will transmit less light than
un-coated lenses..........and I also mentioned several times that cheap lenses will have other problems that will reduce usability.
Just because they transmit more light does NOT mean you can see better under all circumstances, (some yes)
I also said above that coatings are essential.
Without coatings we would only be shooting under controlled conditions.
