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The Best 60MM Spotting Scope On The Planet
By Todd Spotti
 
     A while back, I reviewed the Nikon Fieldscope III in my Ranging Shot column and called it the best 60mm spotting scope around. Well, I was wrong. Itís the second best 60mm spotting scope around. THE very best 60mm spotting scope on the planet is the Nikon Fieldscope III ED. No ifís, ands, or buts. Itís the best period.

     Please understand that I donít make this statement lightly. In my 20 plus years of silhouette shooting, and my 27 plus years of involvement in amateur astronomy (I own an 8Ē Schmidt- Cassegrain telescope and a wide variety of exotic eyepieces to go with it), Iíve looked through a lot of scopes both large and small. In that time, I think Iíve pretty much developed an ďeyeĒ for whatís a good, average, or poor image, and I can confidently say that the image that I see in the Fieldscope III ED is absolutely the best ever for a scope of that size and design.

     OK, you may be wondering ďWhatís the difference between the standard Fieldscope III and the Fieldscope III ED?Ē Well, ED stands for extra-low dispersion glass. OK, so whatís that? Extra-low dispersion glass is a very unique type of optical glass that was originally developed by Nikon and which is now used by just about every other manufacturer of optical instruments. Itís primarily used on first quality astronomic refractor type telescopes and eyepieces as well as high quality microscopes.

     To fully understand the benefits of ED glass weíll have to divert into the esoteric science of optics. When pure white light (like from the sun) is passed through a water droplet or a prism, itís split into its separate color components such as red, blue, and green. (Thatís how all those pretty rainbows are produced.) Each color has a different wave length and so travels at a different speed. Consequently, when those different wavelengths pass from the air into an ordinary lens, each is bent differently than the others. Therefore, each color will have a different angle of refraction. The blue wavelength is refracted the most, followed by red and then green. This change in refraction is called dispersion.

     The practical consequence of this is the fact that each of the three colors, when passed through a simple glass lens, will focus in a slightly different spot. Think of it. Red is focused here, blue there, and green somewhere else. Remember, a lot of what we see are combinations of red, blue, and green. The resulting image will be fuzzy and will have all kinds of color fringing. This effect is called chromatic aberration, or in plain English - color abnormality. Itís interesting to note that Galileo used just such a scope to discover the moons of Jupiter.


     In the 1700ís, it was discovered that if you cemented together two lenses made of glasses which had different refractive indices, chromatic aberration in the red and blue wave lengths could almost be completely canceled out. Almost. Consequently, crown glass (soda-lime-silica) and flint glass (50% lead oxide crystal) have become the standard combination for objective lenses ever since. I can assure you with great confidence that the objective lens of your spotting scope and even in your rifle or pistol scopes, are probably not a single lens at all, but are actually a crown and flint two lens combination glued together into a compound lens. This lens design is called an achromat doublet, or often called a doublet or an achromat for short.

     Achromatís are actually a pretty good design and I use some achromat eye pieces on my telescope when Iím looking at easily viewed objects like features on the moon. However, an achromat can go just so far. While they get the red and blue wavelengths pretty much focused in the same place, itís not exactly perfect. Then thereís the issue of the green wave length which this design can not deal with. While the image that these lenses produce can be very, very good when first quality materials and coatings are used, crispness and color fringing can still be improved.

     This situation was solved with the development of the apochromatic lens, especially when using Nikon ED glass. Apocromatic means ďwithout colorĒ. In other words all the color wave lengths are focused in the same place and consequently, all color blurring and fringing is eliminated. Astronomy geeks refer to these lenses as apoís.

     This type lens is made up of at least three or more elements. In some simple designs, you can have three elements cemented together into a single compound lens (a triplet), and in others there can be a complex combination of single, doublet, or triplet lenses. With some apo's there can even be an air gap between some of the lens elements. These lenses are often referred to as being ďair spacedĒ. The bottom line however, is that the use of ED glass in a apocromatic lens provides the very best levels of definition, resolution, and contrast that is technically available. As a matter of note, the ED Fieldscope III objective lens is an apo made up of five elements, two of which are ED glass.

     By a fortunate quirk, I happen to have available both the standard Fieldscope III which I recently reviewed and a new, sexy, black tactical ED model. Consequently, I decided to do a side by side comparison between the two.  The exterior of the tactical scope is a completely new, very sleek design and the black color will be appreciated by the hunter who wonít have to worry about spooking game. The compact dimensions of the standard Fieldscope are retained in the new model at just under 11 inches in length. Weight has been actually reduced slightly with the use of a improved alloy body so this is an even more portable product. Amazingly, it will also focus down to a mere 12 feet which makes it useful for airgun competition as well as long range work. Field of View at 100 yards is 105í at 20X and 55í at 45X which should make your spotter happy. Both models used in the evaluation were straight thru designs, which I prefer, as pointing them is easier and more natural for me. However, an angled model is also available for both. The standard Fieldscope and the ED models can be had with a jumbo 78mm objective lens as well.

     Let me first say first that ED glass is expensive, very expensive, and that fact is reflected in the price between the two models. Iíve read that a 6 inch blank of ED glass costs something like $5000. Because it's softer than normal optical glass, it's also more difficult to work with. Consequently, you can expect to pay around $300 more for an 60mm ED Fieldscope - depending on where you shop. Given the situation, I then had to ask myself, ďOK, what will the ED Fieldscope do that the standard Fieldscope canít? Is it really that good?Ē. Letís find out.

     One of my favorite targets when evaluating scopes is a very large, eight line electrical transmission tower located about a mile away from my home. I like to use it as such because itís a complex structure with a lot of detail on it. One of the best parts of the tower I find useful in these evaluations is a row of upright metal spikes located above each of its giant ceramic insulators that hold the transmission cables to the tower. The spikes are approximately an inch and a half wide and taper to a sharp point at the top. Theyíre also located around an inch and a half apart and are perhaps around 8 inches high. Their function is to prevent birds and the like from getting on the lines and shorting out the power. With the standard Fieldscope, I could see and count the spikes with no problems. I consider this to be excellent performance because with lesser scopes, the spikes tend to blur and bleed into each other.

     When I trained the ED model on the spikes, it was like someone lifted a gauze curtain from the image. I not only could see the spikes distinctly, but I could also see that they were not round as I had always assumed, but rather were pointed flat medal strips instead. The edges of the strips were straight and distinct and I could even see the variations in the rust patterns on their flat sides. Additionally, for the very first time, I was able to see that one of the spikes was bent forward. Iíd been looking at that tower for a long time now with a lot of different scopes and thatís the first time that I saw that particular detail. Even better, I could also see the tips of the spikes clear as a bell.

     I then cranked up the power on the 20 X 45 eyepiece. On a lot of scopes, cranking up the power is like the kiss of death. Everything falls apart. The image instantly gets dim, and resolution, contrast, and color fidelity turns into you know what. As I started turning up the power on the ED model, the image held together amazingly well and the brightness didnít seem to change very much at all. It wasnít until I got to the top end of the magnification range that I noticed the first significant decrease in the brightness. However, image quality was still holding together. It was just a little dimmer.

     I then cranked the power back down to 20X and then noticed that when I trained the scope away from the dull gray painted tower and around to see other objects, colors were richer and more vivid. I have to admit that I was genuinely shocked and excited. This was definitely a different, higher level in performance.


     Now it was off to the range where weíd look at things in more controlled situation. There, Iíd again use my homemade resolution target that is made up of several rows of ďOísĒ in increasing sizes varying from 72 point type to 9 point. Anyone can make one of these charts on their home computer and it actually works pretty well for this purpose.

     The resolution target was placed at 100 yards. Temperature was in the mid-80ís so fortunately mirage wasnít a big factor. The standard Fieldscope went first. At 20X the 24 point Oís were distinct and crisp and the 18 point Oís were discernable as circles with white centers although they were definitely fuzzy. I then started cranking up the power and the resolution continued to hold together fairly well. Colors started washing out almost immediately however as I advanced the power. At 40X and above, brightness, color, and resolution definitely diminished noticeably. This was really excellent performance. Not too many scopes can resolve written characters that small, especially when increasing magnification that high.

     Now it was the ED modelís turn and it did itís builders proud. The printed characters on the target were extremely crisp and sharp against the white background, and by playing back and forth with the power ring, I could clearly and distinctly see 14 point type, and 12 point type was discernable. The difference between 18 point type with the standard scope and 14 point type with the ED is no small thing (pun intended). Indeed, as I cranked up the power, the image resolution and color quality held together even better than with the standard Fieldscope. I can honestly say that this is the best performance Iíve seen in any 60mm spotting scope Iíve ever used. Compact portability and outstanding optics in the same package. What a deal.

     In conclusion, let me say that I like the standard Fieldscope III. In fact I like it a lot. Itís an excellent, high quality product. However, the ED model is simply an outstanding scope. Itís performance is clearly in a different, higher class. The benefits of ED glass are not subtle, but distinct. This is obviously a scope for those who want the very best thatís technically available and wonít compromise for something less. If you shoot a Freedom Arms revolver, you know what I mean. Consider this the Freedom Arms equivalent in spotting scopes. In other words, itís a long term investment in quality and performance that will never go out of date.
   
Good luck and good shooting, Todd

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Warning: All technical data mentioned, especially handloading, reflect the limited experience of individuals using specific tools, products, equipment and components under specific conditions and circumstances not necessarily reported in the article or on this web site and over which IHMSA, The Los Angeles Silhouette Club (LASC), this web site or the author has no control. The above has no control over the condition of your firearms or your methods, components, tools, techniques or circumstances and disclaims all and any responsibility for any person using any data mentioned. Always consult recognized reloading manuals.