Spotting Scope
You’ve been birding for some time and developed a degree of expertise. You may have built a good life list. Now you want to expand that list and ensure quality sightings at the same time. Binoculars served you well at closer ranges, but what about the birds across the water or on the mud flats, or farther across the prairie, or high in the sky? You are ready for new gear: a spotting scope.
As it is with binoculars, so it is with scopes. One can spend any amount. Often, manufacturers try to accomplish being inexpensive and being lightweight at the same time. Sometimes, this leads to scopes which are not well proofed for water or fog and are not as rugged. Still, recent trends have brought down the price to more affordable levels. Consequently, spotting scopes are not only for the elite, but are becoming both essential and accessible equipment for the avid birder.
The first decision is the eye piece, also know as the ocular. Really, this is two decisions in one. First do you want it configured straight through sited (ST) or angular (AN)? Straight through may make it easier to find birds because it works just like your binoculars. Angular appeals to some because it may be less a strain on the back and neck. If you are the sole user of the scope, ST may be the way to go. If you tend to share with several people when birding, you may wish to consider AN. Secondly, you have a choice of a fixed or variable magnification. Many believe it best to stick with a fixed magnification of 20x or 30x--the larger the magnification the greater the light distortion. Variable magnifications typically are 15x-45x or 20x-60x. You should use the smaller magnification in the range to locate the bird and ramp up to gain more detail. As you ramp up, less light will be let in accompanied by a narrower field of view.
The next decision is the objective lens. These define the field of view and are best if at least 60 mm. Larger objective lenses gather more light as well as allowing a greater field of view. The material used for the lens is important, too. The more expensive scopes have a special type of glass in them call ED, which stands for extra-low dispersion. ED enhances light gathering and corrects for chromatic aberration.
Finally, don’t neglect the support for your scope. Rigid, mid-weight tripods are best. Tripods need to be sturdy and easily adjustable. Consider a tripod with flip locks for secure and quick adjustments.
The acquisition of a quality spotting scope will enhance your experience and enjoyment of the great outdoors.
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Tagged with: Birder • Fog • Light Distortion • Objective Lenses • Spotting Scope
After long fight with fog and winter, This is quit pleasant to feel this a bit worm and sun lighted morning.
Proud to say I have the exact same one.
Hi Linty,
I don't think a serious direct comparison in one article exists, but I would suggest looking at photozone's separate reviews of both lenses:
Canon EF-S 18-200mm f/3.5-5.6 IS:
Sigma AF 18-200mm f/3.5-6.3 DC OS, for Canon:
They used different bodies for the tests (50D for the Canon, 350D for the Sigma), so resolution figures may be slightly affected, but other measurements, like distortion, vignetting, CA, etc., can be directly compared.
I would suggest printing out both tests and comparing each section.
Have you considered the Tamron 18-270 VC (VC = Vibration Control)? It seems to outperform overall both the Canon and the Sigma, though it's also slightly more expensive than the Canon. Here's Photozone's test of the Tamron 18-270 on Canon:
It's tested on the Canon 50D, same model they used for the Canon 18-200 test, so you can directly compare everything, except that I would be careful not to directly compare the Tamron at 270mm to the Canon at 200mm. Fortunately, they tested the Tamron at 200mm in addition to 270mm for all tests.
Good luck, and have fun!
Greg
In Sioux Falls?
CHANCES ARE YOUR HEATER CORE IS GOING BAD
thanks a bunch babe…i was lookin’ at your songs and i’d like to take one and put back-up music to it…will ya let me try one?
frik, you found some truly excellent sounds.
CRISP, CLEAR VIEWING LARGE 42MM OBJECTIVE LENSES GATHER PLENTY OF LIGHT TO. More
Turn on your objective lenses and start viewing the world for what it is…
Melbourne Forecast Tomorrow : Morning cloud or fog. Min 14 Max 22
And what was the piss poor super cool re-invention this time?
I'm a little iffy on this, but seeing that nobody else has ventured an answer, here goes.
First, are you sure you are talking about resolving power and not depth of field. A higher power lens has a narrower depth of field than a lower power lens.
A magnifying lens has greater magnification when the curve of the lens is greater. A greater curve requires a thicker piece of glass.
The more important factor is the quality of the glass and the lens forming job rather than the thickness. If the glass is of poor quality and doesn't transmit light well the image will be degraded. If the curve of the lens is not precise the image will also be degraded.
The thickness of a quality lens does not substancially impact the quality the image or the resolving power of the lens.