[quote:e9717fad32="天星"][quote:e9717fad32="denebman"]拿焦比10的Intes Micro Alter603 六寸马卡镜为例, 中央挡光36%, 根据D-d的经验公式, 它的锐度和反差与3.84寸的APO镜相当(分辨力会好些, 但未必能赢4.5寸的TMB), 难怪目视感觉与FS102或TV102等四寸镜不相上下. 不过其1300欧元(不含运费和税)的价位也离4寸APO镜不远了.[/quote]
也对。4寸APO望远镜，各厂商出的价钱到底是多少呢？
我也想比较一下。最便宜和4寸APO到最贵的4寸APO，它们会差多远？ ^^[/quote]
这里有一只目前售价最便宜的准APO 4寸ED镜, 只售800美元, http://tinyurl.com/5h6fw
看介绍吹得很厉害:
"One of the more frequent questions we get here at Astronomics is, “What sort of telescope do you have that has a wide field, good optics, and is airline portable?” Our answer is limited mainly to refractors, all of which cost between $1500-$4000 with a diagonal. Well, Burgess Optical has changed that answer forever with their SD 101 Backpacker. With a tube length of only 16.5”, which includes the 2” dielectric star diagonal, and an ED f/5.5 doublet optical system the SD 101 Backpacker dares you to find a better performing portable telescope even at twice the price.
The SD 101 Backpacker could be the answer to all of your portable telescope problems. The name should tell you all you need to know about its portability as it comes in a Backpack style soft case with cutout foam for substantial protection against everyday bumps and bruises. The tube comes in at 13.5” long, with the dew shield retracted, and 16.5” long with the supplied 2” dielectric diagonal attached, so airline regulations for carry-on luggage should not be a problem for this particular instrument.
The tube itself is a mechanical marvel from front to back. The fully CNC machined light grey tube will rival any high end refractor with its sliding dewshield and 2” rotatable Crayford focuser. The tube is designed and built by William Optics with their legendary fit and finish. It’s precise mechanical engineering is evident as soon as you pick up the tube.
The great mechanics and finish are nice to talk about, but what about the heart of the telescope? The optical system of the SD 101 Backpacker is no slouch. Its ED f/5.5 doublet objective has been rated by the manufacture to have 8x the color correction of an achromatic lens of similar aperture. While it isn’t quite apochromatic performance, it is far superior to anything else in its class. A refractor of this particular speed should be good for roughly 45x per inch of aperture. Lunar and planetary viewing will be fine, but star clusters, galaxies, and nebulae are really where the rich field should shine.
The Burgess slogan is, “To Make Awesome Affordable” and the included accessories with the SD 101 Backpacker prove that without a doubt. Most manufacturers stop at the optical tube and then have all the other accessories ala carte, not so with the Backpacker. The package includes the SD 101 Backpacker optical tube assembly, the backpack carrying case, CNC machined tube rings (so you can mount the scope on your favorite mount), a 2” dielectric star diagonal with compression rings as well as an 1.25” eyepiece adapter, and a 38mm 2” wide field eyepiece.
If you are a person looking to add another scope to your arsenal, an observer looking for the perfect balance between aperture and size, or and adventurer traveling to the four corners of the earth eclipse hunting the SD 101 Backpacker should fulfill all your wishes and more."
真是林子大了什么鸟都有 |
显身卡
