As I research which telescope is best for me, I find myself wondering about zoom lenses. I am curious- does a 6.8 mm- 16 mm zoom lens mean that it can be adjusted to 6.8, 6.9, 7.0, 7.1, 7.2, etc. until it reaches to 16? If not, what is the normal interval of adjustment of these lenses? (I am also asuming that the decimals are only in tenths; let me know if I am assuming incorrectly here....)
Thank you for clarifying!
2007-06-17 05:49:22 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
h
2007-06-17 06:01:52 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The correct term would be a zoom eyepiece, not a zoom lens, because a zoom lens refers to the "objective" (as on a camera) that is the main lens of the instrument.
The answer to your question is yes, and no.
There are click-stop zoom eyepieces that only adjust at certain specified intervals. There are continuous adjustment eyepieces too. So to be precise, you need to ask whoever is selling it what kind you're getting. The continuous adjustment eyepieces have "infinite adjustment" within their total span.
They are not particularly popular in astronomy due to compromises in the field of view, and the fact that single eyepieces seem to do a better job. The main applications are
1. Some people prefer them for travel (I don't) because you get a lot in one package.
2. The Nagler 3-6mm zoom is popular because it is very high quality and over its limited range is useful for refractors that typically need "a lot of punch" in short focal lengths--for example 3 to 6 mm--to get up to higher magnifications.
The Vixen 8-24mm zoom is a popular model that is not priced sky high.
Hope that helps. GN
2007-06-17 17:14:27 · answer #2 · answered by gn 4 · 0⤊ 0⤋
Zoom lenses have a continuous adjustment in magnification. They are used in photography, but hardly at all in astronomy. That's becase they have a lot of internal lenses, which tends to make them inefficient for dim objects. Also, it is not important to get exactly the right magnification for astronomical objects. As a first "telescope", I suggest binoculars designed for night use or for astronomy, mounted on a camera tripod.
2007-06-17 13:31:05 · answer #3 · answered by cosmo 7 · 1⤊ 0⤋
yes your zoom lens will be able to go anywhere between 6.8mm and 16mm even 10.98237230952387239, although it might be hard to get it that exact ;)
2007-06-17 13:10:05 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Yes, it's a continuous sweep
2007-06-17 13:21:37 · answer #5 · answered by Gene 7 · 0⤊ 0⤋