外国Cloudy Nights 深入讨论月面观察
jhfenimore : 05/12/11 06:32 PM
Am spending more of my observing time on the moon. Have a 4inch APO and a 10 inch Dob with a good mirror. Would prefer to use only one of them as I study the moon so my view is consistent. Average seeing here limits magnification to about 175X. Seeking advice from experienced lunar observers on which one to use as my primary lunar scope. Thanks!
Jack
MANDII : 05/16/11 09:52 PM
I prefer 4" APO , sharp image of APO scope .
The big aperture is not really an important issue on a bright object such as moon. Instead , lens quality is the point . 2ndly, to me , to observe moon is to observe the each big and small craters , and some detail lanscape on the floor of the moon, you need to find it out among the different complex areas . The FUN is the time you navigate the ground on the moon and find a target area that you want to find it out . So you need to have a moon map as well . In finding the specific objects on the moon with the moon map , the difficulty is the image rotation angle is different to the map . For refractor , the image is fixed the angle of rotation( upside down , and east west flip ),ALL the time it's fixed regardless where your scope is pointed to . So that would becomes very easy and straight forward to find an target when you look at the map simutanousely . But with newtonion type scope such as the an DOB , it's very difficlut to check with a map together . The image is always rotated irregularly . Not only upside down and E/W Flipping , but also rotate to some angle which is depending the pointing direction of your scope . So Newtonion is the most difficlut and need the most skills to use with it .
Sarkikos : 05/16/11 10:21 PM from Maryland, USA
I enjoy observing the Moon with all sizes and sorts of scopes - Newts, refractors, MCTs - so that's not an issue for me. The orientation of the image is not much of an issue any more for me either, because I've found good lunar atlases for all the different types of scopes.
During the work week a small scope is more convenient. I like taking out my 90mm Mak for a quick Moon view, the 5" Newt if I have a little more time, the 8" Newt if I feel more energetic. I use the 10" on the weekends - if I want to allow the possibility for seeing more detail on the Moon or planets.
The brightness of the image is also not an issue. A bright object will not allow a smaller aperture to show finer detail than its aperture will allow. Only larger aperture will make finer detail possible.
There are several ways to compensate for the bright image of the Moon, if that is seen as a problem: use filters, install an apodizing mask, increase magnification a bit, keep your eyes at a higher photopic level by looking at the reflection from a bright-white-light flashlight, or all of these methods together.
Mike
MANDII : 05/16/11 10:55 PM
ohh Mike ... may be I am not familar in using the forum , I may have mistake in replying this post . Origianlly I was not reply to your post on 05/16/11 08:46 PM . I reply to Jack the poster .
May I know which moon altlas you are using , that can show the excatly same image orientation of a newtonian scope , when the scope is pointing at different direction ?
To me , how to find a specific object with a map easily , is the basis to enjoy the moon . If the image orientation is different , you are difficlut to find an object . If you can't find out a target , you cannot observe it more detailly .
Sarkikos : 05/17/11 08:41 AM from Maryland, USA
MANDII,
To be more clear exactly who you are replying to, you can type in their name at the top of your post, as I did above, or you can click "Reply" directly on their post so that their name will be referenced.
But these threads are pretty informal. I don't think people here really mind if anyone who has an idea or opinion relating to a certain post responds to that post. It never bothers me.
Mike
Sarkikos : 05/17/11 08:56 AM from Maryland, USA
MANDII,
Here are several lunar atlases which have the inverted (Newtonian) orientation:
- Hatfield Photographic Lunar Atlas, Jeremy Cook
- Kleiner Mondatlas, Antonin Rukl (inverted and reversed views)
- Photographic Atlas of the Moon, Siew Meng Chong et al.
- Moon Atlas, John Moore (natural, inverted and reversed atlases)
I agree. When I'm using a Newtonian scope, I don't want to have to hold the atlas upside down or read the labels upside down. I want the observation session to be as easy and straightforward as possible. Anything that complicates things and gets in the way of my observing needs to be corrected and simplified. It just makes good sense.
Mike
MANDII : 05/17/11 10:52 AM
Thanks Mike for your atlas , yes things should get simple to use .
Sarkikos : 05/17/11 11:50 AM from Maryland, USA
MANDII,
I remember this acronym from my days in programming: KISS - Keep It Simple Stupid! Take no offense, this is a reminder to myself.
Mike |