[分享]Accuracy of Nexstar（提高NexStar跟踪精度）部分内容翻译

更新：排版全乱了，还是看附图吧。
原帖在《Acurray of NexStar》：http://t.cn/zl3pJF0
我简单翻译了个人认为比较重要的部分，蓝色为译文，红色为原文不太理解或者比较关键的地方。翻译水平有限，仅供大家参考。如有错误，请批评指正。

Hi M16SEAL,
Both Francois and Mark have provided excellent suggestions and tips on how to improve the GoTo accuracy of your Nexstar 8SE. For my part, I'm not exactly sure what I can add in these terms so perhaps the best I can do is take you through the whole setting-up and follow-up procedures which I (personally) find, works extremely well for me.
Before starting, you need to balance your 'scope tube away from the mount.

开始前，你要先把镜筒取下来，做好平衡！

Having therefore placed all accessories, (finder, diagonal, eyepiece etc.) on the tube, rest it on a pencil on a flat, (table top), surface and find the point at which it balances. Mark the point and replace the tube on the mount arm so that there is a little fore-end weight bias.

首先，所有附件（包括寻星镜、天顶镜、目镜等）都要先固定在镜筒上面；然后找一个水平面（例如：桌子），将镜筒放到一支铅笔上，找到它的重心，并做上记号；最后，把镜筒装回三脚架的叉臂上。

Now with your 'scope switched on, select "Menu" and then "Scope Set-Up". Press "Enter" and then, by toggling either the 6 or 9 button, find "GoTo Approach".

打开望远镜开关，选择“Menu”里面的“Scope Setup”，按“Enter”并用“6”或“9”找到“GoTo Approach”。

Press "Enter" to find the "Azm Approach" which must be set to POSITIVE. Then similarly, find the "Alt. Approach" Approach". This might be set to NEGATIVE, the default setting. If it is not on default, set it so. You can always change it following experimentation at a later date. The purpose of this exercise is to get you up and running NOW !

按“Enter”，找到“Azm Approach”设置值为“POSITIVE”；同样的，找到“Alt Approach”应该设置为“NEGATIVE”。如果不是这些值，请如上述说明进行设置。

As already mentioned, you now need to ensure that your antibacklash settings are optimised for both the altitude and azimuth axes.

这样，水平和垂直方向的设置就已经优化好了。

To achieve this, (and the operation can be carried out in broad daylight),keep you 'scope loaded with all usual accessories, (finder, diagonal, eyepiece etc.), level it and, as Venus is currently available in the daytime sky, perform a "Solar System Align" on this planet.

要做到这点，你可以在白天进行尝试，装上所有常用的配件（寻星镜、天顶镜、目镜等），调整好水平。现在，金星是白天可见的行星，可以尝试“Solar System Align”去校准到金星。

Note there is no need to seek it out, you are merely trying to achieve "Align Success" on the screen of your hand controller. This will ensure the 'scope is tracking which is necessary to antibacklash adjustment.

注意：并不需要真正的找到金星，而是使得手控可以显示“Align Success”就行。这只是确保望远镜的“ANTI-BACKLASH消齿隙效应”调整有效。

Thus just point your 'scope to approximately where you think Venus to be at the (daytime) time and date you have entered, press "Enter" and "Align" buttons and your 'scope will be tracking thereafter.

然后，把望远镜指到金星大致所在位置，按“Enter”和“Align”，望远镜就应该开始跟踪了。

Now slew your 'scope around and focus it on a distant brick wall or a tiled (shingled) roof. The idea behind using a brick wall or tiled area of a roof is to provide an improvised grid pattern on which to work.

现在，把你的望远镜对着远处的砖墙或瓦房顶（或者类似的建筑物），并且对好焦。目的是找到一个简易的方格图案。

Now select "Menu" and by means of pressing either the 6 or 9 button, select "Scope Set-Up". Press "Enter" once again and use the 6 or 9 to toggle to "Antibacklash". Press "Enter" once again.

再次进入菜单“Scope Setup”的“Antibacklash”。

Let's assume that "Azm. Positive" appears on your hand controller's screen.Press "Enter". A figure between 0-99 will be seen on your screen.

如果现在显示“Azm Positive”，按“Enter”就会显示一个0～99的数字。

Set your slew rate to 3 or 4 and then move your scope HORIZONTALLY ONLY across the brick or tiled grid pattern noting how long it takes before the 'scope begins to move, whether the movement is at all jerky in its action and whether, when you have traversed the grid by a reasonable distance, the motion stops when you take your finger off the direction button.

将转动速率设置为3或4，然后用手控水平方向移动望远镜。通过观察方格图案的方式，看看望远镜在移动时是否会有延时、移动是否平稳等现象出现。移动一段距离后，松开手控。

Move the 'scope several times back and forth across the grid in order to get a "feel" for what how it responds. If the drive take up is exceptionally slow, (and allow a few seconds here and there), or the motion is jerky either on drive take up or on stopping, adjust the shown figure in say, increments of 5.

重复多做几次这样的尝试，去“感觉”一下望远镜的反应。如果启动时特别慢（例如几秒钟），移动不顺畅又或者有时会停止。就是说，要调整增量为5。

When you are satisfied that you have a smooth action, that there is no great delay in drive take-up and that your 'scope stops when you take your finger from the direction button, then "Enter" the figure you have chosen and move to "Azm. Negative", repeating the exercise once more.

当望远镜移动很顺畅，松开手控后也可以立刻停止时，说明调整已经合适了。确认你所设置的数值，然后找到“Azm Negative”，重复同样的调整。

You should have now set both the Azm. Positive and Negative antibacklash.
Now move to adjusting the Alt. Positive and Negative antibacklash in exactly the same way but this time, moving the 'scope tube ONLY UP and DOWN. You will however probably find that the vertical (altitude) axis is much more sensitive in its response to adjustment of the Positive and Negative figures.
The above should now put you in a position to make accurate alignments.

跟上面一样的方法，调整垂直方向的Alt Positive和Negative值。完成水平和垂直方向的调整后，就可以进行精确的星空校准了。

ALIGNMENT:

Choose the "Auto Two Star" method. (This method appears by concensus, to be the most reliable).

选择“Auto Two Star”校准（这个是公认最好的方法）。

Thus with your 'scope tube pointing North and with the mount arm on your left as you stand behind the instrument. Switch on your 'scope and enter all relevant data, Time, Date etc. (I assume from your previous posts that you are acquainted with the procedure and the necessity for the relevant accuracy here).

把望远镜指向北，你站在望远镜后面，叉臂在你的左手边。打开望远镜电源，输入对应的数据：日期、时间等等。

Irrespective of what your hand controller offers, choose Polaris as your first star. (I make the assumption that you can see it). If it is not the first star on offer, you will need to toggle either the 6 or 9 buttons to produce it on screen.

不论手控显示什么，都要将北极星作为第一颗星（假设你可以看到它）。如果手控不是显示北极星，使用“6”和“9”切换。

Now locate it in your finder and, having done so, press "Enter". You should now see it in your eyepiece, (a 25mm will be quite sufficient), although it may not be in focus.

用寻星镜找到它，然后按“Enter”，并且目镜当中也能看见（25mm的目镜就很好），即使没有合焦。

Keep it defocused as I think Francois suggested, so that it looks rather like a large doughnut. This shape allows you to centralise it in your eyepiece far more easily since your eye is very susceptible to the concentricity of rings.
Thus, by comparing the position of the doughnut with the edge of the field of view, you should be able to centre it very accurately.

用脱焦的方法，星点是一个圆环，把它精确的调整到目镜中央。

However, the doughnut may not be in the the centre to start with. No matter ! Using the direction buttons on the hand controller, move it to the bottom left quadrant of your eyepiece.

如果不在中心也没有关系，用手控的方向键，将它调整到目镜中的左下角。

Now from this position, move it right and upward to centralise. If you overshoot, take it back to the bottom left quadrant and begin again. When you are satisfied that you have it centralised it, press "Align" and you will be offered your second alignment star.

然后用向右和向上的方向键，把它调整到中央。如果转过了，先移到左下角重新再来。调整好之后，按“Align”望远镜会自动为你提供第二颗校准星。

This star should be between 30 and 70 degrees in altitude and at least 90 degrees from your first choice; Polaris.

第二颗星，纬度应该是在30～70之间，离北极星至少90度以上。

Let's assume it has chosen or that you have chosen Altair.

假设我们选择牛郎星（河鼓二）。

Press "Enter" and your 'scope will automatically slew to this star. If it "lands" nowhere in the vicinity of Altair you will know immediately that something is wrong, but all being well it should be near. Now merely go through the same procedure as you did when aligning Polaris and you should have a good alignment.

按“Enter”后望远镜会自动转向牛郎星。如果停在一个莫明其妙的位置，你马上就可以发现问题。如果正确的话，牛郎星应该就在附近。同样使用校准北极星的方法，校准牛郎星。

Note that your 'scope will be now tracking in sidereal time and that the "Cordwrap" feature will now be "On" by default. (I choose to operate with it "Off" but I leave that to you. If you leave it "On", you may need to set a "No Cross Line").

注意望远镜追踪速度应该是恒星时间，“Cordwrap”默认是“On”。（我选择“Off”，但这个可以根据个人喜好。如果选“On”要注意你的连接线不要交叉）。

Now for the GoTo and tracking performance of your 'scope.

对于望远镜Goto和跟踪性能

If your alignment has been successful, any object you "GoTo" should be within the field of view of a 25mm eyepiece although not necessarily in its centre. Thus if you wish to bring it to centre, (as is normal), use the same movement (bottom left to the right and up) as used when you aligned, to do so.

如果校准成功，指向任何天体应该都可以用25mm目镜看到，但不一定在目镜中央。如果要移动到中央，要使用校准时的方法，从“左下”往“右上”的方向移动。

There is a caveat however:

有个重要的说明：

This procedure should keep your 'scope tracking well when operating between North and South through East but you may find that objects may begin to slip from the field of view in very short time when operating the 'scope between South and North through West. If this occurs, simply align or realign the "slipping" object by placing it in the UPPER left quadrant of the eyepiece and recentralising it by moving it to the right and DOWN.

在从北到南（沿东边）进行跟踪时，应该可以跟踪得比较好的；但是在从南到北（沿西边）进行跟踪时，如果发现目标在很短的时间内，就会从视野中溜走，那么你应该重新校准这个目标。方法是把它放在目镜的左上角，然后用“右”和“下”的方向键把它移到目镜中间。

I have attached the paper describing this method and its effects to this post which I hope will help you further.​Hoping though that this helps overall,
Best regards,Tel

lz辛苦了

Celestron中国 发表于 2012-10-29 09:16

                               
登录/注册后可看大图

lz辛苦了

还是希望官方能提供更加准确的指引啊！省得初学者盲目的瞎折腾～

Celestron中国 发表于 2012-10-29 09:16

                               
登录/注册后可看大图

lz辛苦了

昨晚天气不错，在双筒的帮助下，终于找到了城市里暗淡的“北极星”！

奇怪的是：
情况1. 如果使用上文推荐的“Auto Two Star(自动两星校准)”，第一颗星指定为北极星，选第二颗星不会“自动”转向对应的星星，非要手动去找；
情况2. 如果使用“Two Star(两星校准)”，只是对准了北极星，手控就说完成对齐了～

luckylz 发表于 2012-11-1 10:32

                               
登录/注册后可看大图

昨晚天气不错，在双筒的帮助下，终于找到了城市里暗淡的“北极星”！

奇怪的是：

手控器+版本和老版本稍有区别，请您再仔细看一下说明书