Hi Ivan,
no, theres is no need for photo.
First of all I have to say that I dont have ST-4 so I cannot help you with setup, but I have old type of EQ-6 mount, I did some modification and Im using it successfully now (you could see some of my pictures).
My experience with old type of EQ-6 mount is that motors are very weak so it has to be gearbox inside with couple of tooth-wheels which cause two main problems:
- huge backslash
- periodic error which si quite big (mine has about 40", but its not main problem) and mainly very rough (did you do some measurement of periodic error ?) because of quality of tooth-wheels used in gearbox
So I decided to do some modification, first of all I disassembled mount completely and cleaned it from old grease and oiled it with new. Then I knew I had to do something with gearbox, because it caused a lot of problems. But at that time was no Skyscan on the market, so friend of mine bought suitable powerful stepper motors and made for me tooth-wheels which I needed. Basically it looked pretty same as Skyscan but without electronics. I did not need new electronics because I bought new one in the time I bought my mount, because I wanted to have autoguider input. So I bought Powerflex MTS-3SDI, which has autoguider input, PEC, backslash compensation, microstep, it enables change frequency of the stepper motors etc. After changing of motors and gears (I had also to reprogram my electronics, which was quite easy) periodic error changed a lot. Size stays the same but its very smooth now so autoguider can handle it.
Other thing which changed was backslash. Before modification I had to use backslash compensation with autoguider. But it was problem with it. Size of backslash was changing a little bit with position of worm, so I had to control it before every exposure and change settings of backslash compensation when needed (It might be also your problem, it might be overcompensated, which is worse than small amount of dead travel). But after modification there is no backslash at all, so I dont have to use backslash compensation.
So my recomendation for you is to buy Skyscan and change motors and gears it will help you a lot. Backslash will be minimal, periodic error will be smoth (I dont say it will be small, but its not so important) and motors wll be more powerful. In adition you will have Goto (which is great for searching of dim objects) and PEC. I have PEC in my electronics but cannot use it because error of my mount is still not periodic.
Maybe it will help a little bit
Radek
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I have the old type, I made an autoguider input into the hand controller.
Not complicate, 5 cables, 4 for the 4 directions, 1 for the ground. If you
need more info i will send photos later.
Ivan
At 22:40 2005. 09. 18.t Conve, you wrote:
>Hi Ivan,
>
>what type of EQ-6 do you have ? New Skyscan version with autoguider input
>or plain ? When plain, how do you connect ST-4 to it ?
>
>Radek
>
>
>
>Hi Guys!
>
>Several weeks ago I had purchased a brandnew(!) st-4 autoguider. I'm in the
>learning phase still, but I have an uncovered problem with the camera.
>
>There is a problem with the backlash compensation, which seems to works not
>properly.
>The problem is: when st-4 change the direction in Dec, it applies the
>increased correction time (due to H2 setting) TWICE, resulting a completely
>false correction.
>
>Does anybody has any idea what might be the problem?
>
>Thanks:
>Ivan
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