rikyuu

Macavity,

do you have access to a voltmeter or multimeter and can you access the soldered connection of the 2 wires to the motor (not wires going to the encoder sensor)?

Baring in mind the potential for damaging the electronics by making accidental short circuits; I would measure the voltage across the motor when it is slewing normally at max speed and then check it again when the fault occurs. This should show up whether the motor is still being driven or not ie. volts or no volts.

From memory, your pictures look very similar to the insides of the Celestron SLT mount which I have.

I had a problem with that too. It sometimes wouldn't move in one direction.

On mine, the cause appeared to be a fault internal to the motor in which one of the power connections was connected to the body of the motor, I suspected a faulty intenal supression capacitor. Hence in one direction it worked (ie. when one connection was meant to be grounded and the other at a positive voltage), but the other direction didn't work (ie, when the positive voltage was applied to the connection that was inadvertantly grounded).

To determine if this is the case, with the mount powered off, disconnect the power connector from the motor to the circuit board (probably the connector on the top right of your photo). With the same multimeter, measure the continuity from each of the two motor power pins to the metal body of the motor. They should both be open circuit. Bare in mind that as the problem is intermittent, any short circuit between the motor power pins and the body may come and go, so you may have to try it a few times to ensure the fault condition of a short circuit exists.

If it does, then a work around would be to insulate the motor body from the rest of the mount by putting little plastic or paper insulators under the clip, which holds the motor, to isolated the motor body from the clip. This worked for me, but in the end the mount was swapped for a replacement.

I hope this makes sense and helps!

It would be great if you could tidy it up and put all the info in one post.

I agree, it's a shame I can't edit the original to added the latest forgoton bits.

DOH!

Cheers themos... I have found that it helps to apply the update to the latest version :S

ah yes, slightly important that, I forgot to mention. It doesn't do it without the update!

oh my goodness, I got a sticky! That's made my day now!

Back to topic; in the more detailed tutorial, there's some mention of setting the RGB values in the RESULT section of the PIXEL MATH window (although I don't really understand the reasons why, but it may be related to what you mentioned earlier Kevin). Sometimes this does not need to be done, but on a couple of occasions, the resulting image comes out strange, eg. totally white. If this happens, editing the RGB numbers as described seems to correct the issue.

It's quite simple to do;

With the original image active, select IMAGE > STATISTICS from the menu bar.

Using the median figures given for R, G and B in the statistics window, enter them into the R, G and B boxes in the PIXEL MATH result section, then proceed as before.

Done

I briefly compared this technique with NC's actions in Photoshop, using the same image. This technique seems to do a better job of removing the gradient, but the results will probably vary from image to image. However, it's quite satisfying to see the actual background in it's extracted form before it gets removed.

hehe, thanks Jamie!

hi,

I'm sure many experts know about this function within PixInsight already, but I just wanted to mention this as a very quick and simple method using this free software from:

PixInsight — Downloads — PixInsight LE

I've only just downloaded this software and given it a go and found this particular function very quick and easy. There are more detailed instructions on the website and various other applications that will perform this funtion, but here's a few quick steps to using this software.

Open the image file containing the vignetting or gradient (see example below)

Press ALT+B to enter dynamic background subtration mode

Click anywhere on the image to open the dynamic background subtration window.

Select the GLOBAL tab and set the auto intervals to 15-20 for a typically sized DSLR image (the more the better, but longer processing times) and click GENERATE next to this number. You will see an even grid of points appear on the image.

Select any that are NOT part of the background and press delete to remove them.

Then click GENERATE at the bottom and wait for it to extract the background (see second attachment).

Select DONE twice. You can switch between the original image and tghe background under the Window menu. The background can be saved as any image file.

Click the pixel math button on the bottom left tool bar.

Select NEW in the PIXEL MATH window.

In the OPERATION pull down menu, select DIVIDE

In the OPERAND pull down menu, select your background image.

Check the 'create new image' box and click apply and then select your original light image from the options

You should end up with a similar result to the last image attached here.

I hope this helps some newbies, I certainly found it a great feature.

I think you just agreed with Steve there. You said he said! It probablly would not work due to in focus. Not that it would not work just probablly would not!

I used a focal reducer on my Skyliner 250p with a 1/2" CCD and it focused no problem. It was only when I started to move the focal reducer away from the CCD with a spacer and filter, that I needed the low profile adapter for in-focus. Alternatively, screwing the existing 1.25" adapter in from the other side of the T-thread adapter works just as well and allows slightly more in-focus.

Just a little tip that Bern told me recently, changing the distance between the reducer and the CCD alters the field of view/magnification. So sticking a spacer or filter between the reducer and CCD zooms out, but requires further wind in of the focuser tube so there's a limit. I was experimenting with this on a terrestrial object last night. In fact I unscrewed the lens off my barlow and attached that in place of the reducer, and hey presto, it zoomed in, requiring the focuser to be wound out of course, but I could use the remaining body of the barlow as a tube extender, cool!

I also tried KKs idea of screwing the 1.25" adapter to the other side of the T-thead adapter so I could effectively get the focuser even further in, this worked great, except the thumb screws on the adapter need shortening as they foul on the focuser. I'm effectively getting the equivalent of about 3mm-12mm lenses using these methods, but I need some stars now to experiment with as my terestrial target is too close!!