Tuesday, 31 January 2012

The scary world of GUIDING! my first attempts

Well after a year of using what is known as an unguided system i.e. (my telescope motors are not being told what to do by a computer or auto-guider so they adjust the tracking of the stars, resulting in a picture with no star trailing and the ability to take a much longer exposures before errors creep in and ruin it)

It has got to the point where I decided I needed to have a guiding system in place in order to take longer exposures and avoid getting star trailing in my images.

Now if like me you are new to the complicated and "nerdy wordy" infested world of guiding your telescope, then this may well help you out, on the other hand, it might make you run in the other direction but here goes..

First of all let’s deal with the Basics.

Question:
What is a guiding system for and why would you want to set one up on your telescope any way?

Answer:
A guiding system provides a way to accurately guide your telescope as it tracks a star or object in the sky, by adjusting the gears that turn the motors on your telescopes axis points it prevents your photographs from getting star trailing when doing longer exposures. You would use it for this purpose when like me; you reach the point where short “unguided exposures” are no longer enough for the imaging you want to achieve.

So now you are faced with the problem of understanding what makes up a guiding system and you will be bewildered by the many ways there are of doing it. It can be very expensive it can also be cheaper by doing some diy modifications and it can be very frustrating trying to understand all of it. I speak from experience here!

I am now at the stage where I am about to get my system set up and working so this is an account of what I am learning along the way.

First I learned that you need a camera or webcam that looks through a guide scope to find a star. Then the camera or webcam sends that information down its cable to a computer or a standalone Autoguider. Then that information is used to send another message to the motors on your telescope that control the RA right ascension and Declination axis points of your telescope. It then adjusts them and corrects them so your image that is being taken with an SLR camera or dedicated CCD camera avoids getting stars trailing in your images.

That is the simple way of explaining it, believe me it can get much more complicated but let’s keep things simple for now.

If you are wealthy then by all means go out and spend thousands of pounds on a lovely expensive astrophotography auto guiding set up and enjoy the benefits of being wealthy. If you’re not then you may want to consider doing it on a budget and follow what I am doing.

Having a cheaper mount that did not come with all the bells and whistles needed for guiding I had to invest in a few extras for my telescope, still cheaper then buying the more expensive telescope mount.

Here is a list of the items I have put together so far.

Now here is a picture showing you how all those items fit together. The only thing missing is my Canon 350D SLR camera that is attached to the main telescope with a T-Ring adapter for doing the actual images.

 The main thing to get to grips with here is this mysterious thing called an ST4 port. It is basic plug in port that enables the information from your Laptop or Auto-guider to communicate with the telescopes motors and gears that move the axis points RA and DEC (which if you dont understand what that means) RA is for Right Accent-ion and DEC is for declination which is the equivalent of longitude and latitude in the coordinates that govern the position of the stars.

So we come up against the first hurdle which was how do I get an ST4 port if my telescope does not have one.
The answer is,you can buy a telescope mount that has one or buy a set of motors for your telescope mount and then modify the control pad of those motors to have an ST4 port on them. Thats what I did with a cheap kit that had an ST4 port and some wires that you solder on to the control pad of your dual axis motor kit. And NO it was not at all difficult to fit so dont panic I am rubbish with electronics and terrible with a soldering iron most times I never ever go near one in fact I'm scared of doing stuff like that.

Then your next problem will be how do I attach a cable from the ST4 port to my laptop if I am running a free guiding software to control the motors? the answer is to buy an adapter called a GPUSB which stands for Guide Port USB ie the USB port on your laptop.

So next up is how to get a webcam and a guide scope that will plug into the laptop and work with the free guiding software and my new motor kit and ST4 port? Well there are several option here but basicly you do some diy on your finder scope and put in a suitable webcam. Do a search for webcams for astorophotography as you cant just use any old webcam.

So you can see from the diagrams above the stuff I have had to get in order to get a guiding set up for my telescope and mount. If you have the same telescope and mount the skywatcher 200p and eq5 mount then keep reading my blog as I will be putting it all through its paces soon.

In the mean time if you have any questions you can find me on the stargazers lounge forums as Quatermass or leave a post on my blog. I dont always have time to check my posts on this blog so it might be better to join stargazers lounge forum and reach me through that. The star gazers lounge forum is packed full of really helpful astronomers so my advice is go there and make some friends.

More to come on the Guiding system as I put it all to the test.
Clear skies
Mark.