Friday, 20 January 2012

How do you take your Astophotos Mark?

How do you take your Astrophotos Mark?
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This question is often asked by people just starting out so I will try to answer it for you to help you out based on my equipment and what I have learned over the last year or so.
First of all the equipment I use.
The Telescope and the mount
This is a Sky watcher 200p Newtonian reflector telescope on an EQ5 mount
Current price for this set up is 395.00 online prices may vary a bit.

To this I added a single axis motor drive kit current price 69.00 pounds.

NOTE: A word of caution here based on hard experience these single and dual axis motor kits that sky watcher sell have 3 parts to them the battery pack the two motors and the control box.
I have used them for over 3 years now and have had no less then 5 of the control boxes burn out on me, I think they are cheap and nasty with no protection from a sudden surge or wrong polarity if you try to use a 6 volt adapter to run one. So if you are going to get one make sure you have a warranty on it so you can take it back and get it replaced. You may be lucky and it may last for several years but based on my experiences with them they are very unreliable and once they burn out your stuffed as you can not image with out one. Hopefully one day sky watcher will fix this and produce a quality product that will last and have good protection from the elements and electrical surges but in the meant time take heed my friend and get yourself a good warranty from the supplier or you may  regret it.

I know no longer use them having purchased an alternative controller from Tom Carpenter a chap who has designed and made the ASTROEQ unit far better in my opinion check it out here.

https://github.com/TCWORLD/AstroEQ


I also use a Canon 350D SLR camera (£130 second hand of eBay) for my photographs, added to this is the adapter to attach it to my telescope(£15.00 amazon) called a T Adapter and a remote timer (15.00 amazon) and also a homemade Bahtinov Mask for getting my camera focused on a distant object in the night sky i.e. a bright star. Cost nothing easy to make and covered in my blog for what it does and why you need one.
So the total cost for all that comes to £624.00 if you already own a canon camera even better as canons are the tool for the job.
So that's the gear but before you start thinking Ok I will get that is seems a good option just a few words of wisdom that will save you a lot of grief so read on...
The mount is all important for astrophotography and although the EQ5 by sky watcher is a good mount it does lack two things that are important to consider.
First it lacks what is called an ST4 port. This port is needed if you want to add an AUTO GUIDER TO YOUR SET UP NOW OR LATER ON.
Let me explain further. To take photographs of the sky and object in it you need to track the object accurately or your photograph will start to get trailing and your images will be blurred.
To avoid this you can add tracking motor kits to the eq5 mount, single or double are used. However these kits do not have an ST4 port. And they can only successfully give you just over 2 minute exposures before you start to get star trails in you images.
For over a year now all my images have been done with just a single tracking motor kit which restricts me to taken exposure of less than 3 minutes. That is the down side.
However to take longer exposures’ you will need to get a guiding system set up which costs more but is better if you want to take longer exposures’.
SO what is a guiding system?
Basically it consists of a web cam or a dedicated camera that uses a second smaller telescope called a guide scope that sits on top of your main scope. This finds a star and sends the tracking information to your telescopes axis motors and keeps them in sync so you get better tracking and therefore longer exposures'.
So as you don’t have the ST4 port on the dual or single axis kits for your eq5 mount is all hope lost. NO. You can buy a cheap modding kit for about 15 quid and buy simply soldering on 4 wires very easy to do you can add the ST4 port to the DUAL axis kit and you can then use a guiding system.
Guiding systems come in to flavours stand alone auto guiders like this one. Sky Watcher Synguider Autoguider stand alone auto guide camera or simply use a webcam with computer software free on line and use that cheaper by far.
Both systems will need that ST4 port, this is a kit that will convert the dual axis motor kits so they have an ST4 port. You can get the kit to convert your dual axis motor kit from http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Imagers-Shoestring.asp?p=0_10_5_0_5_5 or http://www.store.shoestringastronomy.com/products_gp.htm
But the other thing to consider is this if you buy the EQ5 mount you will have to add a single axis kit to make a start, but if you want to auto guide you will have to buy the Dual axis kit and solder on that ST4 port kit as well or (make do with just the single axis kit instead as I have done for the last year) Total cost for doing that is about £100.00
So stop and think a minute. If you buy the other mount called the HEQ5 it comes with better tracking motors and built in ST4 port and is the little brother of the Ultimate mount for astrophotography the EQ6. The choice is yours and down to your budget but my advice a year down the line would be get the HEQ5 if you can afford it or the EQ6 if you’re rich or if you’re poor get the EQ5 like I did. I intend to add a dual axis kit and modd it with the ST4 Port because it’s cheap and I’m not rich. 

PLEASE TAKE NOTE.. I HAVE DONE THIS AND ADDED THE ST4 PORT TO MY DUAL AXIS KIT BUT THIS DOES NOT WORK WITH AN AUTO GUIDER AS THE GEAR SPEEDS ARE NOT ABLE TO GO ANY LOWER THEN 1X SPEED AND AUTO-GUIDERS REQUIRE A LOWER GEAR SPEED TO FUNCTION CORRECTLY THE HEQ6 AND EQ6 MODELS WITH BUILT IN ST4 PORTS DO HAVE THIS AND WILL BE OK WITH AN AUTO-GUIDER BUT NOT THE EQ5 AND MODELS BELOW THAT, AND BECAUSE OF THIS YOU HAVE TO GUIDE WITH A LAPTOP RUNNING THE FREE SOFTWARE PHD (PRESS HERE DUMMY)FOR GUIDING. DO DO NOT DO THIS CONVERSION THINKING YOU WILL BE ABLE TO USE AN AUTO GUIDER LIKE THE ONE ABOVE AS AUTO-GUIDERS REQUIRE A SLOWER GEAR SPEED. IF YOU DO THIS CONVERSION YOU WILL BE USING YOUR LAPTOP AND PHD SOFTWARE NOT AN AUTO GUIDER GOT THAT!!

Ok then that's the gear out of the way.

Now on to taking the photos themselves
Armed with my set up I chose a nice dark night with no moon to washout my images unless its the moon I want to image of course. Dark skies mean better images full stop so remember that.
My first task is to make sure my telescope is balanced please see my video on my utube channel boodlewoodle setting up an eq5 mount for this.
After I have balanced my telescope with the camera attached to it I then polar align my scope also covered in my utube video.
Next is to put the Bahtinov mask on and take a quick photo 15 seconds ISO set to 800 and camera on bulb setting with the remote control unit attached. Take a look at the photo and adjust until your focused on the bright star you have chosen to focus on.
Now you’re in focus so I move the telescope on to my chosen target such as the Orion Nebula a great target to start with. Adjust with the axis controls until I am happy with the way it looks in the picture composition wise and then were ready for action.
I start off by taking 10 shots at about 30 or 50 seconds checking to see that I am not getting star trailing if I am then I move the telescope weights back a tiny amount. This applys pressure to the axis motors and helps them bite. It doesn’t always work but helps sometimes. If all is well then I take another 10 shots at a longer exposure say a minute and 10 seconds. Then another 10 shots at 1minute 20 seconds. If I get star trailing I will reduce the time. The ISO that works best is 800 normally but sometimes I go to 1600 if details is lacking in a faint object.
(Note that I am using an unguided system with a guided system this would mean I could do longer exposures' and not worry so much about star trails in my images)
Ok so now we should have 30 main photographs of our subject these are known as subs for short.
With 30 or 40 subs we now need to take 3 more types of photos that will later be subtracted from the main image to get rid of imperfections.
These are Darks Flats and Bias offset shots.
To take the darks simply put the lid on the telescope and take 30 more shots without changing anything. To take the lights take the lid of and replace a clean white sheet or t shirt stretched over the end and hold a L.E.D. torch in front of the telescope. Take 30 more shots without changing any setting. Lastly for the bias offset shots put the lid back on and take 30 more shots with the shutter speed set to its fastest speed.
You now have 30 subs 30 darks lights and bias offset shots. Typically I tend to take 30 or 40 subs and stick the same in darks flats and bias offsets. More may be needed for other subjects but as a general guide that number is a good starting point.
Also note that your images must be in the RAW format not JPEG camera must be set to bulb settings and manual.
So you should now have collected 30 or 40 images of your chosen subject with the darks flats and bias offset shots as well.
Now on to the final stages of getting the image you really want.
For this you will need the free software Deep Sky Stacker and a photo editing software, I use photo shop and I suggest you do the same if not try one of the free photo editing software packages available to you but for my money photo shop is the business.
You Stack all those photos in deep sky stacker first of all your main pictures or subs then your darks flats and bias offsets. Deep sky stacker will stack that lot for you and subtract the darks flats and bias offsets leaving you with a less then attractive final image that will be saved as a .tiff 16 bit file.
You then take this into photo shop and finish your image off in there by following my 13 video tutorial on astrophotography found on my boodlewoodle channel or my blog.
If you stick with it and take your time you will be able to do what I have done and more beside.
I hope this has helped you out I know how stuck I got when first starting on my astrophotography journey and wish you all the fun and enjoyment that I have had and am still having finding the wonders of the night sky.
Any questions let me know and I will do my best to help you.
You can find me on the stargazers lounge as Quatermass
Clear Skies!