Altair Capture Tutorial 3
THE EXPANSION OF TIME.
But what if we wish to take longer exposures? Again, this depends on how well you know your mount. It may be possible in some cases to take 1 minute exposures or more without autoguiding. Unfortunately, autoguiding is a topic that is far too complicated for this tutorial. Of course, you may be fully versed with autoguiding and if you are then this tutorial will still be viable. For the rest of us then we can at least try for 1 minute exposures which will capture lots more detail. Either way, Trigger mode is our friend. However, there are a few different steps we need to take for it to work.
To begin with we need to set up where your exposures will be saved, and this just involves using the instructions in Article 2, 1st paragraph. Just use the same settings. As before get your object in the middle of the screen as explained in Article 2. Once that's done we can set up the capture. In the Capture & Resolution menu pull the Gain slider all the way to the right so it reads 50.00 and pull the Exposure Time slider all the way to the right so it reads 5 seconds. You should be able to see your target assuming you have slewed and set it up. Leave all settings such as resolution and format as they are. Now comes the interesting bit. If you are going to expose for longer times then this also has a bearing on the gain setting. If you were to use the same high gain setting we used for 5 second exposures but exposed for 60 seconds the capture would be ruined due to over exposure, star bloating, noise etc. So, the higher the exposure, the lower the gain. This is important to remember. With this now firmly rooted in your subconscious, let's go. With your target set up on the screen pull the Gain slider to the left until it reads 6.00. Your target will all but disappear from view. That's fine. Leave the exposure setting all the way to the right at the full 5 seconds. Now press the Trigger Mode button. The settings will now be highlighted. In the Exposure time box click the minute’s box so it reads 1. That is now set for 1 minute exposures. Go down to the Sequence box. Using the box to the right of it click the arrows up to 10. You have now set your camera to take 10 exposures of 1 minute each. Press the Sequence button. Boom, and off it goes!
After the first exposure is done, your screen will brighten and you will be able to see your target again or the target area. This is completely normal and does not affect your exposures. Once the sequence has ended, press the Video Mode button to go back to the normal screen. You must now remember your gain settings because you may want to do another set of exposures after checking your target. It's important that all your exposures are the same exposure time and the gain settings the same. There are certain circumstances where you may need to take different exposure times of the same target, but that is an advanced technique and for the purpose of this tutorial is not needed. To check the target pull the Gain slider all the way to the right. You will now be able to see if the target has moved from the centre or not. If it has moved by quite a lot then obviously your mount is not tracking good and you will have to explore different settings or/and tuning of your mount. If it has not moved at all or only a bit then feel free to take another set of exposures and then check again. Do not forget to take some dark exposures as described before using the same settings with the Trigger Mode. About 10 will do.
Unfortunately, I cannot help with your mount settings as every mount is different. Either way, you should now have a better understanding of this software. Because I have assumed you are a complete beginner, I realize that this tutorial may be long, but once you have done this a few times it will seem second nature and easy to start capturing. If you have any questions or need any help with or about this tutorial please contact me on email or via the website. Good luck.