Astrophotography Adventure (cont'd)

In my prior post, I discussed the telescopic equipment that I decided upon in order to do some astrophotography on the cheap.  As in regular photography, both film and digital, there is a lot you can do with an image via post-processing.  The de-facto standard these days seems to be Photoshop. But I've never been a big Adobe fan and I really am not a fan of their new cloud-based application; and, face it, I'm doing this project on the cheap and there is nothing much cheaper than free. So for image processing, I have downloaded GIMP.  It may not be as intuitive or as glitzy as Photoshop but it should do the basics that I'm looking to get done. And that's all I'm looking for.  There are lots of people out there who know all the tools that these imaging manipulation programs provide and who could probably improve any of my images by about 100%.  But I'm just looking to get something that looks pretty good without a ton of post-processing effort. So GIMP it will be.

Before the Hubble Space Telescope and all these incredible pictures from various JPL programs, most people were totally amazed by their first view of the moon or planets through a telescope.  And I still get that buzz even today. But, more recently, some people's reaction is "it doesn't look like what I expected from the pictures I've seen". And that is absolutely true.  Most visual observations will never have the clarity and detail of a good image of the same object. This is especially true of deep space objects (DSOs) such as galaxies and nebulae. For most visual observers, these are just fuzzy patches in the sky with none of the color and detail that you see in professional images. For example, you might recognize this iconic image of the Horsehead Nebula in Orion:

The fact is that most visual astronomers, even professional astronomers, have never even glimpsed this nebula with their own eyes. And, even the ones who have can not possibly see the range of colors and detail of the image above, which was probably a stack of multiple images taken with multiple filters and then heavily post-processed .  It is only in photographs that the details like gaseous clouds and spiral arms can be captured. And the reason for this is quite simple. Our eyes receive a continuous stream of light that our brain continually translates into an image.  Photographic sensors, on the hand, collect that light and accumulate it. And the accumulated light is what makes for such detailed pictures.  That is also why, in the days of film, astrophotography required tracking for such long periods of time - because the film needed to accumulate as much light as possible.

These days, however, we can cheat a little bit.  Rather than having to track these objects as they rotate across the sky for hours, we can take short videos or multiple 15-30 second exposures and "stack" these images together, basically accumulating almost the same amount of light and, therefore, detail as an equivalent longer exposure.  This stacking technique is also what will allow me to use the alt-azimuth tracking mount for astrophotography as opposed to the typical equatorial mount needed for tracking objects for longer periods as the exposures I will be making will be short enough to avoid any field rotation (essentially the stars seeming rotation around the Earth's polar axis as opposed to directly east to west across the sky).

Happily, the two stacking programs I am going to use are both free - who could have guessed!  Registax is a program that takes video files, picks out the best individual frames from that video, and then stacks those individual frames into an image.  Even if the object travels a bit within the video, the program will still be able to align and stack the individual frames. Registax is particularly useful for imaging planets as it is difficult to take an individual photo of a bright object like a planet at exactly the right moment of least atmospheric disturbance. (The quantity of atmospheric disturbance is known by the highly scientific term "seeing" and usually limits most earth-based telescopes to magnifications under 300x.) Instead, we take a short video and hope that there are enough quality, clear frames to create a good image. Deep Sky Stacker is appropriately named as it is more useful for images of DSOs like nebulae, galaxies, and clusters.  The program takes the individual multiple second exposures you have selected, identifies and aligns a star map of those images, and then stacks them together to produce a final image.  This also allows you take multiple images that are not 100% aligned - the program will do that for you.

Finally, I need to be able to optimize the iPhone camera. For brighter objects, I will need a low ISO and short exposure times. For fainter DSOs, I need high ISO and the ability to take 15-30 second exposures.  To do this, I have installed NightCap Pro at a cost of $1.99 from the App Store. NightCap Pro gives me the ability to control ISO, exposure, focus, light boost, and noise reduction.  It also allows me to set up a series of photos with long exposure times and also has the option for TIFF image quality that is virtually lossless. It is the perfect app for iPhone astrophotography.

With these four programs installed, I'm finally ready to go out and actually take some pictures! I'll keep you updated as the adventure continues...