Lunar South Pole

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Avani Soares

Parsec Observatory, Canoas, Brazil

C14 Edge + ASI 290 + IR 685

This time instead of talking about the formation itself let’s talk about how the photo was taken to get these subtle details that appear here. The telescope used was a Celestron Schimitd Cassegrain Edge line, commonly known as C14 HD. The assembly used was CGE PRO from the same company. The camera used was colored ASI 290 coupled with a Baader IR Pass filter 685 nm.

General considerations

For lunar photography as well as high-resolution planetary a good independent desing telescope is essential, we can not deny that the larger the aperture the greater the resolution capability. The focal length is also a fundamental factor and it is usually ideal to work between f / 20 and f / 35 and for each telescope it is important to define the best d / f in relation to the camera used because this is directly related to the pixel size. In high resolution photography you usually work with oversampling, using large increases. It does not have to be said that a good collimation is fundamental as well as a reasonable seeing always favors obtaining better results, the correct focus is critical to a high resolution photo and the image must be the most perfectly focused on the capture screen.

My Account
Good telescopes have been around for a long time, the breakthrough of high resolution photography was only possible with the appearance of the current generation of cameras that allowed high speeds combined with great sensitivity. Cameras like ASI 174, 224 and 290 allow you to dribble much of the bad seeing and get high quality images. This image of the south pole, for example, was obtained on a medium seeing night, I calculate something around 3/5, but I used speeds of up to 100 fps in frames of 1280 X 960. This allows to capture those brief moments of good atmospheric stability (lucky frames) that will be separated from the bad frames during processing to form the final image. In this photo with ASI 290 of the 2000 captured frames I could use 308 to stack which allows to create a photo with low noise and extract many details.

Filters
Filters are fundamental in high resolution photography and should be used according to the goal you want to achieve, in particular lunar photography, IR filters allow a remarkable gain and even make it possible to take pictures on those nights that without them would be completely impossible. The filter that I use the most is the
IR Pass 685nm which favors long-wave (infrared spectrum) passages, these waves are much less subject to turbulence than the visual spectrum (RGB) waves, but there are others more open or closed and up to a 610 Long Pass nm can help a lot when seeing is a little better. If seeing is really good, I highly recommend using a simple Green color filter, it increases the resolution because it has a shorter wavelength.

Barlows and powermates
In high resolution photography are essential and there is any brand that is suitable. Excuse me skeptics but if you really want to get a high definition photo, quality is a fundamental factor, you should always prefer the powermates because they are one step above the barlows, but if this is not possible you should opt for quality barlows recognized. They are very important because only with them can achieve the appropriate focal reasons for the photos that we want.

Programs of astrophotography
Below I will list in order the programs that I use to make my moles as well as some general considerations about their purpose.

Fire Capture: Undoubtedly it is one of the best free programs for lunar and planetary capture, easy to download (http://www.firecapture.de/). This program seems a little complicated but once you get used to it you can not use another one, in the link itself, where low orientation tutorials exist, it has many features that make it much easier to get good photos and for those who will start using it one of the The main points is the control of the hystogran to obtain even shade photos and easy to process. We should try not to overdo the Gain so as not to make the photo very noisy and all the success of a good capture is directly related to the good balance between Gain, Range and Exposure. There are no fixed values ​​because everything depends on the telescope and aperture used.
2. AS! 2 (AS! 3 already exists): I used Registax 6 to select the best frames and their stack, but AS! 2 or AS! 3 (http://www.autostakkert.com/ ) does this much better because it is a specific program only for this stage of processing. AS! 2 lets you output two TIF files (photos), one of which is already preprocessed and I use it to make the final photo, since I started to use AS! 2 I never needed Registax anymore and thus saved a step delayed post-processing. A brief tutorial of AS! 2 can be seen here: http://astroavani.no.comunidades.net/tutorial-as2
3. Photofiltre: it is an editing program (http://www.baixaki.com.br/download/photofiltre.htm), use only to adjust the brightness and contrast can also be used the filters sharpen and soften in case there is need of give a smoothed or pulled in the details. If anyone is interested in a simple tutorial to test it you can find here: http://astroavani.no.comunidades.net/usando-ophotofiltre-tutorial
4. Fitswork: it is an excellent deconvolution program, with it we can fine tune the image and pull lots of details, can be downloaded here: http://www.fitswork.de/software/softw_po.php I advise to read the tutorials and do a lot of tests with it because in fact it is the program that makes all the difference in the finalization of the photo bringing to the surface numerous details and increasing greatly the final resolution.

Final considerations
Of course reading does not seem complicated, but in fact getting good photographs requires good equipment, a lot of training and practice to realize the subtleties of every step and get that photo that really makes a difference. Patience, perseverance, the will to learn more and more often, and humility to accept compliments and especially criticism, can make us all a great astrophotographer.
Photo and Text: Avani Soares

2018-11-28T00:00:00

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