astrolulu

I will try different methods, but let's face it - the aperture determines the scale and if there is a feeling that the photo would look better when reduced, the only real salvation is the larger diameter of the telescope. I'm working on it too - but so far to no avail ... Meanwhile - Oceanus Procellarum - the land of lunar ejecta... 🙂

I think sometimes it's hard to just reconcile two goals. One is the aesthetic effect, i.e. making a nice picture. The second one has a more documentary character - we want to boast about difficult to "catch" details that we managed to hunt down ... Coming back to the noise problem - I tried version 2 - i.e. pre-filtering the noise on the image stacked with the 1.5x drizzle option. The noise is of course less, but as with noise reduction - everything becomes more "plastic". It seems that the photo should be smaller in this version.

I think even with the 1600 frames I collect, the amount of noise could be reduced. It's good that you paid attention to it. It didn't bother me that much, but it's good to know I'm not representative here. Two methods come to mind. Both consist in reducing the amount of noise at the expense of deteriorating the quality of details, in order to sharpen them later a little more than usual: 1. Using e.g. 15 or 20% of the pool of frames instead of 10% or 2. Use 1.5x drizzle and pre-remove noise before reducing and sharpening the image. In both cases, I would need to sharpen the image a bit more, because both methods result in weaker details at the input.

Your mosaic is razor sharp - and every picture should look like that. Unfortunately, this means that we have to say goodbye to some of the details that we fished so painstakingly from outer space 🙂 Recently, I noticed that in the case of Mars, the opposite effect - the brutal enlargement of the image above its original size - allows you to see details that are not visible on a 1: 1 scale ...

I will mention one more phenomenon that caught my attention. Well, Photoshop uses several degrees of magnification of the image on the screen, between which you can easily switch using keyboard shortcuts. I've noticed that whenever I bring a photo to a scale and sharpening degree that I might call "acceptable", going one notch lower on the screen magnification scale makes it appear much better, almost perfect. It is obvious that by reducing the image (it can be additionally sharpened) we get sharper "drawing and texture". The details themselves get smaller and partially disappear of course. I am talking about this because a cost-free recipe is within easy reach - just reduce the image to make problems such as thickened edges, blur or noise disappear. Of course, the cost does exist - these are the details that we fight for 🙂 66.7% - which is the inverse of the magnification to 150%. This is the picture magnification level where everything seems perfect to me compared to the 1: 1 version ...

Thank you for these thought-provoking remarks. I think they will encourage me to try a bit longer sessions. I have the biggest problem with processing - if the 1.5x drizzle option is used, stacking takes hours for me, and getting a few frames for further processing at 6 mpx resolution often takes 2-3 days. What's worse, I'm going to replace the 178MC camera with an 183 MC, which means a frame with over 3 times more data. It's scary to think how long it will take to process such photos ... Speaking of noise, I meant a slightly different problem. In my opinion, noise allows to avoid artificial definition of an image where resolution does not allow it. I gave the example of the maria areas. Very often we see pictures where such surfaces are perfectly smooth, with very precisely and clearly marked, few craters. This is the effect of artificial noise removal. Togethrer with the noise, all the wealth of details is removed. They are too small to be sharpened and revealed, but certainly should not disappear without a trace, giving the effect of a plastic, almost shiny surface. The presence of noise gives a certain security buffer and allows you to avoid the need to specify e.g. the surface texture, when resolution does not allow it. Filters such as remove noise or median tempt with this possibility - but I try not to use it.

Thanks for comment. You are right - the problem of noise is a separate "methodological" issue and can be approached in many different ways. As I wrote elsewhere, I consider it to be a "technological feature" such as film grain, printing raster or paper texture. An additional advantage of using it is leaving the definition of the smallest details at the level of some understatement, which sometimes seems "truer" to me. What I mean is that applying techniques to produce an attractive looking image, does not always reflect the true nature of the lunar surface. For example, smooth lava is brought to a "perfect finish" and looks almost polished, while in fact it is scratched with an infinite number of smaller and smaller craters. Due to the presence of grain or noise, we cannot say whether they are there - because this scale is already lost in the grain. If the image has been filtered to artificially smooth the lava surface, we can see that nothing is there - although that's not true .... The problem starts in cases like you have shown, where the grain unintentionally appears locally, suggesting that it is due to the presence of some objects on the surface. Meanwhile, here it probably resulted from the algorithm of filters in Photoshop, which above a certain threshold worked differently than in the area next to it. Surely I would like to have less noise, but number of frames I collect is to small to get a better effect ...

You're right - the method of hiding part of the posterization simply has no chance to work where dark area is not big enough - that is, on small details. Cheers 🙂

I think that you have very accurately defined the not always perceived limit of acceptable image sharpening (but also enlarging!). Apart from the noise, it is the effect of posterization and edge duplication that you mentioned, which makes the outlines of objects - such as craters - seem unnaturally thick, as if they were girdled with a bicycle tube. Of course, this effect is more pronounced the smaller the diameter of the telescope, so one of the escape routes seems to be simply escaping into larger diameters. Recently, I have noticed that a good effect is achieved by enhancing the blacks in the shadows in such a way that at least some of the posterization falling on the dark parts disappears (or is less visible). The image seems more precise even though it was not sharpened:

Definitely get back! Fantastic details 🙂

And now Tycho again - it's time to face the beautiful Blue Eye of the South 🙂

Thank you very much for your inspiring and very motivating comments! As for the grain, I still remember the analog times when films with high ISO performance were used. They had a distinct, coarse grain - so I tend to treat this as a "technological feature" that is acceptable. Due to my laziness and impatience, as well as a relatively weak computer, I try not to exceed 1600 frames per photo. And here is the question of how many of this small total number should be used while stacking. Usually, I choose for the finer details, at the expense of more noise, meaning I only use 10% of the pot. 160 frames... - hard to avoid noise while sharpening as much as the fine details allow. But of course - I'd rather have an attractive-looking contrast of the smooth lava surface with the jagged craters of the highlands! When it comes to sharpening, I have the opposite dilemma - I have the impression that I am exaggerating and that I am failing to implement my own postulate, which is: sharpen it so that it looks sharp, but not sharpened! 🙂

27 October, the same setup:

Mars October 27. I've always considered artificial enlargement of photos to be barbaric. By chance, however, I discovered that when I enlarged this image to 150% of its original size, I could see the Olympus Mons right in the vicinity of the terminator. However, the volcano cannot be seen in the photo in a 1: 1 scale. An interesting discovery that contradicts all the rules of photo processing that I was ready to defend so far 🙂

I collected a few frames from that evening. As the seeing deteriorated quite quickly, I reduced the frames size of the whole pictures set to make the quality acceptable and put it into an animation. Cool phenomenon ... On the right, there is a faint Callisto wandering around:

I only meant the size of the camera's sensor and resolution - especially when taking pictures of the Moon, a higher resolution that covers a larger part of the surface suits me very well.

Thanks! I don't want to advertise anything here, but the ASI178 is a really cool camera for such applications - resolution high enough to cover a sensible piece of the sky or the Moon, but not so large to get into problems with coma or alignment ...

Recently I showed here some pictures of the Moon taken with very good seeing: https://stargazerslounge.com/topic/399534-the-moon-with-8/page/4/#comment-4306419 A similar occasion occurred on October 26, during the transit of Europe, casting its shadow over Jupiter. Ganymede has just completed its passage, and its shadow has not yet appeared on Jupiter's disk. Callisto - dark as usual - is visible on the right side of the photo. The conditions were good enough that some albedo features are also visible on its disk.

Thanks, that's right - it's Titan. But with the moons, I had to do a little cheat and increase their brightness, otherwise, apart from Titan, you would not be able to see the other three.

Camera: ZWO ASI 178MC.

Nice 🙂 I have to admit that I am not sure if the name "fluorite" means that the lens is made of natural minerals, or is it just a marketing name for synthetic glass such as FPL-53 etc. But it seems very possible to me that it is a natural material. Fluorite lenses are famous for their fragility - if it were a synthetic material, this problem would probably be overcome...

WOW! Absolutely unbelievable quality - I doubt if I could achieve a similar effect. I'm a bit oversampled at the moment and a slight increase in focal length by using a 2.5x Barlow instead of 2x would probably help to improve the quality of details, but I treat this telescope as a temporary occupation while looking for a larger instrument, so I'm content with what I have at my disposal. 🙂

Hi Mandy, I think there is no doubt about the Newtonian telescope's potential for astrophotography of the planets and the Moon. The discussions - at least here in Poland - concern the usefulness of the Newtonian telescope as an instrument for planetary and lunar visual observations. Many fans of high-quality refractors are trying to prove that the Newtonian telescope is not able to compete in this field with smaller but much more sophisticated instruments such as fluorites or apo. In my opinion, these images show a certain potential of the Newtonian telescope, which may be difficult to use in average seeing conditions, when a smaller, yet high-quality refractor has the chance to show much better picture. However, in very good conditions, it happens that what you can see in the photos becomes available also through the eyepiece - to an extent depending on the seeing quality. Then the 8 '' Netwon will easily beat the 5 '' apo 🙂

Thank you! This time the quality was mainly influenced by the seeing. The pictures are a step ahead in terms of detail compared to what this telescope can show in average conditions. I'm afraid this is an opportunity that we only get a few times a year...

Mars getting closer...