astrolulu

I would like to say hi by presenting some of my photos of the Moon - not necessarily taken in the last few days. I happen to be using two 8-inch telescopes, so I thought to start a thread devoted to photos obtained with such aperture. I think if other 8'' owners would join it, it could be an interesting reference material for people looking for information on what to expect from such diameters in the case of lunar photography. Let me start by presenting a few photos taken with the 8 '' Meade LX200 ACF and the ZWO ASi 178MC camera:

Thanks a lot. One of the questions I ask myself is whether F4 is a good parameter for a planetary-lunar telescope. Fortunately, it is not achromatic 🙂

Hi, you will also receive a residual CA in the case of an APO, and even an SCT telescope, so it is worth learning the techniques limiting this phenomenon also at the stage of processing and post-processing. At the stacking stage, it is worth using the RGB-align option offered, for example, by AutoStakkert! CA remediation tools can also be found in bitmap editors such as Photoshop, which allow you to relatively effectively remove CA residues from a photo. One of the best I know is the optics correction filter in Camera Raw in Photoshop, which allows you to remove artificial tint from aberration without much crippling the image from the color information. The negative effects of its use can be mitigated by combining it with a color noise reduction filter.

Exactly. And here we are talking about the price for OTA only... For now, I have withheld the decision because it also seems to me slightly above the reasonable risk limit - although the temptation to change from 8 to 12 inches is great. And how do you rate the suitability of this model for lunar or planetary photography...?

Hello Roger, I have tried to edit your photo and you can see immediately that its resolution is definitely too low for the instrument you are using. For comparison, I enclose a photo of Jupiter which I took with the old Japanese 60/910 mm refractor (!): Meanwhile, the best version of your photo that I was able to get looks like this: It's hard for me to say what is the reason. I have found that SCTs from 8 inches upwards become very sensitive to seeing and the height of the object above the horizon - maybe this is the source of the problems? For comparison, a photo taken this year with an ordinary, cheap C8-N newt. Your C9.25 should give a much better picture:

Thanks. The seller is in Germany so only distance selling is possible. He would like to get 900 euros, which seems too high to me, considering that the telescope does not have a mirror quality certificate, has an old, rack and pinion focuser that probably requires replacement and of course, regardless of the condition of the mirrors, their optical efficiency after several years is correspondingly lower than in the new one instrument.

The higher you set the gain, the more noisy the image becomes. The more noisy the image, the more difficult it is to sharpen the details while avoiding sharpening the noise grains.

Roger, your picture is processed so strongly that it is impossible to say anything about the original. If you shared a raw image right after stacking, it would be easier to say anything.

Hi, most bitmap editors like Photoshop, or even the simplest ones - like IrfanView - offer the option to increase saturation by adjusting Vibrance and / or Saturation. The problem is that the stacked image usually contains a lot of artifacts, and they often become the most saturated with such processing. As with sharpening, when we start to sharpen artifacts and the grain of noise instead of sharpening the details. If you saturate your picture, you will easily observe it - there will be a whole lot of artificial, colorful (e.g. intensely blue) details. One way to deal with this effect is to remove colored noise before increasing the saturation. This works quite well for images of the moon. In the case of small pictures of planets, however, this often leads to an almost complete loss of color information. Your photo appears to be enlarged very much from its native size. It also does not help - artifacts that would be acceptable on a natural scale become much more visible with this treatment.

I have been using the SW 120ED for a while. In the case of photos, it gave noticeable chromatic aberration - there was a purple halo around the stars, and on the moon you could see an aberration not only on small, contrasting details, but also overall effects such as a colored border running along the edge or a rainbow discoloration running near the terminator. Of course, I am talking about minor effects knowing that residual CA can be observed even in the case of SCT - but it is worth remembering that SW ED is not the same as the expensive 3-element APO.

And what price would you consider fair in such a case?

Thanks, it's worth remembering that we are talking about planetary and lunar imaging. Image stability is not crucial to me. As long as the object remains in the frame, AutoStakkert! it deals with it somehow 🙂 At least I count on it - the question is whether not too optimistic ...

Well - I hope the seller will forgive me for posting them without his permission - maybe I'll just delete them when the discussion is over ...

OTA looks like this one: https://www.cloudynights.com/gallery/image/1096-orion-uk-12/

Dear colleagues, greetings from Poland! I would like to say hello with a question about the Orion UK 12 '' (F4) telescope. I noticed that there are a lot of entries on the forum about it, so maybe there will be someone who will advise me on its purchase. Well, I have the opportunity to buy a used, I think older model, which has clamp rings in green and olive green, resembling the color of Vixen mounts. The second characteristic feature is the traditional rack and pinion focuser. On this basis, I believe that it may be a dozen or so years old. My problem is the necessity to move the equipment over quite long distances, so on the one hand I am looking for an instrument with as large a diameter as possible, mainly for planetary and lunar photography, and on the other hand - a mobile one. This also applies to the mount. The EQ-6 definitely exceeds my lifting capacity, hence my first question. The owner weighed OTA and claims it weighs 12.6 kg without the finder. Do you think I will be able to put it on the Celestron CG-5 mount, which theoretically has a load capacity of 16 kg? Can this tube be relatively convenient to carry, so that it can be mounted and removed during each observation? Second question - what is in your opinion the value of such a telescope, assuming that the optics is in good condition and the tube has only slight dents and traces on the paintwork? I'm not able to judge the seller's price offer because this model is rarely sold second-hand. Thanks in advance Lukasz