Mandy D

The results from it are good. You should certainly be able to see the Moons of Jupiter with it, but will need higher ISO and longer exposure for your phone to image them. Jupiter will image easily with that telescope. Try this link which shows the moons of Jupiter in real time and see if you pick them out with your telescope. https://skyandtelescope.org/wp-content/plugins/observing-tools/jupiter_moons/jupiter.html

I'm not sure (at least, not in every case) that students are not told how some of the practicals link to theory. I certainly recall from my O level chemistry classes that the flame test was linked to orbital electron theory. I am convinced that many students fail to remember pertinent information and, in most cases are incapable of knowledge transfer. I remember at the start of one physics lesson where the teacher stated that we had been taught about quadratic equations in maths class recently because he had asked the teacher before starting this particular lesson. Virtually everyone present was adamant that we had not yet met quadratic equations. It seems to me that what is learnt in the maths classroom stays there and our brains pick it back up once we go through the door into the room, again and the same for every other subject. Strangely, I always found knowledge to be transferable in school, yet today if I walk out of a room with the intention of doing something I will forget what it is and have no chance of recalling until I walk back into the room where I originally had the thought, then it instantly returns. I wonder if this is due to the compartmentalism methods used in our education system or is it just my age? What were we talking about?

@carastro It is interesting to note how many join this site, post a silly question, statement or remark then leave. I was thinking about this only yesterday. I think some just come in purely for the puropse of winding the rest of us up, others are so ignorant of the science that they think they have a better understanding than the scientists. I recall one comment I found through Google many years ago: "Where does the moon go when it's not in our sky? No-one knows!" It is also interesting, as you have noted, how these daft posts seem to generate some of the longest and liveliest discussions in here. The OP has really missed out on a lot of interesting stuff and the potential for actually learning something. He has probably now gone back to posting "Flerf" comments on Facebook.

The Moon was still high in the sky when I got up this morning, so I grabbed a few quick photos with the D800 through the 200P. This is the best one after processing in GIMP.

@Kon Impressive! That will have been a lot of clattering from the mirror on the D3200! When I started looking into capturing an ISS lunar transit, I found one about a mile from home the following day! It was cloudy. I've not bothered looking since, but now I am inspired to try again.

I have, too. I hope many more members of this forum find the time to do so. If we don't act as a community, we may lose access to the night skies altogether at some point.

Does this not make it even more important to do something about the present problems?

I have just received an email from the BAA linking to a survey concerning the increasing numbers of satellites in LEO. "Jonathan McDowell maintains a list of planned constellations on Jonathan's Space Pages where, up to 22-Aug-2023, he shows a maximum total of 543,811 LEO satellites from 18 different planned constellations. He doesn’t give a timescale but, if all are launched as planned, this would eventually represent a more than 90-fold increase over the current number!" It would be in the interests of all to complete the online form and spread the word. The survey should take about 5 minutes to complete. https://form.jotform.com/232251987986069

This stuff: https://www.rothervalleyoptics.co.uk/baader-astrosolar-nd50-safety-film-sheet.html Do NOT use regular ND filters that you see for cameras. You need to attenuate the sunlight by a factor of 100, 000 times for visual observation. Camera filters will NOT do this. Amazon is not really the place to go when looking for things that you depend on for your safety!!! Follow the instructions carefully. There is also photographic density, which is not safe for direct viewing with your eyes. It only attenuates by a factor of 10,000.

Right next to it! How awesome and I missed it despite imaging the Moon at the time!

Baader solar film. Make your own frame for it to go over the full aperture of your scope. Don't forget to cover your finderscope or filter that too. Make sure you get the visual density of film and follow the instructions.

@Pankaj From what I can find, your camera will shoot video at a maximum of 30 fps, not 50. As Nicholas has said, the pixel size is 4.3 micron, which is quite large, so to get Jupiter across a decent number of pixels, you will need a long focal length. However, you also need to consider how the 1200D creates video files! Does it use 1:1 sensor pixel to 1080P video pixel translation, or is it using a larger area of the sensor, then down-converting it to 1080P resolution? I could not quickly find the answer on the internet, so what you should do is shoot some still frames and a few seconds of video, then compare how many pixels across the diameter Jupiter appears in video and still images. I know for fact that the Nikon D800 crops a large area from the full sensor to image the video, but resizes it to 1080P before saving. With the D800, it is possible to record the captured video directly to professional video equipment for broadcast quality video. For Jupiter, with the D800, I shoot only still frames at highest quality and stack them. I can grab, perhaps 100 frames per minute sustained. IIRC, the D800 downscales by a factor of about 2.5:1 on resolution for video. I can get Jupiter across about 80 pixels on my sensor at native focal length shooting stills, or about 30 pixels from video. That is a huge difference.

Now, here is another interesting thought. Phobos chaotically tumbles from time to time in it's orbit and has an irregular shape, so the eclipses can all look very different. If we chose the orbital distance carefully, we could then have a wide range of different types of eclipse, with some not fully eclipsing the Sun when Phobos is centred on it and others where it obstructs a band across the centre-line of the Sun, etc, etc.

Obviously, you can apply Nyquist's theorem to non-sinusoidal signals by virtue of the fact that any complex signal can be reduced to a set of sinusoids via Fourier transforms. The only component necessary to consider for this is the highest harmonic you need to reproduce.

@Mark2022 The centres distance between the end most holes is 309 mm according to my steel rule. My dovetail is bolted to the tube rings on the 200P with M6 bolts, so I assume they are M6 clearance holes and unthreaded, but I have not unbolted it to check. I guess 6.5 mm, but could be 1/4" (6.35 mm). They would be easy enough to drill out, though.

Well, that is very easy to check. I cropped Phobos out of NASA's imagery and scaled my own image of the Sun to the same size as in the original NASA image, then I scaled Phobos to three times it's original size and overlaid everything onto a dark blue background, so you can see what would happen during the late partial stages of a solar eclipse as seen from Mars under your prescribed conditions. Given that Phobos orbits quite close to Mars, it's apparent movement in the sky would be very rapid, so the eclipse would likely last seconds at most.

No, but you can contact me via personal messaging on this forum.

I'm an engineer, but educated in physics and astronomy.

I'm in England. Where are you? <----

It's irrelevant if you are buying a ready made eyepiece. Just get a 25 mm one in a 1.25 inch fitting. A really cheap one will do.

OK, so get yourself a cheap eyepiece of around 25 mm focal length and set the two up about 500 mm apart. Look at something far away (NOT the Sun!!!) and see if you can get it into focus by moving them closer together or further apart. Then get a tube to mount the large lens in and make something to go in the other end that the eyepiece can slide back and forth in = instant telescope. Pat yourself on the back and grab a cup of tea.

You mean 500 mm (millimetres)? Surely?

OK, so what is the focal length of this lens that you have? Don't forget if this is a singlet, you will have huge amounts of chromatic aberration affecting your view.

70 mm aperture is not 150 mm aperture, so how does this help you?

Yet, you imagine making a refractor would be simpler? OK, so you don't have to aluminise the glass in a refractor, but you have two surfaces to grind for each lens. You are going to have massive amounts of chromatic abberation to deal with, so will need at least two objective lenses to even begin reducing that. Sorry, I think building a large refractor at home without experience is far beyond what can be readily done, whereas a reflector is, by comparison, much, much easier. Are you buying all the lenses ready made? Where from? How much are they costing? What is the quality of them? As @cosmic just said, you'd be better buying one ready made.