Nik271

Jupiter is too low in the sky for me, but people in the South hemisphere are in better luck. The storm is visible in this amazing image by astroavani:

When you talk about "performance" is the quality of the image that you get right? Like in a good lens for a dslr? Being Plossls the minimum, what are the next, better, ones? Will a better eyepiece like those costing around 50€, assuming an eyepiece that comes standard in a 500€ telescope, dramatically improves the viewing experience? Actually for telescopes of high focal ratio, say F8 and higher, a Plossl already maxes out for image quality. The more expensive EPs may have wider field of view or better eye relief but I doubt you will see notable increase in image quality. Maybe a little bit but at double and triple prices it's not worth it. I'm still using a 15mm Kellner EP that came with the £50 basic Celestron kit and that's a 3 element design, i.e. not even a Plossl. I'm using it in two Maks at F12 and F15 which are very undemanding on the eyepieces. Expensive eyepieces are worth their money for fast scopes like F4 or F5 Newtonians, especially if you want wide field of view. Nikolay

I'm not in the south west so cannot compare directly the seeing but definitely the low positions of Jupiter and Saturn go a long way towards explaining the bad views for me. Yesterday was so bad I'm not absolutely confident I saw the shadow of Io on Jupiter. It was total mush. As for Mars I have had better success but my best views really kick in around 200x and above. Anything less than that and Mars is tiny and too bright. I doubt it's the scope, have you checked it on some double stars near the zenith? I find Delta Cygni right now is a good one to test for both seeing and scope performance. Nikolay

I think for UK skies anything over 6 inches is too much for visual planetary observation as the seeing is generally worse than the theoretical scope resolution. For imaging or deep sky it's a different story of course. That 20inch Dob must be quite something!

I live under Bortle 5/6 skies and for one year trying I couldn't see the Veil even with a UHC filter on a fast Newt with 2 degree FoV. I know exactly where it is because I have photographed it, but the light pollution is a killer for this object. Then a few weeks ago I went for short holiday in Wales and the skies were Bortle 3. Not super dark but the Milky way is obvious. I had my Celestron Skymaster 20x80 binoculars and of course I tried for the Veil. I saw the Eastern Veil as a dim crescent but could not spot the Western Veil even though I was staring at 52 cygni, the star that sits right in the middle of it. Still I'm very happy to have seen the Eastern Veil. So for me the lesson is: go to darker skies and bring big binos No filters required. Nikolay

Beautiful images, this scope produces very high quality views! I'm sure being higher up in the sky Mars will be spectacular with it.

Nice images, you can scale them down to about 600 pixels and they will look very crisp!

As far as I see there is no real difference between eyepiece projection and prime focus with barlow: both serve the purpose to project an image circle on the sensor. So if you are happy with eyepiece projection just keep going. The only intrinsic property of the image size is how many pixels does it have. All the rest is a function of what pixel per inch density the image is diplayed on the screen or printed on paper. Web browsers always try to fit in the largest possible space in the screen subject to the limitation of the web page and screen resolution. So lets take my laptop: it has screen resolution at 267pixels per inch which is close to what a fine photo print resolution should be for close viewing. If I look at the 448x448 image of Jupiter in windows photo viewer and choose 'view actual size' this will be about 1.5 inch by 1.5inch. Small but very crisp. Normaly the photo viewers and web browsers dispaly at 100pixels per inch as it is good enough for general viewing purposes. This is why the photos above look much bigger on my browser, they seem to be about 3x3 inches in size, so the web browser has chosen to show them at perhaps 120pixels per inch. You can certainly rescale you images, any good photo program has this function. I use Gimp where it is under the image tab. If an image is very sharp in its default size you can rescale it to larger number of pixels as long as you happy with the level of detail. Conversely a fuzzy looking image will look better if is downscaled. For big planets like Jupiter I'm happy if they cover about 100-200 pixels with my gear. There is also a method for producing a higher resolution images from many lower resolution ones called 'drizzling' This is done when you can take multiple images which are lower resolution than you telescope can provide and then use software to get a higher resolution image by exploiting small variations of the image data. It was pioneered for Hubble since its cameras are of lower resolution than the optics can deliver. I don't know much about this but there should be people on this forum who know how to use it. Nikolay

If you record raw files you can replicate any noise reduction in the camera later in software. So my advice is leave it off and deal with it in lightroom. If you are stacking that automatically takes care of the noise. A general practice is to shoot several dark frames at the same time at the same settings with the lens cap on. These basically record the read and thermal noise of your camera. Very useful if you do loooong exposures, like minutes. For 30 seconds with a modern camera I have found that dark frames are not essential. But definitely shoot raw and NR off. The stacking works best if it has as close to raw data as possible. Nikolay

Dear John, You said: > The image size is exactly the same regardless of whether I do a HD video, or take a single shot photo as with my images of Venus and Mercury. The image probably looks the same on the screen because most view programs stretch it to fill all available space within certain limits of dots per inch screen resolution. However when you crop the difference becomes apparent. I took the photo of Jupiter you posted (which is 1080x1920) and cropped it to 448x448: For comparison I then rescaled your image as if was taken at the full resolution: 3600x5400 and again cropped at 448x448: So if you can image at your full resolution you will certainly get larger planetary images (in terms of pixel size) and there is no need to go all the way to F57, something like F15-F20 will do. Most of the spectacular images that people post are with telescopes like a 14inch SCT at F20. A well-collimated 14 inch Newtonian working at F20 should produce very similar images. Nikolay

You are probably limited by the seeing and the low position ofJupiter. To freeze the seeing you should use faster shutter speed, I would recommend 1/125. Don't worry about noise or dim images, as long as you can focus the stacking of hundreds of frames will take care of that. Nikolay

These are massive focal ratios indeed, the images must be dim and hard to focus. Fundamentally eyepiece projection is no different from prime focus with a barlow, both serve to increase the size of the image on the sensor. The reason your images are too small is the change of resolution when recording video: from 20Mp sensor for photos to fullHD video which is a sad 2Mp. That's 10 fold loss of resolution so the image covers 10 times fewer pixels and is about 3 times smaller by diameter than what it could be. You need to find a way to record video at 1-1 pixel resolution. Some people recommend recording the 5x zoomed live view from the camera back screen using Backyard EOS but that will still involve a laptop. If you are set on a self-contained camera you could try the old 550D which records video from just a small central portion of the sensor, or the recent cameras which have the 4K video 'crop' mode like Canons M50 or 250D. Nikolay

Oops I missed something very important: you are taking videos, not still photos with the 6D. The problem is that the video is only HD i.e. 1080 by 1920 while you sensor is 3600x5500 px So the camera software is 'resampling' the image in effect combining several of you original pixels into one. The conversion ruins the image scale: Now your sensor has been converted to fewer and so HUGE pixels, looks like 3 times larger. This means that in the image everything will be 3 times smaller than what I said earlier. No barlow can fix that big difference. (unless there are 6x barlows but they probably have aberrations) Perhaps instead of video you can take 100 still photos, center and crop the planet in PIPP and stack these? Its too few frames but will give larger images than the video in prime focus.

Yes, try with a 2x Barlow - it will make a difference. What matters is the image scale which is measured in arcseconds per pixel. I use this calculator http://astronomy.tools/calculators/ccd With 2x Barlow you are at 3600mm and with 6.5 micron pixels you will get .37'/pixel. Jupiter is about 40' so it will cover about 120 pixels, not bad. Most of the images that people post are crops of 480 by 480 pixels and so Jupiter will be 1/4 width of the image and look nice. To give you an idea of the image size I attach a processed, cropped image of Jupiter I took yesterday at prime focus and my native focal length 2700mm with my canon 250D which has 3.7micron pixels. The image has not been rescaled, only cropped to 480x480pixels. My image scale is .28'/pixel so this Jupiter is only 20% larger than what you will get with 2x barlow. I think with a wide aperture you can use a 2.5x or 3x Barlow and still resolve much more detail than this image. Nikolay

PS: I just noticed you wrote that you use a 14 inch Newtonian. I presume this is F5 so maybe about 1800mm focal length? Then F25 will make it 9000mm which is too much for the seeing in UK. Try with a 3x barlow at F15 first, already at that focal lengths Mars will be bigger and easier to focus.

Hi John, I am imaging with a Canon 250D in prime focus and share your reluctance to move to a dedicated planetary camera since that will involve another gadget, a laptop and more cables to trip in the dark. As people have already pointed out there are many disadvantages to DSLR for planetary: large sensors, large pixels, lossy compression and being limited to 30fps in older models cameras. However I like the fact that I can find the target directly in the optical viewfinder in the camera and get rough focus even before switching live view And its easier to track of course, even manually. There are several things I've learned with trial error and reading this forum: Seeing, focusing and correct image scale (in this order I believe) are more important than the sensor: if you get a sharp good image on your screen this will beat the disadvantages. Even at 30fps you can get 4000 frames on Jupiter easily with these large pixels before the rotation gets too bad for AS!3 to correct. Now for image scale: As a rule of thumb in average seeing you should be imaging with focal ratio at 4x or 5x your pixel size in microns. Your pixels are 6.5 microns so you should be aiming at a focal ratio about 4x6.5= 25. At these focal lengths Mars will be bigger So my advice it to try camera in prime focus first. Nikolay

This is yet another attempt at Jupiter, not easy for me as it rises over a roof at culmination (about 8:30pm) and the thermals make it dance. This time I was using the Skymax 180 without a barlow and the image is small, so I decided to make a composite with the Galilean moons. The moons are a single overexposed frame on Canon 250D so are a bit bloated while Jupiter is from the best 30% of 2000 frames stacked in AS!3 and then sharpened. I used Gimp to make the composite and judged the tilt of Jupiter by eye, so it may not be 100% accurate. Anyway here it is. It's pretty close to what I can see at the eyepiece at around 150x May this clear spell continue! Nikolay

I was very late for observing this morning: 6:30am. The sky was getting very bright so I rushed out knowing that at best I can only get a brief look at the Moon. The scope was left on the mount from the Jupiter session last evening so in goes the 20mm EP giving me 140x and the thin crescent Moon was there in all its glory. Sadly with the bright sky there was little contrast. First I tried to find Mon Rumker but could not identify it. At least I could easily see Grimaldi. Then I looked southwest beyond Grimaldi towards the edge and saw a flattish part of the Moon horizon and what looked like a ring of mountains. I had heard that Mare Orientale is in that general direction and sometimes partly visible in favourable libration. I didn't see the basin itself, just a ring of mountains but I'm really happy! Later this morning, after some online research I found this site listing dates when librations are favourable for Mare Orientale: http://www.packerlighting.com/Lunar_Articles/Moon Article 5of6.html And indeed 14 September 2020 is listed as a suitable date centered on 13:38 UT. So if you live on the west coast of the Americas go and take a look! And maybe tomorrow morning from here it will be possible to see as well. Clear skies! Nikolay

No worries I found the answer in this thread: it's orographic cloud above Arsia Mons. Seems to appear quite regularly at this time of the Martian year.

After doing an online research on SGL I found the answer to my question from the thread below. It's a cloud over Arsia Mons, one of the Tharsis volcanoes.

Nice image with tons of detail! I'm trying to figure out what is the small white bit in the centre. I noticed it also in an image I made from around 4:30am this morning. Since it is in the same location for 24 hours it is probably attached to some fixed Mars feature. Nikolay

Very nice, there is lots of detail on Jupiter too! The curve of the planet can be seen from the ellipse shape of the shadow. Also it's surprising how much bigger the shadow looks compared to Ganymede. I had a look around 8pm but for me Jupiter rises just over a house roof and gas boiler flue and the thermals were hopeless. Nikolay

I got up ridiculously early this morning to look at Mars. There was a little high cloud but fortunately the seeing was OK. I decided to make an image and this is my best effort. Skymax180 with Canon 250d, 4K video, stacked 30% of 5000 frames with AS3!, then wavelets in Registax and finally enlarged and contrast boosted with Gimp. I'm quite pleased with it, worth getting out of bed so early . Looking closely there seems to be a white patch right of centre, maybe a cloud? It was not visible at the eyepiece. I don't think it's Olympus Mons, that should be further north. I'll be interested to know if other images around the same time confirm it and also what it is? Some other mountain? Mist? Nikolay

Nice work! Lots of detail visible. This must be Mare Erythraeum and its 'bays'

I got up just before 6am to try to catch Mars but it was lost in the low mists. The moon was higher and showing trough the cloud so I decided to give it a try. The turbulence of the last few days was mostly gone and I was presented with a serene crisp moon panorama occasionally darkened by passing high cloud. The Posidonius crater was on the terminator and looked stunning, with its double rim and riles. Looking further west I got a glimpse of Rima Hadley in the Appenines mountains but the view was coming and going. Much easier were Rima Hyginus and Rima Ariadeaus: prominent thin lines just south of Mare Vaporum. Further south there were two long triangular shadows from the central peaks of Teophilius. The astronomers of old thought to estimate the height of moon mountains from their shadows. It looks doable even in my telescope if I measure the length of the shadow and estimate the angle of the sunlight from the phase of the Moon. Mental note: a graduated reticle eyepiece for a future puchase... Then a noticed a long line of shadow below Teophilius from either a mountain ridge or an escarpment. It was very long and had several serrated 'peaks'. I consulted my Moon map: it was Rupes Altai. Wikipedia says its 420km long and 1km high in places. This morning it was very impressive, casting a long shadow to the east. The sky was getting too bright and the view was hazy: my telescope lens was misting up. Time to get back to the house for a cup of tea. What a great start of the day with the mountains of the Moon!