lukebl

D'you know, after years of imaging I still don't understand what oversampling and undersampling really means in practice. I just try stuff. And if it works, then great! If not ... whatever! I don’t like rules.

Apparently they described it as a ‘rapid unscheduled disassembly’. In my day, we called it an explosion.

Just realised that I posted this in the 'observing' forum rather than 'imaging'; so here it is again. Despite Venus's relatively small size (15.7 arcsecs, 70% phase), and very blustery winds, I managed to capture some very clear cloud formations with the Baader U-Filter. I see these filters are now over £200, so I ought to make use of it. The really bright patch on the limb at 4 the O'clock position was very prominent. Captured with a 250mm f/4.8 Newtonian, 5x Powermate, ZWO ASI290MM Mini cam, Baader U-Filter and Baader IR-Pass Filter. About 3000 frames captured with the U-Filter, and about 10,000 with the IR Filter. Processed in Autostakkert, Registax and Photoshop. RGB thus: R(IR), G(50%U/IR), B(U)

It's been a very long time since I did anything astronomy-related, but this afternoon I thought I'd get back into things and have a go at imaging Venus. And I'm glad I did. Despite Venus's relatively small size (15.7 arcsecs, 70% phase), and very blustery winds, I managed to capture some very clear cloud formations with the Baader U-Filter. I see these filters are now over £200, so I ought to make use of it. The really bright patch on the limb at 4 the O'clock position was very prominent. Captured with a 250mm f/4.8 Newtonian, 5x Powermate, ZWO ASI290MM Mini cam, Baader U-Filter and Baader IR-Pass Filter. About 3000 frames captured with the U-Filter, and about 10,000 with the IR Filter. Processed in Autostakkert, Registax and Photoshop. RGB thus: R(IR), G(50%U/IR), B(U)

Here's a couple of captures of the aurora from Norfolk last night, captured at around 21:00. I think I was a bit late to the show, as it fizzled out by about 21:15, but was distinctly visible to the naked eye. I've seen vivid displays of the aurora in both Norway and Iceland, but it's nice to see it on your own turf, however faint! Canon 700d, 18-55 lens at f/5, ISO 1600, 15 seconds.

I have the mono version of one of these. The sensor on mine is waaaaay too sensitive to use during daytime. Even if you manage a short exposure, you'll get the shutter partially blocking the view. Even in quite dim twilight it'll still overexpose at the shortest exposure.

Here's 16 of the frames.

Hi folks, I captured this animation of Mars over a period of just over two hours this evening. I haven't viewed Mars for some weeks, and it sure has shrunk. Now only 10.7 arcsecs across, which by my back-of-the-envelope calculations is about the same as a penny at a distance of about 400 metres. However, my maths may be completely wrong! Captured with a 250mm f/4.8 Newt, 5x Powermate, ASI120MC-S cam. 90 second captures of c. 15000 frames at intervals of 6 minutes captured with Firecapture. Stacked in Autostakkert. Wavelets in Registax. Seeing was a bit wobbly, but quite a few features are visible. Sometimes when one processes these images, you're never sure if a blob is a real feature or just an imaging artifact. When you animate the images, it's gratifying when they move with the planet proving they're real.

A view this evening of the conjunction of Venus and Saturn, Banham, Norfolk, about half a degree apart. Canon 700d, 70-300mm zoom at 85mm, f/4.5, 3 seconds, ISO800

Hi all, Just had a long weekend in Iceland, and we really lucked-out with fine weather (albeit at -18°C and with a strong East wind blowing off the central ice cap!) and a nice Auroral display on Saturday and Sunday nights. Here's a few captures. Canon 700d, 18-55mm lens at 18mm, 6 second exposures at ISO 1600 and 3200. This is at Garður Old Lighthouse: A quick animation over a period of about 7 minutes: Here with Jupiter on the left. You don't expect to see Jupiter against the Aurora! Despite the streetlights of Garður, the lights were still bright. The white light here is Garður New Lighthouse The aurora reflected in the sea: Finally, a view of our cosy cabin at Garður

Just been out with my bins, and with a single sweep I could see (in W-E order) Venus, Mercury, Saturn, Jupiter and Mars. Uranus and Neptune too faint in the twilight, but the 5 were good to see as always.

A quick capture of Mars this evening. C. 20000 frames, ZWO ASI 120MC-S , 5x TV Powermate, 250mm f/4.8 Newtonian. It got me thinking that although the darker patches are generally constant, they do seem to change. For instance, I don’t recall the central ‘isthmus’ here, connecting the northern part from the southern part, being so prominent in earlier apparitions. So, if they change, what makes the dark areas different from the lighter areas and why do they change? They don’t seem to directly relate to altitude or other features. I can understand why earlier astronomers thought they may indicate changing vegetation.

Well it’s a small world. 12,756km in diameter to be precise!

Thanks Geof. Out of interest, and without giving too much away, actually how far are you from me? I’m in the village of Banham.

A while back I posted a mono image showing Mars's moons Phobos and Deimos. Always very tricky to capture due to the overwhelming brightness of Mars. Last night (12th December 2022) they were both at elongation again, so I had a go in colour. I captured just c.200 full-frames each of R, G & B with my ZWO ASI290MM, 250mm f/4.8 Newtonian and 5x TV powermate. 200ms exposures at a rate of just 1-2 fps. Processed in Registax and Photoshop. It's a bit messy, but at least you can see them! The detailed image of Mars was a separate capture (below). Mars itself was captured with a ZWO ASI120mc-s colour cam, 250mm f/4.8 Newtonian and 5x TV powermate. About 31,000 frames, 2.7ms exposures, 211fps. The seeing has improved considerably recently, and at last I'm managing to capture at least a bit of detail.

My modest snapshot a few minutes before the clouds rolled in. I was all set up with a high-magnification video but clouds ruined play a few minutes before the occultation. Canon 700d + Tamron 500mm mirror lens.

A washout here! Beautifully clear at 4:30. I was all set up with high-mag and low-mag dual rig. All set to capture movie and stills. 10 minutes before the event the clouds rolled in. 😠😠😠

I intend having a go at this, although being near the east coast there will be clouds and showers passing through. I just wondered why you can't take a single avi of the whole event, rather than several, and then split the avi into sections? You won't get any gaps then. Anyway, that's what I plan to do. We'll see if it works.

OCCULTATED. Nice word!

I've been loooking forward to this for quite a while. Unfortunately, it will be obscured from my obsy by my house roof, so I'll have to set up temporarily in another part of the garden. I don't fancy setting it all up in the wee small hours, so I'll have to do it the evening before. Given the weather forecast, I'm not sure how I'm going the keep the exposed equipment dry/dew-free/frost-free all night! Oh, to live somewhere dry like Arizona.

Is that really necessary? I’d have thought a couple of minutes at 200fps would be sufficient. Law of diminishing returns and whatnot. I’ll have to try it if I ever get a clear night.

Fabulous images. I just wondered if derotation has any great effect with Mars, given that it rotates so slowly compared to, say, Jupiter?

Many thanks! I've only attempted it when both moons are at their greatest elongation. An hour earlier or later and Phobos would have been too close to Mars.

Here's a capture of Mars with 12th magnitude Phobos and 13th mag Deimos this evening. I managed to capture the two moons at Mars's last appearance two years ago, but I think this is a better result. I saw that Phobos and Deimos were both near their greatest elongations simultaneously this evening, so I had a go at capturing them using my ZWO ASI290MM Mini, 5x Televue Powermate and 250mm f/4.8 Newtonian. You have to be quick with Phobos as it orbits three times a day! This was a capture of 568 frames at an exposure of 120ms. Despite high cloud I was amazed that I could just make out both of the moons on the screen with such a relatively short exposure. The ASI290 is amazingly sensitive. I was lucky that they weren't in the diffraction spikes. Stacked in Registax and a bit of processing in Photoshop. Mars is obviously heavily overexposed. Well pleased with the result! labelled: The view on Sky Safari: And with a properly exposed Mars. This was the result of 15513 frames, 0.36ms exposures, 270fps. Processed in Autostakkert and Registax. I really must use this camera a bit more on Mars even though it's a mono cam, as it shows way more detail than I can achieve with my colour camera. I guess that's due to the really short exposures I can manage with it. Incidentally, you can see Olympus Mons as the pale patch at about the 2 O'clock position close to the limb.

Brilliant! Thanks, Alan. That seems to have done the trick. I'm getting 200-300 fps now. I wish I'd found that out at the beginning of the Jupiter season!