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Second Time Around

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Second Time Around last won the day on December 13 2023

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  1. I ought really have said night vision device, although mine can also be used as an eyepiece. They hugely amplify the light coming in but, unlike EAA where the image builds up over time, the effect is immediate and so it's just like looking through a normal eyepiece. They'll show much fainter stars and nebulae, plus with an h-alpha filter most nebulae will really pop! However, they're extremely expensive, especially outside the US (their military doesn't allow exports). Mine cost me over £6000. I could only afford it because I had a lump sum on retiring. Go to https://www.ovni-nightvision.com/en/content/11--ovni-m- Anything further is really off topic, but Cloudy Nights has a specialised night vision forum.
  2. My 10 inch Dob is easily my most used scope. However, it wouldn't be the one I'd choose as a sole scope. That would be my 72mm f/6 ED for the following reasons: 1) It's grab'n go, not needing any cool down time. 2) It's lightweight so easy to carry outside. 3) It's easy to move round the garden to different positions to avoid trees. 4) It's sharp on the moon and planets, although I'm mainly interested in DSOs. 5) It's great on DSOs with my night vision eyepiece, and equivalent to a much larger scope without night vision - especially on globulars and nebulae. 6) It's great for wide field views. 7) It's just about the longest focal length to get whole disc views of the sun including prominences with my Quark. 😎It's great for terrestrial use. 9) It's compact enough to go as cabin baggage in an aircraft. 10) It would be easy and relatively inexpensive to replace if it got lost or damaged. Having said all that, I'd not like to be restricted to just 1 scope. However, I'd happily be restricted to 2, and would add my 10 inch f/4.8 OOUK Dob. This is the biggest I can take in and out the house.
  3. I have 12x36 Canons where the switch has to be held down continuously. However, despite having badly disabled hands I have no problem holding the button. This is because my finger naturally falls into place on the button. If I have no problem others shouldn't either. So don't let this put you off buying such a model.
  4. One point that the video mentioned was that planes often wouldn't have to change course, merely change their height. It was made by a Lufthansa pilot and referred to the same AI research done by Google that the article referred to. I remember the lack of contrails during the first part of lockdown. IIRC it was here, or possibly on Cloudy Nights, where it was observed that both transparency and seeing were better then
  5. Fascinating video, Dave! It's long, but it's basically saying the same as the article I quoted but goes into more detail.
  6. Steve, if you read the entire article you'll see that: ".....reducing contrails by 73% would raise fuel costs by just 0.11% and overall operating costs by just 0.08%. They also noted that rerouting aircraft under such a scenario would only involve 14% of all flights."
  7. Yes, it does of course depend on atmospheric conditions. I didn't quote the entire article but this extract is relevant: ".......used weather and satellite data to create software models and AI prediction tools to determine whether it was feasible to divert planes from airspace that would lead to contrail formation. They found that it appeared possible to reduce contrail formation by approximately 54%."
  8. From article in The Conversation: "When several planes fly in the same general area over the same period of time, the contrails can combine, leading to the formation of cirrus clouds, which can act like a blanket, holding in heat." The article was entitled "Study finds rerouting of airplanes to reduce contrails not as expensive as thought." It seems as though a huge reduction in contrails is possible at minimal cost. The original article is at https://techxplore.com/news/2024-03-rerouting-airplanes-contrails-expensive-thought.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter
  9. Yep, we had reduced water pressure and had bottled water delivered. We didn't have to use it though. Others a few miles away weren't so lucky and had no water at all. Thankfully the situation isn't as bad as 2000 when levels were even higher, and many properties a few villages away were flooded by groundwater rather than rivers.
  10. Ernest's bench tests are partly based on eyepieces supplied to him, mainly I believe by members of his forum. If I remember correctly, he described the Mk III Baader zoom as "battered", which is why it may not have performed well. The supposedly optically identical Mk IV came out much better, and I'm certainly pleased with mine. The Baader is still not as good as my APM, that also has a wider (and constant) 66 degree field of view. The APM is more expensive though. Considerably more expensive still is the Leica. I haven't tried this as it doesn't accept a Dioptrx astigmatism corrector. Perhaps the best value for money is the Svbony 7-21mm zoom, that came out well in Ernest's bench tests. No, it's not as good as the Baader, but it's a fraction of the price. It's currently on sale direct from Svbony at just £32.76!
  11. The inexpensive Solarquest mount will both find and track the sun for you. Max payload is given as 4kgs on European sites, 5kgs on US sites. My 72mm ED at f/6 works fine on it. https://www.firstlightoptics.com/skywatcher-mounts/sky-watcher-solarquest-solar-tracking-mount.html
  12. Or get a 2x Barlow lens. Some of these can also be used at 1.5x as well by unscrewing the black cell at the bottom and screwing it into the filter thread of an eyepiece. This would give you magnifications of 39x and 52x with your 25mm eyepiece, plus 97x and 130x with your 10mm eyepiece. FLO do such a model for just £27. Go to https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html
  13. This is my understanding of the difference between Barlows and Powermates (Televue's name for focal extenders). The reason focal extenders have 4 elements is that they have to first make the rays from the objective parallel. Barlows don't do this so can be just 2 elements. Therefore because of the extra elements focal extenders are more expensive, although not necessarily better. Having said that Powermates are made to a very high standard. However, as said, there are also some very good Barlow lenses on the market. Apart from the ones already mentioned, the 2.7x APM is very highly regarded by experts. Mine is excellent, although I've never used a Powermate so am not qualified to make a comparison. As mentioned above, Barlow lenses increase the amount of eye relief, which may be good or bad. Also on some long focal length eyepieces they may create vignetting. One other point to bear in mind is that the amplification power of a Powermate is fixed or nearly so. On the other hand, with many Barlows it can be changed to give a multitude of amplifications, so Barlows are more flexible.
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