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Captain Magenta

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  • Content Count

    190
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About Captain Magenta

  • Rank
    Star Forming

Contact Methods

  • Website URL
    www.slidingseat.net/stars/stars.html

Profile Information

  • Gender
    Male
  • Location
    Middlesex & SW Ireland
  1. Herewith my first attempt to get a reasonable Moon pic. I was impressed how much extra detail the stacking process gave it compared to trying the same processing on just one sub. Equipment was Canon 7Dmk2 with EOS 300mm f/4L and 2x Converter mk3 giving 600mm f/8, mounted on a Berlebach Report tripod. Each sub was 1/1500sec at ISO 400. 65 still images stacked and integrated in Pixinsight using their "FFTRegistration" script, .tif then imported into Photoshop, though most of the sharpening and contrast work I did in Camera Raw before getting to Photoshop. Thanks for looking, Magnus.
  2. Captain Magenta

    Case for mount

    wil this do? https://www.primalucelab.com/astronomy/geoptik-pack-in-bag-for-skywatcher-az-eq5.html I have the one for the AZ-EQ6 and it's very good Cheers, Magnus
  3. Captain Magenta

    Airborne observing

    Superb. Earthshine from a camera phone through an aircraft cabin window! That top pic a great image by any standards. If you look really carefully you can see me ranting by Blackfriars, having taken my DSLR in to work and on my way home having planned and found the perfect spot and the perfect view with skyscrapers and a lucky perfect clear evening, only to discover the battery was almost dead and useless. I checked it before taking it in this morning, it showed 4 bars BUT IT WAS LYING. Magnus
  4. Talking solely about refractors, which a layman photographer (as opposed to an astro-photographer) would recognize as a "normal-style" lens, the f-number represents the simple geometry of the lens: roughly the length of the lens divided by its width at the front. In other words, the "opening-out" angle from the back to the front is the same for lenses of different focal-lengths but same f-number. But also bear in mind that an object of twice the linear dimensions of another same-shaped one will weigh 8 times as much (2x2x2): the weight increases by the cube of the focal length for a given f-number*. So refractors (normal lenses) get very unwieldy (and hence expensive) very quickly. As an example: I own some big Canon prime lenses, including a 300mm f/2.8 and a 400mm f/2.8. Although the 400 is only 33% longer than the 300, it weighs more than twice as much! Cheers, Magnus * edit: that's assuming everything is scaled up pro rata. In practice the configuration of something like a lens is somewhere between a 2-D object and a 3-D one: lens tubes inparticular are likely to be thinner in a bigger lens, to try to offset this effect. So pone probably should be thinking of a power of perhaps 2.5ish rather than 3 when scaling up like for like
  5. Captain Magenta

    December, er, Observing and LiFePO4 Battery Pack

    Not to worry, thanks for your responses. I'll continue trying to pin it down, my guess is the current for tracking-only on that mount brings it below that 100mA threshhold, I might see if I can measure it. It could also be a glitchv SynScan. I'll see if I can reproduce it this weekend... Cheers, Magnus
  6. It would be great to be able to say it's a Turdus, but alas i don't think it is Magnus
  7. Captain Magenta

    Beehive with 10x50s

    One of my favourite objects, and one of my naked-eye diagnostics for a dark site. Magnus
  8. Captain Magenta

    December, er, Observing and LiFePO4 Battery Pack

    The mount in this case is the SupaTrak one that comes with the SkyMax 127, I'm not sure how much it draws when tracking-only but it wouldn't surprise me if it was less than 100mA, at 12V making it less than 1.2W . I'll have to do more experimentation... As for that cable, it's quite likely I noticed the Celestron mount plug at one end and mentally dismissed it as I don't have a Celestron mount. Ultimately this battery will be used on my AZ-EQ6 and SkyMax 180 and/or SW 300p in Ireland. Magnus PS not sure how my initial post got its weird difficult-to-read font and spacing. I copy/pasted it from Outlook which is where I drafted it, and I haven't been able to edit it to make it look "normal". If a friendly mod would like to edit it and normalise the "look", I wouldn't complain...
  9. Captain Magenta

    December, er, Observing and LiFePO4 Battery Pack

    it's this one, which I think is the double:
  10. This is part (anti-)observation report from December, and part “First Light” account of my new Celestron Powertank Lithium Pro LiFePO4 battery pack. I was in SW Ireland for Christmas and the New Year, where it’s much darker than where I live near London, and it’s where I keep most of my nice astronomy stuff. As ever, I was careful to record the results of my observing through the fortnight before I forgot it: Thick layers of cloud. every.single.night. Also at that time I received, courtesy of Santa, the Celestron Powertank. Obviously, I had no chance to test the battery pack whilst there. This last weekend, though, in the UK, I did finally have time and, it seemed, the right conditions to give this thing its “first light”. Unfortunately, as soon as sufficient darkness arrived on both Saturday and Sunday evenings, so did the clouds and I couldn’t properly get past the 1st alignment star in the initialization routine on either Saturday or Sunday night. Nonetheless, Sunday evening around 6:15pm I did just about get Rigel through cloud as my first alignment star, and by I guessing where Polaris was through impenetrable cloud, the SynScan told me “Alignment Successful”. We-Heh! So I set it to “GoTo” Mars, left it to track, and went inside to get the evening’s chicken on to roast. So far, so good: the power supply appeared to be working fine, the measured voltage reported both by the SynScan and a separate multi-meter showed a tad over 13V. About an hour later I nipped outside to check it was still tracking, to find it had switched itself off! How annoying! It had been fully charged. The manual says under the USB charging section: “The charger automatically shuts off when the load drops below 100mA for 1 hour” – it seems that this holds for 12V telescope powering too, so if you want to observe, say, Jupiter for more than an hour at a time, beware! Also, the manual (see link below) suggests that the box when new contains a cigarette-lighter-plug=>telescope_plug, AND ALSO A CHARGING-PORT=>TELESCOPE_PLUG, meaning that one can power a telescope with a lead from the _charging port_ to the scope. I don’t recall there being a lead like that when I got it (The box itself is in Ireland so I can’t immediately check). It does mean that it has 2 useful 12V outlets, though, which I hadn’t appreciated. A link to the manual: https://s3.amazonaws.com/celestron-site-support-files/support_files/18768_PowerTank_Lithium_Pro_Manual_5lang_Web.pdf Cheers, Magnus
  11. ... just as long as you don’t provoke this reaction https://www.independent.ie/irish-news/bizarre-scenes-as-stargazing-photographer-sparks-armed-garda-response-on-kerry-beach-36753668.html
  12. Captain Magenta

    Triple rise this morning

    Very good - much better than mine Cheers, Magnus
  13. Took the trouble to get my 7D/2 and 24-70/2.8L out before I rode off to work. Lens not sharp enough My holding not steady enough to get any of Jupiter's Moons and alas negligible Earthshine, but nice to record it,,, Magnus
  14. Captain Magenta

    Venus, Jupiter and crescent moon...

    I briefly contemplated going back in to get my camera as I got on my bike this morning at 7:15, but I was slightly late so didn't - thanks for the pic. Magnus
  15. Captain Magenta

    COMPLETED - Astronomy books for sale

    I'll take the Charles Bracken please - PM on its way Magnus
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