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rotatux

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About rotatux

  • Rank
    Star Forming

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  • Location
    France
  1. rotatux

    My Grand Tour of the Solar System 2018

    Very nice ! Damn, where is Earth
  2. rotatux

    Winter Circle

    Hi, looks strange to see Menkalinan brighter than Aldebaran, and Elnath almost invisible when it should be brighter than Menkalinan => Did you use some kind of filter which would achieve that effect ?
  3. rotatux

    Imaging with the 130pds

    Hello fellow 130PDS imagers I've processed these subs of Pleiades taken during last country holidays. It turns out much better than my previous successful try at it, more smooth, still good colors and much more structure. My problem is I've developped two versions of it: * One with moderate stretching, which IMO preserves colors better (especially that Pleiades' electric blue I like so much), and still shows structure on good monitors * Another where I pushed streching more, to ease showing on less good monitors, but it find it faded colors a bit and eventually I have mixed feeling about it. I'm looking for others' opinion/preference/advice about which one to keep, or is more generally acceptable, as myself having good monitors at home I prefer the first one. Thanks for looking.
  4. rotatux

    Imaging with the 130pds

    Correct but YMMV depending on CC model and sensor size: I've seen the SkyWatcher's one being very tolerant, though with a smaller 4/3 sensor. e.g. I have used it at 2 distances separated by 19mm (factors 0.9x and 0.94x) and seen fair enough corner stars in both cases. I recognize however I don't image at the same level as most of you, I'm still a beginner in number of nights
  5. Hello It *is* worth IMO ! There are still plenty Deep Sky objects to view from a light polluted sky, such as open or globular clusters and a few bright nebulas or galaxies. Not speaking of planets of course (but you may need a barlow). And if you have some budget left, buy a cheap 1.25" light pollution filter (look for "dydimium" or "moon and skyglow"). It won't do miracles, but will help with contrast and extend your visual possibilities. Examples: https://www.teleskop-express.de/shop/product_info.php/info/p324_TS-Optics-Optics-Universal-Contrast-Filter-1-25-.html, https://www.amazon.fr/dp/B01CP0LJ5W.
  6. Very nice result for where you come from. Now you've got to find how to tackle that "wild colors". I've had something looking like it, which I call color saturation symptom, and it was preventing correct color calibration (by software at least). But there seems to exist some exposure settings when most stars don't saturate and give enough range for correction, while catching enough light at the same time. Below are two samples of mine with same lens (the MD 50), both with didymium LP filter. Left is a first try at 20s × 3200i × f/2.8 (looks like yours for me), right at 30s × 3200i × f/4 with a bit more experience -- sorry differents subjects but that's all I have at hand EDIT: removed spurious image
  7. Nifty fifties stories I've got that lens too, the 44M-6 variant exactly... It shows maybe a bit less coma than yours but still lots and too much anyway, even closed to f/5.6, so I've stopped using it for astro and tried others. I now test all my "astro" lenses with a home-made artificial star, to check CA and coma depending on relative aperture, before bringing them to the night and waste precious time. My OM-Zuiko 50/1.8 is awful, on the level of your 44M at f/4. It has nice color rendering but that's not enough. My M42 Cosina 55/1.4 is quite bad either, edges and corners always get CA, and coma stops only bit after 5.6 (this has a click-less aperture ring so difficult to say where). My M42 Pentacon MC 50/1.8 is nice and shows little coma and CA since f/3.4. But they never completely disappear from the corners. Good colors. Eventually my king of fifties is a Minolta MD Rokkor 50/1.7. It has nearly no coma nor CA from f/4. Color rendering is a bit less good for astro though with a LP filter it doesn't show. More recently I got a Konica Hexanon AR 50/1.7 but I suspect it had shocks within, and shows (very) strong coma up to f/4 at least (that was a disappointment). So there are some good ones, we just need to try them to find out. PS: those were tested on a MFT body so a bit smaller than APS-C and 4x smaller than full frame. YMMV
  8. Thanks, I never had the slighest reflection with that lens, even with other bright stars, so I had disfavoured that possibility. Anyway by coincidence the bright star is near center and I know my camera's sensor is not pixel-centered under the lens, so this must be a reflexion. Strange for the slight color shift, that must be the coating.
  9. Hello, Having some free time I just processed this image taken on 2018-08-12 and discovered a comet-like object besides Altair and Tarazed, but I don't see it in Stellarium. Given the greenish tint (on my laptop, compared with blue Altair and orange Tarazed) I suspect a comet, but Stellarium searches don't work and anyway I don't know how to search by sky position. Anyone an idea ? Taken with Minolta MD Rokkor 50mm/1.7 at f/4.0 with u4/3 (MFT) camera, left of original image has been truncated, then it was reduced 75%.
  10. rotatux

    Still testing, so what is a blog entry ?

    Ok so blog is a structure like forum, with blog entries therein like threads which can host several posts.
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