Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

  • Announcements

    sgl_imaging_challenge_banner_widefield.jpg.36065d79cb2625eb299137a5b4432c96.jpg

wimvb

Advanced Members
  • Content count

    3,551
  • Joined

  • Last visited

Community Reputation

2,111 Excellent

6 Followers

About wimvb

  • Rank
    White Dwarf
  • Birthday 29/07/1963

Contact Methods

  • Website URL
    http://wimvberlo.blogspot.se/

Profile Information

  • Gender
    Male
  • Location
    Sweden (59.47° North)
  1. Wildcat 'Cans' - Jones-Emberson 1 - WIP

    Great image. And with the central star!
  2. My initial thought as well, but the variation in orientation makes this a huge task. And you run the risk of introducing artefacts which come to haunt you later on in the process. Unless it's a very special image, that needs to be saved, I would hesitate to go down that route. Unless the effect is severe, I would use ordinary star reduction to tone it down. Btw, there is another method: 1. Create an L copy of the image 2. Completely remove the stars from this new grayscale image. 3. Generate a star field with the appropriate script. Blur and dilate (morphological transform) to make it look more natural. 4. Use pixelmath to add the starfield to the starless image. 5. Substitute this new L in L*a*b mode. 6. Run and hide from the purists.
  3. Horsehead Complex HaRGB

    Excellent images, all of them. I'm not sure that L will add anything to the mix. If you've collected that much colour data unbinned, adding L may very likely only result in bloated stars that are difficult to control.
  4. Another imaging beginner

    As in daytime photography, you really need different focal lengths for different targets. There's no single camera/scope combo that does it all. For any camera, the pixel size in combination with focal length, determines resolution (arcseconds of sky per pixel), while the sensor's dimensions in combination with focal length determines field of view. Theoretically, a small sensor with small pixels and a short focal length can give you the same resolution and field of view as a larger sensor with larger pixels and a longer focal length. But if things were so easy, NASA/ESO and many others wouldn't invest in ever larger telescopes. If you already have a dslr, I would suggest using the FOV calculator with different scopes to get an idea of what combination works best for you. M31 is an extreme example as it is one of the larger objects in the night sky. You need a focal lenght of about 300 mm to fit it on the sensor of a dslr. But with such a setup, many other galaxies will get lost in the starfield. If you are interested in wider views, you can either use a lens with a dslr, or invest in a short focal length scope, such as an ED80 (Skywatcher Evostar or similar). Shorter focal length scopes are more forgiving than longer fl in terms of polar alignment, balancing and guiding. Have a look around in the imaging sections, and on astrobin.com, to see what other people are using. Then decide where to put your money. The scope and camera that you buy will most likely not be your final investment. (As I wrote before, AP is a money pit)
  5. The Core of the Rosette Nebula

    GREAT image, Steve. My astronomik also has a guaranteed 90+ % transmittance. But at 12 nm FWHM that's no feat, I guess. A fact that is also reflected in its price. The art of repeatedly producing these specs at the same wavelength and 3 nm FWHM is what costs. Sometimes less costs more. That nice piece of flat glass, sandwiched between the largest Esprit and a QSI really makes an excellent imaging setup.
  6. NGC 2403

    For a moment I thought that galaxy season had already started. But then I saw the date on the original image. (and a very nice image it is) I don't think it will be a match for your ASI1600. I hope you'll have clear skies during galaxy season, so we can enjoy a revisit.
  7. NGC1333 wide field

    Very nice indeed. The reddish background gives a nice contrast to the main nebula.
  8. Sorry, no PixInsight process that I'm aware of. But sometimes the star shapes in a stacked image can be better than in single subs. Probably not if all the subs have the same issue.
  9. Staring mono CCD help

    The stacking edges I usually get don't have these well defined thin (single pixel?) black lines. (I mean the vertical ones, not the short horizontal dashes. Those were explained earlier.) Rather, the image shows a darkening, and very noisy band at the edge of the reference frame. Something like this (extreme crop) But if the sensor has an edge that is not illuminated (effective pixels vs active pixels), I suppose these black lines could show. The dark band at the bottom of the OP's image could have a simple explanation: If a test frame was kept in the stack, and inadvertently used as the reference frame for stacking, an edge like this can be the result. The test frame can be a shorter exposure than the "real" frames, and show as black with only very few stars. (Been there, done that, don't want to wear the t-shirt.) Removing the culprit and restacking will resolve this. As for the stacking edges, you'd crop these anyway.
  10. BBC Microbit

    Be careful with two infinite loops (forever), you'll never know in which order commands are executed. In your example, you should be able to put the commands of both loops in one.
  11. Another imaging beginner

    That is a really small camera (chip). You'll have a hard time centering a target on the chip, if you don't use platesolving. Have a look here for the expected field of view with a 150 mm f/5 Newtonian: http://astronomy.tools/calculators/field_of_view/ The camera is probably good enough for planetary imaging, but Deep Sky Objects will be too severely cropped, in my opinion. https://astronomy-imaging-camera.com/gallery/ (scroll down to ASI120) Cmos cameras have a variable gain (comparable to ISO on a DSLR). This means that you can use longer exposures at lower gain, or shorter exposures at higher gain. Short exposures don't need guiding. Here are a couple of unguided images taken with the (larger) ASI174MM-Cool and a 150 mm Newtonian: Here's the fov of the ASI120 compared to the ASI174
  12. That's why I'm currently experimenting with a Rock64 sbc. It's the same size (and price) as a Raspberry Pi, but with USB3. And since I store the images on the sbc, wifi speed is not critical. (Haven't tested wifi speed yet, since it's still hooked up to an older wifi dongle.)
  13. Focus Travel - How Much Needed. Help!

    Rereading your original post, I can't see where I ever got the idea that you were making a reflector. Moving the objective lens is hardly an option then. Would using spacers make sense? Make the tube/focuser to fit the longest diagonal, and add spacers for shorter diagonals. That way, you would avoid the focuser drawtube moving too far into the tube. (No idea what I'm talking about really, just brainstorming.)
  14. Focus Travel - How Much Needed. Help!

    Will you be making your own focuser as well? I always thought that eyepiece-mirror distance = eyepece_fl + mirror_fl, whereas for camera you use prime focus = mirror_fl. You could do as TS in their ONTC customised Netwonians, and have the primary adjustable. Or play it safe, it's always easier to add spacers to get to focus, than it is to have too little backfocus. Sorry, can't be of any more help than that.
×