What Mac? Software for Stacked Stars w/ Terrestrial Objects in Frame.

Discussion in 'Image Processing' started by tradesmith45, Jun 11, 2013.

  1. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    I know one of you experienced hands on this forum will know the answer to this.

    I want to make multiple captures w/ SS abound 30 sec. & stack the images w/ both stars & terrestrial objects in the frame. I do NOT want to have star trails. The stacking is to reduce noise & increase sharpness.

    I use a Mac. I see photos like this but not sure they were stacked. I realize the stacking issue - stars move, land doesn't. I know the available programs will stack just astronomical objects &/or make great star trails.

    So does one of the Mac stacking programs do this type of stacking - Iris, Nebulosity, Lynkeos, StarStax, PisInsight? As best I can tell these are aimed either at making star trails or stacking to improve images of just astronomical objects. I've looked at each of these programs but can't find whether they can do what I want to do.

    I'm sure I could stack the stars to reduce noise, mask out the (blurred?) terrestrial object once stacked & add a single frame of the terrestrial object back in using PS. I think DSS for Windows can do this but is there a single program solution to do this on a Mac?

  2. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    The way I would do it personally would be to combine multiple exposures. One exposure for the terrestrial objects and another for the stars. You can stack the stars if needed. The longer the exposure you do the more of a trail you will get.
  3. sinclair

    sinclair Mu-43 Veteran

    I 2nd the separate exposed shots for the land and sky. If you want long exposure on the sky without trails, you'll need to invest in a sky tracking mount for your camera. And then for software, I use the GIMP.
  4. Iconindustries

    Iconindustries Mu-43 Hall of Famer

    (This reply is from my 16 year old brother Jonah, who has made his own 6 inch reflector and a 4.5 inch refractor)


    I do a bit of astrophotography and use Nebulosity on my iMac for my stacking.

    Stacking is a great way to increase the signal to noise in an image but you generally require at lest 5 to 10 frames to get the best results.(the more frames the better)

    Stacking is a bit hard with nightscapes that require a sharp foreground, generally only 2 or 3 frames can be used. Some people have had very good results using a star tracker, what they do is take one frame with the tracking to get the sharpest possible stars and then immediately after take another frame without the tracking, stacking these two frames get's the best compromise between the sharpness of stars and foreground.

    The distance you are from your foreground object is also important, I would suggest being as far away as possible to maximise sharpness, and I would try and keep the time between the first and last frame to minimum.

    To reduce exposure time and trailing use the widest fastest lens you can get, and be sure to tack plenty of frames to play around with.

    Nebulosity is a great stacking program, but you would not be able to use it to add a foreground to your picture, I am doubtful whether the other programs you mentioned would be able to either.

    One idea might be (if you were at a very dark site) to take say, 5 frames with a dark foreground, and one frame with the foreground lit up with a torch or flash, once stacked you would get a fairly noise free image of the stars with the nice bright sharp foreground covering up the others.

    Noise increases with sensor temperature, turning the camera off and allowing it to cool down for 10 to 15 minutes before taking your frames can significantly reduce the amount on noise in in them, this is important as you only have two or three frames to stack the noise reduction isn't going to be huge. Having great data to start with will allow you to get a much better image.

    Here are a few examples of stacking.

    This Milky Way I took with a mates Sony SLT-A99V camera and 50mm lens at f2, it is a stack of 10 30second ISO 800 frames, no darks applied. The dark blurred thing at the left bottom is the top of a tree.

    <a href="http://www.flickr.com/photos/50527022@N02/9022858637/" title="Milky Way by iconindustries, on Flickr"> 9022858637_0fb691caf3_c. "800" height="534" alt="Milky Way"></a>

    The effect of stacking with deep sky pictures is astronomical, there is at lest 10 times more detail here than there was in the sub frames.
    I took these with two with a 110mm f4.5 homebuilt refractor.

    Centaurus A Galaxy
    Panasonic GX1 12 128 second exposures ISO 800

    <a href="http://www.flickr.com/photos/50527022@N02/9022876969/" title="Centaurus A 30 minutes by iconindustries, on Flickr"> 9022876969_2dde197870_c. "800" height="533" alt="Centaurus A 30 minutes"></a>

    Carina Nebula
    Panasonic GX1 90 40 second exposures ISO 800

    <a href="http://www.flickr.com/photos/50527022@N02/9025170724/" title="Carina Nebula 75 minutes by iconindustries, on Flickr"> 9025170724_c6aff60b4f_c. "800" height="534" alt="Carina Nebula 75 minutes"></a>

    Milky Way with mates Sony again, 20mm fisheye f3.5 30 seconds ISO 2500.
    This was a single shot taken with a warm sensor, as you can see the noise isn't real good.

    <a href="http://www.flickr.com/photos/50527022@N02/9026723159/" title="Milky Way by iconindustries, on Flickr"> 9026723159_bb91a92203_c. "800" height="534" alt="Milky Way"></a>
  5. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Thanks so much Iconindustries!

    Great images & suggestions.

    I'm usually backpacking or otherwise traveling light when I'm in really dark places. I'm really a landscape photographer (but maybe transitioning to doing astro too). I got interested in this idea a couple weeks ago on a backpacking trip into some beautiful verticle granite where the best lighting I had was a midnight with a low full moon nearly due south.

    Right now in my work, I think what I'm going for is doing good landscapes (at night) & having the stars substitute for dramatic clouds. So the need to travel light while doing this means I'm probably not going to have any tracking drive. So I'll have to rely on post processing software tricks.

    I'm thinking I'll do many star captures to stack in PP in something like Nebulosity to get high IQ & as you suggest add in a well exposed single image of the foreground at the end. I have PS4 which does layer masking so with something like Nebulosity for stacking stars, I might have what I need. But I won't know until I try. This is starting to make me think there is a tracking drive out there in my future.

    This post has been interesting & let me use it to praise this forum. Apparently there aren't many folks doing this kind of hybrid astrophotography/landscape work who are Mac users. I posted this same query on the Astrophotography & Mac Talk section of DPR forums where they got no responses at all. This forum is the only place where I got any response & they were ALL helpful!

  6. RobWatson

    RobWatson Mu-43 Hall of Famer

  7. Iconindustries

    Iconindustries Mu-43 Hall of Famer

    You my friend need to get this: Vixen Polarie
  8. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Yes, there's some good & free code in the Windows world especially for astrophotography. I think I'll be able to get what I need for the Mac but wanted to get some pointers on which path might be the best. Nebulosity might be the choice for stacking.

    Yes, I've seen shots like the one of the tree & have done similar. W/ the OM-D+ 12mm f2, that might get me what I'm trying to accomplish visually most of the time. I've certainly had success with strong moon light w/o any stacking or other tricks.
  9. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Yup been thinking about drives including the Vixen & DIY barn doors. The Vixen videos are pretty cool, thanks for the link. Its a really neat product that opens up lots of possibilities @ a moderate cost.

    But the 1/2 speed on the Vixen seems like only a partial solution for landscape work. Not really crazy about "slightly blurred" foregrounds. Its hard enough getting really crisp images out of the small sensor & a wide open lens. Think I'll try blending stacked star frames w/ a shot of the foreground first. Don't you think that will reduce noise in the sky more than a single frame on a 1/2 speed drive?

    Wouldn't a slightly blurred foreground increase post processing challenges? Been trying out brushing in sky corrections in Aperture & sometimes run into serious halo effects. Need to have really sharp edges to prevent that I think.

    But I do own some ok long optics including an 80mm ED Pentax birding scope which is around a 1500mm f/12 & a Canon FD 400mm f/4.5 + TC. The shutter shock problems w/ the OM-D may be a serious limit for super long optics. I'm still doing tests about that. Don't think it will be a problem for long exposures of dim objects but has been a problem for moon shots @ 500mm.

    I'm a retired physicist so taking glorious images like yours of distant objects is a strong temptation. But I'm already doing sooooooo many things!
  10. RobWatson

    RobWatson Mu-43 Hall of Famer

    If you really want no blur/motion problems then a sneaky, but time consuming, method would be to photograph using an interval of one sidereal day! That way foreground and stars are all in the same place so much less work to stack them.
  11. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    BTW, the latest issue of Pop Photo has a contest winning photo of the Milky Way over "Bonsai Rock" on Lake Tahoe. Unfortunately they haven't posted Willie Huang's excellent photo so I can't link to it.

    But I mention it because it seems like a good example of why stacking might be helpful to get good stars w/ a modestly well exposed foreground. Huang shot a single frame w/ a Canon 5DII +24mm f/1.4 @ f/1.6, 20", ISO 3200. I was surprised there are very short star trails at the frame edges & noise is visible even in magazine repro. I'm guessing this exposure was necessary to get the good detail in the foreground. PP supposed involved lens & other minor corrections in Lightroom/CS5.

    Perhaps what appears as star trails are just a lens/PP lens correction artifact. Iconindustries 30" exposures w/ a 50mm lens showed no star elongation. And stacking several frames even at ISO 3200 would certainly reduce noise.

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