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Night sky noise issue

Discussion in 'Astrophotography' started by Youngjun, Aug 12, 2015.

  1. Youngjun

    Youngjun Mu-43 Regular

    156
    Feb 24, 2015
    USA
    Youngjun
    Hi, I was trying to shoot night sky - stars - with my G5 + 12-50mm lens.
    I see noise specks everywhere in the photo, and I can't figure out what is causing this.

    I would much appreciate if anyone has had this issue and would kindly direct me to resolve this.

    Here is one of the shots. P1010303.JPG

    I have done similar shots before with E-PM2, and had no problem with it. Maybe I was lucky that time.
     
  2. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi,
    We need more info... focal length used, exposure time & ISO?
    RAW or JPEG?

    Generally, noise will go down with lower ISO, but that can lead to motion blur depending on exposure time, FL, and aperture... see the 500 rule: http://petapixel.com/2015/01/06/avoid-star-trails-following-500-rule/ and remember to multiply actual FL by 2 for mu43.

    If you're serious about astrophotography, you'll want to take multiple shots + dark frames and 'stack' them... lots of info in the astrophotography forum topic here about that.
    Also, your lens has a slow max aperture.

    Barry
     
  3. Youngjun

    Youngjun Mu-43 Regular

    156
    Feb 24, 2015
    USA
    Youngjun
    This appears both on the OOC JPEG & RAW...

    I used 12mm focal length (widest on 12-50mm lens), f/3.5 30 sec exposure, each at 160 ISO (the lowest I can go on G5). - Maybe the ISO is too low??
    By the 500 rule, I get around 20 seconds (500/(12*2) = 20.833)of exposure for no motion-blur, but as you have figured, I was taking the star-trails it was not a big deal I assumed.
    I actually had taken 250+ shots (about 2 hours), and all of them are like that.

    I think this is more of an body (Panasonic G5) setting issue, for I had used the lens with E-PM2:
    10861000_10205739900677262_4043147654952445601_o.

    But again, I don't want to leave out the chance of the lens going bad somehow.
    However, I don't see this noise issue when I shoot during the day with bright light.

    Can you guide me how the "dark frames" work on the photo-stacking tools? (I have used startrails before, and want to try the starstaX as well. They both have that function.)
     
    Last edited: Aug 12, 2015
  4. Youngjun

    Youngjun Mu-43 Regular

    156
    Feb 24, 2015
    USA
    Youngjun
    One thing to add to that, I had the long exposure NR option OFF.
    I assumed that post-processing which takes as much time as the exposure itself (I don't know why) would leave gaps in the star trails.
    I don't know if I had it on for E-PM2.
     
  5. MadMarco

    MadMarco Mu-43 Veteran

    298
    Oct 30, 2014
    Guildford, England
    Can you guide me how the "dark frames" work on the photo-stacking tools? (I have used startrails before, and want to try the starstaX as well. They both have that function.)[/QUOTE]

    Try this post as a starter:

    https://www.mu-43.com/posts/744160

    There are many different tools to stack (Lightroom, Photoshop etc.), but I've always found DSS to be the best for starscapes. Best of all it's free.

    Edit: Always use RAW for any astro work, stacking jpegs will not give good results.
     
  6. MadMarco

    MadMarco Mu-43 Veteran

    298
    Oct 30, 2014
    Guildford, England
    Long Exposure NR will more than likely help with the spots that you are seeing, but you will see gaps with multiple exposures. My Olympus E-M10 is surprisingly clean for long exposures, it has a pixel mapping feature which helps a lot. I have no idea if the Panasonic has the same facility.

    http://www.olympusamerica.com/crm/oneoffpages/ask_oly/crm_e_ask_oly_03_09.asp
     
  7. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, the lens isn't going bad.

    You can take your own dark frames by taking shots occasionally with the same settings but with the lens cap on.

    Your final image looks fine to me, btw.

    Barry
     
  8. Randall Gabriel

    Randall Gabriel Mu-43 Rookie

    16
    Aug 19, 2015
    It seems to be more of a body issue than a lens issue. I got the same results as you with my G5 and the kit lens. Stacking really does help though. Here is one of my stacked pics

    11187326_871158612951591_1431878564116038590_o.
     
    • Appreciate Appreciate x 1