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Astrophotography with A7 long processing

Discussion in 'Sony Alpha E-Mount Cameras' started by AndyWear, Mar 7, 2015.

  1. AndyWear

    AndyWear TalkEmount Rookie

    24
    Jan 1, 2014
    I tried to take astrophography for the first time tonight. I had trouble with it because the moon was so bright....so failed. Anyways, this was not the problem.

    I noticed 2 things that bothered me.

    1. When taking long exposures (30 seconds), after each shot there was this long processing going on. Why does it take soooooo long? It feels longer than taking the actual 30 second exposure shot. My friend was with me using his Nikon and there was no long processing after his shot. It just finishes pretty much immediately. Is this a common problem? And am I able to overcome it?

    2. Viewfinder and LCD becomes useless after a certain shutter. I use the viewfinder to light get an idea of how lit my scene is. You can't do that after maybe 1 second of exposure? I can't remember. How do I overcome this? How do people take their shots in the dark with proper composition without seeing anything?


    Bonus Question unrelated.
    What exactly is focus infinity??
     
  2. AndyWear

    AndyWear TalkEmount Rookie

    24
    Jan 1, 2014
    Also, I'm using ZA 16-35 2.8. Theres an infinite sign on it. I tried to put it on the infinite and it didn't focus everything. I shot it at 2.8 and my s ubject was pretty far.
     
  3. southy

    southy TalkEmount Veteran

    370
    Feb 5, 2014
    Australia
    Do you have long exposure noise reduction turned on. I think it's on as a default. This will cause your long processing as the camera takes a second image the same exposure time as the first with the shutter closed. The 2 images are then merged in some way to help reduce noise. Turn it off and your A7 will have fast processing like the Nikon. I think for 30 secs and under it shouldn't be needed.
     
    Last edited: Mar 7, 2015
    • Agree Agree x 2
  4. southy

    southy TalkEmount Veteran

    370
    Feb 5, 2014
    Australia
    As for your second question try setting your composition and focus using an exposure that lets you see though the viewfinder. Lock your focus then set the exposure time you want to shoot with.
     
    • Agree Agree x 2
  5. WestOkid

    WestOkid TalkEmount All-Pro

    Jan 25, 2014
    New Jersey, USA
    Gary
    I second Southy regarding long exposure.

    As for Infinity - I have never used the 16-35 2.8. But there some things to consider regarding infinity markers:
    • Sometimes they are just inaccurate.
    • All lenses with infinity markers allow for manufacturing tolerances as well as how the components are affected by temperature. As a result, manufacturers usually allow focusing past infinity for wiggle room. You may have to dial it back slightly from the marker for infinity marker to achieve infinity.
    • Adapted lenses like the 16-35 2.8 are dependent on the adapter being milled perfectly to spec. Any defect will cause issues with infinity focus. This is a common issue with cheaper adapters. People have even had issues with expensive ones too.
     
  6. izTheViz

    izTheViz TalkEmount Top Veteran

    537
    May 10, 2013
    Paris
    Yannis Marigo
    True. Just disable to noise reduction. I finally disabled it definitely a handle this in LR.
    As for infinity focus, it is reliable on legacy lenses. I use it a lot when shooting with my old FDs and find it more than useful, especially when shooting late.
    I wonder how you guys, focus in low light conditions with native FE lenses...
     
  7. AndyWear

    AndyWear TalkEmount Rookie

    24
    Jan 1, 2014
    Thank you guys! Fixed that problem doing what you all said. Turning off long exposure noise reduction. Does this matter if you shoot in raw at all? This is something for jpegs right?
    I'm trying to figure out how to shoot focus infinity on this 16-35 2.8 lens with the LAEA4 adapter. On the lens itself I can't really move to infinite so I'm not too sure how to do it. It can only go as far as the L sign so I can't tell if I'm using it properly or not. I'll ask this in the lens section maybe there will be more specific answers for that.
     
  8. WestOkid

    WestOkid TalkEmount All-Pro

    Jan 25, 2014
    New Jersey, USA
    Gary
    Long exposure noise reduction is not the same as regular noise reduction(jpegs only). Long exposure noise reduction does affect raw. It is using the second shutter closed exposure to identify hot pixels that can appear in long exposures. Keep in mind that if you have them, they cannot be removed by noise reduction software. You must find them and edit them out with a close brush or whatever. I didn't notice them in my A7 or a6000, but I used to get them in my 5T. It was used and my understanding is that older sensors are more susceptible. Maybe that's why. Shouldn't be an issue unless you are doing really long exposures.
     
    • Like Like x 1
  9. pbizarro

    pbizarro TalkEmount Veteran

    349
    Nov 24, 2014
    Portugal
    If you are doing 30 sec (or longer, or shorter) exposures, use long exposure noise reduction: this takes a dark frame of the same duration, to subtract the noise. The only instance where you should not use it is when you are taking many shots to later combine and create star trails.

    In this case, while the camera takes the dark frame, the Earth will rotate, and your trail will end up with gaps. Take your self a dark frame (put the cap on the lens and shoot) at the beginning and end of the series of shots, and use Star Stax or similar to combine all the frames, including the dark ones. It is a fantastic programme, and free.

    As for infinity, you have to test at what point your lens is focused at infinity during the day, and note that (make a mark on the lens distance scale, if there is one...). Also you can use view magnification to the max, and focus on a distant star manually.

    Check this nice site:

    http://starcircleacademy.com/quick-tips/
     
  10. Lisandra

    Lisandra TalkEmount Veteran

    216
    Jan 28, 2015
    Well...to further complicate the issue (Im awful I know), it actually depends on manufacturer. Nikon for example, im now 100% sure doesnt use the dark frame noise reduction on RAW files. At least on the d800, d600 and d750 (and APS Cs of that gen). Panasonic on the other hand, go so far as to apply any and all noise reduction settings on their raw files, so setting noise reduction to +5 will net you a surprisingly clean (but soft) high ISO raw file. Canon includes the dark frame on long exposures in the RAw file and so does olympus. Sony and pentax?? i dont know
     
  11. pbizarro

    pbizarro TalkEmount Veteran

    349
    Nov 24, 2014
    Portugal
    There are two different things:
    1. Long exposure noise reduction (dark frame subtraction)
    2. High ISO noise reduction (this is not dark frame subtraction)
    Different camera companies call them differently, but they basically revolve around the same principles.
     
    • Agree Agree x 1
  12. tomme

    tomme TalkEmount Regular

    56
    Apr 9, 2014
    Norway
    Tom Erik Sivertsen
    I always use Long exposure noise reduction, hate hot pixels. It is not as bad as it was on my 5DII. To avoid star trails you should use the "500 rule" you divide 500 with the focal length ( 500 / focal length for FF, for crop you use 500 / focal length x crop factor = 1.5 ).

    Example, 500 / 16mm = 31 sec.

    For focusing, as you use the ZA 16-35 2.8 you have a focal scale on your lens. Aim at the sky on a bright day ( focus on the clouds ) and see where the infinity focus is on your lens, so when your going to photograph in the dark just manually set the focus scale where you remembered.
     
  13. tomO2013

    tomO2013 TalkEmount Veteran

    375
    Dec 11, 2014
    Sony and Olympus provide it as an option - you can enable or disable depending on your needs :)

    On a side note this thread needs some photos. I love astrophotography images.
     
  14. Lisandra

    Lisandra TalkEmount Veteran

    216
    Jan 28, 2015
    Alternatively, if youre shooting consecutive shots, you can do the dark frame yourself and then add them in software
     
  15. clydestuh

    clydestuh TalkEmount Regular

    46
    Jul 3, 2013
    I had both problems as OP when I shot the milky way with my old Nex-7. I turned of the in camera NR. Also there are tutorials on astrophotography regarding hot pixels and color correcting.
    For FE and Legacy lenses with inaccurate infinity marks: Have a friend shine an object about 50 feet away with a flashlight and focus peak on it. That should focus to infinity&beyond (buzz lightyear voice).
     
  16. slothead

    slothead TalkEmount Top Veteran

    544
    Mar 1, 2015
    Maryland
    Tom
    My Olympus takes as long to process as it does to expose also. I don't think my Nikons take anywhere near that long, and attributed it to some special image processor operation in the Olys.