1. Veni

    Veni

    Messages:
    16
    Edit My Images:
    Yes
    Decided to try out my 10 stop ND filter for the first today photographing a local reservoir. It is my first attempt at long exposures and with my new lens....

    I'm sure I did the all the right things:- composed shot, AF & VC off, calculated long exposure time etc so why is the shot so dark?

    I've tweaked them in LR (these are the originals), but that's not the point. I'm thinking/guessing the exposure time was too short, but I used the times according to the calculator....

    [​IMG]test2 by Simon Veni, on Flickr

    [​IMG]Test1 by Simon Veni, on Flickr

    Any feedback would be greatly appreciated....
     
  2. gad-westy

    gad-westy

    Messages:
    5,975
    Name:
    Graham
    Edit My Images:
    No
    I don't know which particular ND you're using, but many aren't exactly 10 stops. Your best bet would be to do a little experimenting at home with and without the filter until you can tell exactly what the exposure difference needs to be. It's a common issue.
     
  3. Veni

    Veni

    Messages:
    16
    Edit My Images:
    Yes
    Hi.

    It’s a Neewer branded one - I didn’t want to spend a lot until I knew how to use it properly!

    How would I go about calculating what stop it is?
     
  4. stupar

    stupar

    Messages:
    7,405
    Name:
    Stuart
    Edit My Images:
    Yes
    If we assume that your 10 stop filter is approx that then a 6 second exposure under normal circumstances would be approximately 1/180th shutter speed.

    Now we dont know what your actual light conditions were on the day but unless it was blazing sunshine then I don't think you would get a shutter speed of 1/160 at F16 before you added the 10 stopper.

    When I used to do daytime long exposures with a 10 stop filter I was always somewhere between F8 and F11 and 30 second to 1 min exposures (give or take).
     
    Last edited: Aug 3, 2018
  5. Mr Perceptive

    Mr Perceptive

    Messages:
    3,997
    Name:
    David
    Edit My Images:
    Yes
    The histogram in LR will show you how far off your exposure is, just move the exposure slider to get a good spread on the histogram, that will show you how many stops you were short, each stop doubles the length of time of the exposure.
     
    J Veitch likes this.
  6. J Veitch

    J Veitch

    Messages:
    533
    Name:
    James
    Edit My Images:
    Yes
    Does you camera offer a histogram on the LCD? This can be used to see how far under exposed you are.
     
  7. Veni

    Veni

    Messages:
    16
    Edit My Images:
    Yes
    Cheers Mr P. Seems I was about 2 stops short.

    So these extra 2 stops would take my 6 secs to 30 secs according to my calculator which goes with what stupar said.

    So am I right in thinking I should treat my filter as a 12 stop in future then?
     
  8. Liam_89

    Liam_89

    Messages:
    156
    Name:
    Liam
    Edit My Images:
    Yes
    Looking at your Flickr data the first one was taken at F16 and 6 secs,
    Not sure what kind of day it was or how bright,
    But having a 10 stopper on and stopped down to f16 that’s going to really make it struggle for light,
    6 second exposure might not of been enough to get the light in,
    Maybe drop down to f8 and up the iso to 200 and have shutter open a tad longer should it require it,
    Things might look a little different then
     
  9. Harlequin565

    Harlequin565

    Messages:
    3,151
    Name:
    Ian
    Edit My Images:
    No
    Double or halve the shutter speed for each stop depending on whether you want more or less light.

    If it's too dark for you, you under exposed, and need to increase the exposure. Take a photo without the filter and get it looking how you want it in-camera. *Then* take note of the shutter speed and start multiplying.

    So if a "normal" exposure is 1/125sec, multiply up : 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1sec, 2, 4, & finally 8 seconds would be 10 stops. To let more light in, start with at least double the last setting (so in this case 16 seconds then 32 seconds, then 60, then 2 min, 4 min, 8 min etc)

    When I was starting (I used Welding glass!) I worked it out then wrote the exposures on the (home made) filter so I didn't have to keep calculating. You can see below that the glass was 16 stops.

    [​IMG]
    Heath Robinson
    by Ian, on Flickr
     
  10. Veni

    Veni

    Messages:
    16
    Edit My Images:
    Yes
    I've just done some test images in my back garden of the sky and I'm now happy with the results - I'm treating the filter somewhere between 11-12 stops and altering the f-stop and the results are a lot better.

    Thanks all for your input....
     
    stupar likes this.
  11. Northaway

    Northaway

    Messages:
    157
    Edit My Images:
    No
    FWIW, avoid going over about f11 under any circumstances if you can help it (and want sharpness). Anything over that and you start to lose quality from diffraction.
     
  12. GreenNinja67

    GreenNinja67

    Messages:
    3,614
    Name:
    Terry
    Edit My Images:
    Yes
    If you let the camera do the metering there's your problem I expect.

    Take a meter reading with no filter and adjust accordingly by either maths or an app.
     
  13. Jim_Tod

    Jim_Tod

    Messages:
    1,439
    Name:
    Jim
    Edit My Images:
    Yes
    Set up on tripod at home in a room with blinds/ curtains closed and a consistent light source on a contrasty object. Get a decent exposure histogram without filter. Add filter set new exposure based on 10 stop duration, compare histograms. Adjust exposure up/ down as required to work out what actual stop rating is when histograms match. Set up a spreadsheet and prepare an exposure calculator
     
    Last edited: Aug 18, 2018

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