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Using Hyper Focal Table with 16-35 and 24-70 on a7II

Discussion in 'Sony Alpha E-Mount Lenses' started by brada, Mar 30, 2016.

  1. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    I recently got back from Zion NP where I shot quite a few photos with an a7II, Sony FE 16-35 and 24-70. I had an unusual number of photos that were not sharp enough at 1:1 or even normal. There were a number of scenes where I stopped down to f11 or f16 to cover a foreground within a 2-3 meters all the way to infinity. Using a Hyper Focal Table at 16mm the distance is 0.77 meters at f11 and f16, even closer. After seeing the many blurred images I decided to do some testing in my backyard. I positioned the camera with a tree at 3m (a reference to easily check close focus) from the front of the lens. I shot the photo at 0.7m, 0.8m, 0.9m, 1.0, the tree and everything beyond were blurry. At 2.0m, a little better or acceptable if you don't go 1:1. At 3.0m, sharp, 5m sharp, 10m sharp. At 24mm, 1m, 2m blurry, better at 3m and sharp at 4m and beyond. I then used my 24-70 and had very similar results with the lens at 24mm. The Hyper Focal distance for 24mm is 1.72 at f11.

    I can't quite explain my results.. I first thought it was a focussing issue with the 16-35 until I tested the 24-70. I went through my a7II settings and everything looks normal. Any ideas?

    Brad
     
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  2. chalkdust

    chalkdust TalkEmount Veteran

    283
    Sep 25, 2015
    Bert Cheney
    My response will be in feet (sorry, I was raised that way) but I will put calculated meters in ( ) .

    On my Batis 25mm lens on a A7II at f/11, the OLED shows hyperfocal when focused to 12.5 feet (3.8m). At that focus point, it says that 6.3 feet (1.9m) to infinity will be in "in focus" meaning an acceptable circle of confusion, whatever acceptable means to Zeiss.

    It also tells me that at f/11, if I focus at 5.6 feet (1.72m), I will not get even close to infinity in focus.

    Are you trying to focus on the nearest distance in the hyperlocal range? That does not make sense to me....but I am no expert.

    Does this help? or only add the "circle of confusion"?
     
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  3. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    Not really...
    No I am not trying to focus at the nearest point, that would not be correct and I am sure you are aware of that also.
    If I type in 25mm for your Batis, f11, subject at 3m (10'), the hyperlocal distance is 1.87m (6.14'). So the nearest subject in focus will be at 1.15m (3.78') and infinity should be in focus.

    I use meters because my a7II distance scale is in meters, seems to make sense to keep it consistent.
    I am focussing at the number on the hyper focal tables offered by many and all are very consistent.
    There are a number of hyperlocal calculators out there;
    Hyperfocal & Depth of Field Calculators - Focus Pocus - Outsight Photography
    Another really good one is PhotoPills, I use there app on my iPhone. You can also use one on their website if you do a search for "hyper focal length calculator". There website also has some tutorials as well.

    The calculator says with Sony a7II, 16mm lens, f11, subject at 3m (10')
    By changing the subject distance, the DoF near limit will change to closer, for example 1m, changes to 0.43m. And Depth of Field in front changes, 0.57m.

    Here is the results of the app with subject at 3m;
    Hyperfocal distance: 0.77m
    Hyperlocal near limit: 0.39m
    DoF near limit: 0.61m
    DoF far limit: infinity
    Depth of Field: infinity
    Depth of field in front: 2.39m
    Depth of field behind: infinity

    Brad
     
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  4. firemist

    firemist TalkEmount Regular

    71
    Dec 4, 2015
    Maybe this can help. I'm old school - manual lenses with real distance scales and DOF scales as well.

    Note that for digital, the COC should be a lot smaller than 0.03mm, more like 0.01 or even smaller for the A7R2 if you want a 20x30 print. I mention this because as the article mentions, the "standard" 0.03 COC used by most tables and phone apps is based on viewing a print 8x10 inches, made on film.

    Hyperfocal Distance Explained
     
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  5. pdk42

    pdk42 TalkEmount Regular

    81
    Nov 26, 2014
    The problem with most DOF tables and calculators is that they're based on sharpness thresholds dating back to film days. On modern hi-res sensors, we're much more picky about what's sharp - which reduces the acceptable DOF somewhat. If you use a DOF calculator, set the circle of confusion smaller than what the usual references on the web suggest.
     
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  6. mcvu

    mcvu TalkEmount Regular

    90
    Sep 24, 2014
    Bay Area, CA
    Minh
    According to Merklinger, hyperfocal distance is not good enough for most scenarios.

    "The general rule for scenic photographs, where one wishes to maximize the depth of field, is as follows. Set the focus at the distance of the most distant object. Then set the lens opening to the size of the smallest object to be resolved in the foreground."
    DOF Revisited

    Read this one and experiment yourself to confirm:
    When hyperfocal distance focusing is not good enough
     
  7. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    With PhotoPills app, the CoC is 0.030 and there is no way to change it. With my back yard test, these distances looked really good at f11;
    16mm, 3m
    24mm, 4m
    35mm, 5m

    Didn't go past that yet.
    Interesting articles mcvu, so why have digital apps if they assume analog film cameras as the basis for resolving detail? That does not make much sense.
     
  8. mcvu

    mcvu TalkEmount Regular

    90
    Sep 24, 2014
    Bay Area, CA
    Minh
    Like pkd42 said, HFD concept has been around for ages, and nobody challenged it.
    The best way is to test Merklinger's theory and confirm it yourself.
    For the gritty details, read his book here:
    Download The INs and OUTs of FOCUS

    I've found out that for most of my landscape images, on Sony lenses with no hard stop for infinity, setting manual focus to the last position before infinity works well.
     
  9. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    The testing I did, the apps are not even close!
    Just amazed they can be so far off...

    Thank you everyone.
    Brad
     
  10. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    In Photo Pills if you click on the advanced icon in the dof screen and then click on the CoC in the upper left of the screen, you can turn off Autocalculate on the next screen. You can now click on the CoC value and select whatever you'd like. :)

    You can also change the print size and the viewing distance to change the CoC.
     
  11. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    Bimjo,

    Thank you, very helpful, what would be a good number for modern cameras and digital prints?

    Brad
     
  12. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    Based on what I saw in my test, 24mm lens, f11, 3m subject, looks like the value is around 0.013 for CoC.
    Brad
     
  13. mstphoto

    mstphoto TalkEmount Regular

    134
    Feb 26, 2016
    Aberdeen, NE Scotland
    Mike Stephen
    I watched a video recently regarding HFD and they stated that the CoC today is 0.02.
    The chart that they supply is calculated at this figure and seems to work out fine

    Mike
     
  14. brada

    brada TalkEmount Rookie

    10
    Aug 27, 2015
    thank you!
     
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