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Lumix 25mm and max DOF

Discussion in 'Native Lenses' started by vtsteevo, Dec 12, 2012.

  1. vtsteevo

    vtsteevo Mu-43 Regular

    Nov 20, 2012
    Hey guys,

    I just purchased a GX1 and the 25mm 1.4 lens. I love the shallow depth of field, but am having trouble creating images where everything in the frame is in focus.

    The following 2 shots were taken 4 feet away the subject (flowers were in focus), at both f/1.4 and f/5.6. The wall is about 12 feet behind the flowers. My goal is to have everything in focus, but even at f/5.6 the background is not as sharp as I would have wanted it to be.
    I am using the Single AF, 1-Area (large box) focusing method in the GX1.

    Subscribe to see EXIF info for this image (if available)

    At F1.4, 4 feet away from flowers, focused on flowers.

    Subscribe to see EXIF info for this image (if available)

    At F5.6, 4 feet away from flowers, focused on flowers. Camera bumped ISO to 1600 too.

    What can I do to obtain a sharper focus throughout the image? I could step back, but that would defeat the purpose of this focal length.
  2. vtsteevo

    vtsteevo Mu-43 Regular

    Nov 20, 2012
    I also did check out a DOF calculator (Online Depth of Field Calculator), according to which, at 25mm, f/5.6, 4 feet away from subject:

    Near limit 3.44 ft
    Far limit 4.77 ft
    Total 1.33 ft

    If I am reading this correctly, anything past 4.77 ft will not be sharp. Is this right? What if I wanted to achieve "infinity" focus by having a subject and a landscape background in focus?
  3. Zariell

    Zariell Mu-43 Top Veteran

    Sep 28, 2012
    Bountiful, UT
    You have way to wide of an aperture for what you want to do, I would start at f/8 then try some test shots. As you saw with your dof calculator you only have 1.33 of focus from near to far at that aperture, so you need to stop down to f/8 or even f/11.

    Hope that helps.

    Just used the online calculator for the same lens at f/11 puts near limit 3.02 far limit 5.92 Which puts a total of 2.9 which will still not put the out of area focus as you would like assuming the four foot distance. I would say you could use PP to merge two photographs together, or switch to a different lens, OR move the foreground objects closer to the background.
  4. krugorg

    krugorg Mu-43 Hall of Famer

    Jul 18, 2011
    Minnesota USA
    Love it when the problem with m4/3 is that DoF is too shallow! :biggrin:

    Are you thinking about when you would have people in the foreground and a scenic background that you want to have in focus? I wonder if you would then be that close to the people... ? 4 feet seems quite close with that focal length, if you are trying to have a sharp background.

    I use the PL25 quite a bit for landscape type shots. I usually focus about 1/3 to 1/2 into the frame, beyond foreground objects even that I want to show detail, keep the camera at F4, and have no problem getting everything in focus in most case. In the following, focus was on the fence line (about 15 feet out) and I had plenty of useable DoF beyond the house. This was at F4.

    <a href="http://www.flickr.com/photos/krugorg/8231877072/" title="rambler by Kyle Krug, on Flickr"> View attachment 245871 "1024" height="767" alt="rambler"></a>
    • Like Like x 2
  5. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    IS this the first thread where we have an issue of not enough DOF in m4/3? :smile:

    Seriously though. You'll need f11'ish to get the DOF you need. 5.6 still isn't that deep at these focusing distances.

  6. brokken

    brokken Mu-43 Regular

    Aug 25, 2012
    Well... Ironically, you're gonna have to step down you f/1.4 lens to get greater DOF. :) 
  7. vtsteevo

    vtsteevo Mu-43 Regular

    Nov 20, 2012
    I thought lens diffraction becomes an issue after f8? Not a pixel peeper here... just want focus :) 
  8. vtsteevo

    vtsteevo Mu-43 Regular

    Nov 20, 2012
    Yes, exactly.

    Makes sense that I would need to back up, or switch to a different lens, like the 20mm or the 14mm.

    Thanks for the tip, I am going to try focusing somewhere mid-way, but stopping down to F8 (or even F11) since I can't move 15 feet back inside a room :) 

    Any tips for indoor shots with a large group of people where you can't really back up?
  9. mrjr

    mrjr Mu-43 Top Veteran

    Sep 25, 2012
    I feel your pain. I like the focal length and light gathering with the 25 for working indoors with mommy and infant for instance, but if I get close enough to fill up the frame, and I want to keep my ISO under 3200 by opening up the aperture, I don't have enough DOF for both faces. I've been resorting to a hotshoe flash, but I wish I didn't have to use it.
  10. mrjr

    mrjr Mu-43 Top Veteran

    Sep 25, 2012
    A wider lens and/or more light. Or cranking your ISO.
  11. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    F16 man! F16!
    Great wind-up :bravo-009:

    A tiny-sensored compact camera or a mobile phone will do the job best, no, really. Really.
  12. m0nsieur2

    m0nsieur2 Mu-43 Regular

    Mar 8, 2012
    As you stop down the lens (smaller aperture, larger f number) your shutter speed will decrease (slower shutter). If the shutter is lower than 1/60s handheld and you're not a stiff statue of a person, then the image will turn out blurry. With image stabalization you may be able to achieve 1/15 or 1/30s and still be sharp. This is a problem if there is poor lighting (INDOORS). If you want such a shot indoors with a large DOF and without a flash, you will probably need a tripod. Set your camera to take a self timer photo or use a remote shutter.

    Your second picture looks soft to me, especially the flowers, vase and water bottle in comparison to the first. Probably from a low shutter speed. As others have stated, bumping up the ISO can also help you have a faster shutter speed to avoid motion blur. A tripod would allow you to use a low shutter speed and low ISO to keep the noise level down.
  13. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    F8 is about where you can go to with no visible effects from diffraction. At F11 you *may* see some very slight loss of ultimate image quality, but only if everything else (focus, camera shake colour etc) are spot on. And you'd need to be printing large prints to have any chance of seeing it.

    In the real world F11 is usually fine to use.

  14. WT21

    WT21 Super Moderator Subscribing Member

    Feb 19, 2010
    Why do you want everything in focus? Is this just to test, or do you really want that specific shot. Wide angle lens and moving closer can help. Light the scene with lighting, and stop down is the solution if you need that focal length, though that's easier said than done.

    Grab a tiny-sensored compact? But if you need higher image quality, you are going to have to work around the inherent shallower DOF of larger sensors.

    What are your goals? Is it only for shots like this? Are these like real estate postings or architectural shots for a web site or something?
  15. Mogul

    Mogul Mu-43 Regular

    Nov 9, 2012
    At f11, the numbers would be:
  16. LowTEC

    LowTEC Mu-43 Regular

    This is my very first time reading someone has too shallow dof issue on a m4/3, i wish i have the same problem on every single lens i own :p 
  17. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
  18. greenlight

    greenlight Mu-43 Regular

    Nov 16, 2012
    Colin B
    I came to Micro 4/3 from a small sensor compact, so this is the first time I've really had to consciously deal with a limited depth of field when taking photos.

    As has been pointed out earlier in the thread, you need to do two things:

    1. stop down
    2. place your focus point part way into the image, as the "in focus" area extends towards you from the focus point and away (1/3 in is a common rule of thumb but it very much depends on the distance to the focus point).

    There is a good article that helped me get my head round it here:

    Understanding Your Camera’s Hyperfocal Distance
  19. Doesn't anyone believe what they read on the internet? Blurrier background = better image :smile:
    • Like Like x 1
  20. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    When you need more DOF to get the shot you want, forget about diffraction. The effects of diffraction are generally minor compared with the effects of getting much less DOF than you want in a shot.

    Cross posted from the other thread:

    • Like Like x 1
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