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Depth of field with close up lenses

Discussion in 'Tips and Techniques' started by stepfen, Jan 26, 2019.

  1. stepfen

    stepfen Barracuda

    # of Dives: 200 - 499
    Location: Greece
    480
    259
    63
    Hello,
    I'm currently on my first macro shooting diving trip in Ambon. I use +6 and +8 diopter close up lenses with my camera (Sony a5100, with the kit 16-50mm lens, in a Meikon housing and a s&s YS - 02 strobe).
    I'm trying to get deeper depth of field (DoF) so that I can get more parts from each creature (shrimps, nudies etc) in focus.
    I've noticed that lowering the aperture size doesn't affect much the depth of field. My camera goes down to f/22 and that's what I'm usually using but it is not enough.
    Interestingly wide apertures like f/10 or so don't make much difference anyway.
    Anything else that can be done?
    Thanks in advance
     
  2. chris kippax

    chris kippax Divemaster

    # of Dives: 500 - 999
    Location: Australia
    588
    359
    63
    Distance to the subject, closer = less DOF/ Further away = more DOF
    Less magnification = more DOF, More magnification = less DOF
    Focal plane is also another thing to consider. Front on = less DOF, Side on = more DOF
     
  3. DevilEyeDog

    DevilEyeDog REEF Volunteer

    # of Dives: 100 - 199
    Location: USA
    109
    79
    28
    I was shooting with a Sony a5000, Meikon housing, Sea&Sea Strobe, two sides lights and a Inon UCL Macro lens. Despite my best attempts I was struggling as my photo friends using the Olympus TG4 and TG5 has better macro shots. I spoke to someone from backscatter (who yes is trying to sell Olympus products) and was told that as far as macro the Olympus is the best, but that overall my camera wins all other categories. He said I would have to buy the Sony macro lens for my camera, but I would be stuck in macro for the entire dive as it's an interchangeable lens.

    I kept trying. No avail. My edges just weren't as crisp. Don't get me wrong. They weren't bad, but compared side by side shots on dives with those Olympus cameras for macro they weren't as good.

    I was lucky to score a TG4 for $100 off Craigslist. I hate the video on it. The speed ability isn't as good, but yes...the macro setting...wowza. It's definitely better. Even on land you can tell the different. Because the sony a5000 doesn't come with a macro lens you have to stand a certain distance back from your subject. With the Olympus you can get right up on them and it's crystal clear. Pick the eyelashes of a hermit crab (yes, they have them), zoom in and clear. Try that with the Sony and you can't. You have a lens on it that wasn't meant for macro so you have to stay away from your subject. Backscatter tells me the lenses we add on the outside are more magnifying lenses and not true macro. Not sure how to argue this point, but I can tell.

    So now I'm diving sometimes with my Sony, which I love more and then switching to the Olympus if it's macro diving.
     
  4. Ministryofgiraffes

    Ministryofgiraffes Manta Ray

    # of Dives: 1,000 - 2,499
    Location: Toronto
    821
    639
    93
    You should also post your question on wetpixel forums. Very good for photog questions as sometimes alarmingly quick on responses :) I received solutions to my Z7 TTL exposure issue in about 3 mins :)
     
  5. stepfen

    stepfen Barracuda

    # of Dives: 200 - 499
    Location: Greece
    480
    259
    63
    That's the second BIG issue I have. Maybe indeed it's more important than the DoF.
    Even at it's best focus the images are just not sharp enough.
    Actually there is another guy here who uses a compact Sony camera with two video lights (no strobes) and auto settings in the camera and he makes much sharper images than me. I'm struggling with manual camera settings and the manual strobe and the results are so so at best.
    I have a feeling though that it is something that has to do with the sharpening that the camera does (or actually doesn't) hence I hope I'll be able to correct it in post.
    As it is my first trip I haven't tried how sharpening might improve the result or not.
    Thanks anyway for the replies
     
  6. Rollin

    Rollin Professional Photographer

    # of Dives: 500 - 999
    Location: Belgium
    81
    72
    18
    Dof in macro is very small on f22 and even smaller on f10. I will not go into the technical background, but the larger the sensor, like in a Sony A5000, the dof will even be smaller for the same magnification.

    The Olympus has a much smaller sensor than the Sony, so the dof will be larger, but quality in low light will be worse. It will always be a trade off.

    Getting your exposure right is hard, especially in manual. The only way is practice, also above water. Most of the small critter photographers do not change strobe setup or magnification much during the dive. They test the setup at the beginning of the dive and when happy, they use it for the rest of the dive.

    From my experience, most of the better OW photgraphers do some intensive post production, so don't get fooled by seemingly very sharp, colorfoul and perfectly composed images without any backscatter.
     
  7. bvanant

    bvanant Loggerhead Turtle

    # of Dives:
    Location: Los Angeles (more or less)
    2,195
    346
    83
    Dedicated macro lenses are always going to be superior for sharpness and DOF than zoom lenses, particularly the kit lens. Don't confuse sharpness with DOF. Most lenses are sharpest at the middle of their f-stop range, as you go to smaller fstops (bigger numbers) you will lose sharpness but get a bit more DOF. If you want a lot of DOF then shoot from further away and crop, you can't beat the laws of physics so if you shoot from very close to the critter with high magnification you will get shallow DOF. It would help if you post some pics but I suggest either the lens is just not very sharp or there might be an issue with the port.
    Bill
     
  8. stepfen

    stepfen Barracuda

    # of Dives: 200 - 499
    Location: Greece
    480
    259
    63
    For the DoF I'm now convinced that my camera (APS-C sensor) with the kit lens (~30cm/12inch closest focus distance) + close up is a bad combination for most macro. Sony's 30mm macro lens would be much much better but unfortunately it doesn't fit in my housing. Macro was not in my interests when I bought this system so I couldn't know all these back then.
    That's the bad news. The good news is that the issue of crispness/sharpness is a matter of processing and it can be corrected. By default the camera applies minimal if any sharpening at all. By applying a decent amount of sharpening in post I am able to get decent focused images.
    I am finishing processing these days and I will post at least some examples here to get some feedback.
    I'll let you know.
     
  9. Rollin

    Rollin Professional Photographer

    # of Dives: 500 - 999
    Location: Belgium
    81
    72
    18
    Dof does NOT depend on which type of lens you put in front (zoom lenses, fixed focal, close-up). It depends on aperture combined with magnification. That's it.

    Sharpness is something else, this depends on the quality of the optics indeed.
     
  10. stepfen

    stepfen Barracuda

    # of Dives: 200 - 499
    Location: Greece
    480
    259
    63
    It does depend on focus distance though, isn't it?
    The kit 16-50mm lens has a minimum focusing distance of ~30cm. With a close up lens the focusing distance goes down to few cm. Won't that affect the Dof?
    Thanks
     

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