Focus distance indicator -poll

Discussion in 'Open Discussion' started by marcl, Jul 24, 2016.

  1. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    I recently got a chance to attend the America's Cup Series in Chicago. I took my 100-300 and 35-100/2.8 for the occasion. I was lucky to be on a boat so really close to the action. But i was also unlucky to be on a boat because of the constant movement which made focusing a real challenge. It made me realize that the feature I really miss on my camera is a distance focus indicator. Coupled with a depth of field calculator, it could have helped me use manual focus to improve my keeper rate. There were many markers on the sailing course that I could have used, well, as markers for focusing if I had had a focus distance indicator on the camera, a bit like focus pulling in video. It has to be simple to implement, even as a firmware update for existing camera. It should be a feature that is standard on any pro or enthusiast grade camera like the OMDs.
     
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  2. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    CAF would have solved most if not all of your problems. Not real sure how a focus distance indicator could have helped all that much. The boat is constantly moving as the ones you are trying to photograph, CAF would have been the drive mode of choice for this. Not to mention the terrible manual focus abilit of focus by wire compared to a real mechanically linked manual focus lens.
     
  3. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    They may add the focus distance and also a depth of field calculator. A hacked firmware for Canon compact cameras did this years ago.
    And Panasonic cameras do the depth of field preview graphically with a yellow bar inside the white one while focusing.
    I do not know why nobody does this, I suppose it is quite rare to have situations where this is of practical use.

    If you had a few references like the markers you could AF on those, or even the sea in the proximity, and switch to manual focus/back button focus. And stopping down the lens as much as possible.
     
    Last edited: Jul 24, 2016
  4. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    I tried CAF. It worked very poorly. I could not hold the camera steady enough for it to follow the subject. I had more luck with SAF with a single center point.
     
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  5. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    I did not know that, thank you. I will have to try it on my GM5.
     
  6. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    I totally agree that this is something that should be implemented, and also agree that it was probably the best way to focus in your given situation. I believe Fuji and Sony both have some sort of implementation of this, with varying degrees of accuracy, so it's clearly not that difficult. Just not a priority on the M4/3 side, I guess.
     
  7. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    That would have been what I had done if nothing else worked. If it was as rough as he says in the quote below, I am not sure manual focusing would have been any better.

    In rough conditions SAF and mashing the button the for fastest possible focus to shutter activation would have been the go to method if you were unable to follow the subject.
     
  8. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    That's what I was trying to do going with the roll of the boat. But I could only keep it steady for a second or so, enough time to lock focus some of the times.
     
  9. GBarrington

    GBarrington Mu-43 Veteran

    That seems to be a problem with focus by wire. It's relatively easy for a lens with set positions of the focus collar to mean a specific focus distance, but when there is no natural 'home' position for the focus collar and no maximum position either, Focus distance has to be calculated by the onboard processor every time based on data provided by . . . what? The autofocus system that you have turned off and don't want to use (so it's ALWAYS on, just not being used)? And is the onboard processor fast enough and powerful enough to calculate the distance in realtime as you turn the focusing collar searching for that perfect focal point? And what does all this do to power consumption and heat dissipation?

    I'm not saying this is an impossible or invalid request, but I am saying there are some significant logistical and engineering issues that need to be resolved before the FBW camera can give you a good reliable focus distance number. It might be cheaper and less frustrating for all concerned for Olympus, at least, to produce some manual focus lenses in key focal lengths, with focus distance markings embossed on the lens barrel like in the days of the dinosaur.
     
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  10. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    I think the focus distance is already recorded. It shows up in the extended EXIF data: Exiv2 - Image metadata library and tools. So if the camera already knows what it is, it might be really simple to display, like the focal length when zooming. From there they could even implement an in-camera focus limiter.
     
  11. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    I think it gets this information from the stepping motor steps count. It is an information also available in the EXIF data, it is not calculated it is just the location the motor is at. Converting this "count" to an accurate distance in meters can be quite tricky as it depends on the lens, motor/helicoid tolerances/calibration, resetting the initial the position, etc. In terms of calculation it is about nothing, the processor sits idle most of the time, it could do computations like this millions of time in a second (literally, not a random number).
    It's just a different planet with a different time rate where the turning the focus ring happens in super bullet time.

    But still I do not get what the advantage would be having the actual number on the screen. I can only think of something like this:
    - point on first marker and notice the distance (20mt)
    - repeat for the second marker (50mt)
    - set the camera to 20mt (manually or with AF) and wait for the boat
    - while tracking the boat turn the focus ring trying to do it at the correct boat speed up to the 50mt on screen indication

    Sound quite a task and the advantage over doing follow focus from first marker to whatever seems very little. Am I missing something?

    I tried something like this with a manual focus lens and BiF: you set it to 50 meters and then blindly turn the focus ring in while doing a burst. As insane as it sounds you get a couple of shots in focus.
     
  12. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    It is a simple calculation based on focal length, aperture, and focus distance to give an approximate DoF calculation for hyperfocal shooting. This would be quite useful. Whereas with existing fly-by-wire manual focus, there is no feedback except strictly visual pixel-peeping, or a very rough guideline ("mountain" vs. "flower," how useful!).

    Obviously tolerances in the focusing helicoid, and even the lens mount will make for minor variations. As far as initial position, all M4/3 lenses seem to reset to infinity (presumably one end of the stepper) when the camera is turned off and on, so that shouldn't be a big obstacle.

    But even still, when you figure that when you're using your 100-300 wide open @ 100ft, you've only got just over 5 feet of DoF, having even a vague sense of where that 5 feet is is quite useful.
     
  13. Clint

    Clint Mu-43 All-Pro

    Apr 22, 2013
    San Diego area, CA
    Clint
    You were not unlucky to be on a boat because of the constant movement - there is no way to get the same type of yacht racing photos from the shore line! I see the DoF of 4/3s and the O-MDs focusing system being an asset. Having decent sea legs and anticipating the movement of the boat/yacht one is shooting from is a major benefit in this kind of shooting environment.
     
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  14. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    Not a bad idea to blindly turn the focus ring while doing a burst. I'll have to try that.

    My thought process was that each of the buoy would give me a marker around which to compute enough of a hyper focal range to get my shots in focus.
     
  15. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    These boats go about 50 MPH when they get on their foils. It's amazing. It also makes it a real challenge as they move quickly around the course. At the closest, they were about 300 ft away, and about a mile at the farthest, if not more. Most of the fun action is around the turns which is why I wanted to use the buoys as focus markers and let the DOF take care of the rest.
     
  16. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    I agree but on Lake Michigan, close to shore, the waves were all over the place. It was very difficult to anticipate the movement of the boat. Same thing with the western wind: the projection of the buildings created difficult navigating conditions. 2 of the boats capsized. You don't see that often.
     
  17. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    In this specific case with a long tele the DoF is small, as someone said.

    With a 200mm lens you have this:
    f/8 50mt distance 16mt
    f/8 100mt distance 71mt

    and at 300mm and f/11 it is about half of those values(!).

    With a 100mm lens it is more reasonable:
    f/8 50mt 108mt
    f/8 80mt hyperfocal distance

    So you do not have much freedom of choice regarding DoF when they get close: you need as much as possible.
    Seeing this numbers live on the camera display would be nice, even only as a learning tool or like the histogram, level, etc. so you get a general idea of what you can expect.

    I've just found out that the Zeiss Batis lenses display the focus distance with near and far depth of field references on the small display.
     
  18. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    I think the Batis lenses only display "5+" when the focal distance is longer than 5m. Which is disappointing.
     
  19. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    I would like the lens/camera combo to automatically go to the hyperfocal distance for the lens at a particular aperture when I hit a button. It's a computer, after all, and the camera should be able to calculate the distance, move the lens, and display the range in the VF.
     
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  20. marcl

    marcl Mu-43 Regular

    184
    Jul 8, 2012
    That would indeed be a really convenient feature.