1. Reminder: Please user our affiliate links to get to your favorite stores for holiday shopping!

Olympus 17mm zone focusing.

Discussion in 'Native Lenses' started by TonyZhang, Apr 24, 2015.

  1. TonyZhang

    TonyZhang Mu-43 Regular

    71
    Jul 8, 2014
    New Zealand
    Hello everybody,
    I have had my 17mm for a few weeks now, and am very happy with it. I purchased the lens partially because of the pull back distance scale. I didn't really try it out until two days ago, and it has confused me quite a bit.

    The aperture value brackets (22,11,5.6,5.6,11,22) or whatever you call them near the front element seem to be placed awfully close together. According to this 17mm, to get everything from 5ft to infinity in focus, I would have to be at f22, which is ridiculous obviously.

    Does anybody have a good idea of how zone focusing works on the 17mm? It just doesn't seem to make sense to me.
     
    • Like Like x 1
  2. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    Yes, it's messed up.
    I think they calculated the DOF in feet, but then put the marks on the meter scale.
    At f/11 DOF goes from about 2.7 feet to infinity for this lens. If you line up the right side 11 line with infinity then the left 11 line will sit just to the left of the 3 meter line...
    Rudy
     
    • Like Like x 1
  3. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    So f/5.6 should give about 7ft-infinity, right?

    Someone should make a label to stick over the scale... Maybe I could make one...

    Barry
     
    • Like Like x 1
  4. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    OK... I think I've got this right, can someone double-check my work?
    I haven't tested these, only calculated and measured but I have not confirmed DoF in-camera.

    I need to go to sleep, but if anyone wants to make a label in InkScape or Illustrator, the design is below...

    Height: 5mm, or 3mm if you don't want to cover the blue stripe on the lens.

    Length: 25-30mm or so, depending on fonts, etc.
    I would have the right side end just before the red focus marker; everything rightward from there is already correct on the lens.

    Font: ~6pt to match OEM, or can go bigger if covering blue band.

    Positions, measured from red line on lens, working leftward:
    0-1mm (start) (probably should start at 1mm so as not to cover red line, about where the left f5.6 mark is on the lens)

    8.5mm - f/8

    11mm - f/11

    16mm - f/16

    19.5mm - f/22

    25-30mm (Left end)


    I've got some Avery labels (will have to cut them to fit), but I'm not sure how long they'd stay on with use. Cutting something only 3-5mm wide is going to be tricky, probably impossible with my photo paper cutter.

    Barry
     
  5. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    crappy drawings:
    20150424_001315.
    a. The squiggly line (~) at the top is the blue band on the lens; i.e. the label would be 5mm if covering the blue band and 3mm if not covering it.

    b. '0' on the right is where the Red focus mark on the lens is.


    20150424_001340.
    'R' is the Red focus mark on the lens; everything to the left of that needs to be on the label, except the first mark between R and 5.6 and the scratch above it, that was a mistake.

    Barry
     
  6. Muntjack

    Muntjack Mu-43 Veteran

    200
    Jul 26, 2010
    I think we are a bit awry here. Yes the absolute limits at f11 are from 3ft-ish to infinity but only if one is focused on the hyperfocal distance. Using the camera scale alone will not place the focus anywhere near the hyperfocal if I'm not mistaken?

    I use the scale differently - just setting the aperture to f5.6 or f8 and then turning the focus ring till it points at 3 meters - I already used a DOF calculator to know that this is what I need to get the DOF I want in my most common situations.

    M
     
  7. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    There's two scales, the normal one, and a hyper-focal scale is shown if you retract the clutch.

    Barry
     
  8. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    So, in other words, you are not using the DOF scale at all, just the distance scale. Fine if you have the hyperfocal distances in your head. Nonetheless the scale is wrong.

    I agree that the home made scale proposed needs to go in both directions to allow setting the lens at the hyperfocal distance.

    It's interesting that this lens has been out for so long and none of the illustrious reviewers have noticed this problem and called Olympus on it...
    Rudy
     
    • Agree Agree x 1
  9. Muntjack

    Muntjack Mu-43 Veteran

    200
    Jul 26, 2010
    I don't think this is a true Hyperfocal scale. It will just give you decent zones. I'm sure I checked it about a year ago and the zones work reasonably well.

    The position of focus the lens finds itself in is however not IMHO the hyperfocal distance and therefore the lower limit of the zone is not the best possible.
    I could be wrong but that's just my take on why the scale is so confusing. Have a look at your lens and see if the focusing distance is the hyperfocal when f11 and infinity are set......?
    In my judgement there's no way you can actually set the hyperfocal on the lens without the use of a tape measure (or laser!).

    M
     
    • Funny Funny x 1
  10. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, my understanding is that the part on the right is already correct, which is why I didn't include it. That part is critical to getting the focus right, so no point in re-doing it with potential for error if it's already fine.
    right?

    Barry
     
  11. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    No, both sides need to be fixed.
    The right part of the scale is what you would need to set the focus for the lens to be hyperfocal, i.e. infinity is the upper end of the acceptable focus range. That way you are not "wasting" focus range beyond infiity.
    So if you want to shoot at f/22 you would line the right 22 marker up with the infinity sign on the distance scale. If you do that you see that the red mark which indicates nominal focus distance will be just to the left of the 3m label.
    The correct nominal focus for f/22 however is 2.85 feet (assuming a circle of confusion of 0.015mm, how much blur you still call sharp). That's why my suspicion is that they mixed up units when generating the DOF scale.
    So the 22 marker of the left part of the scale needs to line up with the infinity mark when the lens is focused at 2.85 feet not 2.85m.
    The left side of the DOF scale shows you the closest point that still has acceptable focus and that also needs fixing.
    Rudy
     
  12. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Would moving the Red mark solve the problem for all apertures?
    Otherwise, the distance scale would have to be corrected, but that is unlikely to be fixable with a label as it could interfere with the clutch.
    However, I'm not sure how important the red mark is when using hyperfocal.

    That's what I believe I fixed already, above.

    Barry
     
  13. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    The distance scale is correct and so is the red mark on the DOF scale.
    What's not correct is the position of all the other markers on the DOF scale.
    They need to spread out in both directions.
     
  14. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    OK. I'm not sure if I'm going to have more time to work on it soon, but if the right needs to spread out the same amount as the left, then it's just a mirror copy and should be easy to do in Illustrator or InkScape.

    Barry
     
  15. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    I'm working on this again...
    1. the right and left sides of a new zone or hyper focus scale won't mirror each other.

    2. The focus scale on the lens isn't very accurate... actual, measured focus at 13'/4m shows less than 3m on focus scale.

    Can someone else check theirs? If they're all different, my scale won't work for someone else.

    Also, where does diffraction start to degrade resolution with this lens?

    Barry
     
    Last edited: Apr 25, 2015
    • Like Like x 1
  16. bigboysdad

    bigboysdad Mu-43 All-Pro

    Aug 25, 2013
    Sydney/ London
    I'm watching this thread to see if these issues get resolved. That snap focus on the 17 does seem to have been a bit of a white elephant in the room and this is the first time I've seen the issue properly raised and addressed.
     
  17. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    The ideal solution, instead of a printed label (white) would be to remove the original ring and replace it with a new one. I don't know how difficult replacing it would be, or how expensive, but I do know someone with access to a machine shop.

    I'm guessing anodizing would be needed, then cut out the numbers and marks.

    The one on the lens seems to have the numbers and marks anodized instead; I guess they cut the numbers/marks first, and then anodize, and then polish off the anodizing on the flat parts. I'm not totally clear how they anodize both Red and Black (and Blue).
    (I have the silver lens, fwiw.)

    If the ring cannot be removed, another ring could be installed on top of it, but it would need to be glued in place somehow.

    Barry
     
    Last edited: Apr 26, 2015
  18. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Here's what I've come up with:
    20150425_213134.

    Notes:
    'z' is zone focus
    'h' is hyper-focal; if there's no letter, it's hyper-focal.

    several f-stops on the left side are at the Red mark (aka 0mm) because the near focal distance is closer than what the focus scale shows; e.g. should be at 10' but the scale is reading below 3m, hence it needs to indicate the Red mark.

    I'll create a spreadsheet later with more info on the zone focus ranges I chose, but the rest are using a hyperfocal calculator.

    I verified all the focus points with a tape measure and focus peaking.
    I didn't measure all the close and far ranges with the tape measure, but I did eyeball many of them.

    Barry
     
    Last edited: Apr 26, 2015
  19. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Tony, for now, set the camera to f5.6 and set the focus on the lens to line Infinity up with the f22 mark; you should have a focal range of 7-300ft that way.

    Or f/4 gets 8-41 feet at that setting.

    Barry
     
    Last edited: Apr 26, 2015
  20. TonyZhang

    TonyZhang Mu-43 Regular

    71
    Jul 8, 2014
    New Zealand
    Thanks a lot Barry, that makes sense, should work fine for now. Cheers