Why Auto focus and DMF modes are both there?

Discussion in 'Sony Alpha E-Mount Cameras' started by alaios, Aug 10, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi
    kind of cafeteria discussion during break time. Why a manufacturer gives both choises? Why not give for example only the DMF which for me is auto focus that you can tune of course if you want to. What is the reason to have both and not just the one that can do both?

    First (good) answer gets a free pizza.

    Regards
    Alex
     
  2. Moshe

    Moshe TalkEmount Regular

    44
    May 25, 2013
    I think it has to do with the peaking feature.

    While it is turned on if you go to Mf or DMF it will show the peaking dots.

    If you are in AF doesn't, so for those who do not want to mess with manual focus they have an option free of the peaking dots, while some one like me could use all 3 and appreciate all 3.

    -The MF if I want full control of focus

    -DMF if I want to see the peaking but focus automatically

    AF for when I want a quick snap or hand the camera over to someone to take pictures of the family.

    Sent from my Galaxy Nexus using TalkNEX mobile app
     
  3. gio

    gio TalkEmount Veteran

    382
    Sep 12, 2012
    Manchester, uk
    the thing that gets me with DMF, is that you sometimes have to turn the lens so far to achieve focus, you would think that as you are almost there focus wise, the slightest touch would fine tune it
     
  4. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    actually I have problems using DMF effectively. I have to press the shutter half pressed and at the same time turn the lens... and I really fail on that. I would either shoot accidentally or not have extra hands to exit Magnification mode .... so I do not know what I am shooting :p:p Great stuff :p

    Why in Sony lenses there is no information on the lens at which meter you are focusing as with the adapted lenses? I like to have this information ("now I am focused at 5 meters") and it helps me build understanding..
    Alex
     
  5. Moshe

    Moshe TalkEmount Regular

    44
    May 25, 2013
    I turned off MF Assist because of that magnification that you are referring to. I guide myself only by focus peaking in high and I prefer yellow as my color of choice.

    Sent from my Galaxy Nexus using TalkNEX mobile app
     
  6. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    You never then had problems with the focusing and peaking making you make wrong decisions?
     
  7. Moshe

    Moshe TalkEmount Regular

    44
    May 25, 2013
    What do you mean by wrong decisions?

    Sent from my Galaxy Nexus using TalkNEX mobile app
     
  8. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    out of focus shots
     
  9. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    I was at an antique shop yesterday, and the owner was kind enough to let my daughter and me take pictures in the shop. I can't post pictures right now (I'm at work), but will post them when I get a chance.

    Anyways... The shots include several cases where I used DMF came in handy. One pair of shots I was shooting through a large round crystal at the bottom of a chandelier. The AF picked up the crystal, but what I really wanted in focus was the items seen through the crystal. DMF to the rescue.

    The second set of shots were reflections of items in the store as seen from the top of a grand piano. AF locked onto the piano, not the reflection, so again it was DMF to the rescue.

    I didn't have any problems keeping the shutter half pressed until I achieved the desired focus. My bigger issue was holding still for the 5-seconds for the MF-assist to go away so I could re-check my framing. I've used DMF for a while now, so maybe it just takes practice.
     
  10. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    thanks for sharing that. I also have that problem , how to exit MF zoom mode... when pressing shutter half way down.
     
  11. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    When I use MF lenses, I usually set the MF-Assist time to infinite. Since I'm not half-pressing the shutter, I can play until I get it just right, then half press to clear the assist.

    For AF lenses, you don't want MF-Assist timeout set to no timeout, because it will never go back to the non-zoom state and you can't re-frame. I think the options for MF-assist timeout were two seconds, five seconds, or no timeout. I found two-seconds was too short, and it was going back before I had decided if I needed to tweak the focus more. So I use 5 seconds, which seems like an eternity when you're waiting for it with the shutter half-pressed.
     
  12. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    Here's the DMF pics from the antique shop

    As always, click on a pic to load the 2048px wide version. All taken with the CZ24 wide open at f/1.8

    1030811+Antiques-2.

    1030811+Antiques-1.

    1030811+Antiques-4.

    1030811+Antiques-5.
     
  13. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Neat stuff db.
     
  14. NickCyprus

    NickCyprus Super Moderator

    Oct 11, 2012
    Cyprus
    Nick
    +1
    Especially those crystal ball ones - love the reflection :thumbup:
     
  15. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex

    so back to the initial question. Do you only switch between DMF and MF? And one more question, as extra gift, why the nex lenses do not have these printed numbers like the manual lenses?
     
  16. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    I never use AF, but there might be a reason why you would want to use AF instead of DMF. For example, focus peaking does not show up in AF mode, only DMF and MF. This could be very distracting for some people who never want to use DMF. I leave my camera in DMF, but if I'm going to let my wife use it, I might put it into AF mode so she isn't distracted by the peaking.

    As for the question, "why the nex lenses do not have these printed numbers like the manual lenses?", can you re-phrase it a little better? Either I'm missing some context, or having some other failure in understanding the question. But I can take a stab at it and hope I get it right.

    Older (legacy) lenses from the film days often had two different rings with numbers on them. One was the aperture, and the other was the focus distance. Modern automatic lenses no longer have the aperture ring, since it is controlled by the camera. But some lenses still display the focus distance in a small window. If your question is why don't NEX lenses display the distance? You'd have to ask Sony, but the answer is probably ROI. Very little reward for extra cost to build the feature into the lenses. Most people simple don't care, or don't need to care; So why make the lenses more expensive to satisfy such a small number of consumers?

    If that wasn't your question, please re-phrase, and I'll try again.
     
  17. Nex Tex

    Nex Tex TalkEmount Regular

    46
    Jul 25, 2013
    DMF does not allow use of continuous focus mode but AF does, so there are situations where DMF will not be adequate.

    The three biggest gripes for me, which are easily fixable are:

    (1) having to depress the shutter half-way to manual focus in DMF mode.
    (2) not having the option to assign AF to a button other than the shutter.
    (3) I wish there were an MF assist button that operates independently of the focus dial (i.e. pressing the button zooms in, but focusing does not).