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Some general AF/Type questions

Discussion in 'This or That? (MFT only)' started by mikekiwi, Apr 27, 2013.

  1. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    Hi,

    at this moment I'm evaluating a come-back to M43. (I previously owned a E-PL1).

    My current set-up is a Pentax K5 with a Sigma 17-70+Tamron 70-300. I just sold my backup-camera (Pentax K10D) and my studio-flashes to get a smaller (M43) backup camera. While reading about M43 maybe I sell the K5 as well and move entirely over to M43. Before I do that, I would like to ask you some questions of which I can't find a definitive answer myself.
    I'm still in doubt about several different models and which one to buy, but will read the entire (!) forum first before posing any questions on which one to buy :rolleyes:

    1. On the DSLR''s I have/had I was keen on having AF adjust to be able to correct back- or frontfocus (and needed it). On M43 camera's I don''t see this options and I read somewhere that this was due to the AF-system which is measuring on the sensor and thus focus is always OK. Is that correct?

    2. my E-PL1 could control the FL36R flash from the camera (TTL) but as I can remember the internal flash always was visible in the images as well. Is this still the case on newer models? And can Panasonic camera's control a FL36R wireless as well (TTL)

    3. In fact, I'm very satisfied with my K5, it's a great cam and along with the 17-70 from Sigma pretty versatile. Buying some better lenses is a problem however if you're on a tight budget. New lenses are a bit too expensive and 2nd hand for Pentax is hard to get (and overpriced as well as there are more buyers then sellers).
    So a switch to a G5/6 or E-PL5 from the K5 would also be an option and then add a 20/1.7 and 45/1.8 (OM-D is maybe a bit too expensive for me when needing still a smaller backup and the 20+45).
    Are there reasons to convince me to either keep or sell the K5 ? Just to help me make the decision?

    (for samples of what I usually shoot, take a look at my website; although it is written in dutch you can get an idea from the blogposts and portfolio.)

    Thanks for your input!
     
  2. b_rubenstein

    b_rubenstein Mu-43 All-Pro

    Mar 20, 2012
    Melbourne, FL
    Mirrorless cameras determine focus by analyzing the image formed on the actual image capture sensor. This is different than a SLR where there is a separate AF sensor and that has to be precisely aligned so that what is in focus on the sensor is in focus on the capture sensor. Another significant factor, and the reason one lens may front or back focus and not another, are the algorithms used for determining focus in an SLR. A SLR camera calculates where to focus the lens as much as it does by focus measurement. This is why lenses have to be calibrated, or the body have a user adjustable AF offset for a particular lens. The higher degree of precision of mirrorless cameras and Live View is the reason Nikon recommends using Live View for critical focusing.

    I haven't noticed much effect of the cameras internal flash when controlling an external flash. What I have noticed is a very significant delay (for measuring the light) when using TTL flash. Newer model bodies have faster processors and less delay. My GX-1 is better than my OM-D, but for people pictures, with off camera flash, I prefer radio triggers with the flashes in Auto or Manual mode.
     
  3. ~tc~

    ~tc~ Mu-43 Hall of Famer

    Oct 22, 2010
    Houston, TX
    SLRs use "phase detect auto focus" - as mentioned above, it actually measures the distance to the target, and tells the lens to go to a certain position. Variability in the lens means each one needs to be calibrated for optimum results. PDAF has been around for a LONG time, and is therefore very well developed.

    The other type is called "contrast detect auto focus". The camera moves the lens in and out searching for the position that delivers maximum contrast. Because of this, there are no front or back-focusing errors - it is much more accurate.

    PDAF used to hold a speed edge, but micro 43 has closed the gap (other mirrorless, not so much) at least for still or slowly moving subjects. CDAF has not been around for long enough to have developed the motion tracking capabilities that PDAF has - at least as regards towards/away from the camera. CDAF can do things PDAF can not, though - for example face detection and even face recognition.

    Looking through your blog, I don't see much fast-moving sports photography. I think you will be absolutely blown away by the difference in AF of the modern m43 cameras compared to your EPL1 (which was a bit of a dog in the AF performance, especially with the kit lens)
     
  4. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    Can you explain this to me a bit further? Why do you prefer the GX-1? And don't you trust the Wireless-TTL or are you used to work manual and are sticking to that workflow?
     
  5. supermaxv

    supermaxv Mu-43 Veteran

    273
    Sep 20, 2011
    Yes, but on the Panasonic side, only the GH3 at the moment.
     
  6. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    Thanks for your clear explanation!

    Sports is not one of my interests in photography. Although my 7-year old daughter is testing me sometimes when I try to capture her :biggrin:

    A friend of mine has an OM-D E-M5 and when I tested that one last week in dim lighting I was indeed impressed by its speed of focussing (with PL 25/1.4).

    One of the reasons I'm doubting if I should switch all over to M43, is the AF and face-detection in all modes (had severe problems in getting everything correctly focussed on a wedding a few weeks ago.
    AF is not the strongest point of the Pentax K-5...
     
  7. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Yes that is correct. :)

    It's not supposed to do that. :) Maybe you had the flash on dumb slave instead of TTL? Or maybe it's just light left over (in which case, maybe try a slower shutter speed?). Dumb slave will trigger the external flash at the same time as it sees another flash (you can use a 1/64th power flash to trigger it, if you don't want to see the trigger light in the image), whereas TTL just reads signal lights from the commander then fires the flash after based on those settings. You should have a delay with TTL, but should not see (much) light form the commander.

    The Panasonic GH3 was the first Panasonic camera with a remote flash commander for wireless TTL, so it has to be at least as new as that model. Other than that, the FL-36R can fire from any camera in dumb slave mode.

    Well, a system is nothing without good glass. So if you need to sell something else to fund that glass purchase then do it. Otherwise your body purchase won't be worth much of anything.
     
  8. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    I'm not sure what you mean. You want Face Detection, but it doesn't work so good? I would never shoot a wedding, or anything important (or anything period, lol) with face detection. If it's not working well for you, that's probably because it is face detection and full-grid auto-AF, lol. Try using a single AF point instead, and see how accurate it is. You can't judge any camera's performance using hokey auto-features.
     
  9. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    No, I didn't make myself clear enough apparently:

    1. Pentax K5 AF didn't work good during the wedding in low light. I didn't use Face Detection, but single point AF (which is my 100% AF-mode now).

    2. Face detection can certainly be of help when correctly implemented, and I want to test if it can be of any use. And it won't be enabled constantly, certainly not
     
  10. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    I totally agree. I just sold my backup cam and studio flashes to fund that glass purchase. And now maybe the time to evaluate a system change to have the full benefit of my investment.
     
  11. b_rubenstein

    b_rubenstein Mu-43 All-Pro

    Mar 20, 2012
    Melbourne, FL
    TTL flash requires a preflash so that it can measure the amount of light needed for the exposure. The processor in the camera needs time to make its calculation. The GX1 seems to have a faster processor and there is less of delay between the time you depress the shutter button and the actual exposure takes place than with the OM-D. DSLR's don't have this delay because the camera's meter can measure the light during the exposure, so no preflash is needed. In Auto or Manual mode no preflash is needed.

    People often have fleeting expressions and I want the camera to fire as soon as I hit the button.
     
  12. mikekiwi

    mikekiwi Mu-43 Regular

    82
    Dec 16, 2010
    The Netherlands
    OK, that's clear. For me I would use it for more posed shots and then this should be not such a big issue.
     
  13. Pecos

    Pecos Mu-43 Top Veteran

    775
    Jan 20, 2013
    The Natural State
    The thing I like about OM-D E-M5 (besides small size) is accurate focusing. My Pentax K-5 was a great camera, but missed focus too often. This is because the focusing area is large - it would lock on something inside that central circle with higher contrast than the subject.
    No more missing correct autofocus, no more calibrating lenses for front- and back-focus issues. And what good is a system which focuses fast if it's not accurate? On top of this, the face- and eye-detection on the Olympus is a killer.