'Focus Differential' for 'Focus Stacking'...E-M1

Discussion in 'Olympus Cameras' started by Dave in Wales, Mar 13, 2016.

  1. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    Just started to mess around with FS on my E-M1 for macro.
    The 'Focus Differential' setting is from 1-10 with the default set at 5...as we all know.

    Can I ask, what members have found to be an optimum setting, even if there is such a thing?

    TIA Dave
     
  2. wjiang

    wjiang Mu-43 Hall of Famer

    I find that it really depends on what lens and at what magnification you're working at. Add something like an AF extension tube or close up achromat and it really goes out the window. The 12-40mm natively requires different settings to the 45-175mm with a +8 dioptre DCR-250, for example. I hope to eventually work out some 'go-to' settings for particular combinations though...
     
  3. Growltiger

    Growltiger Mu-43 Top Veteran

    649
    Mar 26, 2014
    UK
    With the 12-40 for example, if you are wanting everything in focus from the closest focus to infinity, then you might need 8. If you want everything in focus from the front of a flower to the back of the flower you might want 2 or 3. You have to experiment.
     
  4. Tall Guy

    Tall Guy Mu-43 Regular

    58
    Sep 15, 2015
    Jeff H
    I found this article that is linked to the Olympus learning center explains things pretty good.

    Focus Bracketing/Stacking
     
  5. wjiang

    wjiang Mu-43 Hall of Famer

    "In all cases it will require experimenting with various settings."

    That doesn't sound like much of an explanation, more like trial and error.
     
  6. Tall Guy

    Tall Guy Mu-43 Regular

    58
    Sep 15, 2015
    Jeff H
    Here's the explanation part...
    Screen Shot 2016-03-13 at 2.35.08 PM.

    Now deciding to stack 5, 10, 20 or thirty or more photos is up to the photographer. Deciding to have your stack to include 10mm, 20mm, 30mm or more in focus is up the photographer. Deciding what aperture to use is up to the photographer. Determining the depth of field per shot based on your aperture and distance to the subject is up to the photographer to calculate.

    So far I've focus bracketed several series of 40 photos and stacked them. I set the focus differential at 3. My subject was around 300mm. The remainder I can't remember.

    There is no magic bullet for the perfect results given the variables the photographer has to decide. I'm sure someone with more mathematical skills than I have, will not have to go through trial and error but that someone is not me. The meat and potatoes of the camera setting is setting focus differential and quantities of shots in the bracket set.
     
  7. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    LOL, what does it explain? Olympus has posted several things about focus bracketing and all of them are completely useless. One day I will get around to doing some experimenting using my focus target and the 60mm Macro to see how much each step actually moves and if the amount of movement is different for different apertures.
     
  8. gary0319

    gary0319 Mu-43 Veteran

    302
    Nov 26, 2014
    Sarasota FL
    This image was taken with an Olympus 25mm at f/5.6, bracket interval is 3, 5 shot stack.

    10_PB290039_stack.JPG
     
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  9. Tall Guy

    Tall Guy Mu-43 Regular

    58
    Sep 15, 2015
    Jeff H
    Haha...It explains all you get...nothing more. The explanation is too simple. Some of us want the solution to the whole, and there is no solution to the whole without experimenting . It explains you get 10 different levels of differential from least to most. That's all there is to it. Explaining the differential amount for all the different focal lengths will probably not be possible. I don't think any of us will find spoon feeding instructions on that. This is nothing more that automating what you can already do manually which is compose-shoot, re-compose-shoot and so forth until you get the range of focus you want then stack your photos.
     
  10. Austrokiwi

    Austrokiwi Mu-43 Regular

    46
    Mar 19, 2016
    I should have checked here before I went and asked Olympus as to what the step increments are when focus bracketing. The answer I got back was effectively..go suck and egg. They sent me a link to a paper on how to calculate depth of field. I should have guessed as Olympus have incorrectly renamed focus stacking as bracketing. I can and will calculate DOF tables but Olympus is a big failure on this.. they have effectively said we will sell you this car but we won't tell you what sized engine its got
     
  11. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    It changes depending on what lens you're using, the focal length (if you're using a zoom), the distance you're focusing, and also which firmware version the lens in question is running.

    There's just too many variables to give you a one size fits all answer.
     
  12. Growltiger

    Growltiger Mu-43 Top Veteran

    649
    Mar 26, 2014
    UK
    Their naming is logical. The E-M1 does both options.
    Bracketing means it takes a series of photos, just like with exposure bracketing.
    Stacking means it takes a series of photos and then stacks them, making one final photo.
     
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  13. mronen

    mronen Mu-43 Regular

    74
    Jul 20, 2012
    In a paper by Dave Pardue on News Archive: December 2015 (I can't find the actual link at the moment) he suggests that one 'Differential' unit for focus bracketing (not stacking) equals to the field depth at the given shooting situation (lens, aperture, distance). Therefore, to avoid 'focus banding' the Differential should be set to 1 (the lowest value). The number of frames required for bracketing will depend on the subject's depth.

    Moshe
     
  14. wjiang

    wjiang Mu-43 Hall of Famer

    That doesn't sound right... The units for stacking and bracketing are the same to me. In fact stacking is just an option to enable inside the bracketing main function. I've also done plenty of stacking of 1:1 macro shots at f/11 to f/16 with a depth of 3-4 with no noticeable gaps...
     
    Last edited: Apr 1, 2016
  15. gary0319

    gary0319 Mu-43 Veteran

    302
    Nov 26, 2014
    Sarasota FL
    I mostly do bracketing with flowers with my E-M1 or E-M5 II, and always hand held. I use interval 3 as my default. I've tried setting the interval to 1 but this sometimes gets mushy results, I assume from overlapping images that are not absolutely on the same focal plane (being handheld). I understand that a lot has to do with the DOF, but interval 3 seems to be a good compromise.

    I also usually do 5 shot brackets, but sometimes use only 3 or 4 for the stack if the 5 bracket gets too much background in focus.
     
    Last edited: Apr 1, 2016
  16. Austrokiwi

    Austrokiwi Mu-43 Regular

    46
    Mar 19, 2016
    Bracketing means taking shots either side. but that just semantics. I have my own DOF calculator ( microscope calibration side mounted at 45 Degrees). I am slowly going through each F stop and several magnification rations.. calculating the movement in microns for each Bracketing setting.. its annoyingly slow.. and a table from Olympus would have earned them so much customer satisfaction
     
  17. gary0319

    gary0319 Mu-43 Veteran

    302
    Nov 26, 2014
    Sarasota FL
    Yes, bracketing normally means taking shots on "either" side, but not with Olympus focus bracketing only, (not stacking). Bracketing starts with the initial point of focus and then moves the focus plane back from that point for the number of shots requested, and at the interval set.
     
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  18. zensu

    zensu An Old Fool

    Aug 8, 2012
    Southeastern USA
    Bobby
    Maybe one day I get it figured out what focus stacking and bracketing features are on which camera body and what lenses do one or both of these with which body? :hide:
     
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  19. System13

    System13 Mu-43 Veteran

    236
    May 11, 2016
    Wisconsin USA
    JR
    Your approach seems the most scientific. Would you please share your results so that we may learn more about this from your work? Thank you
     
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  20. ZulSim

    ZulSim Mu-43 Rookie

    11
    Mar 27, 2013
    Kuala Lumpur
    From my observation, in focus stacking using EM1, 8 shots are taken with 2 shots before and 5 shots after the initial focus point.
     
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