Announcement

Collapse
No announcement yet.

Macro photography.....focus stacking..??

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Macro photography.....focus stacking..??

    Maybe a bit off topic, I don't know. But there is some machining content.

    Focus stacking involves taking a series of digital photos of a small object with a macro lens which has a short depth of focus. The process is taking a series of photos beginning at the nearest point of the object with the lens in focus then continuing until the series has points of focus all the way to the farthest part of the object. The series of photos are merged in software to give a single in-focus photo of a small object.

    Here's the machining content. My thought is to set up a very rigid camera holder (maybe tripod like) with possibly a lead screw to increment the camera forward for each successive in-focus shot. My understanding is the conventional way is to re-focus the camera lens for each successive shot rather than re-positioning the camera. I've been told Fuji (?) and possibly other camera makers have cameras that will do the photos series by automatically re-focusing at certain distance increments (my Sony A6000 won't do this).

    Anybody doing this sort of thing or have thoughts on it?

  • #2
    If you move the camera between shots rather than refocusing a stationary camera and lens the image size on the sensor will be different for each shot. Focus stacking in post production won't work very well.

    Comment


    • #3
      I've contributed to 5 fly tying books using macro photography, I've seen this done, but didn't have the time to adapt this technique to a 100 flies or more. So I flooded the subject with soft light and shot at f22. Seemed to work with most flies. Look on Scott Kelby's website for more on this.

      Comment


      • #4
        Yes, a smaller iris opening (larger f stop number) will increase the depth of field. This has been used by photographers since the days of the art. The traditional trade off is f stop vs. the length of the exposure (shutter time setting). Early lenses had smaller diameters due to the difficulties in designing a "fast" (large diameter) lens. So they often had maximum iris settings of f16, f11, or perhaps f8. By the time that 35mm photography became common in the 50s and 60s lens with aparatures of f2.8, f2, and even f1.7 were popular and some premium 35mm cameras had a standard lens with an f number less than 1: that means the effective diameter of the light path through that lens was longer than it's focal length. But the compromise with these "fast" lenses was that the depth of field was reduced with every improvement in the f number.

        Professional cameras and the high end amateur ones have individual, MANUALLY operated controls for the shutter speed and the f stop. So the photographer could choose a pair of settings to suit the photo being taken. There are modern, digital cameras that have these features, but they are usually quite expensive. The moderately priced cameras make these decisions for you and you have no control. A clever camera manufacturer could add it as a feature. It would only take software changes and would only add pennies to the price, but none seen to do so.

        Another compromise involved here is that all lenses are designed with a number of compromises. Two of these lead to the fact that most lenses will provide the sharpest image at an f stop setting that is somewhere between the fastest (smallest f stop) and the maximum f stop number that the iris will allow. This point is usually 2 or 3 f stop numbers below the wide open setting so a lens with a maximum setting of f2 would provide the best images at f4 or f5.6 (It is a logrithmetic scale). These two compromises are the difficulty of correcting for optical problems with a wide aperture (low f number) and the diffraction effects caused by the edge of the iris. Those diffraction effects come into play when the iris is stopped down to smaller openings (larger f numbers).

        Note: with all this talk about f numbers here is the definition of an f number:

        f number = focal length / effective diameter

        Anyway, the best way to try to increase the depth of field of the lens on most digital cameras would be to use more light in the hope that the camera will choose to set an iris to a higher f number. This may or may not work because the exposure time is also at play and it, the camera, may just adjust that instead. The best way would be to use a manually adjustable camera ($$$$$).

        Another modern development that is useful for small objects is the telecentric lens. This is a special design that uses a large diameter front element combined with a carefully located iris. The f stop is rather small (large number) but the large diameter elements allow the point of view for each point of the image to be parallel to the optical axis. In effect you are looking straight down at every position of the object being photographed. And, due to the small effective aperture, the depth of field is large. But these lenses are quite expensive.

        https://www.edmundoptics.com/c/imagi...nRyaWMgTGVucw2



        Originally posted by Tungsten dipper View Post
        I've contributed to 5 fly tying books using macro photography, I've seen this done, but didn't have the time to adapt this technique to a 100 flies or more. So I flooded the subject with soft light and shot at f22. Seemed to work with most flies. Look on Scott Kelby's website for more on this.
        Paul A.

        Make it fit.
        You can't win and there is a penalty for trying!

        Comment


        • #5
          It's actually easy to do, if you can do it easily.

          A lot of DSLR (and mirrorless) digital cams allow for "tethered shooting". Depending on your camera and software, that can be anything from just instant transfer of the images from camera to computer to being able to control the camera from the computer. I checked and the Sony A6000 allows for some degree of tethered shooting. SO far, so good. However, I didn't go digging to discover just how much tethered control the Sony A6000 allows. You'll have to dig around to find that. It's the sort of thing that isn't always in the ref or user manual.

          I use Nikon cameras. Most of the upper end Nikons allow extensive computer control of focus,aperture, etc. That means that the appropriate software (and cable) can tell the Nikon to focus at <n> steps from <here> to <there>. The software I use is digiCamcontrol. I don't know if digiCamcontrol works with a Sony A6000. It also does the focus stacking image manipulation after taking the photos. It's pretty easy to use. I believe digiCamcontrol is freeware.

          So for me, I can do focus stacking by mounting the DSLR on a tripod, hooking up the cable from the laptop to the DSLR, run the software, compose the image, use the computer to set the exposure shutter speed and aperture, use the computer manual control to set the close focus, use the computer manual control to set the far focus, tell it how many steps, and push <RUN>. See, it's easy... because I can do it easily.


          You can also use Hugin to do focus stacking, but I don't believe it can control the camera. I could be wrong since I have never explored that part of Hugin - used digiCamcontrol instead. You'd have to do the focus steps manually and then transfer the images to Hugin. You might want to become acquainted with Hugin even if you don't use it for focus stacking because it's a pretty good free panorama generator. I believe Hugin is freeware.

          There are also websites that have plans for Arduino controlled focus stacking, including using a stepper motor and lens ring if your camera doesn't allow computer control of focus. I know they exist but since I didn't need them I didn't pay a lot of attention to them.


          Last edited by Dan_the_Chemist; 11-07-2019, 07:48 PM.

          Comment


          • #6

            A mechanical system has been in my ideas file for quite some time although I am primarily interested in extreme telephoto rather than macro shooting. My idea has been to mechanise a bellows set. I will be interest to see what you make.

            John

            Comment


            • #7
              Originally posted by DR View Post
              Maybe a bit off topic, I don't know. But there is some machining content.

              Focus stacking involves taking a series of digital photos of a small object with a macro lens which has a short depth of focus. The process is taking a series of photos beginning at the nearest point of the object with the lens in focus then continuing until the series has points of focus all the way to the farthest part of the object. The series of photos are merged in software to give a single in-focus photo of a small object.

              Here's the machining content. My thought is to set up a very rigid camera holder (maybe tripod like) with possibly a lead screw to increment the camera forward for each successive in-focus shot. My understanding is the conventional way is to re-focus the camera lens for each successive shot rather than re-positioning the camera. I've been told Fuji (?) and possibly other camera makers have cameras that will do the photos series by automatically re-focusing at certain distance increments (my Sony A6000 won't do this).

              Anybody doing this sort of thing or have thoughts on it?
              Nope! The conventional way is to do exactly what you want to do. Lens adjustments are much to coarse at that DOF. They sell commercial products like you intend to make, but not as nice. https://www.amazon.com/Hakuba-SUPER-.../dp/B00004ZCTZ
              21" Royersford Excelsior CamelBack Drillpress Restoration

              Comment


              • #8
                There are several commercial systems for automating focus stacking. Visit https://www.photomacrography.net/forum/index.php for extensive info. I've done focus stacked macro panoramas with up to 5000 individual frames. I'd put a link to photobucket for them, but they're pretty blurry now My system is designed with a fixed position for the lens (entrance pupil at the panorama rotation point), bellows, and a linear slide for the camera. The controller uses a Teensy microprocessor (Arduino compatible) and software I wrote.

                Methods of focus stacking:
                • Olympus as well as some other cameras have in camera focus stacking.
                • Fixed lens, focus by changing bellows draw (I use this).
                • Focus moving camera and lens as one unit.
                • Focus using lens.
                • Focus by moving subject.

                Comment


                • #9
                  Originally posted by Frank K View Post
                  If you move the camera between shots rather than refocusing a stationary camera and lens the image size on the sensor will be different for each shot. Focus stacking in post production won't work very well.
                  Incorrect Focus stacking software handles this easily.

                  Comment


                  • #10
                    We do focus stacking every day (at work); macro photography of rings and jewelry. The camera moves on a lead screw driven by a stepper motor. 50-100 pictures are stacked together (post) in SW for one picture. Beautiful results.

                    Comment


                    • #11
                      This guy uses a Nikon 200mm macro with a Nikon Plan objective. You dont need to use the fancy lens he has (Its a great lens, I have one), you can use just about any 200mm lens, it is just an adapter for the microscope objective which is expecting a 200mm tube length. He focuses by moving the camera. I have a stepper motor and ring gear for that lens so you can stack that way.

                      https://vimeo.com/157712307

                      Comment


                      • #12
                        Originally posted by macona View Post
                        This guy uses a Nikon 200mm macro with a Nikon Plan objective. You dont need to use the fancy lens he has (Its a great lens, I have one), you can use just about any 200mm lens, it is just an adapter for the microscope objective which is expecting a 200mm tube length. He focuses by moving the camera. I have a stepper motor and ring gear for that lens so you can stack that way.
                        can you explain more about the 200mm and how it doesn't matter what lens you use? or did you mean any 200mm macro lens, vs any 200 lens? is 200mm a standard or just a nikon standard? I have one of the small Nikon macros, would making an extension tube work?

                        thanks
                        .

                        Comment


                        • #13
                          Originally posted by elf View Post

                          Incorrect Focus stacking software handles this easily.
                          Okay, thanks, my assumption was the software would handle the image size difference as a result of moving the camera on a lead screw. The recommended "free" software I planned on using is combineZP. This is a low budget project so having to buy higher end software would kill the project.

                          So far my out of pocket has been limited to buying a set of two macro extension lens tubes off Amazon, 30 bucks.

                          BTW, my other photo related interest is photogrammetry which works quite well to scan objects and create 3D models from a series of photos. Free meshroom software does that once you get a good data set of photos. Photogrammetry is something anybody can easily do with a digital camera although it may require a few tries to understand what's involved in getting acceptable images.

                          3DF Zephyr Free is an easy piece of software to use, but is limited to a 50 image data set . Meshroom software is better but requires an nVidia graphics card which all computers don't have.
                          Last edited by DR; 11-08-2019, 10:45 AM.

                          Comment


                          • #14
                            I seem to remember "Really Right Stuff" did some "focusing rails" for macro photography, similar to the link The Metal butcher posted, they were integrated into their clamping system setup.

                            Although no longer listed on their website and out of stock at the usual suspects, there is a description on this page:
                            https://www.reallyrightstuff.com/macro

                            Comment


                            • #15
                              Originally posted by macona View Post
                              This guy uses a Nikon 200mm macro with a Nikon Plan objective. ...
                              https://vimeo.com/157712307
                              Really impressive! He takes 2-3 weeks per photo, 8-10,000 exposures. Then he gets a print: "I'd like a 5 x 10 ... 5 x 10 FEET".

                              Comment

                              Working...
                              X