Focus Stacking – My First Attempt At This With Photoshop

This post is a bit more technical than my usual Blog.  Directed more for laymen and beginner DSLR photographers. 

It’s just about my experience and learning process. 

I found a Mahonia plant starting to bloom today.  So I decided I could use it to have a go at focus stacking.  Picked one of the stems, and brought it into the house so I could set up the photo shoot on the kitchen countertop.  Put it in a vase holder.  Found some bluish purple construction paper for a backdrop, and I was ready to dig out the camera stuff I wanted to use.  Here is the setup. 

Equipment Used

Nikon D750

Tamron 90 mm 2.8 Macro lens

3 Kenko extension tubes – 12, 20 and 36mm

Viltrox jy670n ring light

Sirui Ball Head on my homemade equal of the Platypod (tripod alternative)

Before I explain about focus stacking, I should give a quick understanding of the concept of Depth Of Field or DOF.  This is a range of distance, either side of which the focus of the camera is “acceptably sharp”.   The combination of the camera, the lens, and the camera settings, all affect how wide or narrow this DOF distance is.  Without going into many chapters on the subject, here are some basic laymen examples.  They target how it relates to this Blog post about focus stacking, and are just for a quick understanding, rather than giving a detailed explanation. 

Ignoring camera settings, it is enough to know that a wide angle lens tends to have a wide depth of field.  For example, a subject in the foreground and the trees in the background can all be in focus at the same time.  With a telephoto lens this DOF distance begins to narrow, sometimes only a foot or even less will be in focus.  In this case, even if the subject is in focus, the foreground and background can be out of focus.  With close up and macro photography, the DOF becomes extremely narrow, sometimes less than a fraction of an inch.  An example of this would be a picture that has the insects head in focus, but the body behind the head and other parts of the picture are out of focus.

So how do you get a wider Depth Of Field for more detailed close up photography?

Finally getting to the point of the subject, one way is to use Focus Stacking.  This process is to take a good number of pictures, where the focus point is slightly adjusted each time a picture is taken.  Then all the pictures are put into a program, in this case Photoshop.  The program analyzes each picture to collect the parts that are in focus, and then these parts are all combined into one composite photo.  Walla.  The front, middle and back of the subject are now all in focus……. or are supposed to be.  This is assuming the program has all the necessary photos it needs to come up with a good and complete composite photograph.  You will see that since this is my first crude attempt at this, some flaws in the process show up.  There are parts of each stacked photo I made that the program could not perfect, and are left blurry.

How the focus points are determined broken down into two methods. 

1. Slightly turning the lens focus ring in uniform steps to incrementally change the focus point.  In this first trial run, I simply adjusted for the closest focus point I wanted, and then the farthest point I wanted, and marked those positions on the lens focus ring.  Then I divided up the area between the marks for the number of pics I wanted to take.  Click the shutter, adjust the focus one mark.  Click the shutter, adjust the focus to the next mark.  Again, click the shutter, adjust the focus to the next mark.   Etc. Etc.

2. The other method is to move the entire camera forward or backward to adjust the focus point. They make what is called a Focus Rail just for this purpose.  It allows for very precise movements, but I don’t own one.  In this, my crude application, I made marks on the countertop for the range of focus points I wanted.  So just like above where I changed the focus ring, here I pushed the whole camera rig about 1/8th of and inch or less for each picture.  (Time out – I have to go remove those pencil marks on the countertop before the wife gets home.)

And….. Too Much Writing….. on to some pictures…

Here are single focus and photo stacked comparisons.  Somewhat subtle.  Click on a pic for a larger view.

Single point focus

9 picture focus stack

Single focus point vs. six photo stack

Single point focus vs 17 picture stack

For the Photographers with Adobe Cloud who want to give it a try.

I started by looking for YouTube videos on how to do it.  Isn’t that the way you learn stuff now?  

1. Download the photo shoot pics from the camera into Lightroom
2. Selected the pics you want for a single image and export them to a new file ( I do this for my own organizing purposes)
3. Open Photoshop
4. In the file menu at top -> select “Scripts” -> select “Load files into stack”
5. Use the “files” option -> then click “browse” where you select the files you want to use (from #2)
6. Check the box labeled “attempt to auto align source images” -> click ok
7. Select all the layers -> then in “edit” at the top ->  select “auto blend layers”
8. Select “stack images option” -> check the “seamless tones and colors” box -> click ok
9. Photoshop does its thing.

Conclusion

Interesting.  I see that color is brought along more with the stacking.  I see that the focusing increments of the pictures needs to be more accurate.  Meaning, the in-focus parts of each picture needs to overlap some of the in-focus details of the next picture so that the program can effectively put the pieces together.  I missed some of that with this first attempt.  In my research, I did see some professional work that used HUNDREDS of stacked photos for one finished picture.  That will not be an objective of my future attempts.  But this session was interesting and I learned how to improve the next time I try this.

Thanks for the Look

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