sippyjug104 Loc: Missouri

The information in this post is not intended to be a "sermon for the choir" for it is for those who may have an interest or be new to focus stacking.

This post addresses why focus stacking is necessary at higher magnifications as well as its importance when using some of the lenses or techniques that are different than the conventional camera lens and the beloved 1:1 true macro lenses and the variable magnification macro lenses.

I staged a session this morning of the moth which shows how the antenna is in detail yet just a fraction of a millimeter past is out of focus. This image was taken with a stack of 373 images by advancing the camera 12-micrometers for each shot.

The second image is one of my spiders which is the first image of the stack. Notice how only the 'tip of a hair' is in focus and all else is a blur. These two examples are good examples of why focus stacking is necessary to bring the desired area of the subject into a sharp focus unless total blurr is the goal.

The lenses most commonly used for higher magnification (aside from the variable power macro lenses) are considered "flat depth of field". One such lens often used are "enlarger lenses" mounted either forward or in reverse fashion. When installed on an extension such as a bellows the amount of magnification produced increased with the distance that it is extended from the camera's sensor.

Enlarger lenses are an excellent choice for focus stacking because they are designed for a flat depth of field corner to corner. They are designed to transmit the fine details of a flat film negative, enlarge it and project it onto the developing paper. Sounds a lot like what we want to achieve in our macro photography, doesn't it?

Because the depth of field is as thin as a photo negative the camera needs to work in "slices" and software must be used to "stack" all of the images together to produce one sharp image. I equate it to shooting a loaf of bread one slice at a time and then putting them all together in a program that aligns and combines them in a specialized way.

Microscope objectives are another choice. Once again think about how microscopes are used...they view a flat glass slide and when you see them being used the end of the objective is very, very close to the glass slide. Of course there are specialized objectives that have longer working distances such as those used in tool making and metallurgy which make excellent lenses for focus stacking due to their longer working distances to accommodate illumination of the subject.

Subjects that cannot be covered in view in their entirety can be "stitched" together similar to what one would do in a landscape panorama although quite different in application and technique. The lenses that perform best when a series of shots are taken...the the subject is moved to accommodate the view of another section is to use a telecentric designed lens for it does not have parallax as non-telecentric lenses do.

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Mark Sturtevant Loc: Grand Blanc, MI

Very good. My own take is that focus stacking is of course the only way to get a certain effect that is deemed to be one of the desirable things to do in the hobby. Here one creates an extended depth of focus picture at higher magnification, all while preserving very high details. This is juxtaposed to extremely soft out of focus backgrounds, which adds 'punch' to the exceptional details made visible by focus stacking. So the super soft backgrounds are also very important to the over all appeal of focus stacking, since it is widely viewed that soft out of focus backgrounds adds to the beauty of a picture. One cannot get the same combination of effect with a single frame picture at smaller apertures - not of very small subjects, anyway -- since there is some softening by diffraction (even if only subliminal, it's still there), and the background will also have more detail at smaller apertures. So focus stacking is the only way to get a certain combination of effects that is deemed beautiful by people who appreciate macrophotography.
One can see evidence of the powerful effect of focus stacking by counting the number of "likes" of focus stacked insects on Flickr, versus single frame pictures. Before I got into focus stacking, I was getting a bit jealous!

sippyjug104 Loc: Missouri

Thanks, Mark. I view you and the other regulars on this forum as masterclass experts with myself being someone that has learned and is still learning much from you and them so for this I will always be thankful. Your comments are spot-on as to why one would want to perform a focus stacking session compared to that of a single-shot macro image which have their own beauty and interest.

Unless the subject is 'absolutely flat' and perfectly perpendicular to the camera sensor it is not possible to get all of the subject in focus at higher magnifications with such a shallow depth of field that specialty lenses provide.

For example, the objective that I used for the moth antenna is listed by Nikon to have a 0.017mm depth of field which is designed as a measuring microscope objective at 5X magnification. With a depth of field so near flat, using it for focus stacking is the only practical photographic use for it.

Mark Sturtevant Loc: Grand Blanc, MI

Sippy (if I may call you that), you are of course far, far beyond being only the student. Although it is true we are all learning.

kpmac Loc: Ragley, La

I am still in awe of your work and your gear.

sippyjug104 Loc: Missouri

Thanks, Kpmac. There's nothing special about the camera, it's just a little Fujifilm X-T20 crop sensor mirrorless camera. The bellows and my most often used reverse mounted enlarger lens combined are less than $100 (my special 5X was $300). The digital motorized focus rail is $299 although it can be done with a manual rail which I started out with.

Compared to the $1500 Canon MP-E65 macro lens or the $1350 Nikon 200mm f/4 AF-ED macro lens it's quite a bargain.

FiddleMaker Loc: Merrimac, MA

And with a better overall end result !!

sippyjug104 Loc: Missouri

Thanks for the reply. Of course a typical 1:1 macro lens does an excellent job when used for focus stacking as do the special variable magnification macro lenses. These lenses work great in the field and the ones that will focus to infinity can be used for other venues than macro. The downsides are the price, size and weight. My Nikon 200mm macro weighs 2-1/2 pounds and makes a great club if I would ever need to defend myself from an angry bear.

A typical macro lens can be extended to obtain more magnification and they can even be paired with a Raynox or other brand magnifying lens to boost the magnification. Extending the 'super macro' variable magnification lenses that go from 1X to 5X with extension tubes or bellows is not practical for the working distance is so close to the end of the lens that illumination is impossible at best without getting lens flare.

This is where using alternative methods have a distinct advantage in producing workable higher degrees of magnification. The tradeoffs are that they do not focus to infinity and the depth of field is sooooooo flat that unless they are used to photograph a flat subject, like a stamp, placed perfectly parallel to the camera sensor parts will be way out of focus.

This is where focus stacking becomes necessary to get more depth of the subject in sharp focus.

sscnxy

Yep. I'm still jealous, Mark.

NY