Macro photography stacking: focus shift vs. camera movement

Question

Getting into some high magnification macro photography (Using a Raynox 250 on top of a 105mm FF). Does one get better stacking results by moving the camera (by hand, or on a rail), or does changing the focus on the lens while keeping the camera steady give better results?

I've been having some trouble using the first method, but that may be due to me shooting handheld, and introducing large "angle" differences.

Note that unlike similar questions, I'm not interested in other differences such as ease of use or composition. I'm purely interested in the stacking results: both ease of alignment for software, as well as final blended image stack results.

Answer 1

Both approaches are problematic. One changes the magnification ratio (by altering the lens' focusing distance) without changing the distance between the camera and subject. The other changes the distance between camera and subject without changing the magnification ratio of the lens.

Which works better will vary based upon the specific qualities of the lens used and exactly how much the magnification is altered by the adjustment of the focus position of the lens.

For most well designed macro lenses, altering the camera/lens distance to the subject tends to work better than changing the position of the lens' focusing elements.

When stacking two lenses on top of each other, though, all bets are off. You're just going to have to experiment to see which yields better results. Unless you can find someone who has done technical measurements with that particular combination, you have no way of knowing how much the combination will breath (change the Angle of View) when you alter the focus position on the 105mm lens. You also have no way of predicting how much the geometric distortion contributed by the Raynox adapter will affect the advantage of one approach over the other. Even what percentage of the frame is occupied by your subject and how close to the edges of the frame your subject is can affect which approach might work better.

One thing that can be definitively stated is that trying to do this handheld will be near impossible. Regardless of the advantages/disadvantages of focus position changes versus distance changes, shooting handheld will not cut it for image stacking with macro photography.

Answer 2

[This isn't really a contesting 'answer' - more an additional caveat]

Personally, I've found that the method is far less important than the 'content'.
Low contrast is your enemy, no matter which stacking software you use.

I've found Zerene 'better' at following indistinct edges than Photoshop or Luminar, but it's worse at retaining a smooth background & has a tendency to halo.
End result is that sometimes I need to pull out the background & treat it separately.

Ref to an early part of my learning curve on the subject - Improve focus stacking

In practise, I usually pull focus for larger objects & use a rail when they're down at 2mm or smaller.

Answer 3

The answer, as usual, is that it depends - one size approach does not fit everyone. A lot depends on your subject.

For "big" macro subjects - think flowers and bigger - a focusing rail seems like an overkill, and you can get away with hand holding or internal focusing. Depth of field will be large, and stacking will require three to five images.

For small macro subjects - think insects and smaller - the depth of field decreases to such an extent that you need a lot of photos. For a fly sized subject ten evenly spaced images is about minimum, twenty is better and fifty or even more are not uncommon when photographing pinned insects.

In such a situation a focusing rail works the best. Hand holding is out of the question, and internal focusing is not quite as precise. This is what I use.

I have seen photos of setups where the camera stands still and the subject (a pinned insect) moves, driven by a stepper motor. The results are also acceptable, but I have no personal experience with these.

An inspiring read is a manual on insect photography by Sam Droege, an expert on photography of bees and a minor celebrity on Flickr. He really knows his macro...

Answer 4

Here Are the three ways of shooting stacked macro. Starting off with the worst (extreme macro situations)

1. (Worst) Use a focusing rail and move whole camera and lens together. This alters the perspective and this is a problem in extreme macro when stacking in post.
2. (Not bad) Focus the lens at each shot. This may introduce some perspective change but will definitely introduce magnification through focus breathing even at moderate macro. The amount will depend on your lens. (Nikon D850 will do this automatically without touching the camera)
3. (Best) Use bellows and fix lens to subject distance. Move camera to achieve focus. This maintains the perspective between the lens and subject and eliminates lens focus breathing problems. This method gives your stacking software the best chance of stacking without introducing unwanted artifacts.

Answer 5

My experience -- Moving the entire camera with lens, towards or away from the subject allows for finer increments of adjustment compared to adjustments with camera stationary and using rail focus adjustments.