What is the best way to do focus stacking with a bellow

When I use a bellow for close up, I can change the plane of focus in 3 ways. Which is the best way.

1. Move the lens.

2. Move the camera.

3. Move both lens and camera together.

I would use a macro rail and do #3.

 

Remember that you will see SERIOUS changes in the field of view when moving either the camera or lens.

#3 for sure. Remember that depth of field and depth of focus switch their relationship once you go beyond 1:1

Using a bellow I have the options of doing any of the 3 ways. Although with the bellow I can go beyond 1:1 I don't really have need for that. And thanks I think I would do #3.

Do you mean changing it in order to create a series of images you can stack? Or just to achieve focus for a single image?

 

If you are just trying to achieve focus for a single image, #3 is fine.

 

If you want to create a stack of images for focus stacking, #3 is a bad choice because it changes the location of the entrance pupil. If you are going to stack at the level of magnification you are talking about, then you don't want to move the entrance pupil. You can fix the lens and move the body. However, the simplest thing is to bother with a bellows at all, assuming you have a macro lens. Use the rail (#3 style) to help you achieve the framing you want while focusing on the nearest point of the object. Then leave the rail alone and simply rotate the lens barrel slightly before each additional shot. You can also get software (Helicon Remote, and I think others) that will automate this: once you figure out how large the rotations will be, you just set the near and far points and let it chug along. I do it manually instead.

 

If you want to see a video that more clearly explains this, see

Do you mean changing it in order to create a series of images you can stack? Or just to achieve focus for a single image?

 

If you are just trying to achieve focus for a single image, #3 is fine.

 

If you want to create a stack of images for focus stacking, #3 is a bad choice because it changes the location of the entrance pupil. If you are going to stack at the level of magnification you are talking about, then you don't want to move the entrance pupil. You can fix the lens and move the body. However, the simplest thing is to bother with a bellows at all, assuming you have a macro lens. Use the rail (#3 style) to help you achieve the framing you want while focusing on the nearest point of the object. Then leave the rail alone and simply rotate the lens barrel slightly before each additional shot. You can also get software (Helicon Remote, and I think others) that will automate this: once you figure out how large the rotations will be, you just set the near and far points and let it chug along. I do it manually instead.

 

If you want to see a video that more clearly explains this, see

 

Using a macro lens and turn the focusing ring wouldn't that the same as moving the lens which moves the entrance pupil? However, with modern marco lenses which have internal focusing I am not sure what to expect.

With a unit-focussing (i.e. non-IF lens) there's going to be a shift of scale whichever method you choose. However, at close to 1:1, moving the camera results in a lesser scale change than moving the lens. Whereas a focus-slide keeps the scale constant at the focus plane, but the shift in subject-lens distance still results in a change of perspective and absolute magnification that needs compensating for in the stacking software.

 

Basically, without altering the lens focal length, there's always going to be a scale change with any change in focus.