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Stack Focusing -- move camera or focus ring?

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Surely if you move the camera you are changing the framing? In fact you will be doing the same by moving the focus ring (at least you would with my macro lens).
Can I follow this thread too please?? :-)
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http://www.andrewsandersphotography.co.uk
 
It is often harder to move the camera in precise intervals for focus stacking - big heavy camera. I do a lot of stacking with small objects and find it easier to move the subject with a micrometer stage, but that requires an extra purchase.

It is also easy to adjust the extension/focus ring. If you are shooting above 1:1 you are likely using extension tubes or a bellows. Adjusting the extension/focus ring will generally move the entrance pupil less than moving the camera/object, that would mean less change in perspective. If you are stacking an object with a lot of depth, that is a slight advantage. Not sure how much the entrance pupil will move for an internal focus lens - it may move significantly and may hose up all of the advantage of this method.
 
This reminds me of a dumb question I haven't been able to figure out the answer to: if you're using a focus rail with quick-release plates, how do you mount longer lenses, with their own foot and plate, on the rail? Lens plates are oriented at right angles to camera plates.
 
sfs said:
sfs wrote:

This reminds me of a dumb question I haven't been able to figure out the answer to: if you're using a focus rail with quick-release plates, how do you mount longer lenses, with their own foot and plate, on the rail? Lens plates are oriented at right angles to camera plates.
Click to expand...
The lens with it's own foot/plate would have to be compatible with whatever quick-release system your focus rail uses. IF the foot/plate has a basic tripod (3/4") screw attachment...then you (for example)...could simply attach the Novoflex QPL-1 quick-release to it and then put it on the rail.

Of course, each lens/setup might need to be configured so that it sits very well on the rail, etc. I would imagine that some large lens collar/foot setups might indeed make the rig somewhat unstable, or un-balanced.

KEV
 
sfs said:
This reminds me of a dumb question I haven't been able to figure out the answer to: if you're using a focus rail with quick-release plates, how do you mount longer lenses, with their own foot and plate, on the rail? Lens plates are oriented at right angles to camera plates.
Click to expand...
I use the Kirk focus rail and the quick release clamp can be rotated 90 degrees. It requires an allen wrench and about 30 seconds. You have to loosen the mounting screw and then turn the clamp 90 degrees.

http://www.kirkphoto.com/Focusing-Rail-Macro.html

Another solution is to use two RSS B2-FAB clamps. See the illustration at the bottom of this web page:

http://reallyrightstuff.com/rrs/Itemdesc.asp?ic=B2-FAB&eq=&Tp=
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Bill Janes
 
I think you’ll need to try the two methods on your own to know for sure.

I just tried my first focus stack a few days ago. I was shooting a shot of a lens. The lens was sitting on its end cap and I lit the 6 to 9 o’clock side of the lens (if looking down from the top of the lens) and let the rest fade to black around the barrel of the lens.

I shot two sets of stacks, one by moving the focus ring and one by moving the rig on the rail. The one done by focusing turned out well but the one using the rail came out a little odd. Instead of having a round lens it looked as if part the lens barrel was pushed in.

I haven’t seen anything in the focusing rail stack that shows any inconstancies in the individual shots to explain the odd shot. Since this is my first attempt at stacking I’m chalking it up to user error and moving on.

On another related topic I’m wondering if it’s better to adjust and sharpen the individual shots first (batch processed for consistence) and then run through the stacking program or to start with the stacking program first. I’ll need to start a separate thread for that.

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Snapshott
 
Your experiment matches exactly what I figured would happen. By moving the camera each slice is at the same reproduction ratio when as you go farther back in the stack the slices should be getting smaller to maintain the correct shape in the stacked image.

Larry.
 
I won't even consider the first two solutions: chosing a smaller aperture or using a TC lens: neither will ever give enough DOF in extreme cases !

Now, I tried both other solutions: moving the combo camera/lens and rotating the focus ring, and definitely settled on the latest one !

WHY ??? Simply that -in my case- I happened to have to shoot products DEEPER than any focussing rail would allow !!! Hence, with a "macro" lens, one can focus closer to the nearest part of the object, and by rotating the focus ring, get a sharp CENTER OF IMAGE at any distance beyond that point ! ...and never mind the supposedly distortion created by the apparent change of "size" of the OOF parts or the object, the resulting stacked image is sharp "from head to toes" !

I shot stuff nedding up to more than 50 images -stacked with Helicon Focus- and very seldom had ghosting or other problems !

As an example, here's a full-size (4256x2832) image of a 2-meter ruler ! It's -folded- length is about 11 inches. Even though it's been shot at 45°, it's longer than any focussing rail !



More stacked stuff at http://www.pbase.com/scherrer/studio_work !

Cheers,
J-P.

Photo Galeries at http://www.pbase.com/scherrer
Spherical Panoramas (360x180°) at http://www.360cities.net/profile/jps
Equipment list in profile
 
JP Scherrer said:
Now, I tried both other solutions: moving the combo camera/lens and rotating the focus ring, and definitely settled on the latest one !
Click to expand...
I use focus slide for shallow stacks (few centimeters), and the focus ring for deeper stacks. The first because that give me better control, the last because thats the only solution for deeper stacks.
 
Thanks everyone. The information is very helpful. What I take away is that when the depth of the object is less, move the camera; when the depth is great, use the focus ring. I don't move the subject. I am learning how much to adjust for each photo, so I thin lots of it is by learning-by-doing, as well as estimating the DOF for each photo.

As for moving the camera, I have made several systems, in part because I like the challenge of modifying things from old cheap parts and equipment. Keeps the cost of macro photography down. I have one system for high magnification (1:1 and greater), another for lower magnification (up to 1:1), and one for the field.

If interested, you can see at:

http://www.flickr.com/photos/9476880@N02/4779245118/
http://www.flickr.com/photos/9476880@N02/4719422934/
http://www.flickr.com/photos/9476880@N02/4677798426/

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http://www.flickr.com/photos/9476880@N02/
 
Member said:
JP Scherrer wrote:

I shot stuff nedding up to more than 50 images -stacked with Helicon Focus- and very seldom had ghosting or other problems !
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Hey JP,

When you are stacking 50 images with Helicon...which file format are you using...jpegs? I simply ask that coz I can't imagine any software prog being able to handle say 50 large TIFF files or even 50 NEF files all together at once.

When I try to stack more than say 10 TIFF images in CS4 it starts to puff n pant and has a hard time with it.

Also, in Helicon...are there any specific settings that really improve stack quality?...as I've had rather mixed results with that software (especially with regard to alignment)...so I was thinking that I might possibly be missing something.

Cheers,

KEV
 
A few quick things.

Thanks for the link. I had used in previously for normal shooting, but not for macro.

I have been just visually estimating how much to move or refocus, somewhat hit or miss.

However, it the calculator does not seem to work when I put in small distances that are associated with high (1:1 and greater) magnification. I might be doing something wrong. If that calculator does not work, is there other and easy ways to estimate the DOF?

I also realized that moving the camera is easier and/or more precise if moving by increments of a given distance. The focal ring is non-linear.
JP Scherrer said:
...find the DOF you will get, when using an aperture X, at http://www.dofmaster.com/dofjs.html !

...then, knowing the DOF and the total DEPTH of your subject, it's very easy to calculate the number of shots needed ! (usually, I double the # of images, just to be sure !)

Cheers,
J-P.

Photo Galeries at http://www.pbase.com/scherrer
Spherical Panoramas (360x180°) at http://www.360cities.net/profile/jps
Equipment list in profile
Click to expand...
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http://www.flickr.com/photos/9476880@N02/
 
...whenever I shoot for stacking images, it's almost allways "macro" ! So, my workflow is the following:

1) I move the camera (or the subject) until it's furthest point is near one of the upper corners of the frame and I rotate the focus ring until I get a perfect focus at this point
2) I check the distance on the lens ring

3) I rotate the ring backwards until the NEAREST point is in focus AND as near as possible to the opposite lower corner of the frame
4) I check the distance on the lens ring

...usually I have to re-frame the subject until the nearest and the furthest point IN FOCUS are centered in the frame

5) I rotate the ring slightly before the nearest focussed point, shoot, rotate the ring about 1 to 2 millimeters, shoot again... until I get slightly passed the furthest focus point !

I usually take more pics than really needed, bu I prefer it than having OOF problems because I spaced too much some pics !

Cheers,
J-P.

Photo Galeries at http://www.pbase.com/scherrer
Spherical Panoramas (360x180°) at http://www.360cities.net/profile/jps
Equipment list in profile
 
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