Other than looking it up (if you can find it somewhere), by experimentation. Put the camera on a nodal slide or a full pano head, place a pointy object nearby, line it up in the camera with a pointy distant object, increase the aperture value to let you see both clearly in the shots you take, and start fiddling until you get it right

The point of the near object and the point of the distant object should not move relative to each other at all, when you move the camera from left to right and top to bottom. So, shoot it in the left of the frame, then shoot it in the right of the frame (horizontal for more accuracy), and see how they move relative to each other. Make an adjustment forwards or backwards on the nodal slide. If it gets worse, make an opposite adjustment. If it gets better, make another similar adjustment.

Note that at least in theory, the entrance pupil can move in a zoom as you zoom, and it might move as you focus as well, although I am not sure about that. I have never seen that yet, and I have tried a half dozen different lenses (all primes). In this case, you need to find several points from near-to-far zoom or focal length, and plot the curve, for ultimate accuracy.

And last, but by no means least, one needs a calm spell if there are any objects in the foreground that could/would move if the wind blows.
When I focus stack for landscapes, Live view really works well and is greatly improved by using a Hoodman loupe at least to help with picking your focus points. f8-f11 is my preferred aperture. Shooting in LiveView eliminates mirror bounce too. Hanging weight from the tripod helps. The more one shoots this way the quicker the process becomes.
On a side note...I'm on the wrong side of 70 with a bad back. I started using a SmallHD DP-6 monitor for low angle shots and it really saves my back. The screen view is outstanding and focusing for stacking and tilt/shift lenses is suprb.

Richard

The magnification errors in changing focus for focus stacking is what they call "lens breathing" right?
I have seen an example using CS5 to resize/align two landscape images of the same scene with just a change in focus, so that you could combine the foreground of one with the background of the other using simple masks. A poor man's Helicon Focus. I haven't tried this but it seemed to work ok in the example I saw. Anybody tried it?

Ardea wrote:
I started using a SmallHD DP-6 monitor for low angle shots and it really saves my back. The screen view is outstanding and focusing for stacking and tilt/shift lenses is suprb.


Very interesting product! Can you talk a bit about how you use it, and how the colour accuracy and focus aiding works, as well as brightness in the field?

carstenw wrote:
Ardea wrote:
I started using a SmallHD DP-6 monitor for low angle shots and it really saves my back. The screen view is outstanding and focusing for stacking and tilt/shift lenses is suprb.


Very interesting product! Can you talk a bit about how you use it, and how the colour accuracy and focus aiding works, as well as brightness in the field?

There are several products like this now. Many were made for video dSLR use. The better ones use the dSLR HDMI output, while lower resolution LCD viewfinders use the video out jack.

http://www.bhphotovideo.com/c/product/712236-REG/Marshall_Electronics_M_LCD7_HDMI_B_CE6_M_LCD7_HDMI_CE6_7_Portable_On_Camera.html

http://www.bhphotovideo.com/c/product/760512-REG/Ikan_VL7_7_HDMI_LCD_Monitor.html

http://www.aputure.com/en/product/gigitube_wireless_digital_viewfinder.php
available through Amazon, and is wireless with a remote shutter

http://www.bhphotovideo.com/c/search?Ntt=sony+clmv55&N=0&InitialSearch=yes

there are more, but this will get you started.

Very interesting product! Can you talk a bit about how you use it, and how the colour accuracy and focus aiding works, as well as brightness in the field?

Hi, Pretty busy today, will let you know ASAP. So far VERY pleased with the SmallHD. BTW I have no affiliation with that company.
Richard

I did a test today and the results tally closely with those reported earlier in this thread. To summarize:

Equipment: 5D Mark II with RRS L-plate, RRS basic pano package.

- ZE 50 f/2 Makro Planar: mark is at 11.7cm (+/- 0.1)

- ZE 100 f/2 Makro Planar: mark is at 10.25cm (+/- 0.1)

Rajan Parrikar wrote:
I did a test today and the results tally closely with those reported earlier in this thread. To summarize:

Equipment: 5D Mark II with RRS L-plate, RRS basic pano package.

- ZE 50 f/2 Makro Planar: mark is at 11.7cm (+/- 0.1)

- ZE 100 f/2 Makro Planar: mark is at 10.25cm (+/- 0.1)


Thanks! I just got my RRS pano basic pkg and am about to figure mine out for my 1ds3 and ZE 50MP and CY 100 P. Wondering if there will be any difference between the numbers for 5d2 and 1ds3?

There might be, due to the slightly different placement of the tripod hole, or the shape of the base, if using an L-bracket.