## newbie zerene stacker noise problem

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

johnsankey
Posts: 20
Joined: Fri Mar 02, 2012 6:54 am
jzucker wrote:I have been using an online DOF chart to calculate the distance between exposures for my stacks. That's what I used to create the 1mm spaced exposures for this image in the first place. However, when I re-stacked this project using every 4th image, I was changing the spacing from every 1mm to every 4mm and still the focusing stack looks smooth to me. This is telling me that the DOF chart is showing me a more narrow DOF than what is actually required to create a good focusing stack.

Is there an article discussing this in any detail? Obviously, I'd like to make the minimum of exposures for a given stack in order to maintain a smooth and consistent focus.
DoF is very subjective and depends on the size at which you are viewing the image as well as the importance to our eyes of the detail in the shot. I give formulae based on standard viewing criteria at
http://johnsankey.ca/tripod.html#E
but any such calculation of DoF is only a guide.

jzucker
Posts: 16
Joined: Sun Mar 04, 2012 5:11 pm
Fantastic Stuff John. Thanks for the tips.

I wanted to post my workflow for critique/commentary. I've been getting mixed results so obviously this workflow isn't perfect.

1. Calculate DOF using http://www.dofmaster.com/dofjs.html
2. Measure Depth of subject in which I want DOF within
3. Divide Depth of subject by DOF (Here we probably want to do something like DOF/2 as a fudge factor)
4. Focus on frontmost part of subject
5. Take exposure
6. Increment rail by result of step 3
7. Repeat 5 and 6 until total distance >= result of step 2
[/list][/list]

rjlittlefield
Posts: 21529
Joined: Tue Aug 01, 2006 8:34 am
Location: Richland, Washington State, USA
Contact:
I wanted to post my workflow for critique/commentary. I've been getting mixed results so obviously this workflow isn't perfect.
Sorry I missed this last post earlier.

It's probably just a typo, but as written there's a problem in steps 3 and 6.
3. Divide Depth of subject by DOF
...
6. Increment rail by result of step 3

The division in step 3 will give you the number of frames to be shot, for example 20 mm depth of subject divided by 2 mm DOF gives 10 frames. In step 6, the increment should be the 2 mm, nothing to do with the 10 that resulted from the division.

--Rik

jzucker
Posts: 16
Joined: Sun Mar 04, 2012 5:11 pm
Yes, it was a typo but just to clarify, I increment by the DOF/2 typically.
rjlittlefield wrote:
I wanted to post my workflow for critique/commentary. I've been getting mixed results so obviously this workflow isn't perfect.
Sorry I missed this last post earlier.

It's probably just a typo, but as written there's a problem in steps 3 and 6.
3. Divide Depth of subject by DOF
...
6. Increment rail by result of step 3

The division in step 3 will give you the number of frames to be shot, for example 20 mm depth of subject divided by 2 mm DOF gives 10 frames. In step 6, the increment should be the 2 mm, nothing to do with the 10 that resulted from the division.

--Rik

rjlittlefield
Posts: 21529
Joined: Tue Aug 01, 2006 8:34 am
Location: Richland, Washington State, USA
Contact:
jzucker wrote:I increment by the DOF/2 typically.
Sounds good.

Have you tracked down yet what was producing the "mixed results"?

--Rik

jzucker
Posts: 16
Joined: Sun Mar 04, 2012 5:11 pm
rjlittlefield wrote:
jzucker wrote:I increment by the DOF/2 typically.
Sounds good.

Have you tracked down yet what was producing the "mixed results"?

--Rik
it seems that the stacker software gets confused on high contrast areas that lay over areas of blur. For example, a flower petal that is an inch in front of a leaf. The edge of the flower transitioning to the leaf will often suffer from edge artifacts.

It's too bad the clone tool doesn't have some blend options. It would really make a huge diff.