DoF/3 = step size?

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

Moderators: rjlittlefield, ChrisR, Chris S., Pau

rjlittlefield
Site Admin
Posts: 23561
Joined: Tue Aug 01, 2006 8:34 am
Location: Richland, Washington State, USA
Contact:

Re: DoF/3 = step size?

Post by rjlittlefield »

dhmiller wrote:
Thu Aug 26, 2021 3:13 pm
I assume, however, that the fraction of DoF for step size used will need to be be different with different subjects and level of detail (not to mention lighting).
The optimum fraction will be different with different subjects, and level of detail, and lighting, and I'm not sure what else. Sometimes I think that phase of the moon must factor in somehow.

That said, I expect that you'll pretty quickly figure out what works for you under various conditions, and how hard you're willing to work to get the optimum step size.

Adalbert's approach seems to be simple and effective for what he does: just use DOF/3. That would be a waste of resources for what I do, but on the other hand his results are gorgeous while mine are utilitarian. Horses for courses...

--Rik

Adalbert
Posts: 2426
Joined: Mon Nov 30, 2015 1:09 pm

Re: DoF/3 = step size?

Post by Adalbert »

Hi Rik,
Adalbert's approach seems to be simple and effective
yes, it is very simple, but sometimes there are some problems with noise. It seems to depend on the number of images.

Please have a look at the hilly landscape (last picture on the following page):
viewtopic.php?f=27&t=43903

Best,
ADi

rjlittlefield
Site Admin
Posts: 23561
Joined: Tue Aug 01, 2006 8:34 am
Location: Richland, Washington State, USA
Contact:

Re: DoF/3 = step size?

Post by rjlittlefield »

Adalbert wrote:
Fri Aug 27, 2021 3:47 am
yes, it is very simple, but sometimes there are some problems with noise. It seems to depend on the number of images.
I assume that what you're seeing is noise accumulation by PMax.

The best reference I know for this effect is viewtopic.php?p=234652#234652 .

Did you use entirely PMax for the hilly landscape, or was that some combination of PMax and DMap?

--Rik

Adalbert
Posts: 2426
Joined: Mon Nov 30, 2015 1:09 pm

Re: DoF/3 = step size?

Post by Adalbert »

Hi Rik,
Many thanks for the link!
Yes, for this photo I used PMax exclusively (sub-stacks of PMax), because of the hair.
I have the impression that PMax handles the hairs on different layers (at different depths) better than DMap .
Best, ADi

rjlittlefield
Site Admin
Posts: 23561
Joined: Tue Aug 01, 2006 8:34 am
Location: Richland, Washington State, USA
Contact:

Re: DoF/3 = step size?

Post by rjlittlefield »

Adalbert wrote:
Sat Aug 28, 2021 2:28 am
I have the impression that PMax handles the hairs on different layers (at different depths) better than DMap .
Yes, DMap is prone to producing loss-of-detail halos wherever there is a sudden jump in depth.

--Rik

ray_parkhurst
Posts: 3413
Joined: Sat Nov 20, 2010 10:40 am
Location: Santa Clara, CA, USA
Contact:

Re: DoF/3 = step size?

Post by ray_parkhurst »

I did not see this thread first time around, but I have some input that might be interesting to some.

My subjects are overall fairly flat (coins), but the fields especially have a "basin" to them such that they are lower in the middle than on the edges. This slow-changing topography can create what I would call "distortion" of the final image near the transitions from one frame to the next. In order to get maximum sharpness in the final image, I do not allow the stacking program to scale the image from frame to frame. This works perfectly well for telecentric optics such as the Nikon MM objectives, and minimal distortion is created, but for other objectives such as the Nikon Printing-Nikkors, the lack of scaling creates small mag changes from frame to frame, and these can "distort" the frame boundaries. To mitigate this effect, I will run more shots than are typically needed, thereby minimizing the frame to frame mag changes. This seems to make a better transition between frames and less "distortion" in the final image.

Post Reply Previous topicNext topic