Stitching and "Focus stacking" combined?

[BartvanderWolf]

I have a noob question:

Instead of using stacking software or algorithms, why don't people use masking in photoshop to 'layer in' each plane? Won't that give precise results, or is there a downside?

Hi Sareesh,

I agree with Bill. When you focus at different distances, the magnification factor of the projected image on the sensor will change. Therefore the software must do several things, resize each image, align the images in the stack, adjust variations in exposure, and select/mask the sharper portions of each image, and blend the selection between the successive images to a seamless transition.

That's a lot of (tedious) work to do by hand, especially when the number of images in the stack increase. I've done macro images with more than 100 stacked images each. What's more, programs like Helicon Focus use better resampling algorithms (Lanczos) for these small scale image size adjustments than Photoshop (bicubic) does, and they can use things like a dustmap to automatically remove the shadows of sensor dust particles, which will otherwise leave very noticeable trails of spots due to the resizing.

Cheers,
Bart

[Sareesh Sudhakaran]

Thank you for explaining, Bill and Bart. I didn't consider the agony of having a 100 images to blend in!

[John R]

I tried Zerene and Helicon, each left ghosting. And yes this was for macro work of flowers, mostly creative work. At micro levels, you have to be discerning about what to include in or out of focus. It's a different proposition for landscapes. You mostly want everything in focus. What I did not try was combining large numbers of images. I used only 5 or 6 at most. I am just going to have use the old method of trying different focal points and different apertures to get what I want. With film slides, you didn't waste film!

JR

[BartvanderWolf]

I tried Zerene and Helicon, each left ghosting. And yes this was for macro work of flowers, mostly creative work. At micro levels, you have to be discerning about what to include in or out of focus.

Hi John,

Maybe therein lies the problem, just missing the required shots for a smoother transition. The usual issue is with occluding features. When focusing on features further away, foreground features become somewhat transparent and the blending has trouble deciding which sharp image to use, foreground or background. HeliconFocus' Method B (using a depth map) is better at getting the edges right, because Method A uses averaging which is better for surface structures. The recently added Method C (pyramid) may also work well. It can work well if you combine parts of the the A/B/C output by using the retouching functionality of HF Pro. Zerene also offers  retouching capability if I remember correctly.

It's a different proposition for landscapes. You mostly want everything in focus. What I did not try was combining large numbers of images. I used only 5 or 6 at most.

Depending on the magnification factor, that may be too few. Based on the magnification factor, you can use the (slightly less accurate, but accurate enough) DOF approximation formula for close-up and macro photography, which uses the magnification factor as input. Your sensor size in relation to the size of your object will give you the correct magnification factor to use. The CoC to use in that formula equals the sensel pitch, if you want seamless sharpness per pixel from front to back. If you are going to output at less than pixel per pixel size, you can increase the CoC proportionally.

Cheers,
Bart

[bill t.]

Basically, if you have nearby objects like trees with bare branches where you can see the horizon through openings between the branches, you need to shoot as many focus planes as possible to keep the ghosting down.

However, ghosting is not always bad.  Sometimes very subtle ghosting around nearby vegetation can help separate it from more distant textured background in ways that is really not objectionable in the print.

[Michael H. Cothran]

I have a noob question:

Instead of using stacking software or algorithms, why don't people use masking in photoshop to 'layer in' each plane? Won't that give precise results, or is there a downside?

Using Auto-Align will match up your layers so there are no offsets.
There are many photographers on the Nature Photographers Network - http://www.naturephotographers.net/enter.html
that are churning out superb results using combinations of stacking, stitching, and exposure blending.

NPN member Marc Adamus comes to mind - http://www.marcadamus.com/ .

NPN member Tony Kuyper has produced some excellent actions for creating Luminosity Masks - http://goodlight.us/ , which are quite beneficial. Check out his tutorials.

NPN member Pat Sampson, who is "taking a break" has some exquisite florals that are stacked - http://www.naturephotographers.net/imagecritique/ic.cgi?a=up&pi=PATSAMPSON&ns=1&CGISESSID=bb8866b4fac309c6645e8ea0aa50bf59&u=24287
My favorite Pat Sampson image is titled "Red Tulips" five rows down.

Here's one by NPN member Craig Strand I really like - http://www.naturephotographers.net/imagecritique/ic.cgi?a=vp&pr=179350&CGISESSID=bb8866b4fac309c6645e8ea0aa50bf59&u=23948

Here is a link to a few more NPN stacked florals - http://www.photoportfolios.net/portfolio/pf.cgi?a=sp1&gr=4
Note - select "Flowering Plants," then type "image stack" in Optional Keywords.
                                                                  
Developing good skills through practice can produce amazing results.

[Sareesh Sudhakaran]

Thanks for the links, Michael. Will check them out.

[prairiewing]

Thanks Michael, I hadn't looked at that site for years.  Great work.

[sdwilsonsct]

Great thread for us noobs: thanks, everyone. This explains some of my soft landscapes and I look forward to trying these techniques.
Scott