Fun with Focus Stacking

[pnolan48]

Pete Nolan:  You mention that Helicon has problem with things like ship's railings (which are close to the camera) being fuzzy. That is because none of the photos in the stack contain the focused area of the image which would be directly behind the railing.  When the image in the stack is focused on area behind the railing, the railing is out of focus. Being out of focus, it's silhouette is wider then when the camera is focused on the railing. Since none of the images in the stack contain focused information directly behind the railing, the stacking software leaves that area fuzzy.

Which is exactly why eliminating some intermediate slices often improves the result. I understand how Helicon works--if you can find a copy of Computer Graphics World from late 1984-early 1985, I wrote about the principles, drawing on work from MIT's computer imaging lab in the early 1970s (or earlier). The name of Prof. Negropointe sticks in my mind, but may be a false memory.

The problem with things like railings is well understood. As you said, Helicon tries to determine the optical bloom caused by changing the focus in each slice and sometimes doesn't have enough information. Giving it fewer slices to chew upon often clears up that problem.

[pnolan48]

This is definitely a stacked Helicon image:



In the lowest right corner you can see some halo effect on the rails. They were too close to be in focus at the nearest focus setting.

As I was on forums other than Railwire for a long time, I suspect many of you haven't seen most of my images.

[pnolan48]

The depth of field in this shot is probably 3" to infinity, in this case perhaps 12 feet. The close-in slices were shot a f/22, to make the closest objects as much in focus as possible; the remaining slices were at f/8.

[pnolan48]

This shot would be impossible without Helicon:

[pwnj]

And that's a mother-beautiful bridge (shot), Pete! 

[Jesse6669]

Can I ask a stupid question? 

Does pinhole photography still hold it's own for extreme depth of field, such as with digital pinhole adapters like these: http://wanderlustcameras.com/products/pinwide.html

[DKS]

Can I ask a stupid question? 

Does pinhole photography still hold it's own for extreme depth of field, such as with digital pinhole adapters like these: http://wanderlustcameras.com/products/pinwide.html

Not a stupid question at all. Pinholes create a degree of softness due to diffraction at the edges of the aperture, so it's hard for them to compete with the best image stacking.

To give you an idea, this image was taken with a 300-micron laser-cut aperture mounted in a 50mm lens. The DOF was a fairly healthy 4" to infinity.



One other drawback of pinhole photography is the long exposure times, even when pumping a lot of light onto the scene; the one above was somewhere in the neighborhood of 20 minutes using around 750 watts of light. I melted some models doing pinhole photography back then.

That said, things have come a ways since I was doing this (1990s), so YMMV.

[MVW]

This is definitely a stacked Helicon image:



In the lowest right corner you can see some halo effect on the rails. They were too close to be in focus at the nearest focus setting.

As I was on forums other than Railwire for a long time, I suspect many of you haven't seen most of my images.

That is a jaw-dropper.

Jim

[PAL_Houston]

This shot would be impossible without Helicon:

And even with Helicon it will be a challenge for us lesser mortals!

Thanks for sharing your work, Pete, and also your commentary about techniques.  So far what has sunk in is to use longer f-stops closer and medium f-stops further away.  And by doing this you will start with somewhat deeper focused fields in each image, which may reduce the number of images needed to assemble a final result.  I think you also said it may help to experiment with which images are included in the stack.

I am eager to try outsome of these iseas,and hope to do so this weekend!  More later!

[chicken45]

Guys, I have to say, these shots are incredible. Thank you!

[pnolan48]

Pinhole photography is fun to play with. Back in the early 70s, I sometimes had better luck without a lens, using a sheet of heavy aluminum foil with a quite precise drilled hole. And I did it with a dirt cheap 35mm camera--I wasn't going to play around with my Nikon F. I think the 10-20mm Nikon DX lens, at f/32, has a depth of field of something like 6 inches to infinity, and I think the new one is even wider. It cost me about $1000, but has been one of the best buys I've ever made.

Still, it's hard to beat this kind of depth of field:

[pnolan48]

And Helicon (and the others) works very well with longer telephoto shots:

[DKS]

Pinhole photography is fun to play with. Back in the early 70s, I sometimes had better luck without a lens, using a sheet of heavy aluminum foil with a quite precise drilled hole. And I did it with a dirt cheap 35mm camera--I wasn't going to play around with my Nikon F.

What I did was buy a used 50mm Canon lens--I think it cost me all of $20-30. So it didn't bother me to dismantle it. I mounted the pinhole disk on etched brass legs to make a spider that floated right over the aperture, so when I opened the lens up all the way, there was enough light entering around the pinhole disk that I could compose the image in the viewfinder--otherwise, it was far too dark. To take the shot, I'd just stop the lens down, which sent all the light through the pinhole. Worked like a charm--except I cooked a few models with the photo floods I used... 

While I was busy exercising the pinhole, I also experimented with unusual lighting angles, and did a shooting-into-the-sun shot--



Plus the requisite black-and-white--

[pnolan48]

I bought a used Practika for $28 in 1969. The aperture rings had rusted, so I took apart the lens and removed the rust.  It then worked surprisingly well, and took pretty good pictures once I got used to the recoil caused by the mechanism--it was similar to shooting a BB pistol, and probably louder. Since I had already taken it apart once, it was no big deal to do it a second time and install a pinhole. It produced an extremely soft focus image with a lot of diffraction. The pinhole worked better when I just mounted it across the lens opening, without the lens.

I had a lot of time in 1969, since I had fulfilled all my requirements for graduation, but had another year of college on my scholarship. As a scholar of the college, I co-started its Film Institute, and did experiments like shooting three separate images on B&W film with cyan/magenta/yellow filters to try to make a color image, as NASA was doing on the moon. Yeah, right--try that in a darkroom sometime with paper and chemicals that cost a fortune. My Nikon F with 50mm 1.4 lens cost $368 in 1968--a fortune for a 20-year-old then--but it did launch a career. The Practika was just for fun, but it did introduce me to the idea of always carrying two cameras on a job, which I do to this day.

[PAL_Houston]

I have been experimenting this afternoon, with using some longer f-stops for the closer shots and f-8 for the deeper ones, as well as with various processing sequences.  What seems to be working best so far is to align, balance and then crop all of the pics to be stacked, before doing the stacking so that the program is only working on the interesting parts of the images.  So there are elements to both art and science in this focus-stacking business.  Beyond that, I think I need to improve my photography skills!!

Nothing happening at Galena Jct. today...oh, wait, I see a southbound coming!!



Looking uphill from the marina at Savanna



Heading east out of Savanna on Ill. 64 will take you about an hour to reach Oregon.