Macro landscape stack using compact digital camera

[rjlittlefield]

In a recent pair of postings, Charlie Krebs showed us unique and wonderful views of the Quinalt rain forest shot with his custom OlyMinCan-28 DSLR system.

From a technical standpoint, the key element of that system is that it shoots wide angle from infinity to 1:1 (24 mm x 36 mm), while keeping the lens entrance pupil in exactly the same place. This prevents parallax and allows near-perfect stacking.

Inspired by Charlie's success, but daunted by the prospect of custom machining, I looked around for alternatives. One turned up rather promptly!

It turns out that the lens of my Canon A710 compact digital camera focuses entirely by moving lens elements that are behind the diaphragm. What this means, of course, is that as the lens focuses, its entrance pupil does not move at all. Perfect! And since the camera will focus down to about a 22mm field width with no attachments, it covers the same range of subject sizes as Charlie's DSLR setup.

Alas, I could not find adequate substitutes for either Charlie's subjects or his artistry, so I made do with an urban greenscape.





Canon A710 set for manual everything, 8 frames at f/8, 1/13 second, stacked with Helicon Focus.

This lens has quite a bit of barrel distortion at wide angle, and picks up even more as it focuses closer. I was concerned that I might have to correct for this before stacking, but at least for this stack, it wasn't a problem. For more extreme ranges, or more critical work, it still might be an issue.

Anyway, I know that some of you are interested in the stacked macro landscape effect, and I thought you might be interested in seeing a fairly simple way to pull it off, albeit at lower quality than Charlie's rig will do.

--Rik

[Charles Krebs]

Excellent! I'll have to check out the lens on my Canon A620.

How "fidgety" was it to vary the focus between shots?
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[rjlittlefield]

Adjusting focus didn't seem too bad. I could have shot a lot more steps, but I was a bit spooked because the air was starting to move. Even so, I had to throw out one frame, and the tallest grass isn't quite crisp.

You probably figured out from the 1/13 sec at f/8, this was early morning before the sun was really up. The shot of the camera and tripod was done a bit later, when I figured out I needed it to complete the posting.

--Rik

[Charles Krebs]

Rik,

Checked out my Canon A620 p&s and it appears to focus like yours. Could make for some fun images. And with the "flip-out" and "tilt-able" screen I won't need to eat so much dirt trying see what I'm doing.
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[acerola]

I have a Sigma 17-70 F2.8-4.5 DC lens. It has a little Macro capability. The front element did not move while focusing. I did a test shot, it is promising. It is interesting that the field of view is changing. It is wider in macro mode than in infinity. But CMZ is aligned it well.
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Péter

[lauriek]

Péter,

That doesn't surprise me (FOV changing) - some Prime macro lenses actually change focal length as you change magnification, some around the 100-105mm sort of size are more like 90mm when focused at 1:1!!

Interesting stuff!!

[rjlittlefield]

In searching the web, I ran into a couple of scripts for controlling focus from a PC. The comments indicate that the scripts provide finer control than what you can get by pushing the buttons on the back of the cameras.

I have not played with these things personally, but thought I would include the links here in case someone else is interested (and so maybe I can find them again if I ever want to ).

http://www.projectracker.com/digitaworld/viewscript.htm?scriptid=12 [Edit: as of March 21, 2010, this one has disappeared]

http://chdk.wikia.com/wiki/UBASIC/Scripts:_macro_DOFstacker

The second one specifically mentions Canon A620.

--Rik

[Charles Krebs]

Thanks for those links Rik. I'll definitely look them over more carefully.

Since you first posted this I've played around once or twice with my A620. The shots I did were merely "tests" and the subject matter not worth posting. But there is no doubt in certain situations you could make some very impressive images with this technique. And I don't think it would be that hard to do it "manually", although a script automated method would be neat.

The biggest practical problem is that you need a subject with no movement while shooting the stack. It would also be nice to have a wider lens. But it seems that an "equivalent" 35mm is about as wide as you can get in these P&S digtals right now. There are a few "28mm equivalents" around, but I'd have to check to see if any of those allow the extreme close focus that make this technique so impressive.
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