Six frame focus stack of male Araneus spider

Bruce Williams · #1 (**permalink**) 07-10-2009, 08:24 PM

I thought some of you might be interested in a recent hand-held focus-stack:

I use hand-held focus stacking quite a lot. Not always with the purpose of getting the whole of the subject in focus but often just to generally increase the depth of field to get a more pleasing image.

Normally my subjects are quite tiny (say 5mm or less) so at f/16 or f/18 it only takes 3 frames to ensure most of the subject (excl. legs) is pretty much in focus.

This spider measured approx. 8mm excluding legs so was larger than most of my previous subjects. He was keeping quite still so I decided to go for a stack. I guestimated that 6 frames should cover him (probably should have gone for 8).

Camera: Nikon D300 + Nikon 105mm Macro VR.
Settings: ISO200, manual exposure, f/18 @ 1/250s. Flash was manual pop-up at 1/4 power. Focus was manual.

I always start by focussing on the closest part of the subject and gradually, shot-by-shot move the camera closer to the subject, visually checking the critical point of focus before firing the shutter. I work pretty quickly as I find doing so helps me to select the next point of focus (if I take too long I forget where I focussed on my last shot). Also the less time you take the less chance there is that the subject will move a leg or even do a runner.

I loaded the six images together into a Photoshop 'levels stack' and manually aligned them one by one (rotate and shift) using partial transparency in levels to check alignment. The 'level stack' was cropped and then each level was saved individually with filename suffix a, b, c, d, e and f.

These six manually aligned images were then stacked in Zerene Stacker (alignment is further refined at this stage). The stacked image was then taken back into CS3 for final sharpening, cropping and resizing.

The following two pics show (a) the full image at ~30% full size and (b) the close-up, cropped image at about 60% of full size. The full size image (not shown) is 2648x2648 pixels.

Bruce

Red Squirrel · #2 (**permalink**) 07-10-2009, 10:02 PM

That's a great picture Bruce. You make the process sound so simple. I'm quite envious.

Lancashire Lad · #3 (**permalink**) 07-10-2009, 10:12 PM

Fantastic image Bruce. I don't know how you manage to make such subtle camera movements whilst hand holding - beyond me I think

I've just started dabbling with basic image stacking for small fungi, and am mightily impressed. (And they don't run away while I'm refocussing

).

Regards,
Mike.

Bruce Williams · #4 (**permalink**) 08-10-2009, 08:04 PM

Thanks Red Squirrel and Mike.

This might go without saying.....for stacking the subject really needs to be on a fence, wall or tree trunk (ie, something solid) as even the slightest movement will make accurate step focusing extremely difficult. Also it helps a lot if you can lean against something to steady yourself.

Bruce

AlphaZeroOne · #5 (**permalink**) 14-10-2009, 11:15 AM

Bruce- what can I say! Spot on. Seems that I might have missed some recent developments. Although I can understand how you have achieved this, I tried something similar with varying DoF. However, I am not certain how you have managed to stack these shots into one image. Do you use PS or some specific software or plugin.

Opps - I see now that you have included details re PS and software. I will give it a bash.

Bruce Williams · #6 (**permalink**) 14-10-2009, 08:02 PM

Thanks AlphaZeroOne....and I see you also posted on my earlier "New easy-to-use stacking software" thread.

Bruce

2dogs2000 · #7 (**permalink**) 14-10-2009, 09:37 PM

I don't understand a word of what you're saying

but then I know very little about photography.

Just wanted to say fantastic photos.

Bruce Williams · #8 (**permalink**) 16-10-2009, 08:38 AM

Thanks 2dogs - my wife doesn't understand me either

.

Bruce

AlphaZeroOne · #9 (**permalink**) 16-10-2009, 11:05 AM

HI Bruce. Do you think that this process would work using differing DoF rather than point of focus?

Bruce Williams · #10 (**permalink**) 16-10-2009, 11:07 PM

Interesting question AlphaZeroOne.

Well I don't think "variable aperture" stacking would be anywhere near as useful as focus stacking, however for an entirely different reason there may be some merit in trying it. It could possibly be used to overcome (in part) the loss of fine detail caused by stopping down beyond the diffraction limit of the camera's lens. In my case (Nikon 105mm Macro VR lens) image degredation becomes noticeable from about f/13. However IMO it's not really a significant problem until f/20+.

If you're not familiar with the effects of diffraction limitation check out this website tutorial: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Anyway back to your question:

In the past I have occasionally experimented by taking two different shots of the same macro subject at different apertures. Typically one shot at f/8 focused on the nearest bit of the most important part of the subject (for example the eye) and another shot at f/22ish, focused on the nearest part of the subject overall. Of course the subject must be very still and ideally the camera should be tripod mounted.

The f/8 shot will have a relatively narrow dof, however the eye should be in focus and the image will not suffer from 'diffraction limit' related loss of detail. This means that the subject's eye will show good detail.

The f/22+ shot will have a much deeper dof but there will inevitably have been some loss of detail in the eye due to exceeding the diffraction limit of the lens.

I have then used CS3 to manually merge the (good detail) eye from the f/8 shot onto the (good depth of field) f/20+ image. However (considering your idea) I think I could probably have used Zerene Stacker (or CombineZP) to merge the two images with better results than I was able to achieve manually.

Bruce