Focus stacking for extra depth of field.

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DaveW
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Focus stacking for extra depth of field.

Post by DaveW »

When you wish to get an image on the sensor much above 1:1 depth of field becomes a problem and stopping down to small apertures leads to the image being degraded due to diffraction. The only answer in those cases is to open the lens up to a better aperture and focus stack using multiple images taken at slightly different distances. See:-

http://zerenesystems.com/stacker/docs/t ... orial1.php" onclick="window.open(this.href);return false;

http://dgrin.com/showthread.php?t=61316" onclick="window.open(this.href);return false;

http://www.earthboundlight.com/phototip ... erene.html" onclick="window.open(this.href);return false;

http://mortenaagaard.com/focus-stacking ... ers-guide/" onclick="window.open(this.href);return false;

http://www.britishblades.com/forums/con ... o-Stacking" onclick="window.open(this.href);return false;
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BarryRice
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Re: Focus stacking for extra depth of field.

Post by BarryRice »

Hey folks

I am an experienced plant photographer who works in conventional and macro regimes.
While I've photographed for years, image stacking is a new technique for me. Are there any books you'd recommend? I work on a windows platform--any software packages you'd recommend?
I'll grow it as long as it doesn't have glochids. Gaudy flowers a plus.
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
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Re: Focus stacking for extra depth of field.

Post by DaveW »

My first link above, Zerene Stacker is supposed to be the best stacking software available, but not free though you can download a trial version . Combine ZP is free to download and you could give that a try to see how you get on with stacking:-

http://hadleyweb.pwp.blueyonder.co.uk/CZM/News.htm" onclick="window.open(this.href);return false;

There are some online books on focus stacking in this link below.

Don't be put off by all the meditation stuff at the top, scroll right down the link until you get to the photography ones.

http://spiritgrooves.net/e-Books.aspx" onclick="window.open(this.href);return false;

As an example of how stacking can overcome limited depths of field for insects (and plants as well) see:-

http://www.photomacrography.net/forum/v ... hp?t=19124" onclick="window.open(this.href);return false;

However to avoid diffraction effects when stacking you open up your lens to it's best aperture rather than stop down for depth of field, then take multiple photographs that are combined by the software which selects the sharp parts of each and combines them. It depends what magnifications you need? For plants at lower magnifications simply turning the lens focus ring to advance focus is good enough, but for high magnification work you need a focusing slide that will advance the camera in the steps needed. At very high magnifications that can mean advancing the camera in many sub-millimetre steps, but I doubt you would need that for the plants you want to use it on.
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BarryRice
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Re: Focus stacking for extra depth of field.

Post by BarryRice »

Hey Dave,

Thanks. This will get me started.

You've anticipated my first question---so you're saying I just ideally keep my focus ring fixed, and instead move the camera on its rails, huh?

I assume more photos will be better, as will smaller shifts on the rails...

Is there a rule of thumb on advancement, maybe in units of depth of field? For example, if my stopped down DOF using my lens at F/8, where it's sharpest, is about 5 mm, that my rail shifts should be smaller than 5mm, so that some part of the subject will ALWAYS be in sharp focus in one image or another?

If this is all covered in your link, no need to respond.

Cheers

Barry
I'll grow it as long as it doesn't have glochids. Gaudy flowers a plus.
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
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Re: Focus stacking for extra depth of field.

Post by DaveW »

Yes it is best if the steps overlap slightly as the software will sort out the sharp parts but obviously it cannot sort out sharp parts that are not there if the steps are too wide. For low power stacking you can use the focus ring but for higher power a focusing slide is better and probably best for all magnifications if you have one. For really high power stacking though you need an ultra precise focusing slide that will move the camera in fractions of a millimetre, but I don't think you need to go that high a magnification for plants.

There are in fact automated focusing slides that do move in incredibly small increments for high magnification stacking, but are rather expensive:-

http://www.youtube.com/watch?v=_WnE-KI3cng" onclick="window.open(this.href);return false;

http://www.cognisys-inc.com/catalog/ind ... 5a0ff70dba" onclick="window.open(this.href);return false;

You can even use later versions of Photoshop to stack images:-

http://photo.tutsplus.com/articles/post ... photoshop/" onclick="window.open(this.href);return false;

These may be of interest too:-

http://www.geofflawrence.com/focus_stacking.html" onclick="window.open(this.href);return false;

http://www.laurieknight.net/article" onclick="window.open(this.href);return false;

http://www.janrik.net/insects/ExtendedD ... deoff.html" onclick="window.open(this.href);return false;
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BarryRice
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Re: Focus stacking for extra depth of field.

Post by BarryRice »

Thanks, Dave, these look like great resources.

Barry
I'll grow it as long as it doesn't have glochids. Gaudy flowers a plus.
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