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Author Topic: Digital Blending for Focus  (Read 8107 times)
didjdoctor
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« on: March 17, 2006, 08:27:34 PM »
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Good articles, as in Luminous Landscape, describe blending two exposures of the same scene to increase dynamic range.  What I haven't seen described, and it works very well, is doing the same thing to increase depth of focus.  You can get very close to a foreground element, even using the macro mode if you wish, and take one frame for that element.  Then take one or more with the background in focus, the foreground out of focus.  Later it's simple to place the first as a layer over the second and erase all the background, revealing the in-focus background behind.  Minor inaccuracies in erasing are probably less obvious than is true when blending for exposure differences.  Have others had success with this technique?
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Tim Gray
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« Reply #1 on: March 18, 2006, 08:42:29 AM »
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The problem is that as the point of focus changes the angle of view changes slightly as well so it's a real problem to keep the frames in registration.  There a freeware package called Combine Z that does this for you.  Here's a link to some grand piano shots I did using this software.

http://www.timgrayphotography.com/gallerie...anos/index.html
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Eric Myrvaagnes
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« Reply #2 on: March 18, 2006, 09:25:33 AM »
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Quote
The problem is that as the point of focus changes the angle of view changes slightly as well so it's a real problem to keep the frames in registration.  There a freeware package called Combine Z that does this for you.  Here's a link to some grand piano shots I did using this software.

http://www.timgrayphotography.com/gallerie...anos/index.html
[a href=\"index.php?act=findpost&pid=60560\"][{POST_SNAPBACK}][/a]
Those are stunning results, Tim. I've photographed harpsichords in the past and never got anything better than your first, "straight" photo. I'm going to go get Combine Z.

Eric
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-Eric Myrvaagnes

http://myrvaagnes.com  Visit my website. New images each season.
Tim Gray
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« Reply #3 on: March 18, 2006, 02:23:35 PM »
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First time use can be a bit confusing - here's all you need to do:

Combine Z

File; New; then select images to stack
Macro; Do_Stack
File; Save_Frame_As
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DarkPenguin
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« Reply #4 on: March 18, 2006, 02:24:52 PM »
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This is interesting.  This a black art or something humans can pick up?
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Tim Gray
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« Reply #5 on: March 18, 2006, 03:37:30 PM »
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here's the link http://www.hadleyweb.pwp.blueyonder.co.uk/CZ5/combinez5.htm

It's dead simple if you follow the steps in my previous post.  The application has the ability to tweak a large number of paramaters if you want to go that deep.  Goes without saying you need to shoot from a tripod.  I use a 1D2 and just cycle through the focus points from front to back.
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Anon E. Mouse
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« Reply #6 on: March 19, 2006, 07:43:55 AM »
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This technique is used in microphotography all the time. Look in the member galleries:

http://www.amateurmicroscopy.photomacrography.net/

BTW, this changes "depth of field", not "depth of focus." The "field" is the object space whereas the "focus" is around the image plane.
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elf
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« Reply #7 on: March 24, 2006, 09:48:42 PM »
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The problem is that as the point of focus changes the angle of view changes slightly as well so it's a real problem to keep the frames in registration. 

I've had good luck with CombineZ5 as well. Your grand piano images work well for the technique because there is mostly a gradual change from foreground to background.  It's a little harder to get a good image when there is a big change between the foreground and background.

Here's a couple of images I've done using CombineZ5. The first has 15 images combined in a single frame
http://img.photobucket.com/albums/v649/etfrench/25045f.jpg

This image is also stitched as a panorama. It has 119 individual images blended for DOF in an 4x5 array. Size is 7740x7800 pixels.

http://img.photobucket.com/albums/v649/etfrench/06975904.jpg

Both taken with 4mp Nikon cp4500.


Have you thought of stitching all of your grand piano shots together? It would be quite dramatic.
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Tim Ernst
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« Reply #8 on: March 27, 2006, 09:22:01 PM »
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Anyone know of a program like this for Mac?

Tim Ernst in Arknasas
www.Cloudland.net
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Dave Carter
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« Reply #9 on: April 01, 2006, 04:06:07 PM »
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Quote from: Tim Ernst,Mar 27 2006, 10:22 PM
Anyone know of a program like this for Mac?


TIm,
I believe there is a software package that is similar but not free. It is called Helicon Focus and can be found at:

www.helicon.com.ua

I just checked and they  have a Windows and a Mac version.

I havea never used it.  But I have been tempted.

Dave
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John Hollenberg
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« Reply #10 on: April 01, 2006, 07:25:39 PM »
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I happen to know of a review of both programs :-)

http://www.outbackphoto.com/workflow/wf_72/essay.html

A Mac version has been added for Helicon Focus.

--John
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Tim Ernst
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« Reply #11 on: April 01, 2006, 07:38:08 PM »
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Hey, you are correct - they just added a Mac version a couple of weeks ago - thanks!

Tim Ernst in Arkansas
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nosredla
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« Reply #12 on: April 20, 2006, 02:20:31 PM »
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I have just tried a product called PTGui which is also a front end to Panorama Tools.  I tried it with a four image panorama and was amazed to find it needed no input of control points - it figured everything out by itself extremely accurately.  The reulting file was about 12 mp.

The panorama gave me amazing detail when I viewed it full size, but when I printed it on 8.5 x 11 it looked no better than a single 4 mp image taken of the same subject and printed at the same size.  This surprised me because I thought it would look better.

I assumed creating this big panorama was kind of the equivalent of a medium format camera's image and that, as stated in Luminous Landscape "Even in smaller prints the image quality advantage of medium format isn't subtle, it jumps right out at you".  Can ayone hep me understand this - I am a novice and may be misunderstanding something.

On the same issue, I have seen web examples of medium format photography on the web and must agree they look much, much better.  Still, I am unable to understand how it is that they do look better because the file size for web display is so small that many pixels must have been lost.  Can anyone help me understand this?
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gingerbaker
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« Reply #13 on: April 21, 2006, 11:31:30 AM »
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deleted post.  sorry.
« Last Edit: April 25, 2006, 08:06:33 AM by gingerbaker » Logged
SteveF
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« Reply #14 on: May 26, 2006, 11:45:27 PM »
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Here's am example of the Helicon software on a Mac

Picture is from my front door - it's raining outside, so this is the best you get



Here are two sets of four images. They were all taken with the 35/1.4 at f/7.1 - which is its sharpest aperture.

In each the upper left image is a "merged' version of the other three, which were taken with the focus set at about 3 feet, about 15 feet and infinity.

All of these are actual pixel crops. What is pretty darn exciting is how good the merged version looks on the house compared to the infinity focused version AND AT the same time how good it looks on the child's toy compared with the focus at 3 feet version. In each case the 'merged' version is just a hair softer than it's counterpart for a given focus distance, but it it is clearly a world better then (for example) the infinity focused image on the foreground at 2.5 feet.

Anyway, see what you think. I need to do some more tests and look more closely at a large print, but imagine being able to shoot at f/4 or 5.6 and having all the DOF one needs, without a tilt lens. Pretty cool.




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Steve Fines

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« Reply #15 on: May 27, 2006, 07:46:49 AM »
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Quote
Here's am example of the Helicon software on a Mac

Picture is from my front door - it's raining outside, so this is the best you get


Here are two sets of four images. They were all taken with the 35/1.4 at f/7.1 - which is its sharpest aperture.

In each the upper left image is a "merged' version of the other three, which were taken with the focus set at about 3 feet, about 15 feet and infinity.

All of these are actual pixel crops. What is pretty darn exciting is how good the merged version looks on the house compared to the infinity focused version AND AT the same time how good it looks on the child's toy compared with the focus at 3 feet version. In each case the 'merged' version is just a hair softer than it's counterpart for a given focus distance, but it it is clearly a world better then (for example) the infinity focused image on the foreground at 2.5 feet.

Anyway, see what you think. I need to do some more tests and look more closely at a large print, but imagine being able to shoot at f/4 or 5.6 and having all the DOF one needs, without a tilt lens. Pretty cool.

I had found these 2 softwares due to a post on camera/lenses forum concerning a TS for landscapes.  When I checked Helicon's forum I found this demo too which is similar to yours by Lin Evans  http://helicon.com.ua/forum/viewtopic.php?t=121
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