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 Post subject: Focus stacking
PostPosted: Wed Nov 16, 2011 10:51 am 
One of the main purposes of this site is sharing photographs of models so photography is important. I have been very impressed with the quality of the photographs shared by Kostas Katseas. Recently, in another thread, I asked how he took pictures with such great depth of field. I have taken a large number of model photographs over the years and I know that depth of field is the most difficult aspect to accomplish. It is virtually impossible to get a long, narrow model like a ship completely in focus from one end to the other using the equipment normally available to a hobbyist. There are large format cameras and special lenses that produce better results but their cost makes them impractical for most of us. The other traditional technique is to use a very small aperature (high F number) and a very long exposure. Even this will not get a long ship model completely in focus and the long exposure time means the risk of ruining a shot by camera motion is high. However, Kostas' recent pictures did have a startling depth of field and he was kind enough to explain that he accomplished it using a digital processing technique called "focus stacking." This process has two steps. First, a "stack" of photos is taken of the subject in which each photo is shot at a slightly different focal point. This can be done manually but it is much easier to do using a computer to control the camera. The second step is to "stack" the set of photos using a computer program that analyzes the photos, finds the area of highest focus in each, and digitally combine them into a single photo that is in focus completely from front to back. Kostas said he used a software package called Helicon Focus which is a commercial product that is fairly expensive. I wondered if there was free or, at least, less expensive software that would perform focus stacking and it turns out, there is.

Helicon Focus is a very popular application and it does cover both parts of the process by providing remote control of the camera and focus stacking. First, I should make clear that you don't have to remote control the camera, it's just a lot easier and produces far more consistent results. I did try shooting a series of photos, manually adjusting the focus between each shot, and it worked, sort of. But it was very difficult to do and time consuming. However, remote control is limited to cameras that have a function called "Live View." At this time, as far as I can tell, only some models of Nikon and Canon cameras have this function. Fortunately, one of the least expensive digital SLR cameras, the Canon Rebel XS, does have this capability. So that's what I got. I did an extensive search on line and turned up two other programs besides Helicon Focus that provide remote control (also called "tethered" operation) but both were limited to Canon cameras. One is a commercial application and the other is freeware. The commercial app, DSLR Remote Pro, seemed overly complicated and it cost money. I tried the freeware application, DSLR Bracketeer (http://milosparipovic.com/index.php/dlsr-bracketeer/) and was completely satisfied with its performance. It gave me just the control I needed and was easy to use.

The second step is the processing of the stack of photos taken with the remote control software. There are several free applications for this, too. I tried the most popular, an open source program called CombineZP (http://hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm). It worked very well and the resulting photos appeared to me to be virtually identical to those produced by Helicon Focus. However, I tried another commercial program called Zerene Stacker and it seemed to do a slightly better job than CombineZP in reducing artifacts. I'm still on the 30 day free trial of Zerene Stacker and haven't decided if the difference in quality is worth the cost.

Focus stacking, even with automated remote control of the camera, does take more time and effort than just shooting a single picture. Is it worth it? I think so. Look at the pictures of the last half dozen or so models that Kostas has in the gallery to see how good it can look. Or, here is a sample comparison (sorry it's not a ship but I haven't shot any ship models yet using this technique).


Attachments:
File comment: The first sample picture is a single shot that has limited depth of field.
sample - Batplane 01.jpg
sample - Batplane 01.jpg [ 78.08 KiB | Viewed 2937 times ]
File comment: The second sample is a compilation of that first picture and 28 others, each taken at a slightly different focal length. As you can see, the digital processing produces a picture with depth of field far greater than would be obtainable otherwise, even using a very high F number and long exposure (the traditional way to increase DOF).
sample - Batplane 02.jpg
sample - Batplane 02.jpg [ 130.6 KiB | Viewed 2937 times ]
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 Post subject: Re: Focus stacking
PostPosted: Thu Nov 17, 2011 5:03 pm 
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Joined: Thu Aug 07, 2008 10:24 am
Posts: 431
I've been thinking of trying this, but feel that I need to get a better lens for close ups. Problem is that I can't afford a good Macro at this moment. :(

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 Post subject: Re: Focus stacking
PostPosted: Fri Nov 18, 2011 9:25 am 
Here's a comparison that uses a ship model. I believe the effect is fairly dramatic.


Attachments:
File comment: A single shot in which the bow is in focus but the stern is not.
sample - Thunder Child 01 small.jpg
sample - Thunder Child 01 small.jpg [ 102.93 KiB | Viewed 2838 times ]
File comment: This is a product of focus stacking that includes the above shot.
sample - Thunder Child 02 small.jpg
sample - Thunder Child 02 small.jpg [ 142.98 KiB | Viewed 2838 times ]
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 Post subject: Re: Focus stacking
PostPosted: Fri Nov 18, 2011 9:39 am 
denstore wrote:
I've been thinking of trying this, but feel that I need to get a better lens for close ups. Problem is that I can't afford a good Macro at this moment. :(


I don't have a dedicated macro lens, either. They are expensive. So, I've been using a 10X macro closeup lens that screws onto the front of my regular lens. This type of lens is not expensive and can be found to fit pretty much any camera. The one I'm using was originally purchased to use on a Canon A75 point and shoot camera. I got an adapter ring to use it on my Rebel XS lens. Unfortunately, the focus stacking method does not work well with this arrangement. At least, I haven't got good results yet. I suspect you do need the high end autofocus macro lens to use focus stacking. On the up side, the same tethered camera configuration I use for focus stacking allows me to crank the aperture very small and take very long exposures with the closeup lens. This gives a decent depth of field for the close up shots but not as much as you'd get with focus stacking. The sample shot below was taken with an aperture setting of f/20. As you can see, the center of the ship is in focus but the focus gets a bit soft on the near and far sides. Still, better than nothing.


Attachments:
File comment: Close up shot taken at f/20 with a 10X macro closeup lens.
sample - Thunder Child 03 small.jpg
sample - Thunder Child 03 small.jpg [ 142.1 KiB | Viewed 2838 times ]
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 Post subject: Re: Focus stacking
PostPosted: Mon Nov 21, 2011 4:54 pm 
One more addendum to my original post. I stated that I was doing automatic shooting of the stacks of photos using a tethered camera arrangement. There is another way. Some models of Canon point-and-shoot cameras can be programmed to shoot a series of photos at different focal points so that they can be used for focus stacking.

http://chdk.wikia.com/wiki/DoF_Stacking tells how to do focus stacking with a P&S camera that has CHDK applied.

http://chdk.wikia.com/wiki/CHDK_in_Brief describes what CHDK is.

http://chdk.wikia.com/wiki/CHDK identifies which cameras it works on.


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 Post subject: Re: Focus stacking
PostPosted: Fri Nov 25, 2011 6:46 pm 
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Joined: Wed Mar 21, 2007 5:59 pm
Posts: 404
Location: NW Lower Michigan
I posted my results with CombineZM here,

viewtopic.php?f=4&t=41054&p=272932&hilit=combinezm#p272932

I've used this software a lot and am happy with the results

Timm

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Learn something new about the ship or your job every day. Ignorance is not bliss aboard a warship in wartime. Ignorance could cost the life of yourself, a shipmate, or the loss of the ship.
- Personal Information Booklet CV- 38


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 Post subject: Re: Focus stacking
PostPosted: Tue Nov 29, 2011 3:40 pm 
Capt652 wrote:
I posted my results with CombineZM here,

viewtopic.php?f=4&t=41054&p=272932&hilit=combinezm#p272932

I've used this software a lot and am happy with the results

Timm


Timm,

Have you tried CombineZP? It's the replacement for CombineZM and is supposed to do a better job as it uses the pyramid algorithm for analyzing the images. I compared CombineZP to Helicon and couldn't see any real difference but I did not try CombineZM since it was older so I assumed ZP was better.


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 Post subject: Re: Focus stacking
PostPosted: Sun Jan 19, 2020 9:08 am 
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Joined: Mon Feb 21, 2011 6:38 am
Posts: 707
Location: Czech Republic
Thanks a lot fot the tip on CombineZP - just successfully tried it on creating this photo of Japanese heavy cruisers Chokai followed by Furutaka at the Battle of Savo Island, Aug 8-9, 1942. This is indeed fictional, she was followed by the Aoba. The ships should have aimed on the same side and they should definitely be much farther apart from each other, but this is what my simple test setup allowed for. It clearly works fine :)

The photo was stacked from 7 photos taken by a 70mm macro lens from about 50cm apart from the bow of the first ship. The resulting depth of field here is over 70cm. It´s better to click on the photo and zoom it in on Flickr to see that even the stern of the second cruiser is in focus.

Image

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 Post subject: Re: Focus stacking
PostPosted: Tue Feb 25, 2020 11:06 am 
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Joined: Thu Feb 17, 2005 2:54 pm
Posts: 123
I have a demonstration tutorial on Helicon Focus in my gallery page for John Leyland on this site


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 Post subject: Re: Focus stacking
PostPosted: Fri Jul 03, 2020 3:10 pm 
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Joined: Sat Sep 15, 2007 11:40 pm
Posts: 575
Location: California
I show how to use Helicon Focus at 9:50 in this video ...


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http://paulbudzik.com/current-projects/Neptune/Lockheed_Neptune_Model_Budzik.html
http://paulbudzik.com/tools-techniques/outside_the_box.html


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