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Iron Flash
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Tesselator



Joined: 27 Mar 2010
Posts: 388
Location: Japan

PostPosted: Thu Apr 01, 2010 6:31 am    Post subject: Iron Flash Reply with quote

Iron-Pyrite flashed that is. Smile

I just set up a focus block as described in this thread: http://www.photomacrography.net/forum/viewtopic.php?t=6070 and this is my first attempt and rack-focusing with it.



9mm wide, 8mm high, 15 mm deep, 40 images stacked in Helicon Focus 4.2.1, no post processing or sharpening, for some reason the bottom right corner came out smeary Question


It's not as good as some of the other images here but I thought it looked pretty good for my first time. Smile I used two Kenko closeup filters (#5 and a #3) stacked for a 3.5:1 (3.5x) ratio at 35mm FF equivalence.
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Tesselator



Joined: 27 Mar 2010
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Location: Japan

PostPosted: Thu Apr 01, 2010 6:51 am    Post subject: Reply with quote

Here's the 100% crop from bottom-center if anyone is interested:



Again, no processing or sharpening.

Also to add is that these images were taken at 1/500, F/8, using a flashgun.




.
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Thu Apr 01, 2010 8:22 am    Post subject: Reply with quote

For a first time, this looks great! It looks pretty good even for an N-th time. Very Happy

You mention that "the bottom right corner came out smeary". At the resolution posted, I can't be sure what you're talking about. Can you post out a crop and explain more fully? I suspect it's just some astigmatism caused by the closeup lenses, but it would be easier to tell at larger scale and with some more words.

Subjects like this are great fun for stacking. With crisp high contrast detail over all or most of the surface, and not much 3D overlap, stacking software has a pretty easy time of them. Usually the biggest problems are with sharp-edged halos surrounding specular reflections, like the one shown in the crop you've posted (and at coordinates (625,555) in the original image).

There is one aspect of this image that make me wonder if everything has gone perfectly, however. At several places, the image seems to fuzz out into what I've come to call "stacking mush". Stacking mush occurs in low contrast regions when software has trouble figuring out exactly which frame has the sharpest detail, and ends up forming the image mostly from out-of-focus frames. With this subject, I would expect to see crisp fine detail everywhere. But at several places in the image, I don't. The most obvious area is below the largest crystal at bottom center, coordinates (510,740), (385,740), (300,650), and surroundings. There is another smaller region around (280,170), and several others even smaller scattered around.

Can you check your original source images, please, and see whether there is or is not sharp detail at the locations I've listed? You might find it easier to see what I mean if you brighten up the image a fair bit. Most of the questionable areas are getting into deep shadows.

--Rik
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Tesselator



Joined: 27 Mar 2010
Posts: 388
Location: Japan

PostPosted: Thu Apr 01, 2010 10:11 am    Post subject: Reply with quote

Thanks for the nice comments!

On the bottom right I think I just had a spot on my glasses. Smile I cleaned them and now (although I "remember" it) I'm no longer seeing it. LOL But it looked like the oatmeal my tiny sensor sometimes produces when it's presented with more detail than it can resolve.

Good eye on the "stacking mush" too. That's exactly what it is. Rather detail-less dark areas that the software erred on. I thought about correcting it by editing the contrast masks but the focus differences between frames are too minute and there just isn't enough detail for even me to see. If this were for a publication or $omething I would probably just redo it with one or several more light sources - which I think should cure it.

Nice comments, good critique, Thank you!
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rjlittlefield
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PostPosted: Thu Apr 01, 2010 11:01 am    Post subject: Reply with quote

The reason I am sensitive to stacking mush is that I have wrestled with it a great deal over the years. With your subject, improved lighting would make a lot of improvement, because there really is crisp high contrast detail to be found. With other subjects, even improved lighting is of little or no help.

One of the advantages of Zerene Stacker over Helicon Focus is that ZS is less vulnerable to mush in the first place, and makes it easier to fix by retouching if necessary. In Helicon Focus, you might try using Method B instead of Method A. There are some illustrations HERE that compare Helicon's A and B, and Zerene's PMax, on a troublesome flower.

Also, I notice that you're using HF 4.2.1. Is that the most recent available for your platform? I ask because Helicon has made some significant improvements over the years (see the older thread linked in the article I listed above). On Windows, my copy is now showing 5.0.6.

--Rik
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Tesselator



Joined: 27 Mar 2010
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Location: Japan

PostPosted: Thu Apr 01, 2010 11:51 am    Post subject: Reply with quote

Kewl! Good info man! Thanks! This was helicon B 7 3 (http://tesselator.gpmod.com/Images/_Equipment_n_Tutorials/_Microspope_Related/Focus_Result_B_7_3.jpg). I haven't tried A yet. It looked like it was for panoramas or something different. I just downloaded ZS after seeing some other threads in this sub-forum. I haven't installed it yet though. Smile It might be interesting to compare the two in the same thread with this subject though. Smile

Yeah, windows is probably ahead. I'm on a Mac Pro and I find boot-camp, parallels, and the others like it not very pleasant to use. Anyway I just downloaded it from the home-page today for this so I would hope it's the latest version (on Mac).


I think I'm going to try ZS from now though and see how it goes. Thanks for the idea! Are there any others - maybe free - that are any good?
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rjlittlefield
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PostPosted: Thu Apr 01, 2010 12:20 pm    Post subject: Reply with quote

Tesselator wrote:
Are there any others - maybe free - that are any good?

CombineZP is excellent freeware, but it's Windows only. I don't know of any other good free packages.

BTW, in the interest of full disclosure and all that, I'm the fellow who wrote Zerene Stacker . The reason I did that was because I got tired of wrestling the other packages into giving the results I wanted with the subjects I wanted. But you should be properly suspicious that I'm biased. There definitely are situations where HF has better tradeoffs. It's your own images and workflow that should determine which you prefer.

--Rik
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rjlittlefield
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PostPosted: Thu Apr 01, 2010 1:16 pm    Post subject: Reply with quote

Tesselator wrote:
It might be interesting to compare the two in the same thread with this subject though. Smile

See HERE. Your mileage may vary -- so does mine. Wink

--Rik
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AndrewC



Joined: 14 Feb 2008
Posts: 1436
Location: Belgium

PostPosted: Thu Apr 01, 2010 3:08 pm    Post subject: Reply with quote

Nice picture - we don't see many minerals around here so it makes a change Smile I'll have to go dig in my rock box .....
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"Is that an accurate dictionary ? Charlie Eppes
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Tesselator



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PostPosted: Fri Apr 02, 2010 5:35 am    Post subject: Reply with quote

Thanks RJ.

Andrew, Uh-oh! Competition. Very Happy

Sounds like fun!


So I tried out ZS and it sure does better in the dark areas! It has a lot more trouble with halos tho. It also can't accept my camera RAW files so I had to process the Camera Jpegs. I new there was a reason I shot Jpeg+RAW. Wink

So here are the results and I'll paste the Helicon one after it again for easy compare:

ZS:

Helicon ^

The ZS one also made a mess of the top right black space so I just snuffed it out. Smile

I think if it's an important project it might be I good idea to run both and then pen in a mask so to get the best of both. Smile I suppose that would only be needed if it was a difficult image in the first place however.
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Tesselator



Joined: 27 Mar 2010
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Location: Japan

PostPosted: Fri Apr 02, 2010 5:58 am    Post subject: Reply with quote

While I was messing about i made another stack too. This time I wanted to take advantage of the halos that ZS is so strong at. I set up some really contrasty 2-point lighting to try and maximize the halos. And just to be a total goof-ball I taped an EL Nikkor 63mm/2.8 (reversed) onto the front of my fixed GT lens and used a different transport. Here's what the taped lens looked like:



And here's what the transport looked like:



I wanted to know how important the precise adjustments of the mic's focus block were. They're not. Smile Adjusting small approximate increments on the bellows produced equally stackable images.

Here's the image. Again it's not very good but what the heck. Wink


38 image stack, Subject = About 2mm to 2.5mm wide, Sharpened + Contrast adjustment, 1/80s, f/4.5 ( NL Nikkor @ 2.8 ).
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AndrewC



Joined: 14 Feb 2008
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PostPosted: Fri Apr 02, 2010 6:16 am    Post subject: Reply with quote

Tesselator wrote:
Thanks RJ.

Andrew, Uh-oh! Competition. Very Happy

Sounds like fun!




Not for a while - I last saw my mineral collection 3 house moves ago so it could be anywhere Sad
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ChrisR
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PostPosted: Fri Apr 02, 2010 6:46 am    Post subject: Reply with quote

Interesting comparison between the two stackers, but higher res pics would be moreso!

By the way,
Novel subject support, though I've used a slide copier bellows attachment a lot, which is much the same. There's a clip-on ground glass slide holder for the BPM bellows you have, which costs buttons and would be well worth looking out for. Also there's a focus-slide which goes under the bellows, and a longer version of the same bellows. Your lens/camera adapters would fit of course.
Your method of holding the lens still and moving the subject and camera is, um, odd? Why not just move the lens? Balance?! Razz

I think I've got some rocks, hmmm...
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rjlittlefield
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PostPosted: Fri Apr 02, 2010 11:56 am    Post subject: Reply with quote

Thanks for posting the image pair. I'm always interested in other people's comparisons, both the images themselves and comments / interpretation.

Quote:
I think if it's an important project it might be a good idea to run both and then pen in a mask so to get the best of both.

If you're talking about merging the HF and ZS results, that won't work as well as you might expect. The problem is that HF and ZS (and Photoshop, and CombineZP) will make slightly different decisions while reconstructing the geometry. The resulting images cannot be made to line up with each other. Even if you align them globally, there will be small local deformations such that when you try to merge the two, you'll be fighting with "echos" much of the time.

However, you're on the right track with that thought.

To get the best result with this stack, the trick would be to stack it twice in ZS, once using the PMax method as you have and again using the DMap method, then use the retouching tool within ZS to merge the two.

It's important to do most or all of the merging inside ZS. This is because the ZS retouching tool understands how to transfer detail from one image to the other without visible seams or toolmarks, even when there are local differences in brightness or contrast. This is important because PMax generally alters brightness and contrast at the same time it is pulling out every bit of available detail.

If this were my subject, I would probably end up using DMap as a master, since it generally does a better job preserving colors and tones that may be important in mineral samples. Then I would use a "flash-between" approach to identify places where the DMap result could be improved by retouching from PMax (such as in those shadow regions) and from individual frames (such as around the edges of those bright facets).

This process is illustrated in the video tutorial about retouching, on the Zerene Stacker web site. The subject there is a fruitfly and the problem is bristles, but the general approach is still applicable.

Comparing the two pyrite images that are posted above, here is what I notice:
. ZS PMax has pulled out much more detail in the shadow regions.
. ZS PMax has also preserved more detail on the brightest flat facets, for example the ones at (590,300) and (830,640). This is a bit surprising because PMax has a reputation for making highlights blow out. I don't know what it is about this particular stack that makes PMax keep highlight detail that HF loses.
. ZS PMax has introduced fuzzy white halos around the brightest facets. This is common behavior for PMax with this sort of subject.
. The HF image appears sharper as posted here. That is unusual, and I suspect a difference in post-processing. ZS preserves detail from the original source frames, but specifically does not do any added sharpening, on the presumption that the user will "sharpen to taste" while making other adjustments in post-processing. The copy of HF that I use appears to take the same approach but this may vary between versions.

What you've seen already in this exercise is that different tools and methods generate different results, none perfect, so there are tradeoffs to be considered. Whether it is better to use two-methods-and-merge in ZS, or to use ZS PMax or ZS DMap alone, or to use HF A or HF B alone, depends on what you intend to accomplish and what kind of subject you have to work with.

--Rik
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rjlittlefield
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PostPosted: Fri Apr 02, 2010 12:03 pm    Post subject: Reply with quote

By the way, I don't know if you noticed, but I posted one of my own examples of "stacking mush" and some further discussion, over in the Technique and Technical Discussions forum.

See HERE.

--Rik
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