I’m working on a blog post that isn’t ready for publication. It should be finished sometime within the next day-or-so, so as the title says, please stay tuned.
Walter
Archive for the ‘Fujifilm X-T3’ Category
Please stay tuned …
March 7, 2023How to measure magnification, revisited
March 3, 2023The magnification of any macro photography rig can be determined by using the rig to photograph a metric ruler such as the one shown below.
Plastic 15 cm (6″) ruler from the Natl. Science Teachers Assn. (NSTA).
The following photograph was taken using a Laowa 25mm Ultra Macro lens mounted on my Fujifilm X-T3 digital camera. The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens. Notice that only a small part of the ruler is shown in this “full frame” (uncropped) macro photo.
Segment of an NSTA metric ruler.
The formula for magnification is as follows.
length of camera sensor, in mm / #mm visible in photo frame
Both measurements must be expressed in the same units in order for the units to cancel during division.
The APS-C digital sensor featured in the Fujifilm X-T3 is 23.5 mm long. The annotated image shows ~9.0 mm of the small plastic ruler is visible in the photo frame.
23.5 mm / ~9.0 mm = ~2.6x
Is the actual magnification of the Laowa 25mm Ultra Macro lens slightly greater than 2.5x? I don’t know, but my calculation confirms the minimum magnification setting for the lens is in the neighborhood of 2.5x and that’s good enough for government work.
Photo Credit: Venus Optics.
What are the take-aways?
As a result of photographing the ruler, subject selection should be easier. Now I know ~9 mm is the size limit for subjects to fit entirely within the photo frame when the lens is set for 2.5x magnification. That’s actionable intel.
Related Resources
- How to Calculate Your Camera’s Magnification in Macro Photography, by Stewart Wood (12:02).
- How to measure magnification – a blog post by Walter Sanford that features instructions for using either Adobe Photoshop or Photopea to make measurements of photos.
Copyright © 2023 Walter Sanford. All rights reserved.
Post update: What is it?
February 28, 2023The mystery object shown in my last blog post is a macro composite image of the right eye of Benjamin Franklin, as he appears on a $100 bill. The $100 bill is the largest denomination Federal Reserve note currently issued for public circulation.
Image Credit: Wikimedia Commons.
Tech Tips
2.5x magification | aperture f/4 | shutter speed 1/250 s | ISO 160
The preceding image is a focus stacked composite of 77 JPG photos taken with my Fujifilm X-T3 digital camera plus a Laowa 25mm Ultra Macro lens. The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens.
The camera was mounted on my NiSi NM-200 manual focus rail. A safe step size of 50 microns was used in order to avoid focus banding, as determined by using Zerene Stacker DOF Calculator.
For better composition of the final composite image, I created the stack by focusing past the farthest focus point and moving the rail backward to slightly beyond the closest focus point. (Remember, the subject looks bigger at the farthest focus point than the closest. This almost certainly means it will be necessary to crop the final image if you shoot front-to-back. Going back-to-front helps to avoid this problem.)
The carriage of the focus rail traveled a total distance of 3.85 mm.
77
steps/1 x 50 microns/step= 3,850 microns3,850
microns/1 x 1 mm/1,000microns= 3.85 mm
77 steps is probably more than necessary but I wanted to be sure the entire image is acceptably in focus.
Helicon Focus was used to create the focus stack. The final rendering is saved as a TIF file, by default. I converted the TIF to JPG for posting in my photoblog. The final output, shown above, is unedited otherwise.
Sidebar
A micrometer (also known as a micron) equals 0.001 of a millimeter, or 1/1,000 of a millimeter. In other words, there are 1,000 micrometers in one millimeter. The symbol for micrometer is µm.
Related Resources
- Zerene Stacker DOF Calculator
- Helicon Focus – Quick Start on Mac OS, by HeliconSoft (2:20)
Copyright © 2023 Walter Sanford. All rights reserved.
Zerene Stacker DOF Calculator
February 21, 2023The DOF Calculator featured in Zerene Stacker is by far the best tool for determining depth of field and the safe step size for focus bracketing. Rik Littlefield, creator of Zerene Stacker, recently released an online interactive version of DoF Calculator. Sincere thanks to Rik for sharing his expertise!
How to use the calculator
There are several ways to use the DOF Calculator, as shown in the following screen capture. I used two methods to calculate the “safe step size” (with 20% overlap) for focus bracketing with all of my basic macro photography rigs.
Choose Option 1 for the best quality focus stacked composite images. Set the aperture for your camera lens to its “sweet spot.”
Screen capture used with permission from Rik Littlefield.
Choose Option 4 if you are using a microscope objective for a macro lens.
As you can see in following examples, it isn’t necessary to input values for every field in the calculator.
AmScope / Reakway 4x microscope objective
Determining depth of field – safe step size for a 4x microscope objective is the simplest calculation of all my macro photography rigs. All you need to input is the “NA” (numerical aperture) that’s labeled on the side of the microscope objective. In this case, the NA equals 0.10.
Photo Credit: AliExpress / Reakway.
It’s recommended that you use a 20% overlap between steps. Input a value of 0.2 in the field for “Step overlap.”
Screen capture used with permission from Rik Littlefield.
DoF: 0.054862 mm (54.862 microns)
Step size (suggested) at 20% overlap: 0.04389 mm (43.89 microns)
Let’s apply the output from the DOF Calculator (shown above) to my relatively new NiSi Macro [manual] Focusing Rail NM-200. The larger adjustment knob is shown below. One full rotation of the knob moves the carriage one millimeter, or 1,000 micrometers (microns). The knob is marked in 100 increments, so each increment on the knob is 10 microns. Every numbered increment is 100 microns.
For my 4x microscope objective, I would turn the adjustment knob four (4) increments between shots or 40 microns (rounded down from 43.89 microns). It’s OK to use a smaller step size than the DOF Calculator recommends.
Photo Credit: B&H Photo.
Laowa 25mm Ultra Macro (at 2.5x, f/4) plus Fujifilm X-T3
The Laowa 25mm Ultra Macro lens can be set for magnifications ranging from 2.5x to 5x. The following example shows the lens set for 2.5x. Input a magnification of 2.5, and a lens F-number of 4 (an aperture of f/4 is the “sweet spot” for this lens).
Screen capture used with permission from Rik Littlefield.
DoF: 0.068854 mm (68.854 microns)
Step size (suggested) at 20% overlap: 0.055083 mm (58.038 microns)
For the Laowa 25mm Ultra Macro lens, I would turn the adjustment knob on my NiSi NM-200 five increments between shots or 50 microns (rounded down from 58.038 microns).
Fujinon 80mm macro (1x, f/8) plus Fujifilm X-T3
The Fujinon 80mm macro lens is one of the sharper lenses I own. Maximum magnification is 1:1 (life size).
Screen capture used with permission from Rik Littlefield.
DoF: 0.56306 mm (~563 microns) ← remember 1 mm = 1,000 microns
Step size (suggested) at 20% overlap: 0.45045 mm (~45 microns)
Each increment on the NiSi NM-200 manual focus rail is equal to 10 microns. For my Fujinon 80mm macro lens, I would turn the adjustment knob four numbered increments between shots — equal to a distance of 40 microns (rounded down from ~45 microns).
Canon 100mm macro (1x, f/11) plus Canon EOS 5D Mark II
The Canon 100mm macro is another one of the sharper lenses I own. Maximum magnification is 1:1 (life size).
Screen capture used with permission from Rik Littlefield.
DoF: 1.0647 mm (1064.7 microns) ← remember 1 mm = 1,000 microns
Step size (suggested) at 20% overlap: 0.85176 mm (851.76 microns)
Each numbered increment on the NiSi NM-200 manual focus rail is equal to 100 microns. For my Canon 100mm macro lens, I would turn the adjustment knob eight numbered increments between shots — equal to a distance of 800 microns (rounded down from 851.76 microns).
Canon MP-E 65mm macro lens (1-5x) plus Canon 5D Mark II
The Canon MP-E 65mm macro lens can be set for magnifications ranging from 1x to 5x. The following example shows the lens set for 3x.
Screen capture used with permission from Rik Littlefield.
DoF: 0.12251 mm (122.51 microns)
Step size (suggested) at 20% overlap: 0.098008 mm (~98 microns)
Remember, each increment on the NiSi NM-200 manual focus rail is equal to 10 microns. For my Canon MP-E 65mm macro lens set for 3x magnification, I would turn the adjustment knob nine increments between shots — equal to a distance of 90 microns (rounded down from ~98 microns).
Related Resource
What if you don’t know the magnification of the macro rig you’re using? Or maybe you add an extension tube and/or close-up filter to a 1x macro lens — how does that change the magnification of the lens?
How to measure magnification provides photo-illustrated step-by-step directions, including sample math calculations.
The Backstory
I have been working behind the scenes trying to figure out how to determine focus bracketing step size for a variety of macro photography gear that I own. I have tested many depth of field – step size calculators and all of them are fatally flawed in one or more ways except for the one in Zerene Stacker.
See How to calculate step size for a long thread of posts related to my search for the answer to what turned out to a more complex process than I imagined. Thanks to the many members of photomacrography.net, especially Rik Littlefield, who kindly and patiently answered all of my questions.
Copyright © 2023 Walter Sanford. All rights reserved.
TJ short stack
February 17, 2023Just in time for President’s Day on 20 February 2023, I cooked up a “short stack” composite image of part of a nickel, that is, a five-cent coin in U.S. currency.
The face/head of Thomas Jefferson appears on one side of the nickel. Jefferson was the third president of the United States of America.
Part of a nickel (five-cent coin in U.S. currency).
There are many noticeable scratches on the coin.
The metal nickel has a hardness of 4.0 on Mohs Hardness Scale.
A mineral’s hardness is a measure of its relative resistance to scratching, … Source Credit: Mohs Hardness Scale, National Park Service.
Many minerals/common objects are harder than nickel, such as quartz, glass, and steel, to name a few, and can scratch the coin easily.
Tech Tips
The preceding composite image …
- was created using four photos shot with my Fujifilm X-T3 camera and Laowa 25mm Ultra Macro lens. The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens. A single external flash unit was used to light the photos.
- is focus-stacked for greater depth of field. At a magnification of 2.5x the depth of field is extremely shallow. 0.0896 mm (89.6 microns), to be exact.
- is “full frame” (6240 × 4160 pixels), meaning it is uncropped.
- was created using four unedited JPG files, straight out of the camera, that were focus stacked using Adobe Photoshop.
Related Resources
- GW revisited [George Washington, first president of the United States of America.]
- Trust [Abraham Lincoln, 16th president of the United States of America.]
- One thin dime [Dwight D. Eisenhower, 34th president of the United States of America.]
Copyright © 2023 Walter Sanford. All rights reserved.
One thin dime
February 14, 2023As you can see in the following test shot, a dime is thicker than the old expression would lead you to believe.
Part of a dime (10-cent coin in U.S. currency).
The face/head of Dwight D. Eisenhower appears on one side of the coin. Eisenhower was the 34th president of the United States of America.
Tech Tips
The preceding photo …
- was shot using my Fujifilm X-T3 camera and Laowa 25mm Ultra Macro lens. The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens. A single external flash unit was used to light the photo.
- is a “one-off,” meaning the photo isn’t focus-stacked. At a magnification of 2.5x the depth of field is extremely shallow. The net result is not all of the photo appears to be acceptably in focus.
- is “full frame” (6240 × 4160 pixels), meaning it is uncropped.
- is an unedited JPG file, straight out of the camera.
Copyright © 2023 Walter Sanford. All rights reserved.
Trust
February 10, 2023The following test shot shows part of a penny, that is, a one-cent coin in U.S. currency.
Part of a penny (one-cent coin in U.S. currency).
The face/head of Abraham Lincoln appears on one side of the coin. Abraham Lincoln was the 16th president of the United States of America.
Tech Tips
The preceding photo …
- was shot using my Fujifilm X-T3 camera and Laowa 25mm Ultra Macro lens. The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens. A single external flash unit was used to light the photo.
- is a “one-off,” meaning the photo isn’t focus-stacked. At a magnification of 2.5x the depth of field is extremely shallow. The net result is not all of the photo appears to be acceptably in focus.
- is “full frame” (6240 × 4160 pixels), meaning it is uncropped.
- is an unedited JPG file, straight out of the camera.
Editor’s Commentary
I have been working behind the scenes trying to figure out how to determine focus bracketing step size using a variety of macro photography gear.
Let’s just say it turns out to be far more complex than I ever imagined — every time I feel I’ve made a breakthrough in understanding, I experience some sort of setback and I’m back where I started.
Those who know me well know I won’t give up until I figure it out. In the meantime, I thought you might like to know what’s going on. I’m hoping to share a “Eureka!” discovery soon.
Copyright © 2023 Walter Sanford. All rights reserved.
GW revisited
February 7, 2023The following test shot shows part of a quarter, that is, a 25-cent coin in U.S. currency. I took the shot when I was testing my new NiSi NM-200 manual focus rail.
Part of a quarter (25-cent coin in U.S. currency).
The face/head of George Washington appears on one side of the coin. George Washington was the first president of the United States of America.
Tech Tips
The preceding photo …
- was shot using my Fujifilm X-T3 camera and Laowa 25mm Ultra Macro lens. (I bought the Canon version of the Laowa lens. It’s mounted on my X-T3 using the X-mount adapter available from Laowa.) The lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for this lens. A single external flash unit was used to light the photo.
- is a “one-off,” meaning the photo isn’t focus-stacked. At a magnification of 2.5x the depth of field is extremely shallow. The net result is not all of the photo appears to be acceptably in focus.
- is “full frame” (6240 × 4160 pixels), meaning it is uncropped.
- is an unedited JPG file, straight out of the camera.
Copyright © 2023 Walter Sanford. All rights reserved.
Proof of concept: NiSi NM-200 manual focus rail
January 24, 2023The following focus stacked composite image was created using a Fujifilm X-T3 mirrorless digital camera and Laowa 25mm Ultra Macro lens mounted on a NiSi NM-200 manual focus rail.
Toy dinosaur at 2.5x magnification.
The Laowa lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for that lens.
The subject is a small toy dinosaur, viewed from above the anterior end of the dino. The toy is approximately 3.2 cm long (~32 mm).
The carriage of the focus rail was moved 200 µm (micrometers, also known as microns) per step, equal to 20 increments on the NiSi NM-200. A total of 28 photos were taken. A little back of the envelope math shows the carriage moved a total of 5.6 mm from beginning to end.
200 microns x 28 = 5,600 microns
5,600
micronsx 1 mm/1,000microns= 5.6 mm
The camera was set to record JPG plus RAF files. For simplicity the composite image was focus stacked in Adobe Photoshop using the JPG files straight out of the camera. The final output was slightly cropped and sharpened.
Look closely at the full size version of the composite image. I don’t see any glaring “focus banding” so the 200 micron step size seems to have worked. [See Post Update, at the end of this blog post.] As always, a sample size of one proves nothing. That said, I feel confident the NiSi NM-200 works as expected and will be a useful aid for creating macro focus stacked composite images.
Tech Tips
i used a step size of 200 microns — much larger than the 10 micron precision limit of the NiSi NM-200. My goal was to choose the largest step size that wouldn’t show “focus banding.” I’m not sure what the maximum “safe step size” is, given the settings for my photo gear, but it appears 200 microns doesn’t exceed that value.
Related Resource: “Toy dinosaur” includes a photo (shown below) that shows the entire toy. 2.5x magnification is more than it seems!
08 DEC 2020 | BoG Photo Studio | toy dinosaur
Post Update
In the preceding post I wrote “Look closely at the full size version of the composite image. I don’t see any glaring “focus banding” so the 200 micron step size seems to have worked.”
Well, someone with more experience than me in creating focus stacked composite images actually looked closely at my image, and here’s what he saw.
Annotated image used with permission from Rik Littlefield.
Rik Littlefield, creator of Zerene Stacker, noticed there is in fact a problem with focus banding in my composite image. Rik highlighted the focus bands with a series of black dots.
My decision to use a “safe step size” of 200 microns was based upon the output from a depth of field – step size calculator that I now realize is fatally flawed. Honestly I can’t remember which calculator I used, but I can tell you this — after using Rik Littlefield’s DOF Calculator to determine the safe step size for the same macro rig is 58.038 microns, I knew 200 microns must not have worked as well as I thought. And as you can see in Rik’s annotated image, a step size of 200 microns is too big. Sincere thanks to Rik for his feedback!
Copyright © 2023 Walter Sanford. All rights reserved.
Post update: Which family is it?
December 2, 2022The following odonate exuvia is from a damselfly in Suborder Zygoptera.
The overall shape of the prementum (highlighted by a red rectangle) indicates this specimen is from Family Calopterygidae (Broad-winged Damselflies). Notice the embedded raindrop shape (highlighted by a purple rectangle), located toward the upper-center of the prementum — a key field mark for this family.
Two genera from Family Calopterygidae are common in the Commonwealth of Virginia: Hetaerina; and Calopteryx. For species in Genus Calopteryx the raindrop shape (Fig. 19) looks more like a diamond shape (Fig. 18), so it’s probably safe to infer this specimen is a species in Genus Hetaerina.
Related Resources
- Which family is it? – a blog post by Walter Sanford
- Identification Manual for the Damselfly Nymphs (Zygoptera) of Florida, by Johnny S. Richardson
Post Update: Congratulations to Doug Mills, Wally Jones, and Bob Perkins for correctly identifying the family of this exuvia.
Doug and Wally looked at the shape of the prementum. Bob looked at the antennae.
The long middle segment on the antennae is the key, found only on Calopterygidae nymphs. Nymphs of the other families have antenna segments that are progressively shorter from base to tip. Source Credit: Bob Perkins.
Looking at the prementum should enable you to identify all three families; looking at antennae works for only one family.
Copyright © 2022 Walter Sanford. All rights reserved.
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