Archive for the ‘Photoshop’ Category

Alice in Telecentricity Land (plus Post Update)

August 4, 2023

In a recent blog post, I wrote …

The best advantage of a truly telecentric lens is there should be little or no “focus breathing” as the camera moves closer to/farther from the subject. Essentially that means the apparent size of the subject should remain the same. That should enable better focus stacking because the outline of the subject is constant. Source Credit: Experimenting with a telecentric lens rig (plus Post Update).

Using my clone of Rik Littlefield’s 0.8x magnification telecentric lens rig, there was little or no “focus breathing” in the test focus bracket that I created from 63 JPGs, as shown in the following slideshow.

First, a brief explanation of what is shown in the slideshow. The first frame is Photo No. 1 of 63 from the focus bracket, edited to make it black and white. The last frame in the slideshow is Photo No. 63 of 63, shown in full color.

I loaded the two photos as a stack in Photoshop. Next I changed the opacity of the last image in the slideshow to 0%, meaning the first image, now black and white, is shown completely. Then I flattened the layers and saved the output. I repeated the process, changing the opacity of the last image to 25%, 50%, 75%, and 100%. At an opacity of 100% the last image is shown completely and the first image cannot be seen.

This slideshow requires JavaScript.

Look closely at the slideshow and you might notice the subject shifts slightly to the right (from first to last slide), but nothing like the “focus breathing” that typically occurs when a non-telecentric lens is used to do focus bracketing. This means the photo composition that I saw in the first photograph is essentially the same in the last photo.

The following photo gallery features full-size versions of the same images used to create the slideshow, in order of increasing opacity.

Let’s pause to review. We know the subject should appear to be larger when the camera moves closer to the subject. But in this case, the subject appears to be the same size in both the first and last shots of the focus bracket. Why? Well, this is the point where I might be beyond the limit of my expertise but based upon my understanding of telecentricity I’d say it’s because most of the light rays that pass through the lens rig are parallel.

Things are getting curiouser and curiouser

If my [educated?] guess is true, then parallel lines in a subject should remain parallel from foreground to background.

Let’s start with a thought experiment. Think about a pair of parallel railroad tracks. Many, if not most people have noticed that railroad tracks appear to converge toward a vanishing point in the distance. The same thing happens when you photograph parallel lines. Or does it? Not when a truly telecentric lens is used to shoot the photograph! Let’s look at an example.

I didn’t have time to shoot and post process an entire focus bracket of a small plastic ruler, so I shot two quick and dirty photos near the end points of the ruler. The first photo shows the foreground; the last photo shows the background.

I could have used Photoshop to edit the images so that the vertical blue lines are aligned, but I didn’t because I decided it’s more important to show another example that illustrates lack of “focus breathing.” Plus I think it’s easy to see at a glance the lines are in fact parallel, not convergent.

Yeah, yeah — I could have and should have done a better job of posing the ruler but like I said, the photos are quick and dirty. Expediency trumps perfectionism.

Post Update

Consistent with the “quick and dirty” theme for this post, I used Apple Preview to edit the preceding photos of a small plastic ruler.

I started with the first photo. I drew a horizontal red line between two vertical blue lines on the ruler. Next, I selected and copied a small area from the bottom of the photo.

Finally, I pasted the selected/copied area from the first photo onto the second photo. As you can see the vertical blues lines are virtually the same distance apart at both ends of the ruler. Therefore my Rube Goldberg lens rig is almost perfectly telecentric.

Related Resources

Copyright © 2023 Walter Sanford. All rights reserved.

Henry Moore Sundial Sculpture

June 9, 2023

The Henry Moore Sundial Sculpture is located at Sundial Plaza alongside the Adler Planetarium & Astronomy Museum in Chicago, Illinois USA. (41° 52.006′ N latitude, 87° 36.426′ W longitude.)

Bowstring Equatorial Sundial

This type of sundial is a variety of the classic equatorial sundial, often referred to as a “bowstring equatorial sundial” because it looks somewhat similar to the “bow” in “bow & arrow.”

Remember, an equatorial sundial is a reduced model of the Earth. (More about that in a follow-up blog post.) A bowstring equatorial sundial is a “reduced equatorial sundial” — think of it as a kind of skeleton equatorial sundial.

The large red circle shown in the following annotated photo represents the Earth.

The dial plate (representing the equatorial plane) has been reduced to a semi-circular band that represents approximately one-half of the Earth’s Equator, This part of the sundial is referred to as the “equatorial band.” The equatorial band serves as the “time scale.”

Parts of a “bowstring equatorial sundial.”

The gnomon (or style) is a thin rod (the “bowstring”) representing the Earth’s axis of rotation.

The vertically-oriented “bow” represents a single meridian (line of longitude) and is referred to as the “meridian band.” The bowstring is connected to the bow at the equivalent of the Earth’s North and South Poles.

The bow is attached to a pedestal or “foot” (ped- is Latin for foot).

Time scale or time band, showing time of day.

The hour lines for the bowstring equatorial sundial are laid out on the inner surface of the equatorial band. Every hour is 1/24 of a day, or exactly 15 degrees wide. The shadow of the gnomon (or style), cast among the hour lines on the equatorial band, shows the time. The meridian band (“bow”) bisects the equatorial band (“time scale”); the 12 o’clock noon hour line is located on the time scale where the two bands intersect (since solar noon occurs when the Sun crosses the observer’s meridian). Facing north, morning times are located on the left side of the equatorial band; afternoon times are on the right.

In contrast to the classic equatorial sundial, the primary advantage of the bowstring equatorial sundial is that the style shadow is cast upon a single time scale all year long (regardless of whether the Sun is north or south of the Celestial Equator). Unlike the classic equatorial sundial, the bowstring equatorial sundial should work on the day of the equinoxes (although the author has not witnessed this firsthand).

Setting the Sundial

Similar to setting the correct time on an analog clock or wristwatch (by moving the hands of the timepiece into proper position), properly orienting an equatorial sundial will move the gnomon (or style) shadow into position so that the time scale displays the correct time of day.

The gnomon should be parallel to the Earth’s axis, inclined at an angle equal to the latitude of the observer.

41° 52.006′ N latitude.

North American Sundial Society member Fritz Stumpges is shown using a “SmartTool” to measure the angle of inclination of the gnomon (“bowstring”).

41.9 degree angle of inclination.

The dial plate/equatorial band should be parallel to the plane of the Earth’s Equator (perpendicular to the gnomon), inclined at an angle equal to the complement of the observer’s latitude — the angle that when added to the angle of the observer’s latitude equals a right angle in measure (90°). This angle is also known as the colatitude.

Colatitude 48.1 degrees.

Place the sundial on a horizontal surface; the top of the gnomon should point toward the Celestial North Pole (i.e., Polaris, the North Star). More simply, the sundial should be set so the 12 noon hour line is aligned with your local meridian.

Related Resources

Tech Tips

When I visited this sundial in 2005, I owned almost no photography gear. I used a one-time use film camera to shoot the photographs featured in this blog post. After I returned home, I had the film processed, digitized, and saved to a photo CD. The photo of the time scale/time band has a resolution of 3091 x 2048 pixels.

Copyright © 2023 Walter Sanford. All rights reserved.

TJ short stack

February 17, 2023

Just 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.

Proof of concept: NiSi NM-200 manual focus rail (plus Post Update)

January 24, 2023

The 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 microns x 1 mm/1,000 microns = 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.

Common Green Darner exuviae (male vestigial genitalia)

December 6, 2022

Male odonates in Suborder Anisoptera (Dragonflies) have two sets of sex organs: primary genitalia located on abdominal segment nine (S9); and secondary genitalia located on abdominal segments two-to-three (S2-3).

For some (but not all) species of odonate larvae/exuviae, sex is indicated by either a rudimentary ovipositor (female) or vestigial genitalia (male). These sex organs don’t look exactly the same for all species of dragonflies, but their function is identical.

The following annotated images show the male vestigial genitalia for two Common Green Darner (Anax junius) exuviae collected by Jason Avery during Summer 2022 in Calvert County, Maryland USA. All of the images show the ventral side of the exuviae.

Male No. 1

Summer 2022 | Common Green Darner (Anax junius) | exuvia (male)

Summer 2022 | Common Green Darner (Anax junius) | exuvia (male)

Male No. 2

Summer 2022 | Common Green Darner (Anax junius) | exuvia (male)

Look closely at the following image and you should notice the secondary genitalia appear to extend from S2 to S3. In this case, only the more prominent parts on S3 are labeled.

Summer 2022 | Common Green Darner (Anax junius) | exuvia (male)

Related Resources

Tech Tips

All of the preceding images were photographed by Jason Avery and annotated by Walter Sanford. Thanks to Jason for kindly sharing his photos!

Copyright © 2022 Walter Sanford. All rights reserved.

Post update: Which family is it?

December 2, 2022

The 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.

03 SEP 2022 | Powhatan County, VA USA | (exuviaventral side)

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

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.

Which family is it?

November 29, 2022

An odonate exuvia was collected by Cindy Haddon Andrews on 03 September 2022 along the James River, near the Maidens Boat Landing in Powhatan County, Virginia USA. External gills (3) indicate this specimen is from a damselfly in Suborder Zygoptera.

Pattern recognition can be used to tentatively identify damselfly larvae/exuviae to the family level: the shape of the prementum is characteristic for each of the three families found in the mid-Atlantic region of the United States of America.

Your mission, should decide to accept it, is to identify the family to which the following damselfly exuvia belongs.

03 SEP 2022 | Powhatan County, VA USA | (exuviaventral side)

The camera lens was manually focused on the prementum, located near the anterior end of the exuvia.

Here is the same photo rotated 90° clockwise.

03 SEP 2022 | Powhatan County, VA USA | (exuviaventral side)

If you think you know the family, then please leave a comment. The correct answer will be revealed in a post update.

Related Resource: How to Identify Damselfly Exuviae to Family – a photo-illustrated identification guide by Walter Sanford.

Copyright © 2022 Walter Sanford. All rights reserved.

Archilestes grandis exuvia (female)

November 25, 2022

An odonate exuvia from a Great Spreadwing damselfly (Archilestes grandis) was collected by Edgar Spalding at a small private pond in Middleton, Wisconsin USA.

SEP 2022 | Middleton, WI | Archilestes grandis (exuvia, ventral side)

External gills (3), highlighted by a blue rectangle in the following annotated image, indicate the exuvia is from a damselfly in Suborder Zygoptera.

The camera lens was manually focused on the prementum, located near the anterior end of the exuvia (highlighted by a red rectangle). The overall shape of the prementum indicates this specimen is from Family Lestidae (Spreadwings); the unique shape of the palpal lobes (highlighted by a purple rectangle) indicates Genus Archilestes.

There are two species in Genus Archilestes in North AmericaArchilestes californicus; and Archilestes grandis. I think it’s reasonable to infer this individual is A. grandis since Wisconsin is far out of range for A. californicus.

SEP 2022 | Middleton, WI | Archilestes grandis (exuvia, ventral side)

This individual is a female, as indicated by the rudimentary ovipositor located on the ventral side of its abdomen, near the posterior end (highlighted by a green rectangle in the preceding annotated image).

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Theory into practice

November 4, 2022

What is the “neighborhood play” in baseball?

The “neighborhood play” is a colloquial term used to describe the leeway granted to middle infielders with regards to touching second base while in the process of turning a ground-ball double play. Though it is not explicitly mentioned in the rulebook, middle infielders were long able to record an out on the double-play pivot simply by being in the proximity — or neighborhood — of the second-base bag. Source Credit: Neighborhood Play, MLB Glossary.

And so it is with the 3-D printed plastic “lens” adapter I bought recently for my Fujifilm X Series cameras. The lens adapter, assembled so that it includes all three pieces (photo credit: Nicholas Sherlock Photography), puts a 4x magnification microscope objective in the neighborhood of where it should be for optimal performance.

Naturally I was curious to know exactly where the microscope objective should be mounted  and whether the “lens” actually performs better at that distance.

Theory

I consulted the experts at amateurmicrography.net and asked for guidance specifically for my Fujifilm X-Series mirrorless digital cameras. Thanks to Mr. Rik Littlefield for his quick reply!

First, Rik referred me to an article from the Frequently Asked Questions (FAQ) forum: FAQ: How can I hook a microscope objective to my camera? In this blog post, I will refer to the following annotated image — the first one in the FAQ article.

Photo Credit: Rik Littlefield.

Let me summarize Rik’s detailed answer to my question.

Microscope objectives like the two 4x magnification microscope objectives I own and the 10x objective shown in the preceding annotated image, are designed to work with microscopes featuring a mechanical tube length of 160 mm minus 10 mm for the microscope’s eyepiece. [The microscope objective forms an image at the bottom of the microscope eyepiece, according to Allan Walls in Macro Talk #17 (~8:30).]

The difference of 150 mm (160 mm – 10 mm = 150 mm) is known as the optical tube length, and in photomicrography, is the distance the microscope objective should be mounted from the plane of the camera sensor (as shown above).

Photo Credit: B&H Photo. Fujifilm X-T5 camera (body only).

Fujifilm X Series mirrorless digital cameras have a flange focal distance (FFD) of 17.7 mm, meaning the distance between the plane of the camera sensor and the face of the lens mount on the front of the camera body is 17.7 mm (as shown above). 150 mm – 17.7 mm = 132.3 mm. 132.3 mm is the ideal mounting distance between the “lens” and the outside of the camera body.

The next photograph shows the customized 4x magnification macro rig I was able to cobble together using photography gear I had on-hand already, following Rik’s recommendations. Briefly, several extension tubes were used to mount the “crop” configuration of my 3-D printed plastic lens adapter and 4x magnification microscope objective on a Fujifilm X-T3 digital camera.

My customized 4x magnification macro rig.

Remember, my goal was to move the microscope objective 132.3 mm from the face of the camera body. I combined two 16mm extension tubes and one 10mm extension tube (42 mm total) with the “crop” configuration of the plastic lens adapter (~90 mm from back to front). 42 mm + 90 mm = 132 mm. That’s “good enough for government work” as we say in Washington, D.C.

In contrast, the full size 3-D printed plastic lens adapter moves the microscope objective 142 mm from the face of the camera body — in the neighborhood but a little farther than it should be.

Gear I used

The following equipment list includes all items mounted on the Fujifilm X-T3 camera body shown in the preceding photo.

Finally, a few words about extension tubes designed for Fujifilm X Mount cameras.

Fujifilm makes two extension tubes, as of this writing: the MCEX-11; and MCEX-16. I bought both the 11mm and 16mm extension tubes, although in retrospect, the 11mm is the only one I recommend buying (based upon my usage). It’s good to have found a purpose for the MCEX-16.

When I bought my Fujifilm X-T1 camera more than 10 years ago, Fujifilm didn’t offer extension tubes for sale. “Fotasy” was the first third-party company to sell extension tubes with electronic contacts for Fujifilm X Mount cameras. I bought both sizes that were available (10mm and 16mm) and they worked well, that is until Fujifilm released their proprietary extension tubes — at that point the Fotasy extension tubes were incompatible with newer lenses sold by Fujifilm. Although my older Fotasy extension tubes don’t work with newer Fujifilm lenses, they are perfect in this case because my customized 4x magnification macro rig is all manual all the time.

Gear that could be used (instead of my rig)

What if you don’t have a “junk drawer” of old, unused camera gear like me? Rik Littlefield recommended the following items that could be used for mounting a 4x microscope objective on a Fujifilm X Series camera.

Theory into practice

My customized 4x magnification macro rig was used to photograph a small part of a dime, that is, a 10-cent coin in U.S. currency.

All three photos …

  • were shot handheld (not recommended for this camera rig). A single external flash unit was used to light each photo.
  • are “one-offs,” meaning they aren’t focus-stacked. At a magnification of 4x the depth of field is extremely shallow. The net result is relatively little of each photo appears to be acceptably in focus.
  • are “full frame” (6240 × 4160 pixels), meaning they are uncropped.

For scale, the letters “DIM” are approximately 5 mm wide on the actual coin.

A small part of a dime (10-cent coin in U.S. currency).

A small part of a dime (10-cent coin in U.S. currency).

A small part of a dime (10-cent coin in U.S. currency).

Are these photos better than the test shots I took when I first got the 3-D printed plastic lens adapter? You be the judge, but I think they are qualitatively better.

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Rube Goldberg 2.75x macro photography rig

October 28, 2022

My Rube Goldberg 4-5x macro photography rig can be configured as both a 2.75x and 4-5x magnification macro photography rig. This blog post will focus on the 2.75x configuration.

The first two photos show the 3-D printed plastic lens adapter with the middle segment removed. A Reakway 4-5x microscope objective is screwed into the front of the adapter and the adapter/”lens” combo is mounted on my Fujifilm X-T3 mirrorless camera.

Photo focused on body of Fujifilm X-T3 mirrorless camera.

Photo focused on Reakway 4-5x microscope objective.

A recent blog post featured handheld test shots using the macro rig configured for 4-5x magnification. One of those shots shows the word “Liberty” on a penny, that is, a 1-cent coin in U.S. currency. Remember, the actual size of the word on the coin is approximately 5 mm in length.

A copper penny photographed at 4-5x magnification.

The same penny was photographed at 2.75x using the “crop” configuration of the lens adapter. The camera was handheld, like the 4-5x test shot shown above. Notice how much more of the coin is visible at 2.75x versus 4-5x magnification.

A copper penny photographed at 2.75x magnification.

The last image is a focus-stacked composite of four photos that were shot with the camera mounted on a tripod.

Focus-stacked composite image of four photos at 2.75 magnification.

What are the take-aways?

I own two macro lenses capable of 1-5x magnification: a Canon MP-E 65mm macro lens; and a Laowa 25mm Ultra Macro lens.

The current retail price of the Canon MP-E 65mm macro lens is $1,049.00. It weighs 1.56 pounds (710 g).

The current retail price of the Laowa 25mm Ultra Macro lens is $399.00. The Laowa macro lens is noticeably smaller and lighter than the Canon MP-E 65mm. It weighs 14.11 ounces (400 g).

The 4x microscope objectives from AmScope and Reakway cost ~$25.00 each. (Remember, you need to buy only one objective.) The weight of the “lenses” isn’t listed in their specifications, but they are relatively lightweight. The 3-D printed plastic lens adapter cost $50.00 including $35.00 for the adapter itself and $15.00 handling and shipping from New Zealand. The plastic adapter feels nearly weightless.

For me, the single biggest take-away is for ~$75 I was able to buy an extreme macro photo rig that takes photos that are as good or better quality than comparable macro lenses that cost hundreds of dollars more!

And as a big fan of lightweight camera gear for use in the field, I’m far more likely to carry one of the Rube Goldberg rigs with me than either of its bigger and heavier counterparts.

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.