Alice in Telecentricity Land (plus Post Update)

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.

0%

25%

50%

75%

100%

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

• Experimenting with a telecentric lens rig (plus Post Update)
• Telecentric lens rig revisited
• Telecentric combo at 0.8x to 1.69x, by Rik Littlefield – root of a long thread on photomacrography.net

Copyright © 2023 Walter Sanford. All rights reserved.

Telecentric lens rig revisited

The following composite images show the results of my first test using a new telecentric lens rig, cloned from a similar rig designed by Rik Littlefield.

Helicon Focus was used to focus stack 63 “as is” JPGs from my Fujifilm X-T3 mirrorless digital camera (focused on the head only). “As is” is a descriptor that I use often in my photoblog, but that doesn’t mean the images weren’t edited — rather it means the JPGs were edited in camera using one of the Fujifilm film simulations (PROVIA / STANDARD).

63 JPGs | Helicon Focus | Rendering Method B

In my limited experience using Helicon Focus, rendering Method C seems to work better than Method B. (For what it’s worth, rendering Method A never produces good results for me.) In this case, I can’t see a clear difference in the quality of the output. Do you think one version looks better than the other?

63 JPGs | Helicon Focus | Rendering Method C

Look closely at the full-size versions of the preceding composite images and I think you will agree with me that the image quality is excellent!

Tech Tips

In a recent blog post, I wrote …

Rik [Littlefield] developed another telecentric lens rig that results in lower magnification (0.8x versus 1.69x) but better image quality. I need to order some inexpensive parts before I can build and test that rig. Source Credit: Experimenting with a telecentric lens rig (plus Post Update).

The last part I needed was delivered a few days ago, and much to my amazement all of the parts fit together! (See parts list, below.)

I used my Apple iPad mini 6 to shoot the following quick-and-dirty photos of the new telecentric lens rig.

Here’s a parts list (shown from left-to-right in the preceding photos).

• Fujifilm X-T3 (APS-C) mirrorless digital camera [not shown]
• Fringer EF-FX Pro II
• [1] Canon EF 100mm f/2.8 Macro lens
• [2] 67mm to 52mm step-down ring
• [3] M52-M42 step-down ring
• [4] Fotasy M42-M42 helicoid [15-26 mm long (11 mm travel).]
• [5] M42 tube (7 mm long) [WeMacro 42mm tube set: 7, 14, 28 mm long.]
• [6] 42mm to 52mm step-up ring
• [7] 52mm-43mm step-down ring
• [8] Raynox DCR-250 close-up filter (43mm thread)

Notice the focus ring on my Canon Macro lens is set for infinity [highlighted by a green rectangle]. The distance between the front of the Canon lens and front of the Raynox close-up filter is ~54 mm, based upon guidance from Rik Littlefield.

With the Canon Macro lens set for infinity, the parts in front of the Canon lens work together with the lens to make it telecentric. Adding the Fringer adapter has no effect on the telecentricity of the Canon lens — it’s only used to enable my Canon lens to work with the Fujifilm X-T3 camera.

Safe step size

I used Rik Littlefield’s excellent DOF Calculator plus personal guidance from Rik to determine the safe step size to use for focus bracketing with the new telecentric lens rig.

My input is highlighted by a red rectangle; the calculator output is highlighted in green.

Notice I input a 20% step overlap (0.2) to be sure there was no “focus banding.” The calculator suggested a step size of 0.17589 mm. That’s equivalent to 175.89 µm (micrometers).

Since the smallest increment on my NiSi NM-200 manual focus rail is 10 µm, I divided 175.89 by 10 in order to determine the number of increments to turn the larger adjustment knob on the NM-200. The answer is 17.589 increments. For simplicity and safety, I turned the knob 15 increments between shots.

Copyright © 2023 Walter Sanford. All rights reserved.

Experimenting with a telecentric lens rig (plus Post Update)

I’ve been experimenting with a telecentric lens rig. My rig is cloned from a similar one created by Rik Littlefield, using gear I already own.

I’m guessing you’re thinking “What is a telecentric lens?” The honest answer is “I don’t know.” I’m not sure I’ll ever understand what telecentric lenses are and how they work. I’m hoping practical experience will result in better understanding of the theoretical.

So why have I written a blog post about a topic I don’t really understand? Good question! The simple answer is because I have learned enough, mostly from Rik Littlefield, to know there are practical advantages to using a telecentric lens for macro photography.

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.

My Rube Goldberg telecentric lens rig

Rik Littlefield’s telecentric lens rig features the same gear as mine (described in the next paragraph) minus the Canon-to-Fujifilm lens adapter because he uses a Canon EOS Rebel T1i DSLR camera body with his rig.

My Rube Goldberg telecentric lens rig is cobbled together using a Raynox DCR-250 close-up filter attached to my Canon EF 100mm macro lens using the plastic clip-on adapter supplied by Raynox. The lens assembly is mounted on my Fujifilm X-T3 APS-C digital camera using a Fringer EF-FX Pro II adapter.

Rik developed another telecentric lens rig that results in lower magnification (0.8x versus 1.69x) but better image quality. I need to order some inexpensive parts before I can build and test that rig.

Testing 1, 2, 3.

The following closely-cropped composite image shows the result of my first test of the telecentric lens rig.

I shot 57 images of a toy plastic lizard using my NiSi NM-200 manual focus rail. I used an aperture of f/8 and a step-size of 100 microns, as recommended by Rik Littlefield.

Helcion Focus Method B was used to focus stack the “as is” JPGs from my camera. The resulting TIF file was cropped using Apple “Preview” — that’s about as quick and dirty as cropping gets!

Post Update

The first time I heard about telecentric lenses is when Allan Walls teased the topic during one of his YouTube live-streams. During a subsequent live-stream, Allan demonstrated how to make a lens telecentric using a rig similar to one that Rik Littlefield created.

Telecentric Lenses – Macro Talk Too – from Allan Walls Photography, June 29, 2023 (1:12:10)

Allan’s YouTube live-streams are one hour in duration, but there’s usually a lot of chit-chat during a typical live-stream that might not interest readers of my blog.

In this case, I recommend that you watch the segment from 11:22 to 30:21. A lot of what I have learned about telecentric lenses from Rik Littlefield and Allan Walls is covered during that part of the video. (If you continue watching the video beyond the 30:21 mark, then you will hear my name mentioned twice.)

Copyright © 2023 Walter Sanford. All rights reserved.

L-bracket for Fujifilm X-T5

In a recent blog post, I said …

l use Arca Swiss L-brackets for all of my cameras. Good L-brackets are designed so the bracket doesn’t block any camera doors or ports. But I don’t have one for the [Fujifilm] X-T5 because it’s new enough that the selection of compatible L-brackets is poor. Source Credit: Walter Sanford, Comedy of Errors.

My urgent need for an L-bracket trumped my anxiety about ordering one from AliExpress in China. I decided to buy an L-bracket for my X-T5 from the “GoGlory Store.” US $27.55 plus free shipping helped to incentivize me. I placed my order on 12 March 2023; it was delivered on 20 March. Shipment from China to the east coast of the United States in eight (8) days was a pleasant surprise!

The L-bracket is well-made and fits my Fujifilm X-T5 perfectly without extending the vertical rail (as shown in the top photo, below).

Photo Credit: “GoGlory Store.”

The bracket comes with two Allen wrenches: a larger wrench (shown above); and a smaller one. The “GoGlory Store” Web page says the Allen wrenches are magnetic; they aren’t. Look closely at the full-size version of the preceding photos. Notice two small silver circles on the bottom of the horizontal rail — those are magnets in a groove that fits the larger Allen wrench.

The larger wrench is used to tighten/un-tighten a larger bolt that connects the L-bracket to the 1/4″-20 threaded tripod socket of your camera. The same bolt has a groove for a flat-head screwdriver.

The larger Allen wrench is also used to tighten/un-tighten a slightly smaller bolt that enables you to extend/contract the length of the L-bracket. That bolt does not have a groove for a screwdriver.

The smaller Allen wrench is used for two small bolts that enable you to remove the vertical rail completely.

Battery-chamber door

The following photo shows the L-bracket mounted on my Fujifilm X-T5; the opening in the horizontal rail enables the camera battery-chamber door to open/close freely without removing the L-bracket.

L-bracket, showing opening for camera battery-chamber door.

Camera Connectors (side doors)

The next photo shows the vertical rail of the L-bracket and the left side of my camera. The large cut-out in the L-bracket enables easy access to two small doors on the left side of the camera, and doesn’t block the built-in speaker. Both doors to the camera connectors are open in the following photo.

L-bracket, showing cut-out for camera connectors (side doors).

The vertical rail features four 1/4″-20 threaded sockets (taps) for mounting camera accessories.

What are the take-aways?

During limited testing, I am completely satisfied with the L-bracket I bought from AliExpress. Really, how often do you hear me say that about camera gear? A well-made product that does what it’s supposed to do, all for a good price plus free shipping — what’s not to like?

Copyright © 2023 Walter Sanford. All rights reserved.

Comedy of errors

My first big focus stack turned out to be a comedy of errors. Lots of little things, all of them avoidable, but the one that broke the stack was when the camera battery died approximately two-thirds of the way through the project.

My new Fujifilm X-T5 has a much larger battery than my Fujifilm X-T3 so I never imagined it wouldn’t last long enough to create the stack.

I might have been able to salvage the stack by changing the battery without removing the camera from the focus rail, but the Manfrotto quick release plate partially blocked the battery door. Doh!

l use Arca Swiss L-brackets for all of my cameras. Good L-brackets are designed so the bracket doesn’t block any camera doors or ports. But I don’t have one for the X-T5 because it’s new enough that the selection of compatible L-brackets is poor.

I have two ways to provide continuous power for the X-T5 but I couldn’t use them because the battery door was partially blocked. Double doh!

Making lemonade from lemons

Long story short I used Helicon Focus to stack all the photos up until the power failure and the results look fairly good, as shown below. Oh what might have been. Triple doh!

ISO 400 | 80mm | 0 ev | f/8 | 1/250 s

The preceding composite image was created from 192 of 328 photos. I used a safe step size of 50 µm (microns) between photos. Each JPG photo is ~13 MB, 7728 × 5152 pixels.

The coin is acceptably in focus from the top of the coin to a point about two-thirds of the way toward the bottom. Zoom in on the horse’s head and you should notice sharp focus is lost beginning below its eye.

The amount of detail in the composite image is astounding, as shown in the close-up of the upper-right quadrant.

Close-up, upper-right quadrant.

Related Resource: Post update on 11 April 2023.

Copyright © 2023 Walter Sanford. All rights reserved.

Post update: Which family is it?

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 | (exuvia, ventral 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.

Identification Manual for the Damselfly Nymphs of Florida, p. 13

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.

Depth of field

Once a teacher, always a teacher. I guess that’s the reason I like to create and share blog posts that relate to things I’ve learned about photography. Such as depth of field.

Depth of field, more specifically shallow depth of field, is the reason many macro photographers like to do focus bracketing and focus stacking.

In order to demonstrate shallow depth of field, I arranged the same three studio “models” (used in my last blog post) in a way that would be impossible for the camera to capture all three subjects in focus. For what it’s worth, the distance between the closest and farthest model was approximately six inches.

To add to the challenge, I changed the aperture from f/7.1 to f/5.6 — that’s closer to the “sweet spot” of f/4 for the lens in my Panasonic Lumix DMC-FZ300, but the depth of field at f/5.6 is shallower than f/7.1. How shallow is it? (Queue Johnny Carson.) For the answer, I turned to my favorite online “Depth of Field Calculator.”

Notice I selected “Panasonic Lumix DMC-FZ150” as the camera. That’s because the FZ300 isn’t on the long list of cameras supported by the calculator. No problem. I own both the FZ150 and FZ300 and I can tell you they are virtually identical in every significant way.

My camera was mounted on a tripod so that the front of the lens was approximately five inches from the closest subject. The focal length (mm) of the lens was derived from the EXIF info for one of the three photos shown below.

Depth of Field Calculator

Look at the calculator output, highlighted by the red rectangle in the preceding screen capture. Notice the total depth of field is 0.24 inches — that’s only around 1/4 inch! There’s NO WAY all three subjects can be acceptably in focus using my FZ300 and the camera settings I selected.

Post Focus

I used Panasonic “Post Focus” to capture the scene. This time, I used “Post Focus” to select different focus points after the shot was taken. During playback, I selected three focus points, one at a time, and saved the following JPG files.

For the first photo, I selected a focus point on the toy monkey. Notice the orange dinosaur in the background is clearly out of focus. Wait, did I really just say that? Yeah, go with it — you know what I mean.

Focus point on nearest subject.

For the next photo, I selected a focus point on the green dinosaur. I don’t know whether I’d call the other two subjects “acceptably in focus” but I know they aren’t tack sharp.

Focus point on middle subject.

For the last photo, I selected a focus point on the orange dinosaur. Notice the toy monkey in the foreground is out of focus.

Focus point on farthest subject.

So there it is — if you would like all three subjects to be in focus then focus bracketing / focus stacking is the only way to go.

My last blog post, entitled “Focus bracketing using Panasonic “Post Focus,” explains how Panasonic “Post Focus” can be used with Adobe Photoshop to do focus bracketing and focus stacking.

Related Resources

• How to use the Post Focus / Focus Stacking feature. [An article from Panasonic.]
• Experience 4K Post Focus in Panasonic LUMIX Cameras – Presented by LUMIX Luminary Photo Joseph, by Panasonic North America (4:33)
• Panasonic FZ80/82 Digital Zoom, 4K Post Focus and Manual Focus, by Graham Houghton (15:16) [The segment related to “Post Focus” begins at ~8:22.]

Copyright © 2022 Walter Sanford. All rights reserved.

Sample photos: Fringer EF-FX Pro II lens mount adapter

Oh look, it’s the “Made in the shade” monkey and Buzz Lightyear — two of my favorite studio models! Whenever I need to test new photography gear and/or techniques, they are always willing to help.

As promised in my last blog post, here are a couple of sample photos taken with my Canon EF 100mm macro lens mounted on a Fujifilm X-T3 digital camera body using a Fringer EF-FX Pro II lens mount adapter.

Single point focus was used for both photos. For the first photo, the focus point was located on the monkey’s right eye (bottom eye, relative to the photo). The real world size of the toy monkey is ~4.8 cm long.

“Made in the shade” monkey toy.

The Canon lens is controlled by the Fujifilm digital camera via the Fringer adapter. EXIF information (shown below) is available for each photo. As you can see, the photos in this set were taken using an aperture of f/5.6 and a shutter speed of 1/250 s, the default sync speed for the X-T3.

The “sweet spot” for the Canon EF 100mm macro lens is either f/5.6 or f/8. The depth of field is shallower at f/5.6 than f/8, but I thought the former might be a better test for sharpness than the latter.

Apple Preview | Inspector

Buzz Lightyear reporting for duty, sir. I don’t remember exactly where the focus point was located, but it was probably somewhere near Buzz’s face/head.

Buzz Lightyear plastic toy.

Regular readers of my blog might be happy to know Buzz will be back again for my next blog post.

What are the take-ways?

As you can see, my Canon macro lens works well with the Fujifilm camera. Does it perform better than my Fujinon 80mm macro lens? It’s too early to tell.

The APS-C sensor inside the Fujifilm X-T3 digital camera has a crop factor of 1.5x, so the Canon EF 100mm macro lens has a focal length of 150mm (35mm equivalent) when mounted on an X-T3. The net result is an increase in apparent magnification.

Some of the advantages of mounting the Canon lens on a Fujifim digital camera (rather than my older Canon DSLR camera) are really about features available on the X-T3 that enable me to get more from the same lens.

For example, there are only nine (9) focus points on my Canon EOS 5D Mark II; the Fujifilm X-T3 can be set for either 117 or 425.

The Canon EOS 5D Mark II doesn’t feature focus peaking; the Fujifilm X-T3 does. Focus peaking is a useful aid for focusing the Canon lens manually. More about this topic in my next blog post.

And of course, don’t forget that all of my Canon lenses (including several L-series lenses) can be used with my Fujifilm cameras via the Fringer adapter. I’m especially looking forward to testing the Fringer adapter with my Canon MP-E 65mm Macro lens.

In summary, the Canon/Fringer/Fujifilm rig works as expected. During limited testing, I discovered something that doesn’t work. (Again, more about this topic in an upcoming blog post.) The problem isn’t a deal-breaker and it should be something that can be fixed in a firmware update of the Fringer adapter. Editor’s Note: I just contacted Fringer as of this writing. I’m interested to see whether they are receptive to customer suggestions for improvement. I’ll update this post to include their response. Post Update: Fringer replied to my message promptly. Details in an upcoming blog post.

Related Resources

• How to Find Your Lens’s Sharpest Aperture or Sweet Spot, by Todd Vorenkamp for B&H Photo “Explora.”
• Depth of Field, DOFMaster.

Copyright © 2022 Walter Sanford. All rights reserved.

Blog posts related to instar

A while ago I created a series of single-topic blog posts related to instar. I just converted the Web versions of those blog posts to PDFs (Portable Document Format).

The PDF version of each blog post is available in two “flavors”: an interactive version (with Internet access), meaning the embedded hyperlinks work as expected; and a non-interactive version. Both versions are ad-free.

• “How to estimate instar”: Web version; interactive PDF version, Apple macOS and “Safari” (119 KB); non-interactive PDF version, Apple iOS and “Safari” (533 KB).
• “How to estimate instar, revisited”: Web version; interactive PDF version, Apple macOS and “Safari” (474 KB); non-interactive PDF version, Apple iOS and “Safari” (2.5 MB).
• “How to estimate instar using Photopea”: Web version; interactive PDF version, Apple macOS and “Safari” (154 KB); non-interactive PDF version, Apple iOS and “Safari” (308 KB).
• “Determining final instar the Cham way”: Web version; interactive PDF version, Apple macOS and “Safari” (195 KB); non-interactive PDF version, Apple iOS and “Safari” (1.3 MB).

Related Resources

• How to convert a Web page to PDF – a blog post by Walter Sanford
• Another way to convert a Web page to PDF – another blog post by Walter Sanford

Copyright © 2022 Walter Sanford. All rights reserved.

How to convert a Web page to PDF

It’s possible to save a Web page as a PDF (Portable Document Format). Print-to-PDF, rather than print to an external printer, is a feature of many Web browsers that works well in some cases.

For example, when I pay bills online I use print-to-PDF to make electronic copies of the payment receipts from my bank.

In contrast, print-to-PDF might not work well when printing a blog post with embedded advertisements.

I tested print-to-PDF using Google “Chrome” and Mozilla “Firefox” to save a few of the posts from my photoblog. The results looked bad. I had to find a better solution.

That’s when I discovered Apple “Safari” can be used to convert Web pages to PDFs that look fairly good. Some of the Web page formatting might be lost but the PDFs are ad-free and interactive (with Internet access) — that’s win-win! Here’s how it works.

How to use Apple Safari to convert a Web page to PDF

A computer running Apple macOS is required. Step-by-step directions are as follows.

1. Launch Apple “Safari.”
2. Open a Web page in Safari.
3. Select View / Show Reader
4. Select File / Export as PDF…
5. Click the <Save> button.

The “Reader” view in Safari displays text and graphics only; advertisements are not shown.

For example, I used Safari to create a PDF version of “Collecting odonate exuviae,” one of my recent blog posts. The following graphic shows a screenshot of the first page from the PDF. A link to the entire PDF is provided in the image caption.

(See complete PDF version of “Collecting odonate exuviae.”)

Buoyed by success, I used Safari to create a PDF version of “Hunting spiketail dragonflies in Virginia,” another one of my recent blog posts. The following graphic shows a screenshot of the first page from the PDF.

(See complete PDF version of “Hunting spiketail dragonflies in Virginia.”)

If you compare/contrast the Web version with the PDF version of both blog posts, then you will see the PDF version isn’t a perfect copy of the Web version. Some PDFs will look better than others.

How to use Apple Preview to “mask” unwanted content

Some minor clean-up of the PDF output might be necessary, depending upon the Web page. Here’s how I use Apple “Preview” to “mask” unwanted content.

1. Launch Apple “Preview.”
2. Select View / Show Markup Toolbar
3. Set the border color to White. Set the fill color to White. [See the larger red rectangle that highlights these two settings, as shown in the following screen grab.]
4. To add a new all-white shape, click the Shapes icon and select the rectangle shape; click-and-drag to reposition and resize the rectangle, as necessary. [See the smaller red rectangle that highlights this setting, below.]

Screen grab showing Apple “Preview.”

In case you’re confused by what is shown in the preceding screenshot, notice you can see two iterations of the “Markup Toolbar”: the upper version is the one used to add the red rectangles to the document that appears in the “floating” window; the lower version is the one used to create three white rectangles that were placed over content that I wanted to mask. You can’t see those white rectangles but they are there.

Related Resources

• “Collecting odonate exuviae”: Web version; PDF version, Apple macOS and “Safari” (360 KB).
• “Hunting spiketail dragonflies in Virginia”: Web version; PDF version, Apple macOS and “Safari” (236 KB).

Copyright © 2022 Walter Sanford. All rights reserved.