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.

Connections

I’m not as dumb as I look, you know. (I have a face for blogging, not vlogging.) But I am a little slow sometimes. For example, I was slow to make the connection between the size and shape of two lens adapters I own.

When I bought the Laowa 25mm f/2.8 2.5-5X Ultra Macro lens for Canon EOS cameras, I also bought a Laowa Lens Mount Adapter for Canon EF lenses to Fuji X Series cameras. I remember thinking the adapter is oddly shaped and wondered why it wasn’t designed to be shorter/thinner.

That was before I purchased the Fringer EF-FX Pro II lens mount adapter (Canon EF lenses – Fuji X Series cameras).

The following photo shows two Canon EF to Fujifilm X Series lens adapters: the Laowa EOS-FX (shown left); and the Fringer EF-FX Pro II (shown right).

Canon EF to Fujifilm X-Series lens adapters.

Notice the two lens adapters are the same diameter and thickness (26.3 mm): the former is due to the Canon EF mount (top) and Fujifilm X Mount (bottom); the latter is due to something called flange focal distance (FFD).

The 17.7 mm FFD of my Fujifilm X Series digital cameras combines with the 26.3 mm thickness of the lens adapters (shown above), resulting in an FFD of 44 mm — exactly the right FFD for Canon lenses to work properly on a Fujiflm X Series camera body!

The Backstory

The Laowa lens adapter is manual; the Fringer lens adapter is automatic. The former doesn’t feature electronic contacts that enable auto focus, etc.; the latter does.

Soon after I bought the Laowa lens adapter I used it to mount a Canon EF 100mm macro lens on my Fujifilm X-T3 camera. Although the adapter worked to connect the lens and camera, the experiment was a failure because the Canon macro lens doesn’t have a ring for setting aperture manually, and the Laowa lens adapter doesn’t have electronic contacts that enable a camera to set the aperture of the lens. Same problem with my Canon MP-E 65mm macro lens.

Enter the Fringer lens adapter.

Copyright © 2022 Walter Sanford. All rights reserved.

Fujifilm/Fringer/Canon MP-E 65mm macro lens

In a recent blog post I mentioned that I was looking forward to testing the Fringer EF-FX Pro II lens mount adapter with my Canon MP-E 65mm Macro lens.

The MP-E 65mm doesn’t have a ring for focusing on the subject — you set the magnification ratio (from 1x to 5x) and move the camera/lens rig back and forth until the subject is in focus. For all photos, I focused on one eye of the model.

Dimetron

The first studio model is a toy Dimetron, photographed at a magnification ratio of 1:1. The toy is ~3.6 cm (~36 mm) long. The size of the APS-C sensor in the Fujifilm X-T3 is 23.5 mm x 15.6 mm. At 1x magnification, the entire length of the toy doesn’t fit on screen.

Dimetron toy | 1:1 magnification | 1/16 flash power ratio

With the camera/lens set for the same f/stop, shutter speed, and ISO (f/5.6, 1/250 s, and 400, respectively), less light reached the sensor when the magnification ratio was increased from 1:1 to 2:1. So I increased the flash power ratio by one stop, from 1/16 power to 1/8 power.

Dimetron toy | 2:1 magnification | 1/8 flash power ratio

Triceratops

The last studio model is a toy Triceratops, photographed at a magnification ratio of 1:1. The toy is ~4.3 cm (~43 mm) long.

Triceratops toy | 1x magnification | 1/16 flash power ratio

As with the first model, when the magnification ratio was increased from 1:1 to 2:1 it was necessary to increase the flash power ratio by one stop.

Triceratops toy | 2x magnification | 1/8 flash power ratio

Gear Talk

The Fringer EF-FX Pro II lens mount adapter enables one to mount Canon lenses on Fujifilm X-Series digital cameras. As you can see, my Canon MP-E 65mm macro lens works well with the Fujifilm X-T3 camera.

The APS-C sensor inside the Fujifilm X-T3 digital camera has a crop factor of 1.5x, so the Canon MP-E 65mm macro lens has a focal length of ~98mm (35mm equivalent) when mounted on an X-T3. The net result is an increase in apparent magnification, …

Post Update Update

Just because something looks like a duck and seems to act like a duck doesn’t mean it’s a duck. And so it is with the Fringer EF-FX Pro II lens mount adapter — although it looks like an extension tube, it isn’t. Why was I deceived by its appearance? Because I didn’t understand something called “flange focal distance.”

For an interchangeable lens camera, the flange focal distance (FFD) … of a lens mount system is the distance from the mounting flange (the interlocking metal rings on the camera and the rear of the lens) to the film or image sensor plane. This value is different for different camera systems. Source Credit: Flange focal distance. Wikipedia.

For example, the FFD for Canon EF-mount is 44 mm and the FFD for Fujifilm X-mount is 17.7 mm. In order to make a Canon EF lens perform properly on a Fujifilm X-series camera body, an adapter must move the Canon lens 26.3 mm farther from the digital sensor. (44 mm – 17.7 mm = 26.3 mm)

Not surprisingly, when I remeasured the thickness of my Fringer EF-FX Pro II lens mount adapter it turns out to be closer to 26 mm than my original course estimate of 30 mm (cited below). The net result is the 17.7 mm FFD of my Fujifilm X-T3 combines with the 26.3 mm thickness of the Fringer adapter, resulting in an FFD of 44 mm — exactly the right FFD for the Canon lens to work properly on a Fujiflm X-series camera body!

It’s worth noting that “apparent magnification” is still a real thing when a camera lens designed for a “full-frame” camera is mounted on a camera with an APS-C size sensor. The image formed by the lens is exactly the same size regardless of the size of the digital sensor used to record the image, but a smaller part of the image is “seen” by an APS-C sensor than a full-frame sensor, resulting in the misperception that the image is magnified.

I hope this sets the record straight. Sincere apologies for any confusion I might have caused — I never heard of “flange focal distance” before I bought the Fringer adapter!

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[Post Update: From this point forward everything I wrote is incorrect. Is my face red, or what? I’ll explain further when I have a chance to use a desktop computer to edit this post.] … although the images appear to be magnified more than can be explained by this fact alone.

In the opinion of this author, the Fringer adapter functions like an extension tube. The adapter is ~3.0 cm (30 mm) in thickness. There aren’t any optics inside the adapter but it does move the lens 30 mm farther from the camera sensor. That, my friends, is an extension tube.

I used an online, interactive Macro Extension Tubes Calculator to estimate the effect of a 30mm extension tube on photos taken with the Canon MP-E 65mm macro lens at magnification ratios of 1:1 and 2:1. The calculator shows the magnification ratio increased from 1:1 to ~1.5:1 and 2:1 to ~2.5:1 respectively.

Macro Extension Tubes Calculator | 1:1 magnification ratio

The values for “new minimum focusing distance” are in millimeters, despite the fact that the second “m” only appears when you click an insertion point in the box and scroll to the right. The values for magnification ratio seem reasonable; the values for new minimum focusing distance, not so much.

Macro Extension Tubes Calculator | 2:1 magnification ratio

[End of segment with information that is incorrect.]

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Related Resources

Full-size photos of the preceding studio models are featured in the following blog posts. Those photos should help to give the reader a better sense of how much the subjects were magnified by the Fujifilm/Fringer/Canon MP-E 65mm macro lens rig.

• What is it? (published on 21 DEC 2020)
• What is it? It’s a toy Dimetrodon. (published on 23 DEC 2020)
• Toy dinosaur: focus-stacked composite image (published on 08 JAN 2021)
• Flange focal distance, by Wikpedia.
• Sensor Size and Magnification – correcting a common misunderstanding, by Allan Walls Photography (20:02). Fast-forward to 5:48. See also Sensor Size Matters – Part 1 (the Front Half) – A Demonstration (19:51).

Copyright © 2022 Walter Sanford. All rights reserved.

Fujifilm X-T3: Focus Peak Highlight

I like to use manual focus to shoot photographs with my Fujifilm X-T3 digital camera. Set the small dial on the front of the camera to “M.” The beauty of manual focus on Fujifilm X-series cameras is back-button auto-focus still works!

When the small dial is set for “M” both manual focusing and back-button auto-focusing can be used in combination with what Fujifilm calls “Focus Peak Highlight,” or more simply, “focus peaking.”

The following YouTube video by pal2tech explains a technique that makes it much easier to see the focus peaking.

BEST Fujifilm Manual Focus Setting, by pal2tech (6:01).

The process is simple. Set the camera to record JPG + RAF [Fujifilm’s proprietary raw format]. Select one of the black-and-white Fujifilm film simulations, e.g., ACROS. [More about Fujifilm film simulations in an upcoming blog post.]

The camera display will be black-and-white. As Chris Lee (pal2tech) explains in the preceding video, it’s much easier to see focus peaking on a black-and-white background.

JPG files saved to a memory card are black-and-white too, as shown below.

Buzz Lightyear plastic toy. [Focus Peak Highlight not shown.]

RAF files are saved in full color, as shown below.

Buzz Lightyear plastic toy.

Tech Tips

“Focus Peak Highlight” can be activated when the camera is set for manual focus mode. Using back-button focus (AF-L button) in manual mode enables one to retain full control of the exposure triangle, focus quickly, and see what’s in focus before shooting a photograph.

Fuji Back Button Focus (4:06), a YouTube video by Ashraf Jandali, provides a clear demonstration of how to use back-button focus on the Fujifilm X-T1. The same technique works with the Fujifilm X-T3.

Related Resources

• BEST Fujifilm Manual Focus Setting, by pal2tech (6:01).
• Fuji Back Button Focus, by Ashraf Jandali (4:06).
• The ultimate guide to Fuji’s Film Simulations; A DEEP dive to de-mystify one of Fuji’s best features, by Dave Etchells, Imaging Resource.

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.

What’s wrong with these pictures?

Remember “What’s wrong with this picture?” puzzles? For example, a kangaroo hidden in a tower of giraffes. That’s right, “tower” is the collective noun for a group of giraffes. So what’s wrong with the following pictures?

Nothing is “wrong” with the pictures, other than the fact that they are quick-and-dirty photos taken using my Apple iPad mini 6 camera and built-in flash. But there is something incongruous. Look closely and you should notice that a Canon lens is mounted on a Fujifilm camera body. How is that possible?

A closer view shows a Fringer EF-FX Pro II lens mount adapter located between the Canon lens and Fujifilm camera body. Net result: The Canon lens works with my Fufifilm camera just like Fujifilm/Fujinon lenses.

During limited testing, the lens worked perfectly with the camera. I plan to post some test shots in an upcoming blog post.

The Backstory

The Canon EF 100mm macro lens is one of my favorite lenses — it takes tack-sharp photos that look great! I don’t use the lens as often as I should because my Canon EOS 5D Mark II DSLR isn’t as feature-rich as relatively newer digital cameras such as my Fujifilm X-T3.

I’ve been thinking about upgrading my 5D Mark II to one of the two new Canon APS-C sensor camera models, but for now I decided to save money and buy the Fringer adapter instead. So far so good!

Related Resources

• Fringer EF-FX Pro II Lens Mount Adapter for EF- or EF-S-Mount Lens to Fujifilm X-Mount Camera (avaialable from B&H Photo)
• User’s Manual (provided by B&H Photo)
• Use Canon or Nikon Lenses with Fujifilm Cameras! by pal2tech (5:51).

Copyright © 2022 Walter Sanford. All rights reserved.